Determination of vitamin D2 in emulsified nutritional supplements by solid-phase extraction and column-switching high-performance liquid chromatography with UV detection

This paper deals with a method for solid-phase extraction of trace amounts of vitamin D2 (VD2, 19 ng/g) from emulsified nutritional supplements, which contain 50 kinds of compounds, followed by column-switching high-performance liquid chromatography (HPLC) with UV detection at 265 nm. VD2 is present at 1000-20,000,000 times lower concentration than other components. Bond Elut C18 cartridge was chosen as for the emulsified nutritional supplements after comparison with eight other types. A sample solution was applied to the solid-phase extraction cartridge and VD2 was eluted by methanol followed by HPLC. The effects of sample pH, eluent composition and eluate volume on the retention and elution of VD2 on Bond Elut C18 cartridge were examined. The resulting method was simple, rapid (analysis time: approximately 20 min), sensitive (detection limit: approximately 0.1 ng per injection (200 microl) at a signal-to-noise ratio 3:1), and reproducible (relative standard deviation: approximately 6.2%, n=5). The calibration graph for VD2 was linear in the range of 0.1-3 ng per injection (200 microl). Recovery of VD2 was approximately 80% by the standard addition method.     

Determination of some pesticides and intermediates by ion chromatography

The present paper deals with a method of solid-phase extraction of tocopherol acetate (TA, 49.6 microg/g) from emulsified nutritional supplements, which contains 50 kinds of compounds, followed by high-performance liquid chromatography (HPLC) with fluorescence detection The TA concentration is 5 to approximately 100,000 times lower than that of other compounds in the samples. Measuring the loading capacity of the larger amounts of vegetable oil onto the Bond Elut C18 cartridge was examined for the complete retention of smaller level of TA. A sample solution was applied to a solid-phase extraction cartridge and then TA was eluted by acetonitrile followed by HPLC. This method was suitable for the determination of TA in emulsified nutritional supplements. The proposed method was simple, rapid (analysis time: ca. 15 min), sensitive [detection limit: ca. 0.1 ng per injection (100 microl) at a signal-to-noise ratio of 3:1], and reproducible (relative standard deviation: ca. 2.5% (n=5)). The calibration graph of TA was linear in the range of 0.1 to 100 ng per injection (100 microl). Recovery of TA was over 90% by the standard addition method.     

Simultaneous sample preparation for high-performance liquid chromatographic determination of Vitamin A and β-carotene in emulsified nutritional supplements after solid-phase extraction

Determination of small amounts of the fat-soluble species Vitamin A (VA) (2.5 μg/g) and β-carotene (9 μg/g) from emulsified nutritional supplements containing 50 kinds of co-existing compounds and a fat content between 2000 and 8000 times higher was performed by solid-phase extraction (SPE) and high-performance liquid chromatography (HPLC) with fluorescence detection set at ex. 350 nm and em. 480 nm, and visible detection at 450 nm using an Inertsil ODS 80A (5 μm) analytical column. Mobile phases of methanol-ethanol (50:50) and acetonitrile-ethanol (70:30) were used for the both vitamins. A Bond Elut C₁₈ cartridge was chosen for SPE after comparison with eight other types of SPE cartridge. Retention time of VA and β-carotene was 7 and 8 min, respectively, giving a limit of detection of ca. 0.1 ng per injection at a signal-to-noise ratio 3:1. Recoveries of VA and β-carotene were over 90% by the standard addition method. Relative standard deviation of VA and β-carotene were ca. 2.9 (n=5) and 2.3% (n=5), respectively.     

Determination of vitamin K1 in emulsified nutritional supplements by solid-phase extraction and high-performance liquid chromatography with postcolumn reduction on a platinum catalyst and fluorescence detection

Determination of small amounts of vitamin K1 (0.8 microg/g) in nutritional supplements with high fat content (20 mg/g) was performed by solid-phase extraction and high-performance liquid chromatography (HPLC) with fluorescence detection after reduction on a platinum oxide catalyst. The concentration ratio of plant oils to vitamin K1 (0.8 microg/g) was about 25,000:1. A sample solution was applied to a solid-phase extraction cartridge and vitamin K1 was eluted with ethanol, followed by HPLC. The proposed method was simple, rapid (analysis time: ca. 12 min), sensitive [detection limit: ca. 0.1 pg per injection (100 microl) at a signal-to-noise ratio of 3:1], highly selective and reproducible [relative standard deviation: ca. 1.3%. (n=5)]. The calibration graph of vitamin K1 was linear in the range of 0-2 pg per injection (100 microl). Recovery of vitamin K1 was over 90% by the standard addition method.     

Application of ion-exchange cartridge clean-up in food analysis. V. Simultaneous determination of sulphonamide antibacterials in animal liver and kidney using high-performance liquid chromatography with ultraviolet and mass spectrometric detection

A simple, rapid, and reliable method for the determination of residual sulphonamide antibacterials (SAs) (sulfadiazine, sulfamerazine, sulfadimidine, sulfamethoxypiridazine, sulfisozole, sulfamonomethoxine, sulfamethoxazole, sulfisoxazole, sulfadimethoxine, and sulfaquinoxaline) in animal liver and kidney was developed using a combination of clean-up on a Bond Elut PSA cartridge and HPLC with UV detection. The SAs were extracted with ethyl acetate and then dissolved in 5 ml of 50 v/v% ethyl acetate-n-hexane after being evaporated to dryness. For clean-up of the crude sample, the resuspended extract was applied to a Bond Elut PAS (primary/secondary amine cartridge), and then SAs were eluted from the cartridge using 5 ml of 20 v/v% acetonitrile-0.05 M ammonium formate before being analysed by HPLC. Recoveries of the SAs at the levels of 0.5 and 0.1 microg/g were 70.8-98.2%, the rerative standard deviation were less than 7.0%, and the detection limits were 0.03 microg/g. The present analysis method of SAs in animal kidney and liver using HPLC with a clean-up procedure was demonstrated to be highly applicable to the direct LC-MS-MS analysis without any modification.     

Determination of glycarbylamide in chicken tissue by high-performance liquid chromatography

A high-performance liquid chromatographic (HPLC) method for determining glycarbylamide (GB) in chicken tissue was developed. GB was extracted with acetonitrile, followed by solid-phase extraction cleanup using a Bond Elut cartridge column with neutral alumina. After the extract had been evaporated to dryness, the residue was dissolved in 1.0 mL 0.1 N sodium hydroxide. Then 1.0 mL 0.1 M potassium dihydrogen phosphate solution was added to it. HPLC separation was done on a 250 x 4.6 mm id TSK-GEL ODS 80 column with 0.05M potassium dihydrogen phosphate as the mobile phase. Ultraviolet detection was done at a wavelength of 260 nm. The calibration curve of standard GB solutions was linear between 0.16 and 3 micrograms/mL (correlation coefficient, r = 0.999). The recovery of GB from chicken muscle spiked at 0.8 microgram/g was 88.6 +/- 2.3% (mean +/- standard deviation, n = 5), and the lower limit of determination was 0.05 microgram/g in chicken muscle.     

Solid-phase extraction with liquid chromatography and ultraviolet detection for the assay of antidepressant drugs in human plasma

A solid-phase extraction (SPE) method for sample clean-up followed by a reversed-phase high-performance liquid chromatography (HPLC) procedure for the assay of five antidepressant drugs (trazodone, doxepin, desipramine, maprotiline and imipramine) is reported. The drugs were recovered from plasma buffered at a suitable pH using C18 Bond-Elut cartridges and mixtures of methanol-aqueous buffer as washing and elution solvents. The recoveries of the drugs using other sorbent materials (C8, C2, cyclohexyl, cyanopropyl and phenyl Bond Elut and copolymer HLB waters cartridges) were also examined. The selectivity of SPE was examined by using spiked plasma samples and the CH cartridge gave rise to the cleanest extracts. Cyclohexyl cartridges were conditioned successively with 2 ml of methanol and 1 ml of acetic acid-sodium acetate buffer (0.1 M, pH 4.0). Plasma sample was buffered at pH 4.0 and then applied to the sorbent. The washing step was performed subsequently with 1.5 ml of acetate buffer (0.1 M, pH 4.0), 100 microl of acetonitrile and 1 ml of methanol-acetate buffer (30:70, v/v). Finally, the analytes were eluted with 0.5 ml of methanol-acetate buffer (70:30, v/v). The extract was evaporated to dryness, reconstituted in mobile phase, and chromatographed on a reversed-phase C18 column with ultraviolet detection at 215 nm. The recoveries of trazodone, doxepin, desipramine, maprotiline and imipramine from spiked plasma samples using the CH cartridge were 58 2, 84 3, 83 3, 83 3 and 82 2%, respectively. The within-day and between-day repeatabilities were lower than 6% and 9%, respectively. The linearity of calibrations for the five antidepressants was between 0.005 and 2 microg/ml. The limits of detection were 1 ng/ml for trazodone, doxepin and desipramine and 2 ng/ml for maprotiline and imipramine.     

Simultaneous determination of triclabendazole and its sulphoxide and sulphone metabolites in bovine milk by high-performance liquid chromatography

A simple method has been developed for the simultaneous determination of triclabendazole and its metabolites (sulphoxide and sulphone) in bovine milk by reversed-phase high-performance liquid chromatography (HPLC). A milk sample was homogenized with sodium sulfate anhydrous and acetonitrile, and centrifuged. The supernatant was isolated, rinsed with n-hexane saturated with acetonitrile, and evaporated. The residue was dissolved with 0.1 M potassium dihydrogenphosphate, and 0.1 M sodium hydrogencarbonate, and then cleaned up on a Bond Elut C18 cartridge. The three compounds were separated on a Capcell Pak C18 UG 120 (5 microm, 150x4.6 mm I.D.) column and determined by UV detection at 295 nm. The mobile phase was acetonitrile-0.05 M ammonium acetate (50:50), and the flow-rate was 0.8 ml/min at 40 degrees C. The mean recoveries (n=4) were 89.1-95.0% with a relative standard deviation of 1.1-2.6%. The detection limits were 0.004-0.006 microg/g in milk. The proposed method was used to monitor raw milk samples for the market, and applied to the analysis of milk samples from 10 cows which had been administered with triclabendazole to control the liver fluke. The confirmation of the triclabendazole and its metabolites in the above milk sample has been achieved by electrospray LC-MS for the first time.     

Semi-automated, solid-phase extraction procedure for liquid chromatographic determination of papaverine, diltiazem, desipramine and nicardipine in urine

Summary A solid-phase extraction (SPE) method for sample clean-up followed by a reversed-phase HPLC procedure is reported for the assay of papaverine, diltiazem, desipramine and nicardipine in urine. Disposable extraction cartridges (DECs) filled with C18, C8, C2, CH and PH silica-bonded phases were used. The effect on recovery of sample pH, composition of washing and elution solvents and nature of SPE cartridge were evaluated. The selectivity of SPE was examined using spiked urine samples and the PH cartridge gave rise to the cleanest extracts. Phenyl cartridges were conditioned with methanol and acetic acid-sodium acetate buffer. Urine sample was buffered and then applied to the DEC. The washing step was with acetone-water and subsequently with methanol-acetate buffer. The analytes were eluted with methanol-acetate buffer. The extract was evaporated to dryness, reconstituted in mobile phase, and chromatographed on a reversed-phase C18 column with UV detection at 212 nm. Recoveries of the tested compounds from spiked urine samples using the PH cartridge were in all cases>80%. The within-day and between-day repeatabilities were<5% and 9%, respectively.     

固相萃取和高效液相色谱相结合快速测定苦瓜甙A的含量(英文)

 建立了一个快速、简单、准确的固相萃取和高效液相色谱相结合的测定苦瓜甙A含量的方法。样品经石墨碳固相萃取管 (3mL/ 2 5 0mg)纯化后以高效液相色谱检测。色谱柱为C18,流动相为V(乙腈 )∶V(甲醇 )∶V(5 0mmol/L磷酸二氢钾缓冲液 ) =2 5∶2 0∶6 0 ,流速为 0 .8mL/min ,检测波长为 2 0 8nm。标准曲线自 10mg/L到 10 0 0mg/L呈线形关系 (r2 =0 .9992 )。该方法具有很好的重现性 ,日内或日间的相对标准偏差和相对平均误差均小于 10 %。样品回收率大于 90 %。     

固相萃取-高效液相色谱法测定蜂蜜中的有机酸

建立了固相萃取-高效液相色谱(SPE-HPLC)同时测定蜂蜜中5种有机酸(L-苹果酸、马来酸、琥珀酸、柠檬酸、D-苹果酸)含量的方法。蜂蜜经制样后过Bond Elutes SAX固相萃取(SPE)小柱净化,用C18-MS-II反相色谱柱(250 mm×4.6 mm, 5 μm)进行分离,流动相为2%偏磷酸溶液,流速为0.7 mL/min,检测波长为210 nm。在此条件下5种有机酸在相应的线性范围内其线性相关系数均大于0.9967;方法的回收率为86.0%～103.9%,相对标准偏差为5.7%～9.8%(n=6),检出限为0.06～9.4 mg/kg。所建立的方法可用于蜂蜜样品中有机酸的测定。     

High throughput screening of sub-ppb levels of basic drugs in equine plasma by liquid chromatography-tandem mass spectrometry

This paper describes a high throughput LC-MS-MS method for the screening of 75 basic drugs in equine plasma at sub-ppb levels. The test scope covers diversified classes of drugs including some alpha- and beta-blockers, alpha- and beta-agonists, antihypotensives, antihypertensives, analgesics, antiarrhythmics, antidepressants, antidiabetics, antipsychotics, antiulcers, anxiolytics, bronchodilators, CNS stimulants, decongestants, sedatives, tranquilizers and vasodilators. A plasma sample was first deproteinated by addition of trichloroacetic acid. Basic drugs were then extracted by solid-phase extraction (SPE) using a Bond Elut Certify cartridge, and analysed by LC-MS-MS in positive electrospray ionization (+ESI) and multiple reaction monitoring (MRM) mode. Liquid chromatography was performed using a short C(8) column (3.3 cm L x 2.1mm ID with 3 microm particles) to provide fast analysis time. The overall instrument turnaround time was 8 min, inclusive of post-run and equilibration time. No interference from the matrices at the expected retention times of the targeted masses was observed. Over 60% of the drugs studied gave limits of detection (LoD) at or below 25 pg/mL, with some LoDs reaching down to 0.5 pg/mL. The inter-day precision for the relative retention times ranged from 0.01 to 0.54%, and that for the relative peak area ratios (relative to the internal standard) ranged from 4 to 37%. The results indicated that the method has acceptable precision to be used on a day-to-day basis for qualitative identification.     

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.     

Simultaneous determination of new thioamphetamine designer drugs in plasma by capillary electrophoresis coupled with mass spectrometry

A simple method for the simultaneous identification and quantification of four 2,5-methylenedioxy derivatives of 4-thioamphetamine (ALEPH series) in plasma samples was developed. The method consists of solid-phase extraction (SPE) using a Bond Elut C(18) cartridge and capillary electrophoresis coupled with electrospray ionisation mass spectrometry (CE/ESI-MS). The SPE method used required only simple steps and provided a clean extract from which identification of each drug was feasible, even at low concentrations. The method was validated according to international guidelines. The calibration curves were linear over the concentration range of 50 to 1000 ng/mL for all drugs with correlation coefficients that exceeded 0.998. The lower limits of detection of the drugs were 23-43 ng/mL. The absolute recoveries for the drugs were 64-92% and 75-96% at concentrations of 100 and 500 ng/mL, respectively. The validation data (precision, accuracy, and recovery) show the reproducibility and selectivity of the method. This clean and simple method allows the routine detection of designer drugs such as thioamphetamines which may become a serious problem in the control of illegal drugs.     

Synthesis and evaluation of molecularly imprinted polymeric microspheres for highly selective extraction of an anti-AIDS drug emtricitabine

The molecularly imprinted polymeric microspheres (MIPMs, 3～5 μm), used as high-performance liquid chromatography (HPLC) and solid-phase extraction (SPE) packing materials for anti-AIDS drug emtricitabine (FTC), were synthesized by precipitation polymerization. The effects of ratio of chloroform to acetonitrile on the morphology and diameter of MIPMs were investigated. The prepared MIPMs were characterized by HPLC. The imprinting factor (2.26) suggests that the resultant MIPMs exhibit good recognition and affinity to FTC. In addition, the MIPMs were used in SPE as packing material for separation and enrichment of FTC. The recovery of FTC on MIPMs cartridge was 97.6 % in standard solution. Finally, the MIPMs cartridge was applied to extract the FTC in human serum samples. Impurities in sample have been mostly removed, and the average recovery of 92.5 % was obtained with a detection limit of 0.005 μg/mL and a linear range of 0.02～4.0 μg/mL. The method established can be used to monitor the FTC in human serum sample with good accuracy and selectivity.     

On-line solid-phase extraction-HPLC-fluorescence detection for simultaneous determination of puerarin and daidzein in human serum

Response surface methodology (RSM) was applied to the optimization of on-line solid-phase extraction (SPE) parameters, and an automated system of on-line SPE coupled with high-performance liquid chromatography (HPLC) with fluorescence detection was developed for the determination of puerarin and daidzein in human serum. The human serum sample of 50 μL was injected into a conditioned C18 SPE cartridge, and the matrix was washed out with acetonitrile-KH₂PO₄-triethylamine buffer (0.01 M, pH 7.4) (3:97, v/v) for 3 min at a flow rate of 0.25 mL/min. Then the target analytes were eluted and transferred to the analytical column. A chromatographic gradient elution was programmed with the mobile phase consisting of acetonitrile and KH₂PO₄-triethylamine buffer, and the analytes were determined with a fluorescence detector at excitation wavelength of 350 nm and emission wavelength of 472 nm, respectively. The proposed method presented good linear relations (0.85-170 μg/mL for puerarin and 0.2-40 μg/mL for daidzein), satisfactory precision (RSD < 8%), and accredited recovery (92.5-107.8%).     

固相萃取技术-HPLC测定复方甘草片中吗啡的含量

报道了用ＳＥＰ－ＰＡＫＣ１８小预柱固相萃取技术和反相高效液相色谱法测定复方甘草片中微量吗啡含量的方法。对固相萃取条件进行了研究,最终选择１０％甲醇溶液为清洗溶液,７０％甲醇溶液为洗脱溶液,基本消除了干扰组分对测定的影响,色谱图背景吸收小,基线平稳。色谱柱为μ－ＢｏｎｄａｐａｋＣ１８柱,流动相为０．１ｍｏｌ／ＬＮａＨ２ＰＯ４溶液－甲醇（５１）,检测波长为２８６ｎｍ。平均回收率为（１０１．２±１．５）％,ＲＳＤ为１．５％。     

High-performance liquid chromatographic method for determination of leucovorin in plasma: validation and application to a pharmacokinetic study in healthy volunteers

A sensitive and reliable high-performance liquid chromatographic (HPLC) method, using a solid-phase extraction (SPE), was developed and validated for determination of leucovorin (LV) in human plasma. Plasma sample was extracted by using a Sep-Pak cartridge which could be renewable. The sample was analyzed by HPLC with UV detection at 286 nm. The method was shown to perform selectively and sensitively for LV. The main metabolite of LV, 5-methyltetrahydrofolic acid, and endogenous substances in plasma did not show any interference in the analysis. The limit of detection was 10 ng/mL for LV in plasma and the linear range was 50-1500 ng/mL in plasma. The relative standard deviation (RSD) of intra-day and inter-day assays was 2.8-6.1% and 2.4-5.3%, respectively. The extraction recoveries of LV in plasma were over 90%. The method was proved to be applicable to the pharmacokinetic study of LV in healthy volunteers after a single oral administration (75 mg). The pharmacokinetic parameters and relative bioavailability were investigated for domestic LV tablet and capsule vs an imported tablet.     

高效液相色谱荧光检测法测定蔬菜中残留的甲氨基阿维菌素苯甲酸盐

建立了甘蓝和蘑菇中甲氨基阿维菌素苯甲酸盐的固相萃取-高效液相色谱荧光分析方法。蔬菜样品用乙酸乙酯提取,提取液旋转浓缩近干后用少量乙酸乙酯溶解,再经PRS固相萃取(SPE)柱净化,洗脱液经氮气吹干后用氮甲基咪唑和三氟乙酸酐衍生,衍生物用高效液相色谱分析,采用外标法定量。在添加浓度1.0～20.0 μg/kg范围内,平均添加回收率为78.6%～84.9%,日内相对标准偏差(RSD)为2.7%～6.0%,日间RSD为3.1%～8.9%,检出限为0.10 μg/kg。甲氨基阿维菌素苯甲酸盐衍生物在0.002～0.10 mg/L范围内呈良好的线性关系,相关系数为0.9999。     

Evaluation of mixed mode solid phase extraction cartridges for the preconcentration of beta-lactam antibiotics in wastewater using liquid chromatography with UV-DAD detection

A novel and simple method has been developed for the simultaneous determination of beta-lactam antibiotics (BLAs) (penicillin G, amoxicillin, ampicillin, penicillin V, oxacillin, cloxacillin, dicloxacillin and nafcillin) in wastewater. The method is based on solid-phase extraction (SPE) and high performance liquid chromatography with UV-diode array detection (UV-DAD). Two SPE cartridges have been compared for sample clean up and preconcentration: a reversed-phase silica-based cartridge (Bond Elut C₁₈, Varian Inc.) and a strong polymeric mixed mode anion exchanger (Oasis MAX, Waters). The penicillins have been separated using a LUNA™ C₁₈ (2) (150 mm × 4.6 mm, 5 μm) HPLC column and gradient elution with mobile phases consisting of aqueous trifluoroacetic acid and acetonitrile. The analytical wavelength was set at 220 nm. Under optimised conditions it was possible to preconcentrate up to 1000 mL of Milli-Q water in the Oasis MAX cartridges with recoveries in the range 82-97% (R.S.D. 2-9%) for all the antibiotic tested, except amoxicillin (52%, R.S.D. 8%), and limits of detection in the range of 8-24 ng L⁻¹. The matrix components in industrial and urban wastewater samples reduce the preconcentration efficiency in both sorbents, especially for the Bond Elut C₁₈. The use of the Oasis MAX allowed detection limits between 2.9-25.6, 2.5-12.4 and 2.2-12.7 μg L⁻¹, when processing 250 mL of industrial, influent and effluent sewage treatment plant (STP) samples. Recoveries ranged between 46-91, 28-91 and 39-114% (industrial, influent and effluent STP, respectively) for samples spiked with all the antibiotics at 25 and 75 μg L⁻¹ (n = 3 for each level).