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The first electrochemical sensor application in the literature is described for the sensitive and selective determination of the selective Janus kinase (JAK)-1 inhibitor abrocitinib (ABR). ABR is approved by the U.S. Food and Drug Administration (FDA) for the treatment of atopic dermatitis. The molecularly imprinted polymer (MIP)-based sensor was designed to incorporate zinc nanoflower (ZnNFs)-graphene oxide (GO) conjugate (ZnNFs@GO), synthesized from the root methanolic extract (RME) of the species Alkanna cappadocica Boiss. et Bal. to improve the porosity and effective surface area of the glassy carbon electrode (GCE). Furthermore, the MIP structure was prepared using ABR as a template molecule, 4-aminobenzoic acid (4-ABA) as a functional monomer, and other additional components. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR) were used to characterize the surface and structure of the synthesized nanomaterial and MIP-based surface. Among the electrochemical methods, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were preferred for detailed electrochemical characterization, and differential pulse voltammetry (DPV) was preferred for all other electrochemical measurements using 5.0 mM [Fe(CN) 6 ] 3-/4- solution as the redox probe. The MIP-based sensor, which was the result of a detailed optimization phase, gave a linear response in the 1.0 × 10 -13 - 1.0 × 10 -12  M range in standard solution and serum sample. The obtained limit of detection (LOD) and limit of quantification (LOQ) values and recovery studies demonstrated the sensitivity, accuracy, and applicability of the sensor. Selectivity, the most important feature of the MIP-based sensor, was verified by imprinting factor calculations using ibrutinib, ruxolitinib, tofacitinib, zonisamide, and acetazolamide., (© 2024. The Author(s).)

In the present work we have studied photo-induced decomposition of iprodione on silica support with different additions of titanium dioxide. Both the experimental and theoretical (DFT) approaches have been applied. It was found that 16 hours visible light exposure of the samples with 0.1% and 1.0% of TiO 2 leads respectively to 48.28% and 21.05% of residual amounts of iprodione in these samples. A number of intermediates and end products were identified by means of GS-MS and LC-MS chromatography. The iprodione isomer (RP 30228) and its decay product 1-(3,5-dichlorophenyl)-5-isopropyl biuret (RP 36221) were identified among them. Our DFT calculations have revealed the detailed mechanisms of formation of the above products and the mechanism of accelerated proton-induced decomposition of iprodione molecules adsorbed on the TiO 2 surface. Also, the intra-molecular reasons for iprodione stability in acidic media were clarified together with the mechanism of hydantoin cycle opening under the action of hydroxyl anions.

An improved liquid chromatography tandem mass spectrometry method is reported for the determination of residues of captan (+tetrahydrophthalimide), captafol, folpet (+phthalimide), and iprodione in fruits and vegetables. The optimized electrospray ionization parameters (high cone gas flow, and a low desolvation temperature) did not result in degradation of target compounds, rather they provided a significant advantage over the conventional GC-MS/MS methods, which lack sensitivity and repeatability. Strategies for minimizing losses in recovery of these compounds during sample preparation included cryogenic comminution, extraction with acidified ethyl acetate or acetonitrile, and dilution of the final extract with acidified water prior to LC-MS/MS analysis. The method performance complied with the SANTE/11813/2017 guidelines, with recoveries in the range of 70-120% at the LOQ of 0.01 mg/kg across the tested matrices at various pHs. The efficiency of the method was reflected in its precision (RSDs < 10%) for incurred residues., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

In this study, we propose an improved analytical method for the multiresidue analysis of captan (plus its metabolite, tetrahydrophthalimide), folpet (plus its metabolite, phthalimide), captafol, and iprodione in cereals using liquid chromatography tandem mass spectrometry (LC-MS/MS). As captan, captafol, and folpet are easily degraded during homogenisation and extraction, samples were comminuted with liquid nitrogen, and both QuEChERS and ethyl acetate-based extraction workflows provided a satisfactory method performance. The optimised LC-MS/MS procedure with electrospray ionisation did not degrade these compounds, and offered sufficient method selectivity by resolving and minimising co-eluting matrix-derived interferences. The method also resolved the problem of non-specific mass spectra that these compounds usually produce on GC-MS analysis involving electron ionisation. The method performance was satisfactory for all 6 compounds at 0.01 mg kg -1 and higher levels of fortification, and validated as per the SANTE/11813/2017 guidelines of analytical quality control in a wide range of cereals including rice, wheat, sorghum, and corn. The method provides special advantage of simultaneous analysis of captan, and folpet along with their metabolites (tetrahydrophthalimide, and phthalimide, respectively) in combination with captafol, and iprodione in a single chromatographic run. Although iprodione is known to degrade to 3,5-dichloroaniline, since this metabolite is not a part of the residue definition, it was not included in the scope of this method. As the method demonstrates satisfactory selectivity, sensitivity, accuracy, precision, and robustness in a wide range of cereal matrices, it is recommended for regulatory testing of these compounds in cereals.

Iprodione is a fungicide widely used in viticulture in most agricultural countries. It was banned recently in the European community because of its carcinogenic and endocrine disrupting characters. In this work, a cheap analytical method able to monitor iprodione in a white wine was developed. Molecularly imprinted sol-gel polymers (MIS) specific to iprodione and using green solvents were synthesized. An experimental design having the following factors (solvent volume and crosslinker quantity) was used to prepare an optimal MIS. In terms of selectivity, the optimal MIS showed the best partition coefficient towards iprodione in a white wine containing four other competing fungicides (procymidone, pyrimethanil, azoxystrobin and iprovalicarb). A solid phase extraction method using the optimal MIS was optimized and applied to analyse iprodione in a white wine. Low detection and quantification limits were reached 11.7 and 39.1 µg/L respectively., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

This study reports the optimization of a binary dispersive liquid-liquid microextraction method for the determination of iprodione, procymidone, and chlorflurenol by gas chromatography mass spectrometry. The study was aimed at using two extraction solvents to increase the extraction efficiency of all analytes. The binary solvents recorded results higher than the mono-solvents. After examining the effects of main experimental parameters and their interactions by analysis of variance, 200 μL of binary mixture (dichloromethane and 1,2-dichloroethane), 2.5 mL of ethanol, and 15 s vortex were obtained as optimum parameters. The detection and quantification limits calculated for the analytes were found to be between 0.30-1.6 and 1.0-5.3 ng/mL, respectively. Enhancement in detection power calculated as a ratio of the binary extraction detection limit to the detection limit of direct GC-MS analysis was 105-, 214-, and 233-fold for chlorflurenol, iprodione, and procymidone, respectively. In order to check the accuracy of the developed method, recovery study was performed. Water sampled from a lake and two wastewater samples from treatment facilities were spiked at two concentrations, and the percent recovery calculated for the samples ranged between 87 and 116%. These results confirmed the suitability of the method to real samples for accurate determination of the analytes at trace levels.

A biopurification system based on the adsorption and degradation capacity of a biomixture to degrade a mixture of pesticides (atrazine, chlorpyrifos, iprodione; 50 mg kg -1 each) in repeated applications (0, 30, and 60 days) was evaluated. Tanks of 1 m 3 packed with a biomixture (ρ 0.29 g mL -1 ) with and without vegetal cover were used. The biomixture contained soil, peat, and wheat straw in a proportion 1:1:2 by volume, respectively. Pesticide concentrations, biological activities (urease, phenoloxidase, and dehydrogenase), and microbial community changes (DGGE and qPCR) were evaluated periodically. Pesticide dissipation was higher in tanks with vegetal cover (> 95%) and no variation was observed after the three applications; contrarily, pesticide dissipation decreased in the tank without vegetal cover after each application. The presence of vegetal cover decreased the half-life of pesticides by at least twice. Biological activities were in general not affected by the application and reapplication of pesticides in the same treatment; however, they exhibited some differences between tanks containing and lacking the vegetal cover. High similarity between microbial groups (actinobacteria, bacteria, and fungi) was observed, suggesting no influence ascribable to the successive pesticide applications. The number of copies of bacteria and actinobacteria remained almost constant during the assay. However, the number of copies of fungi was significantly higher in the uncontaminated tank without vegetal cover.

AICAR (5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside), is a naturally occurring substance which is part to the World Anti-Doping Agency (WADA) Prohibited List. It is claimed to improve physical performance when administered as a supplement. As for other endogenous compounds such as steroids, the gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) analysis remains an efficient tool to differentiate endogenous substances from exogenous ones. A protocol was described in the literature for the analysis of AICAR by GC-C-IRMS. The aim of the present study was to implement this protocol in our laboratory and to propose solutions to avoid the difficulties encountered. The first point discussed in this study is the derivatization step. Due to the structure of the AICAR molecule, conventional derivatization for GC-C-IRMS such as acetylation could not be applied and silylation was preferred. The improvement of the derivatives stability was achieved thanks to several derivatization conditions tested. This adjustment led to a reproducible derivatization pattern with the 3-TMS form as major derivative product. The second point discussed in this study is the diminution of extracts' background noise. Indeed, the implementation of the published protocol was not easy due to high performance liquid chromatography (HPLC) problems encountered when concentrated urine was injected into our system. Also, too many interferences in the endogenous reference compound fractions were observed. The addition of both a wash step before the HPLC purification and a HPLC purification step for the endogenous reference compound (ERC) fraction allowed us to increase the robustness of the method. This study presents the modified protocol compared to the original protocol as well as the evaluation of the whole method performances. Copyright © 2017 John Wiley & Sons, Ltd., (Copyright © 2017 John Wiley & Sons, Ltd.)

The use of biopurification systems can mitigate the effects of pesticide contamination on farms. The primary aim of this study was to evaluate the effect of pesticide dissipation on microbial communities in a pilot biopurification system. The pesticide dissipation of atrazine, chlorpyrifos and iprodione (35 mg kg -1 active ingredient [a.i.]) and biological activity were determined for 40 days. The microbial communities (bacteria, actinomycetes and fungi) were analyzed using denaturing gradient gel electrophoresis (DGGE). In general, pesticide dissipation was the highest by day 5 and reached 95%. The pesticides did not affect biological activity during the experiment. The structure of the actinomycete and bacterial communities in the rhizosphere was more stable during the evaluation than that in the communities in the control without pesticides. The rhizosphere fungal communities, detected using DGGE, showed small and transitory shifts with time. To conclude, rhizosphere microbial communities were not affected during pesticide dissipation in a pilot biopurification system.

Acadesine, 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside, commonly known as AICAR, is a naturally occurring adenosine monophosphate-activated protein kinase (AMPK) activator in many mammals, including humans and horses. AICAR has attracted considerable attention recently in the field of doping control because of a study showing the enhancement of endurance performance in unexercised or untrained mice, resulting in the term 'exercise pill'. Its use has been classified as gene doping by the World Anti-Doping Agency (WADA), and since it is endogenous, it may only be possible to control deliberate administration of AICAR to racehorses after establishment of an appropriate threshold. Herein we report our studies of AICAR in post-race equine urine and plasma samples including statistical studies of AICAR concentrations determined from 1,470 urine samples collected from thoroughbreds and standardbreds and analyzed in Australia, France, and Hong Kong. Quantification methods in equine urine and plasma using liquid chromatography-mass spectrometry were developed by the laboratories in each country. An exchange of spiked urine and plasma samples between the three countries was conducted, confirming no significant differences in the methods. However, the concentration of AICAR in plasma was found to increase upon haemolysis of whole blood samples, impeding the establishment of a suitable threshold in equine plasma. A possible urine screening cut-off at 600 ng/mL for the control of AICAR in racehorses could be considered for adoption. Application of the proposed screening cut-off to urine samples collected after intravenous administration of a small dose (2 g) of AICAR to a mare yielded a short detection time of approximately 4.5 h. Copyright © 2017 John Wiley & Sons, Ltd., (Copyright © 2017 John Wiley & Sons, Ltd.)

The aim of this study was to determine the behaviour of strobilurin and carbocyamides commonly used in chemical protection of lettuce depending on carefully selected effective microorganisms (EM) and yeast (Y). Additionally, the assessment of the chronic health risk during a 2-week experiment was performed. The statistical method for correlation of physico-chemical parameters and time of degradation for pesticides was applied. In this study, the concentration of azoxystrobin, boscalid, pyraclostrobin and iprodione using liquid chromatography-mass spectrometry (LC-MS/MS) in the matrix of lettuce plants was performed, and there was no case of concentration above maximum residues levels. Before harvest, four fungicides and their mixture with EM (1 % and 10 %) and/or yeast 5 % were applied. In our work, the mixtures of 1%EM + Y and 10%EM + Y both stimulated and inhibited the degradation of the tested active substances. Adding 10%EM to the test substances strongly inhibited the degradation of iprodione, and its concentration decreased by 30 %, and in the case of other test substances, the degradation was approximately 60 %. Moreover, the addition of yeast stimulated the distribution of pyraclostrobin and boscalid in lettuce leaves. The risk assessment for the pesticides ranged from 0.4 to 64.8 % on day 1, but after 14 days, it ranged from 0.0 to 20.9 % for children and adults, respectively. It indicated no risk of adverse effects following exposure to individual pesticides and their mixtures with EM and yeast.

Adenylosuccinate lyase (ADSL) deficiency is a rare inborn error of metabolism resulting in accumulation of metabolites including succinylaminoimidazole carboxamide riboside (SAICAr) and succinyladenosine (S-Ado) in the brain and other tissues. Patients with ADSL have progressive psychomotor retardation, neonatal seizures, global developmental delay, hypotonia, and autistic features, although variable clinical manifestations may make the initial diagnosis challenging. Two cases of the severe form of the disease are reported here: an 18-month-old boy with global developmental delay, intractable neonatal seizures, progressive cerebral atrophy, and marked hypomyelination, and a 3-month-old girl presenting with microcephaly, neonatal seizures, and marked psychomotor retardation. In both patients in vivo proton magnetic resonance spectroscopy (MRS) showed the presence of S-Ado signal at 8.3 ppm, consistent with a prior report. Interestingly, SAICAr signal was also detectable at 7.5 ppm in affected white matter, which has not been reported in vivo before. A novel splice-site mutation, c.IVS12 + 1/G > C, in the ADSL gene was identified in the second patient. Our findings confirm the utility of in vivo proton MRS in suggesting a specific diagnosis of ADSL deficiency, and also demonstrate an additional in vivo resonance (7.5 ppm) of SAICAr in the cases of severe disease., (Copyright © 2012 Wiley Periodicals, Inc.)

Field experiments were conducted in two different locations to determine the residue levels and dissipation rates of iprodione in tobacco leaves and soil. Iprodione 50% wettable powder formulation was sprayed once at 12.50 g/ha to study the dissipation behavior and three to four times at 8.33 g/ha (recommended dose) and 12.50 g/ha (1.5 times the recommended field dose) to determine the residue levels of iprodione in tobacco leaves and soil after repeated applications. Iprodione residues in both green tobacco leaves and soil dissipated to about 50% of the initial deposits after 7 days and then further dissipated to more than 90% after 35 days.The dissipation of iprodione followed first order kinetics and the calculated half-life values (T (1/2)) were 5.64-8.80 days in green tobacco leaves and 7.50-9.93 days in soil, respectively. Iprodione residue levels in flue-cured tobacco leaves 21 days after the third and fourth applications ranged from 7.61 to 40.98 mg/kg. Meanwhile, the residues detected in soil decreased to 0.010-0.117 mg/kg 21 days after the last treatment.

Background: Greenhouse tomato production is intended exclusively for fresh consumption. Typical greenhouse conditions provide a conducive environment for the development of different fungi, principally late blight and grey mould, that can destroy plants and fruits. For this reason, different fungicides with different sites of action are used in integrated pest management strategies. Famoxadone, fenamidone, fenhexamid and iprodione (fig. 1) are fungicides of difference classes with different actions that could be used to control tomato pests., Results: The QuEChERS method showed good recoveries, and the analytical method allowed good separation of the fungicides selected. Good results were obtained in terms of repeatability and intermediate precision, with a coefficient of variation of < 9.8%. The limits of determination and quantification of the method were far below the maximum residual levels (MRLs) set by the EU for these fungicides in tomatoes. The analysis of fungicide residues showed that cv. Shiren accounted for higher residue levels than cv. Caramba. The dissipation curves were similar in the two cultivars, indicating that the decrease in pesticides was not related to the tomato type., Conclusions: Care should be taken when using pesticides in greenhouse conditions, because degradation mainly affects fruit growth. The size of the tomato, in particular its surface/weight ratio, is very important for defining pesticide residues. All fungicides used showed residue levels below the MRLs at the preharvest interval., (Copyright © 2011 Society of Chemical Industry.)

A new type of low thermal mass (LTM) fast gas chromatograph (GC) was designed and operated in combination with gas chromatography mass spectrometry (GC-MS) with supersonic molecular beams (SMB), including GC-MS-MS with SMB, thereby providing a novel combination with unique capabilities. The LTM fast GC is based on a short capillary column inserted inside a stainless steel tube that is resistively heated. It is located and mounted outside the standard GC oven on its available top detector port, while the capillary column is connected as usual to the standard GC injector and supersonic molecular beam interface transfer line. This new type of fast GC-MS with SMB enables less than 1 min full range temperature programming and cooling down analysis cycle time. The operation of the fast GC-MS with SMB was explored and 1 min full analysis cycle time of a mixture of 16 hydrocarbons in the C(10)H(22) up to C(44)H(90) range was achieved. The use of 35 mL/min high column flow rate enabled the elution of C(44)H(90) in less than 45 s while the SMB interface enabled splitless acceptance of this high flow rate and the provision of dominant molecular ions. A novel compound 9-benzylazidanthracene was analyzed for its purity and a synthetic chemistry process was monitored for the optimization of the chemical reaction yield. Biodiesel was analyzed in jet fuel (by both GC-MS and GC-MS-MS) in under 1 min as 5 ppm fatty acid methyl esters. Authentic iprodion and cypermethrin pesticides were analyzed in grapes extract in both full scan mode and fast GC-MS-MS mode in under 1 min cycle time and explosive mixture including TATP, TNT and RDX was analyzed in under 1 min combined with exhibiting dominant molecular ion for TATP. Fast GC-MS with SMB is based on trading GC separation for speed of analysis while enhancing the separation power of the MS via the enhancement of the molecular ion in the electron ionization of cold molecules in the SMB. This paper further discusses several features of fast GC and fast GC-MS and the various trade-offs involved in having powerful and practical fast GC-MS., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Pesticides residues in aquatic ecosystems are an environmental concern which requires efficient analytical methods. In this study, we proposed a generic method for the quantification of 13 pesticides (azoxystrobin, clomazone, diflufenican, dimethachlor, carbendazim, iprodion, isoproturon, mesosulfuron-methyl, metazachlor, napropamid, quizalofop and thifensulfuron-methyl) in three environmental matrices. Pesticides from water were extracted using a solid phase extraction system and a single solid-liquid extraction method was optimized for sediment and fish muscle, followed by a unique analysis by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). Limits of quantification were below 5 ng L(-1) for water (except for fluroxypyr and iprodion) and ranged between 0.1 ng g(-1) and 57.7 ng g(-1) for sediments and regarding fish, were below 1 ng g(-1) for 8 molecules and were determined between 5 and 49 ng g(-1) for the 5 other compounds. This method was finally used as a new routine practice for environmental research., (Copyright © 2011 Elsevier B.V. All rights reserved.)

Identifying the use of non-approved drugs by cheating athletes has been a great challenge for doping control laboratories. This is due to the additional complexities associated with identifying relatively unknown and uncharacterized compounds and their metabolites as opposed to known and well-studied therapeutics. In 2010, the prohibited drug candidates and gene doping substances AICAR and GW1516, together with the selective androgen receptor modulator (SARM) MK-2866 were obtained by the Cologne Doping Control Laboratory from Internet suppliers and their structure, quantity, and formulation elucidated. All three compounds proved authentic as determined by liquid chromatography-high resolution/high accuracy (tandem) mass spectrometry and comparison to reference material. While AICAR was provided as a colourless powder in 100 mg aliquots, GW1516 was obtained as an orange/yellow suspension in water/glycerol (150 mg/ml), and MK-2866 (25 mg/ml) was shipped dissolved in polyethylene glycol (PEG) 300. In all cases, the quantified amounts were considerably lower than indicated on the label. The substances were delivered via courier, with packaging identifying them as containing 'amino acids' and 'green tea extract', arguably to circumvent customs control. Although all of the substances were declared 'for research only', their potential misuse in illicit performance-enhancement cannot be excluded; moreover sports drug testing authorities should be aware of the facile availability of black market copies of these drug candidates., (Copyright © 2011 John Wiley & Sons, Ltd.)

The applicability of micellar electrokinetic capillary chromatography (MEKC) for the analysis of temozolomide (TMZ) and its degradants, 3-methyl-(triazen-1-yl)imidazole-4-carboxamide (MTIC) and 5-amino-imidazole-4-carboxamide (AIC) has been studied. Using short-end injection, the analysis of TMZ and its degradants could be performed within 1.2 min. The obtained precision of migration times was better than 1.6 RSD%, and the limit of quantitation (LOQ) was 0.31-0.93 microg/mL. The therapeutic concentration of TMZ in blood samples can be determined after direct sample injection and conventional on-capillary UV detection. The proposed MEKC method was applied to study the stability of TMZ in water and serum at different pH values. It was established that the half-life of the TMZ in vitro serum at room temperature was 33 min, close to the half-life (28 min) obtained in water at pH 7.9.

Iprodione is an agricultural fungicide that is difficult to detect in foods by HPLC because it coelutes with natural compounds in the food. We previously showed that food matrix could be degraded with titanium dioxide powder (TP). Here we describe an improved method for detection of iprodione using silica gel supported titanium dioxide (SGT). To synthesize SGT, titania-sol was mixed with diethanolamine, 2-propanol, and titanium tetraisopropoxide. After titania-sol was infiltrated into the silica gel (particle diameter 4 mm), the mixture was dried and then heated. Crude basil extract containing iprodione was mixed with SGT in a quartz vial, and the vial was irradiated with a UV light to selectively decompose the matrix interfering with the iprodione determination. In HPLC chromatograms of the treated solution, the interference peak decreased 35 times faster with SGT than with TP. When SGT (11 g) was added to the extract (20 mL) of dry basil (2 g), black light irradiation for 30 min was enough to quantify iprodione. The recovery rate of iprodione was 99.1%. Thus, the photocatalytic cleanup method using SGT is effective for analyzing residual iprodione in dry basil.

A combination of fast GC with narrow-bore column and bench top quadrupole mass spectrometer (MS) detector in negative chemical ionization (NCI) mode (with methane as reagent gas) is set up and utilized for the ultratrace analysis of 25 selected pesticides. The observed pesticides, belonging to the endocrine disrupting chemicals (EDCs), were from different chemical classes. A comparative study with electron impact (EI) ionization was also carried out (both techniques in selected ion monitoring (SIM) mode). The programmed temperature vaporizer (PTV) injector in solvent vent mode and narrow-bore column (15mx0.15mm I.D.x0.15microm film of 5% diphenyl 95% dimethylsiloxane stationary phase) were used for effective and fast separation. Heptachlor (HPT) as internal standard (I.S.) was applied for the comparison of results obtained from absolute and normalized peak areas. Non-fatty food matrices were investigated. Fruit (apple - matrix-matched standards; orange, strawberry, plum - real samples) and vegetable (lettuce - real sample) extracts were prepared by a quick and effective QuEChERS sample preparation technique. Very good results were obtained for the characterization of fast GC-NCI-MS method analysing EDCs pesticides. Analyte response was linear from 0.01 to 150microgkg(-1) with the R(2) values in the range from 0.9936 to 1.0000 (calculated from absolute peak areas) and from 0.9956 to 1.0000 (calculated from peak areas normalized to HPT). Instrument limits of detection (LODs) and quantification (LOQs) were found at pgmL(-1) level and for the majority of analytes were up to three orders of magnitude lower for NCI compared to EI mode. In both ionization modes, repeatability of measurements expressed as relative standard deviation (RSDs) was less than 10% which is in very good agreement with the criterion of European Union.

Titanium dioxide was used as a photocatalyst to decompose interfering substances for a quantitative analysis of a fungicide (iprodione) in dry basil by HPLC. A quartz vial containing basil extract and titanium dioxide was irradiated with black light. The interfering substances were almost completely decomposed by 180 min of irradiation, whereas 88.3% of iprodione remained. The recovery of iprodione was 102.6% by the proposed method in basil extracts. This may have been due to different decomposition rates of the analyte and interfering substances.

A rapid method using programmed temperature vaporiser injection-low-pressure gas chromatography-high-resolution time-of-flight mass spectrometry (PTV-LP-GC-HR-TOF-MS) for the analysis of multiple pesticide residues in fruit-based baby food was developed. The fast and inexpensive buffered QuEChERS (quick, easy, cheap, effective, rugged, and safe) extraction method and "conventional" approach that employs ethyl acetate extraction followed by gel permeation chromatography (GPC) cleanup were employed for sample preparation. A PTV injector in solvent venting mode was used to reduce volume of acetonitrile and acetic acid (from the buffered QuEChERS extracts) that caused higher column bleed without their elimination. Otherwise, the time-to-digital converter would become saturated in HR-TOF-MS. For fast GC separation allowing analysis of 100 analytes within a 7 min runtime, both a high temperature programming rate and vacuum conditions in a megabore GC column were employed. The use of HR-TOF-MS allowed the unbiased identification and reliable quantification of target analytes through the application of a narrow mass window (0.02 Da) for extracting analyte ions and the availability of full spectral information even at very low levels. With only a few exceptions, the lowest calibration levels for the pesticides tested were

Two methodologies based on vibrational spectrometry--making use of Fourier transform infrared absorption (FTIR) and Raman spectrometry--were developed for iprodione determination in solid pesticide formulations. The FTIR procedure involved the extraction of iprodione by CHCl(3), and the latter determination involved measuring the peak area between 1450 and 1440 cm(-1), corrected using a horizontal baseline defined at 1481 cm(-1). FT-Raman determination was performed directly on the powdered solid products, using standard chromatography glass vials as sample cells and measuring the Raman intensity between 1003 and 993 cm(-1), with a two-point baseline correction established between 1012 and 981 cm(-1). The sensitivities obtained were 0.319 area values g mg(-1) for FTIR determination and 5.58 area values g g(-1) for FT-Raman. The repeatabilities, taken to be the relative standard deviation of five independent measurements at 1.51 mg g(-1) and 10.98% w/w concentration levels, were equal to 0.16% and 0.9% for FTIR and FT-Raman, respectively, and the limits of detection were 0.3 and 0.2% w/w (higher than those obtained for HPLC, 0.016% w/w). FTIR determination provided a sample frequency of 60 h(-1), higher than those obtained for the Raman and reference chromatography methods (25 and 8.6 h(-1), respectively). On the other hand, the new FT-Raman method eliminates reagent consumption and waste generation, and reduces the need for sample handling and the contact of operator with the pesticide. In spite of their lack of sensitivity, vibrational procedures can therefore provide viable environmentally friendly alternatives to laborious, time- and solvent-consuming reference chromatography methods for quality control in commercially available pesticide formulations.

This work reports on the fundamental characteristics of a commercial enzyme-linked immunosorbent assay (ELISA) for iprodione and the application to residue analysis in agricultural samples. The ELISA had enough analytical sensitivity (I50 value 4.0 ng g(-1); limit of detection 0.3 ng g(-1)) to determine a trace of iprodione residue and had a high selectivity. Only administering simple dilution of sample extracts very easily surmounted the most troublesome matrix interference in ELISA for pesticide residue analysis. Consequently, a rapid and simple detection method for iprodione was reached by the combination of the sample dilution and the devised extraction method in which it required no instruments for extraction. The average recovery values from spiked samples with the ELISA were between 106.4 and 115.8% with the average coefficients of variation between 3.0 and 4.0%. The results obtained with the ELISA correlated well with those by the reference chromatographic method for all tested agricultural samples (r>0.993). These findings strongly indicate that the proposed ELISA was an adequate and reliable detection method for iprodione residues.

The aim of this paper was to present occurrence of pesticide residues in raspberries in 2000-2005. Gas chromatographic and spectroscopy methods were used. The most frequently found were tolylfluanid residues (43% of the analysed samples), procymidone residues (33%), pyrimethanil residues (15%), ethylenebisdithiocarbamates (EBDC) residues (8%) and iprodione residues (5%), while insecticides (mainly synthetic pyrethroids) cypermethrin residues (6%) and bifenthrin (4%). In 8 % of analysed samples EBDC residues exceeded the national Maximum Residue Level established for raspberries. On relatively the highest level EBDC occurred.

Traditionally, the screening of unknown pesticides in food has been accomplished by GC/MS methods using conventional library-searching routines. However, many of the new polar and thermally labile pesticides are more readily and easily analysed by LC/MS methods and no searchable libraries currently exist (with the exception of some user libraries, which are limited). Therefore, there is a need for LC/MS libraries that can detect pesticides and their degradation products. This paper reports an identification scheme using a combination of LC/MS time-of-flight (accurate mass) and an Access database of 350 pesticides that are amenable to positive ion electrospray. The approach differs from conventional library searching of fragment ions. The concept consists of three parts: (1) initial screening of possible pesticides in actual market-place fruit extracts (apple and orange) using accurate mass and generating an accurate mass via an automatic ion-extraction routine, (2) searching the Access database manually for screening identification of a pesticide, and (3) identification of the suspected compound by accurate mass of at least one fragment ion and comparison of retention time with an actual standard. Imazalil and iprodione were identified in apples and thiabendazole in oranges using this database approach.

Comprehensive two-dimensional gas chromatography (GCxGC) with nitrogen-phosphorus detection (NPD) has been investigated for the separation and quantitation of fungicides in vegetable samples. The detector gas flows (H(2), N(2) and air) were adjusted to achieve maximum response of signal whilst minimizing peak width. The comparison of different column sets and selection of the temperature program were carried out with a mixture of nine N-containing standard fungicides, eight of which were chlorinated. The results from GCxGC-NPD and GCxGC with micro electron-capture detection (muECD) were compared. External calibrations of fungicides were performed over a concentration range from 1 to 1,000 microgL(-1). The peak area calibration curves generally had regression coefficients of R(2)>0.9980, however for iprodione which was observed to undergo on-column degradation, an R(2) of 0.990 was found. The limit of detection (LOD) and limit of quantitation (LOQ) were less than about 74 and 246 ng L(-1), respectively. The intra-day and inter-day RSD values were measured for solutions of concentration 0.100, 0.500 and 1.50 mg L(-1). For the 0.500 mg L(-1) solution, intra- and inter-day precision of peak area and peak height for most of the pesticides were about 2% and 8%, respectively. Excellent linearity was observed for these standards, from 0.001 to 25.00 mg L(-1). The standard mixture peak positions were identified by using GCxGC with quadrupole mass spectrometry (qMS). To illustrate the potential and the versatility of both GCxGC-NPD and GCxGC-muECD, the method was applied to determination of fungicides in a vegetable extract. Decomposition of one fungicide standard (iprodione) during chromatography elution was readily observed in the two-dimensional (2D) GCxGC plot as a diagonal ridge response in the 2D chromatogram between the degrading compound and the decomposition product.

A solid-phase microextraction -- coupled to a gas chromatography -- ion trap tandem mass spectrometry (SPME-GC-MS/MS) method was developed for the quantitative determination in rainwater of 8 pesticides amongst the most used in France and 3 triazines metabolites. The main factors affecting the SPME process were studied. Using a 3 mL sample, the method developed showed good linearity for concentrations ranging from 0.05 to 50 microgL(-1) with correlation coefficients between 0.997 and 0.9999 and relative standard deviations (% RSD) below 14%. The study of matrix effects showed that rainwater was too diluted to have any significant influence on the extraction efficiency. To validate the method, a field campaign was carried out on the rain events, which occurred in Strasbourg during a one-year period. The rain concentrations showed patterns of high pesticide concentrations during spring months, which were correlated to the spraying periods of most of these substances.

The dicarboximide fungicides vinclozolin, iprodione and procymidone were analyzed in white wines using stir bar sorptive extraction (SBSE) in combination with thermal desorption-capillary GC-MS analysis (TD-cGC-MS). The method was optimized using spiked water samples in a concentration range between 0.5 and 100 microg/l. Iprodione was measured as its degradation product 3,5-dichlorophenyl hydantoin. Limits of quantification in the full scan MS mode are 0.5 microg/l for vinclozolin and procymidone and 5 microg/l for iprodione. In the ion monitoring mode, concentrations 100 times lower can be dosed. Because of wine matrix effects on the recoveries, quantification of the target fungicides in wine had to be carried out by standard addition. For the thermolabile iprodione, the accuracy of SBSE-TD-cGC-MS was verified using SBSE followed by liquid desorption and analysis by liquid chromatography-atmospheric pressure chemical ionization mass spectroscopy. Procymidone and iprodione were detected in wines in concentrations up to 65 microg/l while the highest concentration of vinclozolin detected was smaller than 3 microg/l.

A rapid, reliable method for the multiresidue analysis of eight commonly used fungicides by micellar electrokinetic chromatography (MEKC) was developed. Excellent separation of the eight fungicides (carbendazim, metalaxyl, captan, procymidone, folpet, captafol, vinclozolin and iprodione) is achieved within about 10 min by using optimized electrophoretic conditions that include the addition of a mixture of organic modifiers to the running buffer for improved resolution. The sensitivity of the method is enhanced by using an enrichment step that involves on-column high-salt stacking. Limits of detection in the microgram-per-liter region and relative standard deviations from 2.1 to 5.9% are thus obtained for the fungicides without detracting from peak resolution. These results reveal that the high-salt stacking method provides highly improved sensitivity and enables highly flexible adjustment of the selectivity of the separation method. Also, the method surpasses other stacking alternatives used in MEKC and affords routine analyses of fruit juice containing fungicides at trace levels following a straightforward sample treatment. The robustness of the high-salt stacking method as demonstrated in this work makes MEKC methods involving stacking procedures an attractive choice for routine analyses.

This paper describes the determination of 3,5-DCA in commercial composts, a common metabolite in a class of fungicides, and dicarboximides (Vinclozolin, Chlozolinate, Iprodione, Procymidone) which are commonly used in agriculture. The extracts, obtained in acetonitrile by sonication, are analysed by HPLC/DAD without clean-up. This method has shown several advantages: reduced manipulation of samples, good recovery (80-90%) and good reproducibility (RSD% <7). The limit of detection (DL) of the analytical method has been estimated as 15 microg/kg for the common metabolite, and 35-145 microg/kg for the four fungicides in the matrices.

The association between application rate of a pesticide and its residue in ripe tomatoes was studied. The average residue level (R) of any pesticide in ripe tomatoes remained in quantitative relation to its dose (D), expressed by the following regression equation: R = 0.24 D (mg/kg), where the numerical factor, 0.24, represents the average residue in mg/kg after application of 1 kg active ingredient per hectare with relative standard deviation of 23%. Quantitative association between these 2 factors enables evaluation of greenhouse tomato growers with respect to their observation of Good Agricultural Practice rules and the Plant Protection Act, obligatory in Poland since 1996, and thus may be a reliable basis for the registration of new agrochemicals.

For the 5-year period 1991 to 1995, 1536 vegetable and 802 fruit samples were analyzed. The purpose of this study was to determine if pesticides were present on Ontario-produced fruits and vegetables, and if so, to determine if residues violated maximum residue limits (MRLs). Overall, 31.5% of the samples had no detectable pesticide residues, whereas 68.5% contained one or more residues. Most of the residues were present at very low concentrations; 48% of the detections were < 0.1 parts per million (ppm), and 86% were < 1 ppm. However, violations of MRL were observed in only 3.2% of the vegetables samples and 3.1% of the fruit samples. In addition, 4.8% of the samples contained a "technical" violation, that is, there was no specified MRL for the pesticide-commodity combination and the residues exceeded 0.1 ppm. Of the detectable residues, 63% were < 10% of the MRL, whereas 89% were < 50% of the MRL. More fruit samples (91.4%) had a detectable residue, compared with vegetable samples (56.6%). Fruit is often treated close to harvest or post harvest to ensure that wholesome produce reaches the consumer. Forty-six percent of the samples contained 2 or more residues, and 2% of all samples had more than 5 different pesticides detected; fruit samples tended to have more multiple residues. The most frequently found pesticides were captan, the dithiocarbamate fungicides, endosulfan, azinphos-methyl, phosmet, parathion, and iprodione. These pesticides were also used in the greatest quantity for crop production. Overall, the data agree fairly closely with those reported for the U.S. Department of Agriculture Pesticide Data Program because the 2 programs have similar analytical goals and objectives.

A gas chromatographic method is presented for the simultaneous determination of the antiscald ethoxyquin and the fungicides imazalil and iprodione in peel and pulp of Blanquilla pears. Fruits were cold-stored in commercial chambers in normal atmosphere and in controlled atmosphere with low oxygen content (oxygen and carbon dioxide were held at 2.5% and 1.5%, respectively). The method uses gas-liquid chromatography (GLC) with an alkaline flame ionization detector (detector of N-P, NPD) and allows the detection of the mentioned compounds to minimum levels of 0.08-0.12 mg/kg in fresh fruit. With this system the evolution of residues in fruit was monitored throughout the period of cold storage. In the surveys carried out the residue levels of these compounds were found to be below the limits allowed by the legislation of European Union. For the three studied products residues in pulp are lower and disappear more quickly than in peel.

The fate of three fungicides (dichlofluanid, procymidone, and iprodione) applied under field conditions was studied during strawberry processing to juice, wine, and jam. An untreated control was compared to raw material treated with fungicides according to recommended doses and to a sample with 6-fold higher application rates. The highest residue values were found in the pomace after pressing. Residue values in readily produced juices and fruit wines were very low and did not exceed legally required maximum residue levels. Generally, processing steps such as pressing and clarification diminished fungicide residues from 50 to 100%. If the whole fruit is processed, as in fruit preparations or jam, the residue levels remain higher due to missing processing steps.

Three multivariate calibration methods, partial least squares (PLS-1 and PLS-2) and principal component regression, were applied to the simultaneous determination of the five pesticides iprodione, procymidone, chlorothalonil, folpet and triazophos by high-performance liquid chromatography with diode array detection. Such detection gives multiwavelength chromatograms from a single analysis of one sample. In this paper, calibration models at two different wavelengths were developed to resolve mixtures of five pesticides with overlapping chromatographic peaks. The first model, carried out at 220 nm as detector compromise wavelength, yielded satisfactory sensitivity for accurate estimation of the concentration of iprodione, procymidone, chlorothalonil and folpet and the second model, at 200 nm, was used for accurate estimation of triazophos. Both calibration models were evaluated using the chromatograms and first-derivative (1D) chromatograms by predicting the concentrations of independent test set samples. Finally, the proposed 1D calibration models were successfully applied to the determination of these pesticides in groundwater and soil samples. In all cases, the PLS-1 calibration method showed superior quantitative prediction ability than the PLS-2 or principal component regression methods.

Solid-phase extraction with a novel porous carbon sorbent CARB GR was used for the clean-up step of dicarboxyimide fungicides residues from variety of Slovak grape wines with subsequent capillary gas chromatography-flame ionization detection, -electron-capture detection (ECD) and -mass spectrometry-ion-trap detection (MS-ITD) analysis. Recovery was tested at various concentration levels of vinclozolin and iprodione in standard solutions (R = 80-97%, R.S.D. < or = 5). The value of recovery in spiked wines is dependent on concentration level (studied in the range of 5.9 micrograms/1-1.96 mg/l) and on the variety of wine (R = 80-96%; R.S.D. = 3-5%). Limits of quantitation (for sample volume 50 ml) were determined to be with GC-ECD for both fungicides in ppt range and with GC-MS-ITD in the multiple ion detection mode monitoring in ptt range for vinclozolin and ppb range for iprodione. Concentration levels of vinclozolin residues were determined in treated wines (with 0.1% Ronilan 50 WP) as well as iprodione residues (with 0.15% Rovral 50 WP) and a strong dependence on the protective term before the harvest is shown.

Aminoimidazole-containing compounds have been found to be electroactive and can be detected by amperometric electrochemical detection (ECD) with a high degree of sensitivity. A liquid chromatography (LC) method using ECD was developed for measuring plasma concentrations of the aminoimidazole-containing drug GP531, a potent adenosine-regulating agent. Plasma samples were extracted with 2-propanol and analyzed by LC under isocratic conditions using a mobile phase of methanol-sodium phosphate (pH 6.3; 3.3 mM) (32:68, v/v). The potential of the glassy carbon working electrode was set at +800 mV. The limit of quantitation was 12.5 ng ml-1 of GP531 using 100 microliters of plasma. The method was used to define the pharmacokinetics of GP531 in monkey following i.v. administration.

We report a new screening method for adenylosuccinate lyase (ASase) deficiency using capillary electrophoresis (CE). This enzyme defect causes secondary autism and psychomotor retardation in early childhood. In all body fluids of these patients, two succinylpurine metabolites can be found that are normally not detectable: succinyladenosine and succinylaminoimidazole carboxamide (SAICA) riboside. A Beckman P/ACE 2050 capillary electrophoresis system was used with a 47.1 cm capillary, 75 microns ID, and the P/ACE Beckman UV absorbance detector. Untreated urine, injected for 1 s, was separated in a pH 8.63 borate buffer at 20 kV. The two succinylpurines (migration times 13.36 and 13.60 min) were detected at 254 nm only in urine of patients with ASase deficiency but not in control samples.

The pharmacokinetics of 5-(3,3-dimethyl-1-triazeno)imidazole-4-carboxamide (DTIC, dacarbazine) given at a dose of 850-1,980 mg/m2 as a 10- to 30-min infusion was studied in cancer patients, and the plasma concentration-time curves were adjusted to a two-compartment model, with a mean t1/2 alpha value of 0.17 h (range, 0.1-0.26 h) and a mean t1/2 beta value of 2 h (range, 1.5-2.7 h) being found. The mean volume of the central compartment of (Vc) and the apparent volume of distribution (VB) were 0.42 1 kg-1 (range, 0.24-0.54 1 kg-1) and 1.49 1 kg-1 (range, 0.88-1.74 1 kg-1), respectively. The mean total body clearance of DTIC was 0.58 1 kg-1 h-1 (range, 0.26-0.82 1 kg-1 h-1), and the mean renal clearance was 0.28 1 kg-1 h-1 (range, 0.17-0.49 1 kg-1 h-1). Unchanged DTIC recovered from urine within 24 h varied from 11% to 63% of the delivered dose, with an inverse correlation being found between the DTIC dose and the amount excreted. The metabolite aminoimidazole carboxamide (AICA) was detectable in plasma from the start of DTIC infusion, and its concentration-time curve showed a monophasic decay, exhibiting a mean t1/2 value of 3.25 h (range, 1.77-5.82 h). Mean AICA renal clearance was 0.15 1 kg-1 h-1 (range, 0.05-0.32 1 kg-1 h-1). The amount of AICA excreted in urine increased with increasing DTIC dose and varied from 1.2% to 13.6% of the delivered DTIC dose. Both DTIC distribution and disposition and AICA production and renal excretion seemed to be limited after high DTIC doses as compared with the pharmacokinetics of low-dose DTIC. Nonlinear pharmacokinetics for high-dose DTIC could not be clearly excluded.

The cancer chemotherapeutic drug, 5-(3,3-dimethyl-1-triazeno) imidazole-4-carboxamide (DIC, DTIC, NSC-45388), is metabolised in rats to a structurally related product which was detected by thin-layer chromatography. The novel metabolite has a lower mobility and a colour reaction that is indistinguishable from the parent compound. The metabolite is not retained on an anionic exchanger which is inconsistent with the expected covalent binding of the drug to endogenic anionic substrates (e.g. glucuronic acid). Since both DIC and the metabolite yielded 5-[(4-ethylamino-1-napthyl)-azo]imidazole-4-carboxamide through release of 5-diazoimidazole-4-carboxamide, followed by coupling with N-ethyl-1-napthylamine, no biotransformation (hydroxylation) of the imidazole moiety of the injected DIC had occurred. By corollary, the lowered chromatographic mobility of the metabolite was explicable by the introduction of a polar but non-acidic function into the terminal dimethylamino group of the triazene side-chain. The metabolite was identified as 5-(3-hydroxymethyl-3-methyl-1-triazeno)imidazole-4-carboxamide by co-chromatography with an authentic sample of HMIC and by its methylating capacity for nucleophilic substrates.

A number of antagonists of nucleotide metabolism with anti-cancer activity affect the de novo purine pathway. To determine the biochemical mechanisms of cytotoxicity of these drugs, assay procedures have been developed for measurement of the levels of intermediates proximal to IMP in the pathway for de novo purine biosynthesis in mouse L1210 leukemia cells. Purine precursors have been synthesized in vitro from [14C]glycine using enzymes from chicken liver. These 14C-labeled intermediates have been used as marker compounds to define retention times for metabolites of leukemia cells separated by HPLC and the chromatographic mobilities of these intermediates after two-dimensional thin-layer chromatography. These new chromatographic procedures have been used in combination to determine the steady-state concentrations for purine precursors in mouse L1210 leukemia cells in the exponential phase of growth: N-formylglycineamide ribotide (16 microM); N-formylglycineamidine ribotide (4.7 microM); 5-aminoimidazole ribotide (4.0 microM); 4-carboxy-5-aminoimidazole ribotide (0.46 microM); N-succino-5-aminoimidazole-4-carboxamide ribotide (11 microM); 5-aminoimidazole-4-carboxamide ribotide (16 microM); 5-formamidoimidazole-4-carboxamide ribotide (2.7 microM); and IMP (57 microM). The metabolic effects of tiazofurin (25 microM) upon mouse L1210 leukemia cells growing in culture define a "metabolic crossover point" at the reaction catalyzed by IMP dehydrogenase (EC 1.1.1.205) which confirms previous reports of inhibition of this enzyme.

A high-pressure liquid chromatographic method has been developed that allows for the simultaneous analysis of dacarbazine (DTIC), 5-aminoimidazole-4-carboxamide (AIC), and 2-azahypoxanthine (2-AZA) in plasma or urine. Plasma samples were prepared by ultrafiltration, whereas urine samples were filtered and diluted for analysis. Chromatography was done with a C18 mu Bondapak column along with gradient elution of the drugs. The mobile phase consisted of 100% 0.5 M sodium acetate (pH 7.0) and 25% acetonitrile in 0.05 M sodium acetate (pH 5.5) with detection at 280 nm. Linearity was observed up to 500 micrograms/ml for DTIC and up to 53 micrograms/ml for AIC and 2-AZA. The assay methodology was reproducible, with a lower limit of detection of 5.0, 0.5, and 0.5 micrograms/ml for DTIC, AIC, and 2-AZA, respectively. Interday and intraday coefficients of variation ranged between 4 to 14% and 2 to 16%, respectively. The analytical method was applied to the analysis of plasma and urine samples resulting from the isolation perfusion chemotherapy of an extremity with 57 mg of DTIC per kg in a patient with melanoma.

Methotrexate (MTX) causes an inhibition of purine de novo synthesis (PDNS), resulting in increased intracellular availability of 5-phosphoribosyl-1-pyrophosphate (PRPP) in human malignant lymphoblasts with an active PDNS. Normal bone marrow cells and peripheral blood lymphocytes lack this capacity. The increased levels of PRPP can be used for enhanced incorporation of 6-mercaptopurine (6MP), indicating a potential time-, sequence- and dose-dependent synergism of both drugs. The effects of 0.02 microM and 0.2 microM MTX on the PDNS of MOLT-4 (T-), RAJI (B-) and KM-3 (non-B-non-T-) human malignant lymphoblasts were studied with respect to PRPP levels, aminoimidazolecarboxamide ribonucleosidemonophosphate (AICAR) levels and the incorporation of labeled glycine into purine metabolites. These results were correlated with the activity of the PDNS (labeled glycine incorporation) and the purine salvage pathway (labeled hypoxanthine incorporation) in untreated cells. Inhibition of PDNS by 0.02 microM MTX was complete in KM-3 cells with a moderately active PDNS and salvage pathway. RAJI cells, with a relatively low PDNS and high salvage pathway, demonstrated an incomplete, but increasing inhibition of PDNS, whereas inhibition of PDNS in MOLT-4 cells with both pathways active was minimal and recovered in time. Treatment with 0.2 microM MTX resulted in a complete inhibition of PDNS in all cell lines. After treatment with MTX an enhanced incorporation of labeled hypoxanthine and 6MP was noticed, confirming the potential rescue from MTX cytotoxicity by hypoxanthine and a potential synergism of MTX and 6MP on cytotoxicity. The enhanced incorporation of 6MP was more obvious in RAJI and KM-3 cells in comparison with MOLT-4 cells. These data demonstrate the important role of both the activities of the PDNS and the purine salvage pathway in malignant lymphoblasts of different subclasses with respect to the synergism of MTX and 6MP.

One of the cornerstones of an architectural approach adopted by this laboratory in screening vegetables for pesticides and industrial chemicals is the extensive use of element-selective gas chromatographic detectors followed by gas chromatography/mass spectrometry. In this particular case history, a recently introduced European fungicide, iprodione, was thought to be the first reported incidence in mache imported from France. An analytical protocol involving chemical ionization was devised to confirm this finding as well as search for possible potential metabolites.

Methotrexate (MTX) and 6-mercaptopurine (6MP) are common drugs in the oral maintenance therapy of acute lymphoblastic leukemia (ALL). On the basis of their biochemical effects on cell metabolism, a sequence-dependent synergism might be anticipated. In order to investigate this hypothesis, MOLT-4 human malignant T-lymphoblasts were incubated with various concentrations of MTX. The time at which maximal increase of intracellular 5-phosphoribosyl-1-pyrophosphate (PRPP) levels was found correlated with the concentrations of MTX used. Determination of aminoimidazolecarboxamide ribonucleoside monophosphate (AICAR) levels and labeled glycine incorporation into purine metabolites revealed an incomplete inhibition of purine de novo synthesis after incubation with 0.02 microM MTX, and a complete inhibition with 0.2 microM MTX. After prolonged periods of incubation, glutamine exhaustion of the medium caused inhibition of purine de novo synthesis in MTX-untreated cells, with a concomitant increase of PRPP levels. Addition of glutamine to the medium prevented this phenomenon. The increased availability of PRPP after pretreatment with MTX can be used for enhanced intracellular incorporation of hypoxanthine and 6MP in their respective nucleotides. The time- and dose-dependent effects of MTX on PRPP levels correlated with the enhanced incorporation of hypoxanthine and 6MP. The data presented in this study demonstrate that a synergistic action of the combination of MTX and 6MP can be anticipated in malignant lymphoblasts with an active purine de novo synthesis depending on the concentration of MTX and on the time and sequence of administration of both drugs.