Search

A capillary zone electrophoresis (CZE) method has been developed for the determination of the antibiotic ofloxacin in tablets. The CZE separation was performed using 75 µm × 35 cm fused silica capillary under the following conditions: 25°C; applied voltage, 12 kV; 25 mM H3PO4-NaOH running buffer (pH 8.5). The detection wavelength was 254 nm. Flumequine was used as internal standard. The method was suitably validated with respect to linearity, limit of detection and quantification, accuracy, precision, specificity, and robustness. The calibration was linear from 5 to 50 µg mL-1 and the limit of detection and quantification were 1.24 and 4.01 µg mL-1, respectively. Recoveries ranging from 99.71-102.4% were obtained in the determination of ofloxacin that were spiked to placebos. Excipients in the commercial tablets and degraded products from different stress conditions did not interfere in the assay. The method was successfully applied to the determination of ofloxacin in pharmaceutical tablets. [ABSTRACT FROM AUTHOR]

Radio Frequency Identification (RFID) technology can be applied to a number of pharmaceutical processes, as ample of information can be stored and read rapidly from an RFID tag. Applications may range from inventory control, to access control, to telemedicine, to supply chain management and, most importantly, in combatting counterfeit products. Overall health care services can be improved by using this technology. This technology is gaining popularity in various fields, but is still costly and regulatory considerations are restricting its use. This paper explains the basics of RFID technology and some potential applications related to the pharmaceutical industry. [ABSTRACT FROM AUTHOR]

A sequential injection analysis/immunosensor system is proposed for the analysis of thyroxine (L-T4) in serum and in pharmaceutical formulations with a rate of 75 samples/hour. The immunosensor design is based on the physical immobilization of anti-L-T4 in carbon paste. The working concentration range of the immunosensor in the sequential injection analysis system is between 36 and 1080 ng/mL with a limit of detection of 24.6 ng/mL. The system is very reliable and very easy to design and operate. [ABSTRACT FROM AUTHOR]

Microwave assisted extraction (MAE) and ultrasound assisted extraction (UAE) methods were applied for the first time for the extraction of anthocyanins from red grape skins, and the results of these methods were compared with the maceration method. The extracted samples were analyzed by high performance liquid chromatography (HPLC) and nine anthocyanins were identified by liquid chromatography tandem mass spectrometry (LC-MS/MS). The effects of sample weight to solvent volume ratio, temperature, and time of extraction on the efficiency of extraction in MAE were investigated by two full factorial designs at three levels. The results of two designs show that sample weight to solvent volume ratio and temperature were more important than the time of extraction in MAE. UAE has no variable parameters similar to MAE. The suitable solvent and required time for the UAE method were described. The recoveries of MAE, UAE, and maceration methods were 90%, 82%, and 98%, respectively. [ABSTRACT FROM AUTHOR]

A capillary zone electrophoresis (CZE) method has been developed for the determination of the antibiotic sparfloxacin in tablets. The CZE separation was performed using 75 µm×35 cm fused-silica capillary under the following conditions: 25°C; applied voltage, 12 kV; 25 mM H3PO4-NaOH running buffer (pH 8.5). The detection wavelength was 254 nm. Flumequine was used as internal standard (IS). The method was suitably validated with respect to linearity, limit of detection and quantification, accuracy, precision, specificity, and robustness. The calibration was linear from 10 to 60 µg mL-1 and the limit of detection and quantification were 5.38 and 9.46 µg mL-1, respectively. Recoveries ranging from 95.68%-102.4% were obtained in the determination of sparfloxacin that were spiked to placebos. Excipients in the commercial tablets and degraded products from different stress conditions did not interfere in the assay. The method was successfully applied to the determination of sparfloxacin in pharmaceutical tablets. [ABSTRACT FROM AUTHOR]

The chiral resolution of environmental pollutants is an urgent need of today. Therefore, the chiral resolution of the environmental pollutants by capillary electrophoresis was reviewed. Various aspects of the chiral resolution by capillary electrophoresis such as chiral selectors, optimization of capillary electrophoresis conditions [composition of the back ground electrolyte (BGE), pH of the BGE, ionic strength of the BGE, structures and types of the chiral selectors, applied voltage, temperature, structures of the chiral pollutants, use of organic modifiers and other parameters, optimization by dependent variables], detection, sample treatment, validation of the methods and the chiral recognition mechanisms have been discussed. [ABSTRACT FROM AUTHOR]

Enantioanalysis of biomedical substances is very important for clinical analysis because the L- and D-enantiomers of the same chiral compound may be markers for different illnesses. A sequential injection analysis (SIA) system using amperometric biosensors as detectors is proposed for the simultaneous determination of L- and D-pipecolic acid (PA). The amperometric biosensors were based on L-amino acid oxidase (L-AAOD) or/and horseradish peroxidase (HRP) for the assay of L-PA and D-amino acid oxidase (D-AAOD) and/or HRP for the assay of D-PA. The linear concentration ranges are of pmol/L to nmol/L magnitude order, with very low limits of detection. The SIA/biosensors system can be used reliably on-line for the simultaneous assay of L- and D-PA from serum samples, with a frequency of 34 samples per hour. [ABSTRACT FROM AUTHOR]

A capillary zone electrophoretic (CZE) method has been developed for the determination of gemifloxacin and lomefloxacin in pharmaceutical tablet formulations. The CZE separation was performed using a 75 µm×35 cm fused silica capillary under the following conditions: 25°C; applied voltage, 12 kV; 25 mM H3PO4-NaOH running buffer (pH 8.5). The detection wavelength was 254 nm. Flumequine was used as internal standard. The method was suitably validated with respect to linearity, limit of detection and quantification, accuracy, precision, specificity, and robustness. The calibration was linear from 5 to 50 µg mL-1 for gemifloxacin and 10 to 60 µg mL-1 for lomefloxacin, and the limit of detection and quantification were 2.93, 4.91 µg mL-1, and 3.87, 8.93 for gemifloxacin and lomefloxacin, respectively. Recoveries ranging from 94.4-108.6% were obtained for both drugs. The method was successfully applied to the determination of gemifloxacin and lomefloxacin in pharmaceutical tablets. Excipients present in the tablets and degraded products from different stress conditions did not interfere in the assay. [ABSTRACT FROM AUTHOR]

This study was designed to evaluate free amino acid (FAA) composition and total protein in mature human milk from Turkish mothers. Free amino acid concentrations in mature human milk were determined in all subjects using a high-performance liquid chromatography (HPLC) with postcolumn derivatization system, with a fluorescence detector. Total protein content was determined by the classical biuret method. Total protein concentration was found to be 1.3±0.4 mg/dl. Glutamic asid plus glutamine is the most abundant amino acid (1275 µmol/L), followed by taurine (353 µmol/L) and alanine (261 µmol/L). Glutamic acid plus glutamine accounts for the most free amino acids in mature human milk and their sum represents 40% of total FAA. On the other hand, some amino acid derivatives such as citrulline, ethanolamine, ammonium, ornithine, ortophosphoserine, and phosphoethanolamine, not usually a part of protein, are determined and this fraction represented ∼21% of the total FAA in mature human milk in the present study. [ABSTRACT FROM AUTHOR]

A capillary electrophoretic method for the separation of the enantiomers of ofloxacin using carboxymethyl-β-cyclodextrin (CM-β-CD) as chiral selector is described. The effect of the type of cyclodextrin and its concentration, buffer concentration, and its pH, as well as instrumental parameters, such as applied voltage and temperature were systematically studied. The highest resolution of ofloxacin enantiomers obtained was around 2.8. This was achieved using Tris-citrate buffer (pH 4.5) that contained 3 mg mL-1 CM-β-CD and using UV detection (254 nm), applied voltage (12 kV), and capillary temperature of 25°C. Acceptable validation criteria for selectivity, precision, linearity, limit of detection, and quantitation were also included. Recoveries between 98.3-103.4% were obtained when the method was used to determine the enantiomers of ofloxacin that were spiked to placebos. The proposed method is fast, sensitive, inexpensive, and its usefulness was demonstrated for the analysis of five pharmaceutical preparations, two of which just contained the S-ofloxacin while the other three contained both isomers as racemic mixtures. [ABSTRACT FROM AUTHOR]

Microwave-assisted extraction (MAE) has been applied for extraction of paclitaxel from a cell culture. Solid phase C18 has been used for clean up of the sample obtained from the optimized condition of MAE. The factorial design shows that the temperature and ratio of methanol to water (as an extraction solvent) are effective and extraction time is not an essential parameter for MAE of paclitaxel from the cell culture. Recently, we introduced MAE for extraction of paclitaxel from the needle of Taxus baccata L. Paclitaxel was extracted from the cell culture and the needle of Taxus baccata L, have been purified by heart-cutting two dimensional high performance liquid chromatography (2D-HPLC) in analytical and semi-preparative scales. The columns used in the analytical chromatography were a Eurospher-100 C8 and Nucleosil-100 C18, respectively, and paclitaxel was eluted at a flow rate of 1 mL min-1 with 40:60 v/v and 45:55 v/v water/acetonitrile, respectively. These conditions used in analytical chromatography, have been extended to a semi-preparative scale in which the first column was a Eurospher-100 C8 and the second was a Eurospher-100 C18, but the mobile phase used consisted of 40:60 v/v water/acetonitrile eluted at a flow rate of 11 mL min-1. Detection has been carried out at a wavelength of 227 nm throughout the analysis in both methods. The yield and purity of paclitaxel obtained by this method were 89 and 89% for the cell culture and 85 and 83% for the needle of Taxus baccata L., respectively. [ABSTRACT FROM AUTHOR]

The comprehensive quality index (CQI) method which is used in evaluating the response performance of an ion-selective electrode has been presented recently. Under this strategy, a set of weighting factors (fs, fLR, fLD, ft,) involving a numerical calculation of CQI is the key parameter, not only influencing the magnitude of CQI value, but also inducing a different conclusion on the optimization of composition for poly(vinyl chloride) (PVC)-based sensing membranes, which was formulated with an electroactive substance, PVC, and plasticizer. In the present work, two techniques, multivariate regression and extremum analysis of a multiple function are used to study the optimization of the weighting factor. The best set of weighting factors obtained is as follows: fs=0.38, fLR=0.30, fLD=0.20, ft,=0.10. [ABSTRACT FROM AUTHOR]

The scope of the present study is to quantify copper in pharmaceutical products of veterinary use, using flame atomic absorption spectometry (f_AAS). The determination is carried out after samples' mineralization in a HCl:HNO3 (20:1, v:v) mixture followed by the instrument quantification and the validation of the result. The validation indicates that the interferences from the whole analytical system and their measurement do not influence the results and ensure that there are no other effects which have not been considered. [ABSTRACT FROM AUTHOR]

A nalbuphine ion-selective PVC membrane electrode based on ion-pair complex of nalbuphine with tetra phenyl borate was prepared with di-butyl sebacate as a plasticizer. The electrode exhibits a linear response with a Nernstain slope 59.6 mV decate-1 at 25°C with the concentration range of 1×10-6-1×10-2 M nalbuphine. The electrode response was not sensitive to pH changes from 3.5-7 and not affected by possible interfering species such as common inorganic cations, sugars and amino-acids. The electrode shows good stability, reproducibility and fast response. These characteristics of the electrode enable it to be used successfully for the determination of nalbuphine hydrochloride in pure form and in pharmaceutical preparations. [ABSTRACT FROM AUTHOR]

A method for direct determination of amoxicillin in pharmaceuticals using flow injection analysis (FIA) with UV detection adjusted at 228 nm, along with potentiometer and condoptometric methods are described. The best carrier solvent system consisted of an aqueous solution of methanol (10% v/v) with pH 9 pumped at a flow rate of 1 mL · min-1. The limit of detection (LOD) and quantification (LOQ) for FIA was calculated to be 3.3×10-7 M (S/N=3) and 1.0×10-7 M (S/N=10), respectively. Two pharmaceutical formulations containing amoxicillin were studied. In the analysis of the tablets, the RSD values were found to be 1.36 and 1.21 and 1.18 (for AMOKLAVIN®), 1.10 1.16 and 1.14 (for REMOXIL®) for FIA, potentiometer, and conduct metric methods, respectively. The proposed methods were applied to the pharmaceutical tablets and good results were obtained. These proposed methods are simple, fast, accurate, precise, and cost effective for the routine determination of amoxicillin in pharmaceutical preparations. [ABSTRACT FROM AUTHOR]

In this study some heavy metal uptake in mushroom species, their metal content in soil substrate and the relation in between metal concentration in mushroom and soil were investigated. Mushroom species and soil in which mushroom species were grown were collected from Tokat region of Turkey. Six different mushroom species and their underlying soil (0-10 cm layer) samples were analyzed for some heavy metals (Cu, Pb, Fe, Zn, Cd, Mn, Ni, Cr and Co). The analysis was performed with an atomic absorption spectrometer. The results indicate that in general, heavy metal contents in all mushroom species were lower than the underlying soil substrates except for some mushroom species. The results obtained from the analyses of mushroom and underlying soil samples were evaluated using linear correlation analysis and concentration factors to identify the metal accumulation of mushrooms. [ABSTRACT FROM AUTHOR]

A rapid, simple, and sensitive method is described for the determination of the food preservative sodium benzoate in soft drinks, various jams, and ketchup. The method utilizes high performance liquid chromatography followed by diode array detection. Chromatographic separation was achieved using a C18 reversed phase column and methanol: water (70:30, v/v) adjusted to pH 3.45 with glacial acetic acid as mobile phase, 0.45 mL . min-1 flow rate, and UV detection at 245 nm. Amoxicillin was used as the internal standard. The retention time observed for sodium benzoate and amoxicillin were 5.01 and 12.07 min, respectively. The method is selective, reliable, and reproducible with a relative standard deviation of 0.66 and linear in the range of 50-450 ng/mL sodium benzoate concentration. The limit of detection and limit of quantification concentrations were 61 pg/mL and 203 pg/mL, respectively. The proposed method can be used for the routine analysis of sodium benzoate in soft drinks and jams. [ABSTRACT FROM AUTHOR]

A simple, fast, and reproducible capillary electrophoretic method is developed and validated for analysis of melatonin in pharmaceutical preparations. The CE method was developed by using a fused silica capillary (60 cm×50 µm I.D.), phosphate buffer (50 mM, 3.0 pH) as the background electrolyte (BGE), 20 kV applied voltage with UV detection at 214 nm, and at a working temperature of 23±1°C. Linearity was observed in the concentration range from 10 to 100 µg/L with a correlation coefficient (R2) of 0.9996. The limits of detection and quantification achieved were 10 and 15 µg/mL, respectively. The percentage recovery of melatonin from pharmaceutical preparations was 95.0. Validation parameters prove the precision of the method and its applicability for the determination of melatonin in pharmaceutical tablet formulations. [ABSTRACT FROM AUTHOR]

A Fourier transform infrared (FT‐IR) spectrometric method was developed for the rapid, direct measurement of coenzyme Q10 (CoQ10) in different pharmaceutical products. Conventional KBr spectra were compared for the best determination of active substance in drug preparations. Lambert‐Beer's law and two chemometric approaches, partial least squares (PLS) and principal component regression (PCR+) methods, were used in data processing. [ABSTRACT FROM AUTHOR]

Carbon paste based biosensors for the determination of creatine and creatinine have been integrated into a sequential injection system. Applying the multi‐enzyme sequence of creatininase (CA), and/or creatinase (CI) and sarcosine oxidase (SO), hydrogen peroxide has been detected amperometrically. The linear concentration ranges are of pmol/L to nmol/L magnitude, with very low limits of detection. The proposed SIA system can be utilized reliably for the on‐line simultaneous detection of creatine and creatinine in pharmaceutical products, as well as in serum samples, with a rate of 34 samples per hour and RSD values better than 0.16% (n=10). [ABSTRACT FROM AUTHOR]

Method validation is one of the most important requirements of capillary electrophoretic (CE) methodologies. In spite of the advanced CE equipment available, this technique is still suffering with the problem of reproducibility due to certain nonconstant operational parameters. This article discusses the factors and reasons for nonreproducibility in CE methodologies, which include buffers, capillary, modes of injections, and applied voltage. Suggestions have also been presented to achieve maximum reproducibility in capillary electrophoresis experiments. [ABSTRACT FROM AUTHOR]

A simple and sensitive high performance liquid chromatographic method (HPLC) and direct flow injection analysis method (FIA) are described for the determination of trimetazidine HCl (TMZ) in tablets. A mobile phase consisting of methanol:0.02 mol · L -1 potassium dihydrogen phosphate:0.005 mol · L -1 sodium dihydrogen phosphate (62:5:33 v/v/v) was used for the resolution of the compound on a reversed phase column for HPLC. For the FIA method; the best solvent system was found to be consisting of methanol:water (10:90 v/v). A flow rate of l.2 mL · min -1 was pumped and active material was detected at 210 nm. Limit of detection (LOD) and limit of quantitation (LOQ) values were found to be 1.2×10 -7 mol · L -1 and 3.5×10 -7 mol · L -1 , respectively, for HPLC. LOD and LOQ values were found to be 2.35×10 -7 mol · L -1 and 7.04×10 -7 mol · L -1 , respectively for FIA. The results obtained from the analysis of TMZ tablet formulations were comparable using both methods. [ABSTRACT FROM AUTHOR]

A Fourier transform infrared (FT‐IR) spectrometric method was developed for the rapid, direct measurement of chromium (tris) picolinate [Cr(pic) 3 ] in different pharmaceutical products. Conventional KBr potassium bromine spectra were compared for best determination of active substance in drug preparations. Lambert‐Beer's law and two chemometric approaches, partial least squares (PLS) and principal component regression (PCR+) methods, were used in data processing. [ABSTRACT FROM AUTHOR]

S‐Carvone was isolated from Mentha spicata ( Fam. Lamiaceae ) and purified using chromatographic methods, and also characterized with GS‐MS, FTIR, and NMR techniques. The antioxidant activity of S‐carvone obtained from Mentha spicata was evaluated as in vitro using a total antioxidant activity test. Results were compared with a standard antioxidant, α‐tocopherol. The results indicate that S‐carvone possess high antioxidant activity compared to α‐tocopherol. [ABSTRACT FROM AUTHOR]

This study aimed at evaluating the in vitro antioxidant activity of water and ethanol extracts of juniper ( Juniperus communis L., Family Cupressaceae) fruit. The antioxidant properties of both Juniper extracts were studied using different antioxidant assays, including reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities. Both the water and the ethanol extracts exhibited strong total antioxidant activity. The concentrations of 20, 40, and 60 µg/mL of water and ethanol extracts of juniper fruit showed 75%, 88%, 93%, 73%, 84%, and 92% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, 60 µg/mL of standard antioxidant such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and a-tocopherol exhibited 96, 96, and 61 inhibitions on peroxidation of linoleic acid emulsion, respectively. However, both extracts of juniper had effective reducing power, free radical scavenging, superoxide anion radical scavenging, hydrogen peroxide scavenging, and metal chelating activities at these same concentrations (20, 40, and 60 µg/mL). Those various antioxidant activities were compared to BHA, BHT, and a-tocopherol as standard antioxidants. In addition, total phenolic compounds in both aqueous and ethanolic juniper extracts were determined as gallic acid equivalents. Accordingly, these results indicate that juniper has in vitro antioxidant properties and these may be major reasons for the inhibition of lipid peroxidation properties. [ABSTRACT FROM AUTHOR]

A rapid, sensitive, and reproducible HPLC method was developed and validated for the analysis of haloperidol in pharmaceutical preparations. The analysis was carried out on a monolithic silica column Chromolith Performance RP‐18e (100×4.6 mm). The mobile phase consisted of sodium phosphate (100 mM, pH 3.0)‐ acetonitrile (70∶30, v/v) at a flow rate from 1.0 mL/min with UV detection at 230 nm. The detection limit of haloperidol was 1 ng while the linearity range was 1 to 100 ng. The retention time and capacity factors were 4.26 min and 2.41, respectively. [ABSTRACT FROM AUTHOR]

Asthma is a public health problem for developed countries. It attacks all age groups but often starts in childhood. Theophylline ethanoate of piperazine in a suppository form is one of the treatments of asthmatic children. The pharmacokinetics of theophylline were evaluated in 24 healthy male subjects after administration of theophylline ethanoate of piperazine suppositories (PR) (Minophylline 500 mg. Alexandria Co.) and single injection intravenous (IV) of theophylline ethanoate of piperazine (Minophylline ampoules 500 mg Alexandria Co.). The theophylline serum levels were determined by an ELISA method. Peak theophylline plasma concentration, C max , (mean±S.D) was 21.5±2.10 µg/mL & 14±0.90 µg/mL; AUC (0‐t) values were 80.9 and 67. 4 µg · ml · hr for the reference IV preparation and suppositories, respectively. The median peak time, T max , was 0.5 hr for theophylline rectal administration. The above mentioned results demonstrate the possibilities of using theophylline (Minophylline Suppositories—500 mg Alexandria Co.) in asthmatic children in rural and desert areas away from health care personnel. [ABSTRACT FROM AUTHOR]

A direct high performance liquid chromatographic enantioselective separation of a set of racemic acidic drugs on the new immobilized and conventional coated amylose tris‐(3,5‐dimethylphenylcarbamate) chiral stationary phases (Chiralpak IA and Chiralpak AD, respectively) was studied using n ‐hexane and 2‐propanaol (80∶20 v/v), containing TFA (0.1%) as mobile phase. The separation and elution order of the enantiomers on both columns under the same conditions were compared. The effect of the immobilization of the amylose tris‐(3,5‐dimethylphenylcarbamate) chiral stationary phase on silica (Chiralpak IA) on the chiral recognition ability was noted, as the coated phase (Chiralpak AD) possesses a higher resolving power than the immobilized one (Chiralpak IA). A few racemates, which were not or poorly resolved on the immobilized Chiralpak IA were most efficiently resolved on the coated Chiralpak AD. However, the immobilized phase withstands the prohibited HPLC solvents such as dichloromethane, ethyl acetate, tetrahydrofuran, and others when used as eluents or as a dissolving agent for the analyte itself. The versatility of the immobilized Chiralpak IA in monitoring reactions performed in dichloromethane using direct analysis techniques without further purification, workup, or removal of dichloromethane, was studied on a representative example consisting of the lipase‐catalyzed enantioselective esterification of flurbiprofen, with n ‐butanol in dichloromethane as organic solvent. [ABSTRACT FROM AUTHOR]

The efficiencies of herbal medicines depend on the amount of active components in them, which could vary significantly in contents. Therefore, the quality control of herbal medicines is a very important issue. This review summarizes the true and false, producing region identification and quality evaluation of herbal medicines by means of their component overlapping infrared spectra (defined as infrared fingerprint spectra or IR FPS). The true and false identification could be performed with specific peaks and their absorption ratios. The producing region and quality of herbal medicines could be determined by analyzing the IR FPS with mathematical classification methods, such as potential component analysis, cluster analysis, and correlation coefficient analysis. [ABSTRACT FROM AUTHOR]

This article describes a new method for analysis of IR fingerprint spectra (FPS), which characterizes traditional Chinese medicine (TCM). Two new indices of IR FPS are introduced, namely, common peak ratio and variation peak ratio. Their values are calculated by means of the sequent analysis method, in which each sample's IR FPS of the components extracted from Glycyrrhizae root is as a standard, and the sequences are made in accordance with the values of their common peak ratios. This method can distinguish the Glycyrrhizae samples correctly, which belong to different species and are produced in different regions. The dual-index sequent method enables us to identify the Chinese herbs conveniently. [ABSTRACT FROM AUTHOR]

A high-throughput, high performance liquid chromatographic method was developed and validated for the determination of clopidogrel in pharmaceutical dosage forms. The analysis was performed at room temperature using a reversed phase monolithic silica column Chromolith Performance 18e (100 mm×4.6 mm I.D.). The mobile phase consisted of acetonitrile:phosphate buffer (50:50 v/v , pH 3.0) at a flow rate of 4.0 mL/min. The photodiode array detector was set at 235 nm. The developed method showed a good linear relationship in the concentration range from 1.0 to 40.0 µg/mL with a correlation coefficient of 0.999. The limit of detection and limit of quantification were 0.97 µg/mL and 3.52 µg/mL, respectively. [ABSTRACT FROM AUTHOR]

A simple HPLC analysis for the identification and quantification of vardenafil in a pharmaceutical tablet formulation was performed on a conventional Cm and Chromolith Performance RP-l8e monolithic columns with acetonitrile-phosphate buffer mixtures as mobile phases. The effects of the proportion of organic solvent (from 20% to 90%), phosphate buffer pH (from 2 to 7.5) and flow rate (from I to 5 mL/min) were studied. The best chromatographic conditions were 20:80 (v/v) acetonitrile-10 mM phosphate buffer, pH 3.0, as mobile phase at 1 mL/min flow rate for the C18 column, whereas 30:70 (v/v) acetonitrile-10 mM phosphate buffer, pH 3.0, as mobile phase at 2mL/min flow rate was best for the monolithic column. Methanol was found to be a suitable solvent for extraction of the active substance from tablets. For the C18 and monolithic column, the calibration plots were linear (R²= 0.9996 and 0.9997, respectively) in the concentration range 10-1000 μL. Limit of detection (LOD) and limit of quantification (LOQ) values were 0.10 and 0.31 μig/mL for the C18 and 0.11 mL and 0.32 μg/mL for the monolithic column. Intra-assay and inter-assay precision studies reflected a high level of reliability and reproducibility of the method. The proposed method is selective, precise (RSD - 0.45%), and accurate (recovery = 103-107%) in both columns used. [ABSTRACT FROM AUTHOR]

This article describes the synthesis of new conjugated progesterone-bovine serum albumin substances, used to obtain specific antisera toward this hormone and for progesterone assay kits. In general, these kits are designed to be used on the farm or at the local veterinary clinics. [ABSTRACT FROM AUTHOR]

The pharmacokinetics parameters and relative bioavailability studies of generic formulation enalapril tablets (Anapril® 20), the test product manufactured by Birzeit Pharmaceutical Company (Birzeit, Palestine) compared to the reference product Vasotec® tablets (Merck Sharpe Dohme, USA) were conducted in 18 healthy male volunteers following a single does, two-period, crossover design. Each volunteer received 20 mg enalapril tablets of both formulations with a one week washout period. Plasma collected over a period of 24 hours after administration were analyzed for the active metabolite enalaprilat by high performance liquid chromatography (HPLC). Pharmacokinetic parameters were determined by using non-compartmental analysis. The results indicated that Cmax 46.44 and 45.17 ng/ML. Tmax of 2.0 and 1.5 hr, AUC(0-24) of 244.06 and 237.41 ng · mL/hr, AUC(0-∞) were 294.71 and 282.21 ng · hr/mL and MRT were 4.74 and 4.70 hr, T1/2 4.95 and 5.0 hr, in test and reference products, respectively. The relative bioavailability based on AUC(0-∞) is 104.4%. It was concluded that both formulations were bioequivalent and that the test formulation can be used in clinical practice. [ABSTRACT FROM AUTHOR]

Recently, several studies have been reported on the trace element composition of milk, especially human milk. However, there is limited study comparing different types of milk collected from different animals and humans. This study describes the analysis of four trace elements (Cu, Zn, Cd, and Ni) in cows', goats', ewe', and human mature milk collected in Tokat, Turkey. Analysis was carried out by flame atomic absorption spectrometry (FAAS) and microwave digestion technique method, which was used to extract the trace elements from the milk samples. Our results are in agreement with the values reported in the literature, with the exception of nickel concentration in ewes' milk, which has the highest value reported. [ABSTRACT FROM AUTHOR]

A rapid high performance liquid chromatographic method was developed and validated for the determination ofα-lipoic acid in pharmaceutical dosage forms. The analysis was performed using a reversed phase Supelcosil LC-18(150 × 4 mm, 3 µm) column. The mobile phase consisted of acetonitrile:0.05 M potassium mono-phosphate, pH 2.5(45:55 v/v) at a flow rate of 0.8 mL/min. The UV-detector was set at 332 nm. The developed method showed a good linear relationship in the concentration range from 10–500 µg/mL with a correlation coefficient from 0.9999. The limit of detection and limit of quantification were 4.4 and 16.8 µg/mL, respectively. These values are high due to the low absorption coefficient of pure lipoic acid(ℇ = 150) at 332 nm. Statistical analysis proves that the method is reproducible. [ABSTRACT FROM AUTHOR]

Two enantioselective, potentiometric membrane electrodes, based on macrocyclic glycopeptide antibiotics—vancomycin and teicoplanin—were designed. Acetyl-L-carnitine was selected as model analyte. The linear concentration ranges for the proposed electrodes were 10−5–10−2 mol L−1 for the vancomycin-based electrode and 10−4–10−2 mol L−1 for the teicoplanin-based electrode, with slopes of 58.1 and 55.0 mV/p(acetyl-L-carnitine), respectively. The enantioselectivity was determined over D-carnitine. The surfaces of the electrodes are easily renewable by polishing on alumina paper. [ABSTRACT FROM AUTHOR]

A simple, fast, inexpensive, and reproducible high performance liquid chromatography and solid phase extraction (HPLC-SPE) method was developed for the analysis of 4-cyanophenol, phenol, 4-nitrophenol, and 4-chlorophenol in wastewater. The column used was a monolithic silica column, Chromolith Performance RP-18e 100-4,6 (100 × 4.6 mm). The mobile phase used was water–acetonitrile (80:20, v/v) at the flow rate ranging from 1 to 10 mL/min. The detection was achieved by using the ultraviolet (UV) mode at 246 nm. The detection limits of these phenolic compounds ranged from 1 to 5 ng. The separation of these phenolic compounds was achieved at a maximum time of 1.22 min by using 10 mL/min as the flow rate. The separation factors of all the studied phenols were in the range of 2.11 to 17.58, while the resolution factors were from 1.00 to 2.33. [ABSTRACT FROM AUTHOR]

Potentiometric, enantioselective electrodes responsive to R(+)- and S(−)-propranolol were constructed, based on a lipophilic cyclodextrin, 2-hydroxy-3-trimethylammoniopropyl-β-cyclodextrin as an ionophore. Different plasticizers, ortho-nitrophenyl octyl ether (o-NPOE) and bis(t-butylphntyl) adipate (BBPA), and inner filling solutions were studied. Electrode A, prepared with O-NPOE as a plasticizer, and 1.0 × 10−3 M R-enantiomer solution as an inner filling solution, has a sensitivity of 59.1 mV decade−1, with a limit of detection, −log a = 4.92. Electrode B, prepared with BBPA as a plasticizer and 1.0 × 10−3 M NH4Cl as an inner filling solution, shows a sensitivity of 60.0 mV decade−1, with a limit of detection, −log a = 5.28. Inorganic cations (Na+, K+, Ca2+, Zn2+) and racemic and R-sabutamol did not interfere with the measurement. The enantioselectivity coefficient (K±pot), determined in 1.0 × 10−3 M appropriate enantiomer solutions, was 0.20. [ABSTRACT FROM AUTHOR]

The antioxidant properties of marshmallow (Althaea officinalis L., Fam. Malvaceae) ethanolic extract was evaluated using different antioxidant tests, including reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities. The extract of marshmallow (A. officinalis L.) exhibited strong total antioxidant activity. The concentration of 50, 100, and 250 µg/mL of ethanol extract of marshmallow (A. officinalis L.) showed 85.5%, 91.2%, and 96.4% inhibition on peroxidation of linoleic acid emulsion, respectively. On the other hand, 100 µg/mL of standard antioxidant such as butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), and α-tocopherol exhibited 94.5%, 99.1%, and 80% inhibition on peroxidation of linoleic acid emulsion, respectively. The extract of marshmallow (A. officinalis L.) had effective reducing power, free radical scavenging, superoxide anion radical scavenging, and metal chelating activities at same concentration (50, 100, and 250 µg/mL). Those various antioxidant activities were compared with standard antioxidants such as BHA, BHT, and α-tocopherol. [ABSTRACT FROM AUTHOR]

The construction of an enantioselective, potentiometric membrane electrode (EPME) based on carbon paste impregnated with macrocyclic antibiotic vancomycin (VCM) as chiral selector is described. The proposed electrode was applied for the assay of S-perindopril (S-Pdp) raw material and from its pharmaceutical formulation (Coversyl® tablets) by use of a direct potentiometric method. The surfaces of the electrode can easily be renewed by simply polishing on an alumina paper. [ABSTRACT FROM AUTHOR]

A direct enantioselective high-performance liquid chromatography (HPLC) method was employed successfully for determination of the enantiomeric purity of L-arginine. The elaborated method used teicoplanin macrocyclic antibiotic chiral stationary phase (CSP), known as Chirobiotic T, with a reversed-phase mobile phase consisting of methanol:50 mM sodium dihydrogen phosphate buffer, pH 4.6 (2:8, v/v), at a flow rate of 1.0 mL/min and UV detection at 214 nm. Linearity, precision, accuracy, and the quantitation limit were determined. The method proved to be capable of determining 0.0025% (w/w) of D-arginine (the enantiomeric impurity) contrary to the pharmacopoeial limit measurement, in which only amounts of D-arginine higher than 1.5% (w/w) caused the measurement to fail. [ABSTRACT FROM AUTHOR]

The enantiomers of eight pyrethroid insecticides have been separated by three polysaccharide-based chiral stationary phases (CSP), namely Chiralcel OD-R, Chiralpak AD, and Chiralcel OJ, both in reversed and normal phase modes. Deltamethrin, fenpropathrin, and lambdacyhalothrin could be baseline separated on Chiralcel OD-R in reversed phase mode with Rs values of 1.39, 1.29, and 1.17, respectively. However, the best separations for deltamethrin and fenpropathrin and tau-fluvalinate were achieved when the mobile phase was 15% of ethanol in water. Lambda-cyhalothrin enantiomers were separated using a mobile phase composed of 30% of acetonitrile : water (30 : 70 v/v). In normal phase mode, Chiralcel OJ gave better chiral separation for those pyrethroids than that of Chiralpak AD. The chiral separation conditions for eight pyrethroid insecticides have been discussed. [ABSTRACT FROM AUTHOR]

This investigation was carried out to evaluate the bioavailability of the generic product of digoxin 0.25 mg (cardixin) relative to a reference product, lanoxin (0.25 mg) tablets. The two formulations were found to be similar in in vitro assay (dissolution) as stipulated by USP XXIII. The comparison is carried out on 12 healthy male volunteers, who received a single dose (0.25 mg) of cardixin (product A) lanoxin (product B) as a reference product orally in the fasting state, in a randomized balanced two-way crossover design. After dosing, serial blood samples were collected for a period of 12 hr. Plasma samples were analyzed for digoxin by a sensitive and validated enzyme immunoassay method (ELISA). The maximum plasma concentration curve, up to the last measurable concentration (AUC0-24), was analyzed under the assumption of a multiplicative model. The time to maximum concentration (Tmax) was analyzed, assuming an additive model. The parametric confidence intervals (90%) of the mean values of the pharmacokinetic characteristics (AUC0-12 and Cmax) for A:B ratio were, in each case, well within the bioequivalence acceptable range of 80-125%. [ABSTRACT FROM AUTHOR]

Monocrystalline natural diamond, L-amino acid oxidase (L-AAOD), D-amino acid oxidase (D-AAOD), and paraffin oil were used for the design of the modified diamond paste. The technique used for the direct voltammetric assay was differential pulse voltammetry (DPV) with applied potential pulse amplitude of 25 mV vs. Ag/AgCl. Using the new amperometric biosensors L-pipecolic acid (L-PA) and D-pipecolic acid (D-PA) were determined reliably from serum samples at 700 and 200 mV vs. Ag/AgCl, respectively, with low limits of detection. [ABSTRACT FROM AUTHOR]

A sequential injection analysis/immunosensor system is proposed for the analysis of T3 in serum with a rate of 75 samples/hr. The immunosensor design is based on the physical immobilization of anti-T3 in carbon paste. The working concentration range of the immunosensor in a sequential injection analysis system is between 3.4 and 340 ng/mL with a limit of detection of 2.19 ng/mL. The system is very reliable and very easy to design and operate. [ABSTRACT FROM AUTHOR]

A simple, fast, inexpensive, and reproducible method was developed for the analysis of cerivastatin in human plasma and identification of its metabolite by capillary electrophoresis (CE). The back ground electrolyte (BGE) used was phosphate buffer (50 mM, pH 3.5) with 15 kV as the applied voltage. The detection was achieved by using UV mode at 254 nm and the detection limit of cerivastatin and its metabolite was approximately 5 µg mL−1. The separation and resolution factors were 1.07 and 4.01, respectively. The recovery of cerivastatin from plasma using SPE was 80%. [ABSTRACT FROM AUTHOR]

A novel, rapid, accurate, and sensitive automated high-performance liquid chromatographic assay was developed to determine biotin (BI) in pharmaceutical dosage forms and to follow its dissolution pattern. An efficient separation of BI was performed using a stainless steel Supelcosil LC-18 column (25 cm × 4.6 mm; 5 µm particle size) preceded by a Sentry guard column. The mobile phase consisted of an 80% aqueous solution (pH 2.5 adjusted with phosphoric acid) containing 20% acetonitrile delivered at a flow rate of 1.5 mL/min. The compound of interest was detected using a photodiode array detector at 190 nm. Under these conditions, the assay run time was 6 min since the retention time of BI was 3.8 ± 0.2 min. The detector response was linear for BI in alkaline solution (r > 0.999) in the range of 0.01–2.00 µg/mL. The detection and the quantification limits for BI were 0.005 and 0.01 µg/mL, respectively. The dissolution data showed RSD% of 3.6–12.7% for all BI determined concentrations. No interferences were observed from the tablet's excipients. The drug content in each tablet ranged from 100 to 102.5%. The dissolution study of BIOTIN® tablets revealed that BI in USP media (pH 1.2) showed no dissolution up to 3 hr. However, a first order release kinetic, with dissolution T50% of 14 ± 1.3 min, was observed in USP media (pH 7.4). [ABSTRACT FROM AUTHOR]

Molecular mechanics (MM) and molecular dynamics (MD) were used to study the π–π interaction between polynuclear aromatic hydrocarbon (PAH) and pyrene bonded silica phase. There was a good correlation coefficient (r = 0.9330, P = 2.4 × 10−4) between the logarithmic retention time (ln Tr) of PAHs and −ΔG. However, there was no linearity between the retention time of substituted benzene or naphthalene compounds on pyrene bonded silica stationary phase and ΔG. Quantitative structure–retention relationship (QSRR) had been used to study the relationship of retention time and microstructure. However, by using QSRR for the substituted benzene or naphthalene derivatives, we obtained good correlation coefficient between retention time and microstructures (r2 = 0.962, F-test = 104.198). The MM, MD, and QSAR are very useful methods to study the π–π interaction in chromatography. [ABSTRACT FROM AUTHOR]

The enantiomers of fourteen O,O-dialkyl-2-benzyl-oxycarbonyl-aminoaryl- methyl-phosphonates are directly separated on tris(3,5-dimethyl-phenylcarbamate) amylose chiral stationary phases, known as Chiralcel AD. All of the selected compounds are baseline separated. The influence of the position and properties of substituents in benzene rings, the length and steric hindrance of alkoxyl groups of the phosphonate ester on the chiral separation are discussed. When the substituents are in the para-position of the benzene ring, the separation factor is in the following order αp-NO2 ≫ αp-Cl > αp-CH3 > αp-H > αp-OCH3. When the same substituent is in a different position of the benzene ring, the order of the separation factor is αp-Cl > αm-Cl and αp-NO2 ≫ αm-NO2. The values of the separation factor α of the enantiomers where R1 substituent is a hydrogen (R1 = H) are always smaller than those of the enantiomers with p-Cl substituent, whether R2 was Me, Et, Pr or i-Pr. Compounds with different substituent R2 and R1 where the substituent is H or p-Cl, the α values always show an order of αPr > αEt > αMe > αi-Pr. The chiral discrimination in the amylose tris(3,5-dimethyl-phenylcarbamate) was based on π–π interaction and H-bond interaction. [ABSTRACT FROM AUTHOR]