Showing papers in "Journal of Chromatographic Science in 2009"

Determination of Paracetamol and Tramadol Hydrochloride in Pharmaceutical Mixture Using HPLC and GC-MS

Abstract: Two simple, rapid, and selective analytical procedures were developed for the simultaneous determination of paracetamol (PR) and tramadol hydrochloride (TR) in a binary mixture using high-performance liquid chromatography with UV detection (HPLC-UV) and gas chromatography with mass spectrometry (GC-MS) techniques. HPLC resolved the two compounds on a Hypurity Advance column using a mobile phase consisting of phosphate buffer pH 6.3 and acetonitrile (90:10, v/v). PR and TR were detected by their UV absorption at 220 nm. GC-MS involved separation of the two compounds using 100% dimethylpolysiloxane (Rtx-1) column with temperature programming. The EI mass spectrum of PR was characterized by [M](+) at 151 and a base peak at m/z 109 while TR mass spectrum was characterized by [M](+) at 263 and a base peak at m/z 58. Quantification of the analytes in both methods was based on measuring the peak areas. The reliability and analytical performance of the proposed methods including linearity, ranges, precision, accuracy, detection, and quantification limits were statistically validated. Calibration curves were linear over the range 10-400 microg/mL for both PR and TR using the HPLC method and over the ranges of 75-500 and 25-350 microg/mL for PR and TR, respectively, using the GC-MS method. The proposed methods were successfully applied for the determination of the two compounds in laboratory-prepared mixtures and in commercially available tablet formulation. No interference peaks were observed from common pharmaceutical adjuvants. The results compared favorably with those obtained by a derivative spectrophotometric method.

On-line coupling of solid-phase extraction to liquid chromatography--a review.

Abstract: Solid-phase extraction (SPE) is an effective sample preparation method for removal of interfering compound and enrichment of analyte. Liquid chromatography (LC) with various detectors is a main separation and detection technique used in the analytical field. This article reviews the literatures about the on-line coupling of SPE with LC. The advantages of on-line coupling are reduction of analysis time, sample contamination, and analyte losses, as well as improvement of precision and accuracy. The SPE sorbents including traditional materials, such as chemically bonded silica, ionexchange and carbon-based materials, and some novel sorbents, such as restricted access material, molecularly imprinted polymer, immunosorbent, and monolithic material, used in the on-line analysis are discussed in detail. The on-line coupling of SPE-LC to other sample preparation techniques, such as supercritical fluid extraction, subcritical water extraction, microwave-assisted extraction, ultrasound-assisted extraction, and derivatization technique are also reviewed.

The Analysis of Halogenated Flame Retardants by GC-HRMS in Environmental Samples

Abstract: The analytical conditions required to determine polybrominated diphenylethers (PBDEs) and a variety of other halogenated flame retardants (HFRs) by gas chromatography-high resolution mass spectrometry (HRMS) in environmental samples are reported. HRMS can be used to analyze brominated diphenylethers (BDEs), 2,2',4,4',5,5'-hexabromobiphenyl (BB-153) as well as for a number of other emerging HFRs like allyl 2,4,6-tribromophenyl ether (ATE), 2-bromoallyl 2,4,6-tribromophenyl ether (BATE), 2,3-dibromopropyl 2,4,6-tribromophenyl ether (DPTE), octabromotrimethylphenylindane (OBIND), pentabromoethylbenzene (PBEB), hexabromobenzene (HBB), 1,2-bis (2,4,6-tribromophenoxy) ethane (BTBPE), decabromodiphenylethane (DBDPE), Dechlorane Plus (DP), hexachlorocyclopentadienyl-dibromocyclooctane (HCDBCO), tetrabromoethylcyclohexane (TBECH), 1,2,5,6-tetrabromocylcooctane (TBCO), 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EHTeBB), and bis(2-ethly-1-hexyl)tetrabromophthalate (BEHTBP). The detection in environmental matrices and use of these non-BDE flame retardants is reviewed. A method for the analysis of PBDEs by isotope dilution HRMS and 16 other halogenated compounds primarily used as flame retardants is reported. A survey of selected environmental samples, which included Lake Ontario surface and tributary sediments, municipal wastewater effluent, sludge, and mussel tissues, detected PBDEs, DP, DBDPE, BTBPE, PBEB, BB-153, and HBB.

A single-step extraction method for the determination of nicotine and cotinine in Jordanian smokers' blood and urine samples by RP-HPLC and GC-MS.

Abstract: A simple, rapid, reliable, and low cost one-step extraction method is developed and validated for the determination of nicotine and cotinine in human plasma and urine in smokers using reversed-phase high-performance liquid chromatography (RP-HPLC) and gas chromatography-mass spectrometry (GC-MS). The run times are 16 and 10 min for HPLC and GC-MS, respectively. The method is validated over a wide linear range of 1-5000 ng/mL with correlation coefficients being consistently greater than 0.9985. The criteria considered for validation are: limit of quantitation, linearity, accuracy, precision, recovery, specificity, and selectivity. This study is aimed to estimate the nicotine and cotinine in Jordanian smokers' blood and urine samples; to study the relationship between the concentration of nicotine in urine and plasma samples; and to investigate the effect of pH on the extraction of nicotine and cotinine in urine samples. In the presented study, one hundred blood and urine samples are collected from eighty smokers and twenty nonsmokers. Samples are taken from the same volunteer at the same time after each volunteer fills in a questionnaire. Results of nicotine concentrations in smokers' plasma are in the range of 181-3702 ng/mL with an average of 1263.1 ng/mL, whereas nicotine in urine samples is in the range of 1364-1972 ng/mL, with an average of 1618 ng/mL. Cotinine concentrations in smokers' plasma are in the range of 21-4420 ng/mL with an average of 379.4 ng/mL, whereas cotinine in urine is in the range of 6-3946 ng/mL with an average of 865 ng/mL. Statistical analysis indicates highly significant differences in nicotine and cotinine concentrations in smoker samples compared with nonsmoker samples (p<0.05).

Simultaneous Determination of Seven Active Flavonols in the Flowers of Abelmoschus manihot by HPLC

Abstract: A high-performance liquid chromatography method is developed for the simultaneous quantification of seven flavonols, namely quercetin-3-O-robinobioside, hyperin, isoquercetin, hibifolin, myricetin, quercetin-3'-O-glucoside, and quercetin, in the flower of Abelmoschus manihot. These seven flavonols are selected as chemical markers because they are the major pharmacologically active constituents in the flower. The method involves the use of a Thermo ODS-2HYEPRSIL reversed-phase column (5 microm, 250 x 4.6 mm) at 25 degrees C with a mixture of acetonitrile and aqueous H(3)PO(4) as the mobile phase and detection at 370 nm. The recovery of the method is 94.31-107.08% with an RSD 0.9996) is obtained for all the flavonoids. The current assay method can be readily utilized for the determination of the flavonols present in the flower and is considered to be suitable for the quality control of A. manihot samples. The comparison of flowers collected from nine locations shows that flavonoid glucoside is more stable than aglycon in the flower. This is the first study that analyzes the stability of flavonoids in the flower of A. manihot. This research also provides important evidence that the flower is a potentially abundant resource for obtaining hibifolin.

GC Determination of Acetone, Acetaldehyde, Ethanol, and Methanol in Biological Matrices and Cell Culture

Abstract: A gas chromatography with flame ionization detection method (GC-FID) with direct injection, using a capillary column, was validated to determine ethanol, acetaldehyde, methanol, and acetone in different human matrices, such as whole blood, vitreous humour, and urine, with clinical and forensic interest. This method was also employed to quantify these compounds in cell culture medium, thus being useful in basic research. A good peak resolution was achieved, with linear correlation between concentration and peak areas for all the compounds in all the matrices. The inter- and intra-day precisions of the method were always under 15% and 10%, respectively. The accuracy of the method, calculated as the percentage of the target concentration, was within the acceptable limits. The obtained limits of detection were below 0.85 mg/L for acetaldehyde and below 0.75 mg/L for the other considered compounds. The small injection volume and the high split ratios applied, allied to the high performance of the GC column, resulted in very good peak resolution and high sensitivities. This method is easy to perform, making it suitable for the routine of clinical biochemistry and forensic laboratories.

Analytical challenges and recent advances in the determination of estrogens in water environments.

Abstract: Estrogens have been shown to be present in the water compartment, mainly due to the inefficient removal in wastewater treatment plants (WWTP). The concentrations of these compounds, although very low (low ng/L), are sufficient to induce estrogenic responses and alter the normal reproduction and development of wildlife organisms. The compounds have been determined, by a variety of analytical procedures, in the influents and effluents of WWTP, fresh waters, rivers, and even drinking waters. Determination of natural and synthetic estrogens and progestogens in natural water is, however, a difficult analytical task, because of the very low detection limits required and the complexity of the matrix. Thus, in general, complicated, timeconsuming extraction and purification processes, usually based on the application of solid‐liquid extraction, are performed before final determination by immunoassay, high-performance liquid chromatography, or gas chromatography, very often coupled with mass spectrometry. This paper reviews the analytical methods so far described for the analysis of estrogens, which are currently important environmental pollutants presented in natural and wastewaters. Discuss of the main steps, from sampling up to analysis, and the techniques most commonly used in the determination is presented.

Comparison of liquid/liquid and solid-phase extraction for alkaline drugs.

Abstract: The extraction of drugs from biological matrices is an essential specimen preparation step in current forensic postmortem laboratories. Traditionally, liquid/liquid extractions (LLE) were developed and employed to screen for the general unknown. However, solid-phase extractions (SPE) are becoming more popular as the availability of columns with suitable stationary phases increased. The purpose of this work was to determine if switching from an existing LLE to SPE was feasible. The limits of detection (LOD) for 122 drugs and metabolites were determined in blood following SPE and compared to previously determined LOD's by LLE, if available. There were 41 drugs that had LOD's in blood established by both methods; LLE had a lower LOD for 8 drugs (19.5%), SPE had a lower LOD for 16 (39%), and the LOD's were comparable in the remaining drugs. Although SPE cartridges were more expensive than LLE, SPE was determined to be a faster technique and doubled the number of specimens that could be extracted by one analyst within a specific timeframe. The SPE method utilized enabled the detection of several drugs not detectable after LLE (most notably, morphine and benzoylecgonine) and allowed the extraction of weakly acidic and neutral drugs with only one extra step.

Degradation of tocopherols in rice bran oil submitted to heating at different temperatures.

Abstract: The objective of this study has been to evaluate the stability of alpha-, (gamma+beta)-, and delta-tocopherols in rice bran oil chemically refined submitted to heating in a heater without air circulation and shielded from light, at temperatures of 100 degrees C and 180 degrees C. The collection of samples took place after 48, 96, 144, 192, 240, 336, and 432 h of heating and were stored in amber-colored flasks and frozen (-18 degrees C). The analyses of tocopherols took place in accordance with the method by Chen and Bergman (2005), with slight modifications, utilizing a system of high efficiency system of liquid chromatography. It was observed that the alpha-tocopherol is present at higher concentration in rice bran oil (328.4 mg/kg), followed by (gamma+beta)-tocopherol (99.1 mg/kg), and delta-tocopherol (7.7 mg/kg). The alpha-tocopherol in rice bran oil submitted to 100 degrees C showed a reduction of 28.65% at the end of 432 h of heating whereas when submitted to 180 degrees C temperature; its reduction was of 100% at the end of 240 h of heating. The contents of (gamma+beta)- and delta-tocopherol in rice bran oil at the end of 432 h of heating at 100 degrees C was of 79.9 and 6.4 mg/100 g, respectively.

Eugenol and methyl eugenol chemotypes of essential oil of species Ocimum gratissimum L. and Ocimum campechianum Mill. from Colombia.

Abstract: Essential oils chemical constituents of leaves of O. gratissimum and O. campechianum of the Lamiaceae family, collected in Choco of northwest Colombian, were obtained by microwave-assisted hydrodistillation and analyzed by gas chromatography coupled with mass spectrometry. A total of 33 and 37 compounds were identified in the essential oil of O. gratissimum and O. campechianum, respectively. O. gratissimum's main essential oils were eugenol (43.2%), 1,8-cineole (12.8%) and beta-selinene (9.0%); in the O. campechianum essential oil, the main components were methyl eugenol (12.0%), germacrene D (10.1%), and eugenol (9.0%). Main distribution of compounds in these essential oils are 25.0% monoterpenes hydrocarbons, 15.0% monoterpenes oxygenated, 35.0% sesquiterpenes hydrocarbons, 7.5% other oxygenated components for O. gratissimum, 33.9% sesquiterpenes hydrocarbons, and 10.7% their respective oxygenated derivates; for O. campechianum, the distribution was 10.7% monoterpenes hydrocarbons and 7.1% their respective oxygenated derivates and 3.6% phenylpropanes. According to the essential oils chemical composition of Ocimum gratissimum and O. campechianum, they are classified as eugenol and methyl eugenol chemotype, respectively.

A simple RP-HPLC method for the simultaneous quantitation of chlorocresol, mometasone furoate, and fusidic acid in creams.

Abstract: A simple, specific, and precise high-performance liquid chromatographic method is developed and validated for the simultaneous determination of chlorocresol (CC), mometasone furoate (MF), and fusidic acid (FA) in a cream formulation. The isocratic mobile phase consists of 1.5% w/v aqueous ammonium acetate buffer-acetonitrile, 55:45 (v/v) of pH 3.8. The column contains octylsilyl chemically bonded to porous silica particle (Symmetry C8, 150x3.9 mm, 5 microm). The detection is carried out using variable wavelength UV-vis detector set at 240 nm. The solutions are chromatographed at a steady flow rate of 1.0 mL/min. The current method separates CC, MF, and FA in less than 8 min with good resolution and peak shapes, minimal tailing, and with retention factors between approximately 1 and 5. Linearity range and percent recoveries for CC, MF, and FA are 10-30, 10-30, and 200-600 microg/mL; and 100.31%, 100.38%, and 100.34%, respectively. The method is validated according to International Conference on Harmonization guidelines and proven to be suitable for stability testing, content uniformity testing, and quality control of these compounds in pharmaceutical preparations.

Monolithic Silica Stationary Phases in Liquid Chromatography

Abstract: During the last few decades, monolithic stationary phases (based on silica and polymers) have been used for fast separations in high-performance liquid chromatography (HPLC) and capillary electro-chromatography (CEC). The present article describes the preparation, properties, and applications of these stationary phases. Attempts have been made to discuss the preparation of reversed-phase monolithic HPLC columns and CEC capillaries. The chromatographic properties of these phases have been described. The applications included their use in HPLC and CEC modalities of liquid chromatography. The optimization of separations of various molecules on these phases has been discussed. Efforts were also made to predict the future perspectives of monolithic stationary phases.

High-performance liquid chromatographic method for the determination of cyromazine and melamine residues in milk and pork.

Abstract: A high-performance liquid chromatography method is described in this paper. The method uses NH(2) column and 97% acetonitrile eluate to determine the insecticide cyromazine and metabolite melamine residues in milk and pork. Samples were treated with NaOH and extracted with acetonitrile containing 20% NH(4)OH. Target analytes of samples were cleaned up and concentrated by C(18) column solid-phase extraction. A separation for cyromazine and melamine was achieved, and respective retention times were 8 and 12 min. The calibration curves for cyromazine and melamine were linear in a concentration range of 0.01-1.0 microg/mL, with correlation coefficients of 0.9999 and 0.9997, respectively. The limit of detection of both compounds was 0.2 ng, and the limit of quantitation was 0.02 mg/kg. Recoveries of cyromazine and melamine at fortified levels of 0.02, 0.05, and 0.1 mg/kg ranged from 84.5-90.8%, and 83.6-91.3%, respectively, with coefficient of variation of 3.1-7.8%.

Rapid Identification of Polyphenol C-Glycosides from Swertia franchetiana by HPLC-ESI-MS-MS

Abstract: High-performance liquid chromatography coupled to positive ion electrospray ionization tandem mass spectrometry (MS) and diode array detection was employed to identify the polyphenol C-glycosides in the extract of Swertia franchetiana, a traditional Chinese/Tibetan herb. The neutral loss scan of the extract of S. franchetiana using the characteristic losses of 120 and 150 u provided a detailed profile of the polyphenol C-glycosides in the complex mixture. On-line UV spectroscopy along with MS-MS and MS-MS-MS mass spectra analysis produced with and without in-source collision induced dissociation was contributed to discriminate and identify the polyphenol C-glycosides. Three xanthone C-glycosides (i.e., mangiferin, isomangiferin, and 1,6,7-trihydroxyl-2-C-glucosexanthone) and three flavone C-glycosides (i.e., isoorientin, isovitexin, and swertisin) were tentatively identified. Isomangiferin and 1,6,7-trihydroxyl-2-C-glucosexanthone were for the first time found in this plant.

QSRR Prediction of the Chromatographic Retention Behavior of Painkiller Drugs

Abstract: Quantitative structure-retention relationship (QSRR) analysis is a useful technique capable of relating chromatographic retention time to the chemical structure of a solute. A QSRR study has been carried out on the reversed-phase high-performance liquid chromatography retention times (log tR) of 62 diverse drugs (painkillers) by using molecular descriptors. Multiple linear regression (MLR) is utilized to construct the linear QSRR model. The applied MLR is based on a variety of theoretical molecular descriptors selected by the stepwise variable subset selection procedure. Stepwise regression was employed to develop a regression equation based on 50 training compounds, and predictive ability was tested on 12 compounds reserved for that purpose. The geometry of all drugs was optimized by the semi-empirical method AM1 and used to calculate different molecular descriptors. The regression equation included three parameters: n-octanol-water partition coefficient (log P), molecular surface area, and hydrophilic-lipophilic balance of the drug molecules, all of which could be related to retention time property. Modeling of retention times of these compounds as a function of the theoretically derived descriptors was established by MLR. The results indicate that a strong correlation exists between the log tR and the previously mentioned descriptors for drug compounds. The prediction results are in good agreement with the experimental values.

HPLC Determination of Eight Polyphenols in the Leaves of Crataegus pinnatifida Bge. var. major

Abstract: A simple high-performance liquid chromatographic (HPLC) assay using the internal standard method is developed for the simultaneous determination of eight polyphenols. The analyzed compounds isolated from the leaves of Crataegus pinnatifida Bge. var. major include chlorogenic acid, vitexin-4"-O-glucoside, vitexin-2"-O-rhamnoside, vitexin, rutin, hyperoside, isoquercitrin, and quercetin. HPLC analysis is performed on a Diamonsil C18 analytical column (150 x 4.6 mm, i.d., 5-microm) using solvent (A) acetonitrile-tetrahydrofuran (95:5, v/v) and (B) 1% aqueous phosphoric acid as the mobile phase with UV absorption at 270 nm. The calibration curves of the eight polyphenols are linear (r(2) > 0.9992) over the concentration range of 0.0894-120.0 microg/mL. The mean recoveries are 95.4% to 98.1%. The results indicate that the HPLC method developed can easily be applied to the determination of eight polyphenols in the leaves of Crataegus pinnatifida Bge. var. major.

Determination of Organophosphorus Pesticides in Underground Water by SPE-GC-MS

Abstract: A rapid and effective method is developed for the determination of organophosphorus pesticides (dichlorovos, methyl parathion, malathion, and parathion) in underground water by solid-phase extraction (SPE)-gas chromatography-mass spectrometry. Some important extraction parameters including types of SPE adsorbents, elution solvents, and injection volume of water samples are optimized. The use of Cleanert-PEP polymer SPE column improved higher extraction efficiencies than the C18 SPE column commonly used. Water samples are extracted using Cleanert-PEP as SPE adsorbent and ethyl acetate as elution solvent. Precision values expressed as relative standard deviation for 1 microg/L of spiked water sample are in the range of 1.6-4.0%. Dichlorvos, methyl parathion, malathion, and parathion are linear in the range of 0.1-1.0 microg/L (r2=0.9976), 0.1-2.0 microg/L (r2=0.9883), 0.1-2.0 microg/L (r2=0.9798), and 0.055-1.1 microg/L (r2=0.9790), respectively. The limits of detection for spiked water samples are in the range of 4-10 ng/L. The optimized method is applied to the determination of underground water samples. Recoveries are between 59.5% and 94.6% for spiked underground water samples. The benefit of the method developed is rapid, simple, and has good repeatability.

Trace Analysis of Polar Pharmaceuticals in Wastewater by LC-MS-MS: Comparison of Membrane Bioreactor and Activated Sludge Systems

Abstract: In order to assess the efficiency of wastewater treatment plants in removing pharmaceuticals from wastewater, sensitive and reliable methods are necessary for trace analysis of these micropollutants in the presence of a highly complex matrix. In this study, conventional activated sludge (CAS) and membrane bioreactor (MBR) treatment systems are compared in eliminating pharmaceuticals in wastewater. The pharmaceuticals investigated include aceclofenac, carbamazepine, diclofenac, enalapril, and trimethoprim. Analysis is performed using a liquid chromatograph with hybrid linear ion-trap mass spectrometer equipped with a polar reversed-phase column to achieve good separation and minimize matrix effects. To pre-concentrate the samples, the use of two types of solid-phase extraction packing materials in tandem assures good recoveries of all the target analytes. In the influent, the concentration of these compounds ranges from 0.09 to 1.4 microg/L. Diclofenac shows resistance to degradation in the CAS but is amenable to degradation in the MBR. Trimethoprim and enalapril are only slightly eliminated in the CAS but are reduced by more than 95% in the MBR. Carbamazepine removal is negligible, while aceclofenac is only 50% reduced in CAS and MBR. In general, these results indicate that MBR has a higher efficiency in removing some polar pharmaceuticals in wastewater.

Effect of mobile phase pH and organic content on LC-MS analysis of nucleoside and nucleotide HIV reverse transcriptase inhibitors.

Abstract: The HIV-1 reverse transcriptase inhibitors tenofovir (TFV), emtricitabine (FTC), and lamivudine (3TC) are widely used in the treatment of HIV-1-infected persons and are now being considered as chemoprophylactic drugs for the prevention of sexual HIV transmission. Assays that measure these drugs after either oral or topical application are critical to the understanding of the pharmacokinetic profiles of the drugs and allow a rational design of chemoprophylaxis modalities for evaluation in macaque models and human trials. We developed a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method for sensitive measurement of FTC, 3TC, and TFV in plasma from macaques. To achieve detection limits of 10 pg on column, the plasma analytes were measured using acidic mobile phase and positive electrospray ionization MS-MS detection. However, this caused various chromatographic peak distortions, which were minimized by using mobile phase additives that induced ion-pairing interactions. Chromatographic peak tailing was minimized by adjusting the organic mobile phase concentration while considering the simultaneous effect of organic content on buffer and analyte pKa. Injection solution interferences were corrected by chromatographic peak focusing using column switching. The final method provides simultaneous measurement of all three analytes with a wide linear range of 1-3000 ng/mL using 0.1 mL plasma (10 pg on column) and coefficients of variation from 5% to 15% in the high ng/mL concentration range and from 16% to 20% in the low ng/mL concentration range.

Rapid and chemically selective nicotine quantification in smokeless tobacco products using GC-MS.

Abstract: In recent years, there has been a rapid proliferation of smokeless products with a wide range of nicotine content and flavoring formulations that may appeal to new users and existing cigarette smokers. The CDC nicotine method, which employs gas chromatography-flame ionization detection (GC-FID), provides a robust means for measuring nicotine in smokeless tobacco. However, several compounds, identified in a few flavored smokeless products, interfere with nicotine quantification using GC-FID. In response, the standard nicotine method (26.7 min run time) was modified to use faster GC ramping (3.7 min run time) and detection with mass spectrometry (GC-MS) in selected ion-monitoring mode to reduce signal interferences that can bias nicotine values. Seven conventional smokeless samples (n = 12) and blank tobacco samples spiked at three nicotine concentration levels (n = 5) were analyzed using the GC-FID and GC-MS methods and found to be in excellent agreement. However, only the GC-MS method provided confirmation of chromatographic peak purity in certain highly flavored products. The GC-MS method is not intended to replace the GC-FID method but to provide a method versatile enough to analyze a wide range of nicotine values in domestic and international samples of varying complexity. Accurate nicotine quantification is important for determining total nicotine content in tobacco and in subsequent calculations of un-protonated nicotine content.

Simultaneous Determination of Salbutamol, Ractopamine, and Clenbuterol in Animal Feeds by SPE and LC—MS

Abstract: A liquid chromatography-mass spectrometry (LC-MS) method for the simultaneous determination of salbutamol, ractopamine, and clenbuterol in commercial feeds was developed. Samples were extracted with phosphoric acid-methanol solution, and further clean-up was achieved with a C18 cation exchange mixed mode cartridge. Separation of analytes was developed on a C18 column with 0.01 M aqueous ammonium formate solution (pH 3.8)-acetonitrile by gradient program, and characterized by LC-MS on a quadrupole detector, in electrospray positive ion mode. This method provides average recoveries for salbutamol, ractopamine, and clenbuterol of 83-110% and coefficients of variation of 1.5-11% in feeds spiked in the range of 0.5-500 mg/kg. The limits of detection and quantification in feeds were 0.01 mg/kg and 0.05 mg/kg, respectively. Such limits are well below the dose of 2-25 mg/kg feed proposed as effective.

Quantitative HPLC Determination and Extraction of Anthraquinones in Senna alata Leaves

Abstract: A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of four anthraquinones: rhein, aloe-emodin, emodin, and chrysophanol in Senna alata leaves. The method involves the use of a TSK-gel ODS-80Tm column (5 microm, 4.6 x 150 mm) at 25 degrees C with the mixture of methanol and 2% aqueous acetic acid (70:30, v/v) as the mobile phase and detection at 254 nm. The parameters of linearity, precision, accuracy, and specificity of the method were evaluated. The recovery of the method is 100.3-100.5%, and linearity (r(2) > 0.9998) was obtained for all anthraquinones. A high degree of specificity as well as repeatability and reproducibility (relative standard deviation values less than 5%) were also achieved. The solvent for extraction of anthraquinones from S. alata leaves was examined in order to increase the anthraquinone content of the leaf extract. It was found that a solution of 5% hydrochloric acid (v/v), 5% ferric chloride (w/v), and 15% water in methanol (v/v) was capable of increasing the anthraquinone content in the leaf extract up to 1.67% (w/w).

Fingerprint of Selected Salvia Species by HS-GC-MS Analysis of Their Volatile Fraction

Abstract: Twenty species of Salvia, naturally grown or cultivated in Poland, are investigated by headspace gas chromatography‐mass spectrometry analysis. The main components of the volatile fraction of Salvia species are identified as a-pinene, camphene, β-pinene, thujol, camphor, β-c hamigrene, and cadina-3,9-diene. T here are also the compounds that can be considered as chemotaxonomic markers, namely β-m yrcene for Salvia la vadulifolia, β-phelandrene for Salvia verticillata, τ-terpinene for Salvia stepposa, and isocaryophyllene and caryophyllene for Salvia officinalis. Certain compounds (such as o-cymene present in Salvia canariensis and Salvia stepposa; β-trans-ocymene present in Salvia la vadulifolia, Salvia sclarea, and Salvia amplexicaulis; thujenone present in Salvia staminea, Salvia atropatana, Salvia jurisicii, and Salvia officinalis; and thujone present in Salvia azurea, Salvia lavandulifolia, Salvia hians, and Salvia triloba) can constitute chemotaxonomic advice for the aforementioned species. Also, the lack of certain compounds otherwise common in the individual sage species can be considered as chemotaxonomic advice (e.g., Salvia sclarea has no α-pinene and β-pinene; Salvia la vadulifolia lacks camphene; Salvia triloba lacks β-pinene and camphene; and Salvia officinalis lac ks β-c hamigrene, thujol, and cadina-3,9-diene).

Determination of ten haloacetic acids in drinking water using high-performance and ultra-performance liquid chromatography-tandem mass spectrometry.

Abstract: Haloacetic acids (HAAs) are a class of byproducts resulting from the reaction of chlorinated disinfectants with natural organic matter. These chemicals have been found in animal studies to possibly influence hepatic, reproductive, and developmental functions, and they may be mutagenic and carcinogenic. Because HAAs are hydrophilic and strongly acidic, it is a challenge to measure them at low levels. In this study, nine traditional HAAs and monoiodoacetic acid, an emerging disinfection byproduct, are analyzed in water directly. HAAs were separated on a BetaMax Acid column or a HILIC UPLC column, and they were detected by negative electrospray ionization-tandem mass spectrometry. Although the on-column limits of detection of HAAs were lower when using an HILIC UPLC column (0.08‐2.73 µg/L) than when using a BetaMax Acid column (0.18 to 71.5 µg/L), to use an HILIC UPLC column, it was required to dissolve water samples in 90% acetonitrile before injection and result in sample dilution. BetaMax Acid column was found to be more suitable for the analysis of HAAs in drinking water because there was no need of sample preparation. Major species of HAAs, such as dichloroacetic acid and trichloroacetic acid, and other primary species (e.g., dibromoacetic acid, bromochloroacetic acid and bromodichloroacetic acid) can be detected using the BetaMax Acid column at concentrations higher than 1‐3 µg/L.

Chemometric evaluation of adulteration profile in coffee due to corn and husk by determining carbohydrates using HPAEC-PAD.

Abstract: The detection of impurities in coffee samples already roasted and ground is a constant concern mainly in order to verify the incidence of frauds. Carbohydrates contents are important as variations on original constitutes of different matrixes may be able to reveal the final composition of the product. In this sense, a study is performed in this paper in order to evaluate the quality through concentration of total carbohydrates in Arabic roasted and ground coffee. Chemometric methods were applied in order to verify an adulteration pattern by coffee husk and corn, by the mixture of different amounts of these contaminants to coffee, following a statistical design of Simplex-Centroid. It could be concluded that this method was efficient in distinguishing different matrixes. In pure coffee, higher concentrations were found for galactose and mannose with levels of 8.25% and 9.65% (w/w), respectively. However, in the pure husks, the main carbohydrates were mannitol (with a level of 0.64%), arabinose (with 4.24%), and xylose (with 3.40%). For the corn sample, glucose was detected in greater quantity, with 52.53% (w/w). Models presenting the influence of adulterants incorporated to coffee in the carbohydrate level were obtained.

Validation of LC for the Determination of α-Mangostin in Mangosteen Peel Extract: A Tool for Quality Assessment of Garcinia mangostana L.

Abstract: Mangosteen, Garcinia mangostana L., is known as the "Queen of fruits" and can be cultivated in the tropical rainforest such as Malaysia, Indonesia, and Thailand. Compounds isolated from the fruit peel of mangosteen contain abundant xanthones (especially alpha-mangostin). It has been used as traditional medicine such as anti-inflammatory and antibacterial and is popularly applied to cosmetic and pharmaceutical products. However, there is little information for quality and quantity determination of alpha-mangostin in mangosteen. Thus, the aim of this study was to set up a validated and stability-indicated isocratic reverse-phase high-performance liquid chromatographic (HPLC) method for quality control and quantity determination of a-mangostin from mangosteen peel extract. The assay was fully validated and shown to be linear (r(2) > 0.999), sensitive (LOD = 0.02 microg/mL and LOQ = 0.08 microg/mL), accurate (intra-day was between 98.1-100.8%, inter-day was between 90.0-101.3%), precise (intra-day variation < or = 1.8%, inter-day variation < or = 4.3%), specific, and with good recovery. Total analysis was approximately 8 min. The finalized method is also a stability-indicating assay. The present method should be useful for analytical research and for routine quality control analysis of alpha-mangostin in mangosteen peel extract and products of mangosteen.

Recent applications of organic monoliths in capillary liquid chromatographic separation of biomolecules.

Abstract: Monolithic columns are an attractive alternative to traditional particulate solid phases for capillary liquid chromatography. A monolith is a continuous interconnected skeleton with large through-pores. This structure reduces the diffusion path and provides high permeability, resulting in excellent separation efficiency. The integral structure enhances the mechanical strength, while the large through-pores (a few microm) have very low flow impedance. This combination allows smaller diameter monolithic columns to be operated at higher flow-rates, simultaneously increasing both sensitivity and throughput. Polymeric monoliths were first described back in the 1960s, but the first successful ones designed for protein separations appeared much later, in the late 1980s. Organic monoliths are based upon copolymerization of a monofunctional and a bifunctional (uncommonly trifunctional) organic precursor in the presence of a suitable initiator and porogenic solvents. During the last 15 years, a vast number of different monomers and crosslinkers have been introduced and copolymerized using different polymerization techniques and initiators. Various mechanisms, including thermally- and UV-initiated free radical polymerization, as well as ring opening metathesis copolymerizations, have been demonstrated for the preparation of monolithic columns. In this review, we summarize the recent application of different organic monoliths, including styrene-, acrylate-, methacrylate-, and acrylamide for the liquid separation of biomolecules (e.g., proteins, peptides, and oligonucleotides).

Validated High-Performance Liquid Chromatographic Technique for Determination of 5-Fluorouracil: Applications to Stability Studies and Simulated Colonic Media

Abstract: A simple isocratic stability-indicating high-performance liquid chromatographic method with UV detection using thymine as an internal standard is developed The method is validated and the degradation products are determined The method is applied for the assessment of the stability of 5-fluorouracil in rat caecal content as a simulated colon medium under anaerobic conditions The drug decomposes under acidic, alkaline, thermal, and oxidative stress The drug is highly susceptible to acidic, alkaline, and oxidative hydrolysis as compared to alkaline conditions Separation of the drug from major and minor degradation products is successfully achieved on a C 18 analytical, μ-bondapak column The detection wavelength is 260 nm The method is validated, and the response is found to be linear in the drug concentration range of 01-20 μg/mL The high linearity of the standard calibration curve of 5-fluorouracil in the rat content is found to be R 2 = 0998 in the concentration range from 05 to 5 μg/mL No degradation occurred after incubation of 5-fluorouracil in the rat caecal contents The standard deviation and coefficient of variation values for intra- and inter-day precision study exhibit acceptable accuracy and precision data throughout the concentration range investigated

RP-HPLC Analysis of Rhinacanthins in Rhinacanthus nasutus: Validation and Application for the Preparation of Rhinacanthin High-Yielding Extract

Abstract: A reversed-phase high-performance liquid chromatographic method is described for the simultaneous determination of rhinacanthin-C, rhinacanthin-D, and rhinacanthin-N in Rhinacanthus nasutus leaves. The method involved the use of a TSK-gel ODS-80Ts column (5 microm, 4.6 x 150 mm i.d.) with the mixture of methanol and 5% aqueous acetic acid (80:20, v/v) as the mobile phase. The parameters of linearity, repeatability, accuracy, and specificity of the method were evaluated. The recovery of the method was 94.3-100.9%, and good linearity (r(2) > or = 0.9999) was obtained for all rhinacanthins. A high degree of specificity as well as repeatability and reproducibility (relative standard deviation values less than 5%) were also achieved. The limit of detection and quantification of all rhinacanthins were 0.75 and 3.0 microg/mL, respectively. The solvents for extraction of rhinacanthins from R. nasutus leaves were examined in order to obtain the leaf extract with high rhinacanthin content. It was found that ethyl acetate was an appropriate solvent for rhinacanthin extraction. Fractionation of the ethyl acetate extract using a basic anion exchange resin (Amberlite IRA-67) eluted with 10% acetic acid in methanol afforded a rhinacanthin-rich extract (HRn). The total content of rhinacanthins was increased from 37.4% w/w to 77.5% w/w. The antifungal activities of HRn against Trichophyton rubrum, T. mentagrophytes, and Microsporum gypseum were also improved.

Evaluation of methods for the simultaneous analysis of cations and anions using HPLC with charged aerosol detection and a zwitterionic stationary phase.

Abstract: This paper describes the development and qualification of a method capable of analyzing inorganic ions as salts and counter-ions of both active pharmaceutical ingredients and other compounds such as lysine. The use of a polymeric zwitterionic column with a binary high-performance liquid chromatography gradient enables the separation of several anions and cations in a single run. A generic gradient (method #1) was developed and validated with respect to specificity, correlation, intermediate precision, accuracy, and sensitivity (limits of quantitation and detection) for four anions and two cations. Furthermore, the ability to alter chromatographic selectivity by simple gradient manipulation (without altering the mobile phase composition or column type) is demonstrated for nine anions and three cations (method #2). The simultaneous measurement of cations and anions at the parts per billion level using the Corona charged aerosol detector with zwitterionic chromatography-polymeric hydrophilic interaction chromatography is a viable alternative to traditional techniques used for ion analysis.