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Chiral macrocyclic dimers, trimers, and tetramers composed of paraphenylene and tethered binaphthyl were synthesized, and their molecular structures and chiroptical properties were investigated. X-ray analysis and theoretical calculations revealed that multiple twisted molecular structures - dimers, trimers, and tetramers - adopt figure-of-eight, Möbius triangle, and concave rectangle structures, respectively. These homologues have large ϵ values in their UV-vis absorption spectra because of the π-conjugation of the naphthalene-phenylene-naphthalene frameworks. Owing to the shape-persistent ring structure and tethering with -OCH

Aminoglycosides are a class of broad-spectrum antibiotics with several clinical uses. Owing to the ototoxicity and nephrotoxicity of aminoglycosides, therapeutic drug monitoring is required. This study aimed to devise a high-throughput method for identification and quantitative determination of aminoglycoside antibiotics in human plasma samples using ultra-performance liquid chromatography–quadrupole time-of-flight-mass spectrometry (UPLC–Q-ToF-MS). Plasma samples (100 µL) spiked with five aminoglycosides (streptomycin, spectinomycin, amikacin, kanamycin, and gentamycin) and an internal standard (ribostamycin) were diluted and centrifuged in aqueous formic acid and acetonitrile. The clear supernatant extract was evaporated and reconstituted in the mobile phase, of which 4 µL was subjected to UPLC–Q-ToF-MS. Prominent peaks were observed for the drugs within 3 min. The recoveries of five aminoglycosides from plasma samples were 92.6–120%. The regression equations showed excellent linearity (0.9999 ≥ r2 ≥ 0.9987) within the range of 1.0–100 µg/mL, and detection limits of 0.5–2.0 µg/mL. The coefficients of the intra- and inter-day variations for five drugs were less than 11.8%, while the accuracy of quantitation was in the range of 89–111%. In this study, a novel method was presented for identification and determination of aminoglycosides in human plasma samples using UPLC–Q-ToF-MS analysis. This method can be applied to high-throughput analysis used for clinical and environmental purposes.

Rationale We developed a new high-throughput method to analyze tegafur (FT) and 5-fluorouracil (5-FU) in tear and plasma samples using hydrophilic interaction liquid chromatography (HILIC)/tandem mass spectrometry (MS/MS). Methods The tear samples (10 μL) spiked with FT, 5-FU, and 5-chlorouracil (internal standard) were diluted using 40 μL of 2 M ammonium acetate and 250 μL of acetonitrile with 2% formic acid; 20 μL of plasma spiked with the two drugs and internal standard was diluted with 80 μL of 2 M ammonium acetate and 500 μL of acetonitrile with 2% formic acid. After centrifugation, the clear supernatant extract (15 μL) was directly injected into the HILIC/MS/MS instrument, and each drug was separated on a Unison UK-Amino column (50 mm × 3 mm i.d., 3 μm particle size) with a linear gradient elution system composed of 10 mM ammonium acetate (pH 6.8) and acetonitrile at a flow rate of 0.7 mL/min. We performed quantification by multiple reaction monitoring (MRM) with negative-ion atmospheric-pressure chemical ionization. Results Distinct peaks were observed for the drugs on each MRM channel within 2 min. The regression equations showed good linearity within the range 0.04-4.0 μg/mL for the tear and plasma samples with detection limits at 0.02-0.04 μg/mL. Recoveries for target analytes (FT and 5-FU) for the tear and plasma samples were in the 94-128% and 94-104% ranges, respectively. The intra- and inter-day coefficients of variation for the two drugs were lower than 10.8%. The accuracies of quantitation were 97-115% for both samples. Conclusions We established a high-throughput, reproducible, and practical procedure for analyzing FT and 5-FU in human tear and plasma samples using HILIC/MS/MS analysis with an aminopropyl-bonded mixed-mode separation column. This method can be applied to the high-throughput routines used in clinical analyses.

A new high-throughput method was developed for analysis of valproate in human plasma samples by QuEChERS extraction and gas chromatography–tandem mass spectrometry (GC-MS/MS). Plasma samples (0.2 ml) spiked with valproate and secobarbital- d 5 (internal standard) were diluted with 1.3 ml of distilled water. Acetonitrile (1 ml) was added followed by 0.4 g MgSO 4 and 0.1 g NaOAC. After a centrifugation step (2000 g for 10 min), 1 ml of the supernatant was transferred to a dispersive-solid phase extraction (dSPE) tube containing 150 mg MgSO 4 and 50 mg C 18 . This mixture was vortexed and centrifuged at 3000 g for 5 min, and then the upper layer was evaporated to dryness under a stream of nitrogen. The residue was dissolved in 40 μl ethyl acetate, and a 1-μl aliquot was injected into the GC-MS/MS. The GC separation of the compounds was achieved on a fused-silica capillary column Rxi-5Sil MS (30 m × 0.25 mm i.d.; 0.25-µm film thickness) and detected by MS/MS operating in electron ionization ion source mode. The regression equations showed excellent linearity ( r > 0.9997) from 50 to 5000 ng/ml for plasma, with limit of detection of 10 ng/ml. The extraction efficiency of valproate for plasma ranged between 71.2%–103.5%. The coefficient of variation was

A simple and sensitive method was developed and validated here for the analysis of thirteen nonsteroidal anti-inflammatory drugs (NSAIDs) in human plasma samples by hydrophilic interaction liquid chromatography (HILIC)-tandem mass spectrometry (MS/MS). A small volume of plasma (20μL) spiked with compounds was diluted with 80μL of 10-mM ammonium acetate followed by a simple protein precipitation with 400μL of acetonitrile. After centrifugation, the clear supernatant extract was directly injected into the HILIC-MS/MS, without any solvent evaporation and reconstitution steps. The chromatographic separation of the NSAIDs was achieved on a Unison UK-Amino HILIC column (50mm×3mm i.d., particle size 3μm) with a linear gradient elution system composed of 10mM ammonium acetate (pH 6.8) and acetonitrile at a flow rate of 0.4mL/min. The mass spectra obtained by HILIC-MS showed base peak ions due to [M+H](+) for indomethacin, oxaprozin, ketoprofen, alminoprofen, zaltoprofen, tiaprofenic acid, pranoprofen, and ketoprofen-d3 and due to [M-H](-) for etodolac, ibuprofen, diclofenac, fenoprofen, loxoprofen, naproxen, and ibuprofen-d3. Recoveries of these thirteen NSAIDs in plasma were 34.8-113% and the lower limits of quantitation were 0.125-1.25μg/mL. The intra- and interday coefficient of variations for all drugs in plasma were less than 14.6%. The data obtained from actual plasma determinations of zaltoprofen, ibuprofen, and diclofenac are also presented.

Solid-phase extraction (SPE) using micropipette tips is a useful technique to prepare samples prior to mass spectrometry. However, most commercial SPE tips have loading capacities that are insufficient for quantitative determination. In this paper, we describe a rapid method for quantitative microanalysis of five phenothiazine derivatives, chlorpromazine, levomepromazine, promazine, promethazine and trimeprazine, using a recently introduced C(18) monolithic silica SPE tip, the MonoTip C(18), for extraction from human plasma. The drugs could be extracted within 5 min from 0.1-mL plasma samples, eluted with methanol, and the eluate injected directly into a gas chromatograph prior to mass spectrometry analysis. Only 0.7 mL of solvent was required for each step of the extraction process. The recoveries of the five phenothiazines spiked into plasma were 91-95% and the limits of quantification for each drug were between 0.25 and 2.0 ng/0.1 mL. The maximum intra- and inter-day coefficient of variation was 11%. The validated method was successfully used to quantify the plasma concentration of levemepromazine in a human subject after oral administration of the drug. This new method is expected to have wide applications as a pretreatment for the rapid, quantitative determination of drug concentrations in plasma samples.

A method for the simultaneous extraction of four tricyclic antidepressants from human plasma samples using pipette tip SPE with MonoTip C(18) tips is presented. Human plasma (0.1 mL) containing four tricyclic antidepressants (amitriptyline, amoxapine, imipramine, and trimipramine) and an internal standard (IS), protriptyline, was mixed with 0.4 mL of distilled water and 100 microL 1 M NaOH solution. After centrifugation of the mixture, the supernatant was extracted to the C(18) phase of the tip by 20 repeated aspirating/dispensing cycles using a manual micropipettor. The analytes retained in the tip were eluted with methanol by five repeated aspirating/dispensing cycles. Without evaporation and reconstitution, the eluate was directly injected into a gas chromatograph injector and detected by a mass spectrometer with SIM in the positive-ion electron impact mode. Recovery of the four antidepressants and IS spiked into human plasma was 80.2-92.1%. The regression equations for the four antidepressants showed excellent linearity in the range of 0.2-40 ng/0.1 mL. LODs and LOQs for the four drugs were 0.05-0.2 ng/0.1 mL and 0.2-0.5 ng/0.1 mL, respectively. Intra- and interday CVs for the four drugs in plasma were no greater than 9.5%.

Methamphetamine and amphetamine were extracted from human whole blood samples using pipette tip solid-phase extraction (SPE) with MonoTip C(18) tips, on which C(18)-bonded monolithic silica gel was fixed. Human whole blood (0.1 mL) containing methamphetamine and amphetamine, with N-methylbenzylamine as an internal standard, was mixed with 0.4 mL of distilled water and 50 microL of 5 M sodium hydroxide solution. After centrifugation, the supernatant was extracted to the C(18) phase of the tip (pipette tip volume, 200 microL) by 25 repeated aspirating/dispensing cycles using a manual micropipettor. Analytes retained in the C(18) phase were eluted with methanol by five repeated aspirating/dispensing cycles. After derivatization with trifluoroacetic anhydride, analytes were measured by gas chromatography - mass spectrometry with selected ion monitoring in the positive-ion electron impact mode. Recoveries of methamphetamine and amphetamine spiked into whole blood were more than 87.6 and 81.7%, respectively. Regression equations for methamphetamine and amphetamine showed excellent linearity in the range of 0.5-100 ng/0.1 mL. The limits of detection for methamphetamine and amphetamine were 0.15 and 0.11 ng/0.1 mL, respectively. Intra- and interday coefficients of variation for both stimulants were not greater than 9.6 and 13.8%, respectively. The determination of methamphetamine and amphetamine in autopsy whole blood samples is presented, and was shown to validate the present methodology.

A method for the simultaneous determination of selegiline and its metabolite, desmethylselegiline, in human whole blood and urine is presented. The method, which combines a fiber-based headspace solid-phase microextraction (SPME) technique with gas chromatography-mass spectrometry (GC-MS), required optimization of various parameters (e.g., salt additives, extraction temperatures, extraction times and the extraction properties of the SPME fiber coatings). Pargyline was used as the internal standard. Extraction efficiencies for both selegiline and desmethylselegiline were 2.0-3.4% for whole blood, and 8.0-13.2% for urine. The regression equations for selegiline and desmethylselegiline extracted from whole blood were linear (r(2)=0.996 and 0.995) within the concentration ranges 0.1-10 and 0.2-20 ng/ml, respectively. For urine, the regression equations for selegiline and desmethylselegiline were linear (r(2)=0.999 and 0.998) within the concentration ranges 0.05-5.0 and 0.1-10 ng/ml, respectively. The limit of detection for selegiline and desmethylselegiline was 0.01-0.05 ng/ml for both samples. The lower and upper limits of quantification for each compound were 0.05-0.2 and 5-20 ng/ml, respectively. Intra- and inter-day coefficients of variation for selegiline and desmethylselegiline in both samples were not greater than 8.7 and 11.7%, respectively. The determination of selegiline and desmethylselegiline concentrations in Parkinson's disease patients undergoing continuous selegiline treatment is presented and is shown to validate the present methodology.

Ten antihistamine drugs, diphenhydramine, orphenadrine, chlorpheniramine, diphenylpyraline, triprolidine, promethazine, homochlorcyclizine, cyproheptadine, cloperastine and clemastine, have been found to be extractable from human plasma samples using MonoTip C18 tips, inside which C18-bonded monolithic silica gel was fixed. Human plasma (0.1 mL) containing the ten antihistamines was mixed with 0.4 mL of distilled water and 25 µL of a 1 M potassium phosphate buffer (pH 8.0). After centrifugation of the mixture, the supernatant fraction was extracted to the C18 phase of the tip by 25 repeated aspirating/dispensing cycles using a manual micropipettor. The analytes retained on the C18 phase were then eluted with methanol by five repeated aspirating/dispensing cycles. The eluate was injected into a gas chromatography (GC) injector without evaporation and reconstitution steps, and was detected by a mass spectrometer with selected ion monitoring in the positive-ion electron impact mode. The separation of the ten drugs from each other and from impurities was generally satisfactory using a DB-1MS column (30 m × 0.32 mm i.d., film thickness 0.25 µm). The recoveries of the ten antihistamines spiked into plasma were 73.8–105%. The regression equations for the ten antihistamines showed excellent linearity with detection limits of 0.02–5.0 ng/0.1 mL. The within-day and day-to-day coefficients of variation for plasma were not greater than 9.9%. The data obtained from determination of diphenhydramine and chlorpheniramine in human plasma after oral administration of the drugs are also presented. Copyright © 2006 John Wiley & Sons, Ltd.

A sensitive method for the simultaneous determination of quazepam and two of its metabolites, 2-oxoquazepam and 3-hydroxy-2-oxoquazepam, in human urine was developed using gas chromatography–mass spectrometry (GC/MS) with an Rtx-5MS capillary column. The quazepam and its metabolites were extracted from human urine using a simple solid-phase extraction Oasis ® HLB cartridge column, and the 3-hydroxy-2-oxoquazepam was derivatised using BSTFA/1%TMCS and pyridine at 60°C for 30min. The mass spectrometric detection of the analytes was performed in the full scan mode, m / z 60–480, and selected ion monitoring (SIM) mode, m / z 386, for quazepam; m / z 342, for 2-oxoquazepam; m / z 429, for 3-hydroxy-2-oxoquazepam-TMS; and m / z 284, for alprazolam-d5 (internal standard), by electron ionization. The calibration curves of quazepam and its metabolites in urine showed good linearity in the concentration range of 2.5–500ng/0.2ml of urine. The average recoveries of quazepam and its metabolites from 0.2ml of urine containing 500ng and 50ng of each drug were 71–83% and 88–90%, respectively. The limits of detection of quazepam, 2-oxoquazepam and 3-hydroxy-2-quazepam in urine by the selected ion monitoring mode were 0.096–0.37ng/ml. This method would be applicable to other forensic biological materials containing low concentrations of quazepam and its metabolites.

The evidence that some older patients with essential hypertension have low urinary dopamine excretion has brought into question the levels of urinary dopamine and plasma dopa, the major source of urinary dopamine, in young patients with essential hypertension. Twenty-four-hour urine sodium, creatinine, dopamine and noradrenaline and plasma dopa were evaluated in 48 patients with essential hypertension aged 18 to 27 years and 25 normotensive subjects. In comparison with age-matched normotensive subjects, the hypertensive patients had higher urinary dopamine (1920 +/- 80 vs 1520 +/- 130 nmol/day, p < 0.01) and noradrenaline (216 +/- 11 vs 179 +/- 12 nmol/day, p < 0.05) excretion. There was a significant correlation between urinary dopamine and noradrenaline excretion. There was no difference in plasma dopa levels between normotensive and hypertensive subjects. These results suggest that the elevated conversion of dopa to dopamine in the kidney is leading to increased urinary dopamine excretion in young patients with essential hypertension.

A novel method is described for the extraction of methamphetamine, amphetamine, and methylenedioxyphenylalkylamine designer drugs, such as 3,4-methylenedioxy-methamphetamine, 3,4-methylenedioxyamphetamine, 3,4-methylenedioxyethylamphetamine, N-methyl-1-(3,4-methylenedioxyphenyl)-2-butanamine, and 3,4-(methylenedioxyphenyl)-2-butanamine, from human whole blood using molecularly imprinted solid-phase extraction as highly selective sample clean-up technique. Whole blood samples were diluted with 10 mmol/L ammonium acetate (pH 8.6) and applied to a SupelMIP-Amphetamine molecularly imprinted solid-phase extraction cartridge. The cartridge was then washed to eliminate interferences, and the amphetamines of interest were eluted with formic acid/methanol (1:100, v/v). After derivatization with trifluoroacetic anhydride, the analytes were quantified using gas chromatography-mass spectrometry. Recoveries of the seven amphetamines spiked into whole blood were 89.1-102%. The limits of quantification for each compound in 200 μL of whole blood were between 0.25 and 1.0 ng. The maximum intra- and inter-day coefficients of variation were 9.96 and 13.8%, respectively. The results show that methamphetamine, amphetamine, and methylenedioxyphenylalkyl-amine designer drugs can be efficiently extracted from crude biological samples such as whole blood by molecularly imprinted solid-phase extraction with good reproducibility. This extraction method will be useful for the pretreatment of human samples before gas chromatography-mass spectrometry.

Dimemorfan was extracted from human plasma samples (100 μL) using MonoTip C(18) tips, which were packed with a C(18)-bonded monolithic silica gel attached to the inside of the tip. The samples, which contained dimemorfan and trimeprazine as an internal standard (IS), were mixed with 300 μL of distilled water and 50 μL of 1M glycine-sodium hydroxide buffer (pH 10). The mixture was extracted onto the C(18) phase of the tip by 20 sequential aspirating/dispensing cycles using a manual micropipettor. The analytes retained on the C(18) phase were then eluted with methanol by five sequential aspirating/dispensing cycles. The eluate was injected directly into a gas chromatograph and detected by a mass spectrometer with selected ion monitoring in positive electron ionization mode. An Equity-5 fused silica capillary column (30 m × 0.32 mm i.d., film thickness 0.25 μm) gave adequate separation of the dimemorfan, IS, and impurities. The recoveries of dimemorfan and the IS spiked into plasma were ≥83%. The regression equation for dimemorfan showed excellent linearity from 0.25 to 32.0 ng/100 μL of plasma, and the limit of detection was 0.125 ng/100 μL of plasma. The maximum intra-day and inter-day relative standard deviations were 13%, while accuracy ranged from 88% to 105%. Dimemorfan was stable for at least 12 h at 4°C, 4 weeks at -80°C, and three freeze-thaw cycles in plasma. This new method is expected to have application as a pretreatment for the rapid, simple, and quantitative determination of dimemorfan in plasma samples.

Dextromethorphan was extracted from human plasma samples (100 μL) using MonoTip C(18) tips, which are packed with C(18)-bonded monolithic silica gel that is attached to the inside of the tip. The samples, which contained dextromethorphan and trimeprazine as an internal standard (IS), were mixed with 200 μL of distilled water and 50 μL of 1 mol/L glycine-sodium hydroxide buffer (pH 10). The mixture was extracted to the C(18) phase of the tip by 20 sequential aspirating/dispensing cycles using a manual micropipettor. The analytes retained on the C(18) phase were then eluted with methanol by five sequential aspirating/dispensing cycles. The eluate was injected directly into a gas chromatograph and detected by a mass spectrometer with selected ion monitoring in positive electron ionization mode. An Equity-5 fused silica capillary column (30 m × 0.32 mm i.d., film thickness 0.5 μm) gave adequate separation of the dextromethorphan, IS, and impurities. The recoveries of dextromethorphan and the IS spiked into plasma were >87.4%. The regression equation for dextromethorphan showed excellent linearity from 2.5 to 320 ng/mL of plasma, and the limit of detection was 1.25 ng/mL of plasma. The intraday and interday coefficients of variation were less than 10.5% and 14.7%, respectively. The accuracy ranged from 91.9% to 107%. The validated method was successfully used to quantify the plasma concentration of dextromethorphan in a human subject after oral administration of the drug.

Chlorpromazine, levomepromazine, promazine, triflupromazine, and trimeprazine were simultaneously determined in human whole blood and plasma by combining headspace solid-phase microextraction and gas chromatography with nitrogenphosphorus detection. Extraction efficiency for the phenothiazine derivatives was 0.0130.117 for both sample types. Regression equations were linear [correlation coefficient (r) 0.99510.9999] within the range 2.5200 ng/0.5 mL for triflupromazine and trimeprazine, and 6.3200 ng/0.5 mL for chlorpromazine, levomepromazine, and promazine. The limit of detection for each compound was 0.23.9 ng/0.5 mL whole blood and plasma. Intraday and interday coefficients of variation for all phenothiazines in both human samples were commonly

This paper describes a fully automated on-line method combining in-tube solid-phase microextraction (SPME) in which sample clean-up and enrichment are conducted through an open tubular fused-silica capillary column and high-performance liquid chromatography (HPLC)/tandem mass spectrometry (MS/MS) detection for the determination of six butyrophenone derivatives (moperone, floropipamide, haloperidol, spiroperidol, bromperidol, and pimozide) in human plasma samples. The six butyrophenones were extracted by repeatedly aspirating and dispensing plasma sample solutions on a DB-17 capillary column (60 cm x 0.32 mm i.d., film thickness 0.25 microm). The analytes retained on the inner surface of the capillary column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. Extraction efficiencies ranged from 12.7% to 31.8% for moperone, spiroperidol, and pimozide, and from 1.08% to 4.86% for floropipamide, haloperidol, and bromperidol. The regression equations for all compounds showed excellent linearity, ranging from 0.05 to 50 ng/0.1 mL of plasma, except for moperone and spiroperidol (0.01 to 50 ng/0.1 mL). The limits of detection and quantification in plasma for each drug were 0.03-0.2 and 0.1-0.5 ng/mL, respectively. The intra- and inter-day coefficients of variation for all compounds in plasma were not greater than 13.7%.

Diazepam and its major metabolites, nordazepam, temazepam and oxazepam, in human urine samples, were analyzed by liquid chromatography (LC)/tandem mass spectrometry (MS/MS) using a hydrophilic polymer column (MSpak GF-310 4B), which enables direct injection of crude biological samples. Matrix compounds in urine were eluted first from the column, while the target compounds were retained on the polymer stationary phase. The analytes retained on the column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. All compounds showed base-peak ions due to [M+H]+ ions on LC/MS with positive ion electrospray ionization, and product ions were produced from each [M+H]+ ion by LC/MS/MS. Quantification was performed by selected reaction monitoring. All compounds spiked into urine showed method recoveries of 50.1-82.0%. The regression equations for all compounds showed excellent linearity in the range of 0.5-500 ng/mL of urine. The limits of detection and quantification for each compound were 0.1 and 0.5 ng/mL of urine, respectively. The intra- and inter-day coefficients of variation for all compounds in urine were not greater than 9.6%. The data obtained from actual determination of diazepam and its three metabolites, oxazepam, nordazepam and temazepam, in human urine after oral administration of diazepam, are also presented.

A detailed procedure for the analysis of four beta-blockers, acebutolol, labetalol, metoprolol and propranolol, in human plasma by high-performance liquid chromatography (LC)-tandem mass spectrometry (MS-MS) using an MSpak GF column, which enables direct injection of crude plasma samples, is presented. Protein and/or macromolecule matrix compounds were eluted first from the column, while the drugs were retained on the polymer stationary phase of the MSpak GF column. The analytes retained on the column were then eluted into an acetonitrile-rich mobile phase using a gradient separation technique. All drugs showed base peak ions due to [M + H]+ ions by LC-MS with positive ion electrospray ionization, and the product ions were produced from each [M + H]+ ion by LC-MS-MS. Quantification was performed by selected reaction monitoring. The recoveries of the four beta-blockers spiked into plasma were 73.5-89.9%. The regression equations for all compounds showed excellent linearity in the range 10-1000 ng/mL of plasma, with the exception of propranolol (10-800 ng/mL). The limits of detection and quantification for each drug were 1-3 and 10 ng/mL, respectively, of plasma. The intra- and inter-day coefficients of variation for all drugs in plasma were not greater than 10.9%.

Methamphetamine and amphetamine were extracted from human urine samples using pipette tip solid-phase extraction (SPE) with MonoTip C18 tips (pipette tip volume, 200 microl), in which C18-bonded monolithic silica gel was fixed. A sample of human urine (0.5 ml) containing methamphetamine, amphetamine, and N-methylbenzylamine as internal standard (IS), was mixed with 25 microl of 1M sodium hydroxide solution. The mixture was extracted into the C18 phase of the SPE tip by 25 repeated aspirating/dispensing cycles using a manual micropipettor. Analytes retained in the C18 phase were then eluted with methanol by five repeated aspirating/dispensing cycles. After derivatization with trifluoroacetic anhydride, analytes were measured by gas chromatography/mass spectrometry with selected ion monitoring in the positive-ion electron impact mode. Recoveries of methamphetamine, amphetamine, and IS spiked into urine were more than 82.9, 82.2, and 78.2%, respectively. Regression equations for methamphetamine and amphetamine showed excellent linearity in the range of 0.25-200 ng/0.5 ml. Limit of detection was 0.04 ng/0.5 ml for methamphetamine and 0.05 ng/0.5 ml for amphetamine. Intra- and inter-day coefficients of variations for both stimulants were not greater than 10.8%. The data obtained from actual determination of methamphetamine and amphetamine in autopsy urine samples are also presented for validation of the method.

Seven phenothiazine derivatives, perazine, perphenazine, prochlorperazine, propericiazine, thioproperazine, trifluoperazine, and flupentixol, have been found to be extractable from human plasma and urine samples using disk solid-phase extraction (SPE) with an Empore C18 cartridge. Human plasma and urine (1 mL each) containing the 7 phenothiazine derivatives were mixed with 2 mL of 0.1M NaOH and 7 mL distilled water and then poured into the disk SPE cartridges. The drugs were eluted with 1 mL chloroform– acetonitrile (8 + 2) and determined by liquid chromatography with ammonium formate/formic acid–acetonitrile gradient elution. The detection was performed by ultraviolet absorption at 250 nm. The separation of the 7 phenothiazine derivatives from each other and from impurities was generally satisfactory using a SymmetryShield RP8 column (150 × 2.1 mm id, 3.5 μm particle size). The recoveries of the 7 phenothiazine derivatives spiked into plasma and urine samples were 64.0–89.9% and 65.1–92.1%, respectively. Regression equations for the 7 phenothiazine derivatives showed excellent linearity, with detection limits of 0.021–0.30 mg/mL for plasma and 0.017–0.30 μg/mL for urine. The within-day and day-to-day coefficients of variation for both samples were commonly below 9.0 and 14.9%, respectively.

Paraquat (PQ) and diquat (DQ) in human whole blood and urine were analyzed by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) with positive ion electrospray ionization (ESI). The compounds were extracted with Sep-Pak C18 cartridges from whole blood and urine samples containing ethyl paraquat as an internal standard. The separation of PQ and DQ was carried out using ion-pair chromatography with heptafluorobutyric acid in 20 mM ammonium acetate and acetonitrile gradient elution for successful coupling with MS. Both compounds formed base peaks due to [M-H]+ ions by HPLC/ESI-MS and the product ions produced from each [M-H]+ ion by HPLC/MS/MS. Selective reaction monitoring (SRM) showed much higher sensitivity for both body fluids. Therefore, a detailed procedure for the detection of compounds by SRM with HPLC/MS/MS was established and carefully validated. The recoveries of PQ and DQ were 80.8-95.4% for whole blood and 84.2-96.7% for urine. The calibration curves for PQ and DQ showed excellent linearity in the range of 25-400 ng ml(-1) of whole blood and urine. The detection limits were 10 ng ml(-1) for PQ and 5 ng ml(-1) for DQ in both body fluids. The intra- and inter-day precision for both compounds in whole blood and urine samples were not greater than 13.0%. The data obtained from the determination of PQ and DQ in rat blood after oral administration of the compounds are also presented.

To investigate the hypothesis that insulin resistance plays a role in the etiology of hypertension and hyperlipidemia, we measured serum lipid levels, the fasting glucose/insulin ratio, and the insulin response to oral glucose (GTT) in a group of young obese subjects (n = 21) with hypertension and normal glucose tolerance and in normotensive subjects (n = 36) with normal glucose tolerance, matched for age and body mass index. Leisure time physical activity was evaluated by a questionnaire outlining three levels of physical activities during leisure time. Subjects with hypertension had higher fasting serum insulin (19 +/- 2 v 13 +/- 1 microU/mL, P < .01) and lower fasting glucose/insulin ratio (5.3 +/- 0.2 v 7.1 +/- 0.5 mg/dL/microU/mL, P < .01) than normotensive subjects. Subjects with hypertension had higher peak serum insulin and lower plasma glucose area/insulin area ratio in response to glucose (1.8 +/- 0.2 v 2.4 +/- 0.2 mg/dL/microU/mL, P < .05) than normotensive subjects. Serum total cholesterol, low-density cholesterol, and triglycerides were higher in the obese hypertensive subjects than in obese normotensive ones. Blood pressure correlated with either fasting serum insulin, fasting glucose/insulin ratio, or glucose area/insulin area ratio during GTT. The level of leisure time physical activities was lower in obese hypertensive subjects than in obese normotensive ones. There were significant correlations between the levels of physical activity and the fasting plasma glucose/insulin ratio (r = 0.371, P < .01) or the fasting serum insulin concentration (r = -0.282, P < .05). The study provided evidence that a low level of leisure time physical activity is associated with insulin resistance and resultant hyperinsulinemia, which are the key metabolic abnormalities that link hypertension, obesity, and hyperlipidemia in young subjects.

The effects of L-dopa on blood pressure, heart rate, plasma renin activity, norepinephrine, epinephrine and prolactin were studied in a randomized single-blind trial in 36 patients with essential hypertension. In response to L-dopa, 250 mg administered orally, the blood pressure decreased significantly as compared with the results of placebo treatment. The heart rate and plasma norepinephrine and epinephrine were unchanged. The plasma renin activity and prolactin decreased as a result of L-dopa administration. The administration of a peripheral DA2 dopamine receptor blocker, domperidone (20 mg, orally) prevented the L-dopa-induced reduction in plasma prolactin but failed to block the fall in blood pressure and plasma renin activity. These results suggest that the blood pressure-lowering effect of L-dopa may be mediated through multiple sites involving D1 dopamine receptors, the central nervous system, and the renin-angiotensin system.