High-performance liquid chromatographic method for the determination of eclanamine and its N-desmethyl and N,N-didesmethyl metabolites in urine

A high-performance liquid chromatographic method has been defined for the determination of eclanamine (free base of eclanamine maleate) and two of its metabolites, N-desmethyleclanamine and N,N-didesmethyleclanamine in urine. The method employs 10-ml urine samples, has a linear range from 5 to 500 ng/ml for the three compounds, and has a detection limit of 0.5 ng/ml for each compound. Sample preparation uses a cyanopropylsilane extraction column with washes of water, acetonitrile-water (30:70, v/v), and acetonitrile, and elution with 2% trifluoroacetic acid in acetonitrile. The eluate is evaporated to dryness, the residue dissolved in 1.0 ml acetonitrile-water (10:90, v/v) and 100 microliter are injected onto a Supelcosil LC-CN column. Eclanamine and its metabolites are eluted with an acetonitrile-water (35:65, v/v) eluent containing 0.01 M triethylamine and adjusted to pH 7.0 with phosphoric acid. The method has been validated by preparing and analyzing a series of fortified urines (range 2-500 ng/ml for each compound) on four separate days. Good linearity, precision, reproducibility, and specificity were obtained. Certification of the analytical method was accomplished by analyzing urine specimens collected from one volunteer administered a single oral dose of 45 mg eclanamine maleate. The data suggest that the metabolites of eclanamine have long elimination half-lives with levels still quantifiable in the 72-96 h collection interval.     

Determination of chlorpyrifos and its metabolites in rat brain tissue using coupled-column liquid chromatography/electrospray ionization tandem mass spectrometry

A method has been developed to quantify chlorpyrifos (O,O-diethyl-O-[3,5,6,-trichloro-2-pyridyl] phosphorothionate) and its metabolites chlorpyrifos-oxon (O,O-diethyl-O-[3,5,6,trichloro-2-pyridinyl] phosphate) and TCP (3,5,6,-trichloro-2-pyridinol) in rat brain tissue by coupled-column liquid chromatography/electrospray ionization tandem mass spectrometry (LC/LC/ESI-MS/MS). Rat brains were homogenized and treated by protein precipitation using ice-cold acetonitrile. The supernatant was directly injected onto the coupled-column system. Sample clean-up was achieved on a Zorbax Extend-C(18) column (2.1 x 50 mm, 5 microm) using a mobile phase of acetonitrile/water with 0.0025% formic acid (40:60, v/v). The compounds were separated isocratically on a Zorbax Eclipse XDB C(8) column (2.0 x 150 mm, 5 microm) using a mobile phase of acetonitrile/water with 0.0025% formic acid (75:25, v/v). Chlorpyrifos and chlorpyrifos-oxon were detected in positive ion mode using multiple reaction monitoring (MRM). TCP was detected in negative ion mode using precursor-to-precursor transition monitoring. The method was validated and the specificity, linearity, limit of quantitation (LOQ), precision, accuracy, stability, and recoveries were determined. Calibration curves for all three analytes yielded correlation coefficients of 0.993 or greater. The LOQs were 25.3 ng/g for chlorpyrifos and 6.3 ng/g for chlorpyrifos-oxon and TCP. All precision relative standard deviations (RSDs) were less than 16% for the LOQ and less than 11% for the other QC samples. This method was successfully applied to six rats that were injected subcutaneously with chlorpyrifos.     

Simultaneous determination of caffeine and its primary demethylated metabolites in human plasma by high-performance liquid chromatography.

An improved high-performance liquid chromatographic method for the simultaneous determination of caffeine and its three primary metabolites (theophylline, theobromine and paraxanthine) in human plasma is described. The four substances were separated on a reversed-phase column (5 microns TSK gel ODS-80TM, 150 mm x 4.6 mm I.D.) by use of the mobile phase methanol-0.1 M NaH2PO4 (30:70, v/v) with a flow-rate of 0.8 ml/min. Absorbance was monitored at 274 nm. The detection limit was 5 ng/ml for theobromine and caffeine and 10 ng/ml for paraxanthine and theophylline. The linearity and reproducibility were sufficient for drug monitoring of caffeine and its primary methylxanthines.     

Determination of ondansetron and its hydroxy metabolites in human serum using solid-phase extraction and liquid chromatography/positive ion electrospray tandem mass spectrometry

Ondansetron and its hydroxylated metabolites were determined in human serum using solid-phase extraction (SPE) and liquid chromatography/positive ion electrospray tandem mass spectrometry. Pyrimethamine was used as the internal standard. The analytes were eluted from the SPE cartridge using 2 x 1 ml of methanol containing 0.5% triethylamine, evaporated under vacuum and the residue was reconstituted in the mobile phase. The liquid chromatographic separation was achieved on a silica column using a mobile phase of aqueous 20 mM ammonium acetate (pH 4.7)-acetonitrile (85 : 15, v/v) at a flow-rate of 0.4 ml min(-1). The method was linear over the range 1-500 ng ml(-1) for ondansetron and each of the metabolites in human serum. The intra-day accuracy was better than 9.1% and the precision was <10.3%; the inter-day accuracy was better than 9.5% and the precision was <12.6%. The limit of detection was 250 pg ml(-1) based on a signal-to-noise ratio of 3. The absolute recovery from serum for all analytes was >90%.     

Studies on Turkish Rose Concrete, Absolute, and Hydrosol

The production of rose absolute from fresh flowers of the cultivated Rosa damascena Miller was realized using traditional and modern techniques, such as molecular distillation, extraction with liquified gases, etc. Headspace trapping and SPME techniques were employed in the sampling of volatile constituents in the concrete, absolute, and hydrosol, for analysis by GC/MS.     

Simultaneous determination of three organophosphorus pesticides in different food commodities by gas chromatography with mass spectrometry

A sensitive and selective gas chromatography with mass spectrometry method was developed for the simultaneous determination of three organophosphorus pesticides, namely, chlorpyrifos, malathion, and diazinon in three different food commodities (milk, apples, and drinking water) employing solid‐phase extraction for sample pretreatment. Pesticide extraction from different sample matrices was carried out on Chromabond C₁₈ cartridges using 3.0 mL of methanol and 3.0 mL of a mixture of dichloromethane/acetonitrile (1:1 v/v) as the eluting solvent. Analysis was carried out by gas chromatography coupled with mass spectrometry using selected‐ion monitoring mode. Good linear relationships were obtained in the range of 0.1–50 μg/L for chlorpyrifos, and 0.05–50 μg/L for both malathion and diazinon pesticides. Good repeatability and recoveries were obtained in the range of 78.54–86.73% for three pesticides under the optimized experimental conditions. The limit of detection ranged from 0.02 to 0.03 μg/L, and the limit of quantification ranged from 0.05 to 0.1 μg/L for all three pesticides. Finally, the developed method was successfully applied for the determination of three targeted pesticides in milk, apples, and drinking water samples each in triplicate. No pesticide was found in apple and milk samples, but chlorpyrifos was found in one drinking water sample below the quantification level.     

液相色谱-串联质谱法检测动物肝肾组织中3种雌激素

建立了动物肝、肾组织中雌酮、17β-雌二醇、雌三醇药物残留检测的液相色谱-串联质谱(LC-MS/MS)分析方法。样品以叔丁基甲醚提取,于45 ℃下氮吹至干,用正己烷-二氯甲烷(6:4, v/v)重新溶解,过硅胶固相萃取小柱净化,氮吹至干,用1 mL乙腈-水(7:3, v/v)定容后测定,用Poroshell 120 EC-C18柱分离,以乙腈和水作为流动相进行梯度洗脱,电喷雾负离子模式电离,多反应监测模式检测,外标法定量。该方法对3种雌激素的线性范围均为1.0～20.0 μg/kg,相关系数大于0.99,定量限为1.0 μg/kg。在不同基质中,1.0、2.0、10.0 μg/kg 3个添加水平的平均回收率范围为70.2%～114%,相对标准偏差范围为2.01%～14.5%。该方法具有快速简便、净化效果好、灵敏度高等特点,适用于动物肝、肾组织中雌激素的检测。     

Simultaneous Determinations of Cinobufagin and Its Metabolites by Reverse-Phase High Performance Liquid Chromatography in Rat Serum and Urine

Abstract

A high-performance liquid chromatography was developed for simultaneous determinations of Cinobufagin (CB) and its metabolites deacetylcinobufagin, 3-epideacetyl-cinobufagin, 3-ketodeacetylcinobufagin, 3-epicinobufagin and 3-ketodeacetylcinobufagin in serum and urine of rat. The biological samples were extracted with diethylether-ethylacetate (4:1v/v) in the presence of bufalin as the internal standard. Recoveries for CB and all other compounds were in the range of 80.8%–100.2%. Excellent resolution was obtained by reversed-phase chromatography on a 4.6 mm I.D.×150 mm ODS column using acetonitrile:water (50:50 v/v) as the mobile phase at a flow-rate of 0.7 ml/min with UV detector at 300 nm. Standard curve data revealed linearity over a range of 10–500 ng per ml serum and urine. The detection limits of CB and its metabolites were less than 10 ng/ml. Coefficients of variation for the analysis were less than 10. CB and its some metabolites were observed in     

Determination of lafutidine in human plasma by high-performance liquid chromatography-electrospray ionization mass spectrometry: application to a bioequivalence study

A rapid, sensitive and specific high-performance liquid chromatography-electrospray ionization mass spectrometry (LC/ESI-MS) method was developed and validated for the first time to determine the concentration of lafutidine in human plasma. After the addition of diazepam (the internal standard, IS) and 1 M sodium hydroxide solution to 0.5-ml plasma sample, lafutidine was extracted from plasma with n-hexane : isopropanol (95 : 5, v/v). The organic layer was evaporated and the residue was redissolved in 200-microl mobile phase. The analyte was chromatographically separated on a prepacked Shimadzu Shim-pack VP-ODS C(18) column (250 x 2.0 mm i.d.) using a mixture of methanol-water (20 mM CH(3)COONH(4)) = 80 : 20 (v/v) as mobile phase. Detection was performed on a single quadrupole mass spectrometer using an electrospray ionization interface and the selected-ion monitoring (SIM) mode. The method showed excellent linearity (r = 0.9993) over the concentration range of 5-400 ng/ml and had good accuracy and precision. The within- and between-batch precisions were within 10% relative standard deviation. The limit of detection was 1 ng/ml. The validated LC/ESI-MS method has been successfully applied to the bioequivalence study of lafutidine in 24 healthy male Chinese volunteers.     

Determination of cetirizine in human urine by high-performance liquid chromatography.

A high-performance liquid chromatographic method for the determination of the histamine H1-receptor antagonist cetirizine in human urine was developed. Cetirizine and the internal standard are extracted from acidified (pH 5) urine (0.5 ml) into chloroform and the organic layer is evaporated to dryness. The residue is chromatographed on a Spherisorb 5ODS-2 column using Pic A (5 mM aqueous tetrabutylammonium phosphate)-methanol-tetrahydrofuran (33:65:2, v/v) as the mobile phase with ultraviolet detection (230 nm). The calibration graph is linear from 0.1 to 10 micrograms/ml and using 0.5 ml of urine the detection limit is 20 ng/ml. The within-run relative standard deviation is less than 6% and the accuracy is within 10% of the theoretical value at concentrations between 0.1 and 10 micrograms/ml in urine. There is a good correlation (r = 0.99606) with a previously described capillary gas chromatographic assay.     

Validation of a column liquid chromatographic method for the analysis of pramipexole and its five impurities

In this paper, a previously optimized method for HPLC analysis of pramipexole and its impurities was subjected to method validation in accordance with official regulations. The optimized chromatographic conditions were as follows: mobile phase acetonitrile-water phase [15 + 85, v/v, water phase contained 1% triethylamine (TEA), pH adjusted to 7.0 with orthophosphoric acid]; detection at 262 nm for pramipexole, BI-II 751 xx, BI-I 786 BS, BI-II 820 BS, and 2-aminobenzothiazole and at 326 nm for BI-II 546 CL; column temperature, 25 degrees C; and flow rate, 1 ml/min. Acetonitrile and TEA content, pH of the water phase, flow rate, column temperature, and column type were factors studied in robustness testing. According to the experimental plan defined by a Plackett-Burman design, five dummy variables were added in order to have 12 factors. As output, resolution factor was chosen. Robustness was assessed by graphical (half-normal probability plots and Pareto charts) and statistical (t-test) methods. Also, nonsignificance intervals for significant factors were estimated, and limits for the system suitability test were determined. Finally, linearity, accuracy, and precision of the proposed HPLC method were defined. LOD and LOQ values for analyzed impurities were determined. The method was completely defined by these experiments.     

Determination of repaglinide in pharmaceutical formulations by HPLC with UV detection.

A simple, precise and rapid RP-HPLC method was developed for the determination of repaglinide in pharmaceutical dosage forms. The method was carried out on a Shim-pack, RP-C18 column using a mixture of methanol: 0.1% v/v triethylamine (pH adjusted to 7 with orthophosphoric acid) and detection was done at 235 nm using nimesulide as internal standard. The linearity range was 0.1 to 0.5 microg/ml. The intra-day and inter-day precision were in the range of 0.48 to 1.01 and 0.15 to 1.15, respectively.     

Simultaneous enantiomeric analysis of pharmacologically active compounds in environmental samples by chiral LC–MS/MS with a macrocyclic antibiotic stationary phase

This paper presents a multi‐residue method for direct enantioselective separation of chiral pharmacologically active compounds in environmental matrices. The method is based on chiral liquid chromatography and tandem mass spectrometry detection. Simultaneous chiral discrimination was achieved with a macrocyclic glycopeptide‐based column with antibiotic teicoplanin as a chiral selector working under reverse phase mode. For the first time, enantioresolution was reported for metabolites of ibuprofen: carboxyibuprofen and 2‐hydroxyibuprofen with this chiral stationary phase. Moreover, enantiomers of chloramphenicol, ibuprofen, ifosfamide, indoprofen, ketoprofen, naproxen and praziquantel were also resolved. The overall performance of the method was satisfactory in terms of linearity, precision, accuracy and limits of detection. The method was successfully applied for monitoring of pharmacologically active compounds at enantiomeric level in influent and effluent wastewater and in river water. In addition, the chiral recognition and analytical performance of the teicoplanin‐based column was critically compared with that of the α₁‐acid glycoprotein chiral stationary phase. Copyright © 2017 John Wiley & Sons, Ltd.     

Determination of alpha-tocopherol in the Traditional Chinese Medicinal preparation Sea buckthorn oil capsule by non-aqueous reversed phase-HPLC

A non-aqueous reversed phase HPLC was developed for determining alpha-tocopherol in Sea buckthorn oil capsule without the need for saponification. A reversed phase column (Alltima C(18), 4.6 x 250 mm, 5 microm) was used with a mobile phase of methanol-acetonitrile (95 : 5, v/v) and flow rate of 1 ml/min. The contents in capsule were extracted with n-hexane. Detection wavelength was set at 292 nm. Each analysis requires no longer than 20 min. The linearity range for alpha-tocopherol was 9.4-47.0 microg/ml. The detection limit was 0.94 microg/ml. The mean recovery was 95.82 (RSD 2.3%). This method is suitable for quantitative analysis of alpha-tocopherol in Sea buckthorn oil or its Traditional Chinese Medicinal preparation.     

A Simple and Rapid Reversed Phase High Performance Liquid Chromatographic Method for Quantification of Alprazolam and α-Hydroxyalprazolam in Plasma

Abstract

A simple and rapid reversed-phase liquid chromatographic method for the determination of alprazolam and a-hydroxyalprazolam in plasma is described. Flunictrazepam was used as internal standard. Plasma samples were buffered with sodium borate and extracted with dichloromethane /n-pentane 4:6 v/v for 60 sec on a vortex apparatus. Extraction solvent was evaporated to dryness and extraction residues were reconstituted in the mobile phase. Samples were chromatographed on a 5μ Lichrospher RP-18 column (25cm × 4mm i. d) using acetonitrile/water 40:60 v/v as the mobile phase. The column effluent was monitored at 230nm. The lower limit of detection was 1ng/ml for alprazolam and a-hydroxyalprazolam while the lower limit of quantification was 2ng/ml for both compounds. Peak height and plasma     

Determination of gliclazide in serum by high-performance liquid chromatography using solid-phase extraction.

A simple and sensitive high-performance liquid chromatographic method for a routine assay of gliclazide in serum is described. Serum samples spiked with glibenclamide (internal standard) were applied to Bond Elut C18 cartridges. After washing with phosphate buffer (pH 7.5) and water, the cartridge was eluted with 60% methanol. The eluate was evaporated to dryness. The residue was dissolved in methanol and injected onto an octadecyl silica column (5 microns, 150 mm x 4.6 mm I.D.). The mobile phase was 0.04 M potassium dihydrogenphosphate (pH 4.6)-acetonitrile-isopropyl alcohol (5:4:1, v/v). Ultraviolet detection at 227 nm was used. The minimum detectable level of gliclazide was 20 ng/ml.     

Solidification of floating organic droplet microextraction for determination of seven insecticides in fruit juice,vegetables and agricultural runoff using gas chromatography with flame ionization and mass spectrometry detection

Liquid microextraction employing solidification of the floating organic droplet, with vortexing and heating to optimize extraction efficiency, was developed for the determination of seven insecticides in fruit juice, vegetables, and agricultural runoff water. The extracts were analyzed by gas chromatography with both flame ionization and mass spectrometry detection for the determination of chlorpyrifos, prothiofos, profenofos, ethion, λ‐cyhalothrin, permethrin, and cypermethrin, respectively. Using 20 μL of 1‐undecanol in 10 mL of aqueous solution containing 1% w/v sodium chloride provided preconcentration factor of 500. The enrichment factor of the analytes was in the range of 355 to 509 with extraction recovery >71%. The linearity ranges were 4–200 μg/kg for gas chromatography with flame ionization detection and 1–100 μg/kg for gas chromatography with mass spectrometry, with limits of detection ranging from 0.04 to 1.2 μg/kg, which are lower than the international maximum residue limits for vegetables and fruit juice. Intra‐day and inter‐day precisions are less than 5.4 and 7.0% relative standard deviation, respectively. The method was successfully applied to the determination of the seven insecticides in samples of vegetables, fruit juice and agricultural runoff, with recoveries ranging from 61.7 to 120.8%. The extraction method is simple, efficient and environmentally friendly.     

Determination of chlorpyrifos, penconazole, fenarimol, vinclozolin and metalaxyl in grapes, must and wine by on-line microextraction and gas chromatography

A rapid gas chromatographic method for determination of residue levels of one insecticide (chlorpyrifos) and four fungicides (penconazole, fenarimol, vinclozolin and metalaxyl) in grapes, must and wine is described. An on-line microextraction method was used. The matrix, once extracted with a mixture of acetone-dichloromethane (1:1, v/v) was filtered and concentrated. Electron-capture detection for chlorpyrifos, penconazole, fenarimol and vinclozolin and mass-selective detection in the selected-ion monitoring mode for metalaxyl were utilised. No clean-up was necessary because there were no interferences in the area of interest of the chromatogram. Linearity of both detectors, in the range 0.02-2 ng/microliter, was checked. In all cases, the correlation coefficient was the same or superior to 0.997. Recoveries from spiked grapes, must and wine ranged from 78% to 101% (fortification level, 0.1-1 mg/kg). Limits of determination were between 0.01 mg/kg for metalaxyl and 0.001 mg/kg for vinclozolin.     

基质分散固相萃取-超高效液相色谱-串联质谱法测定蔬菜风险监测中的9种农药残留

建立了基质分散固相萃取-超高效液相色谱-串联质谱测定蔬菜中多菌灵、氧乐果、克百威、涕灭威、毒死蜱、甲胺磷、甲拌磷、对硫磷、甲基对硫磷9种农药残留的方法。蔬菜通过乙腈提取、盐析分配、基质分散固相萃取净化后,采用Waters BEH C18柱(100 mm×2.1 mm, 1.7 μm),以乙腈和0.1%甲酸水溶液作为流动相,梯度洗脱,电喷雾电离正离子(ESI⁺)、多反应监测(MRM)模式测定,基质匹配标准溶液工作曲线法定量。该方法的检出限为0.8~4.0 μg/kg,回收率为72.8%~117.4%。50批蔬菜样品中毒死蜱、多菌灵和氧乐果残留的检出率分别为42.0%、14.0%和2.0%,毒死蜱超标率为8.0%,其他农药未检出。该法可同时测定食品风险监测中蔬菜的农药残留,具有操作方便、准确率高、重复性好等优点,可满足蔬菜中农药残留的检测要求。     

Alkanol-based supramolecular solvent microextraction of organophosphorus pesticides and their determination using high-performance liquid chromatography

A sensitive method for extraction and determination of three organophosphorus pesticides (chlorpyrifos, diazinon, phosalone) using a supramolecular solvent (SUPRAS) made of inverted hexagonal aggregates of alkanol and high-performance liquid chromatography with ultraviolet detection (HPLC–UV) was developed. The studied factors were alkanol amount, THF percentage (v/v), pH and vortex time. According to the full factorial design results, the effective parameters were alkanol amount, THF percentage (v/v) and pH. Then, a CCF was applied to obtain optimal conditions. The optimized conditions were obtained at 100 mg of alkanol, 5% of THF and pH 3.9. The limits of detection of pesticides were 0.5–1.3 ng/mL. The linearity was 1.6–500.0 ng/mL for different pesticides. Relative standard deviations for intra- and inter-day extraction of pesticides were 3.3–5.0 and 5.1–6.3, respectively, for five measurements. The method was also successfully applied for the determination of the pesticides in fruit juice and tap water samples.