Determination of vitamin K1 in medical foods by liquid chromatography with postcolumn reduction and fluorometric detection

A liquid chromatographic (LC) method is described for the determination of vitamin K1 in medical foods. The sample is enzymatically digested with lipase and alpha-amylase and extracted with 1% sodium bicarbonate solution-isopropanol (1 + 1). After C18 solid-phase extraction, vitamin K1 is separated by nonaqueous reversed-phase LC, converted to the hydroquinone by postcolumn zinc reduction, and quantitated by fluorescence detection. The limit of detection is 8 pg (3 sigma), and the limit of quantitation is 27 pg (10 sigma) on column. Linear response ranged from 0.1 to 1.0 ng vitamin K1 (r= 0.9999). The mean recovery (n = 38) for all spiking levels was 101.6 +/- 2.85%. Analysis of Standard Reference Material 1846, Infant Formula, gave a mean value of 0.95 +/- 0.088 mg vitamin K/kg (K or K1?) (n = 31) with a coefficient of variation of 9.26.     

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.     

Simultaneous determination of vitamin K1, vitamin K1 2,3-epoxide and menaquinone-4 in human plasma by high-performance liquid chromatography with fluorimetric detection

A highly sensitive method for measuring endogenous vitamin K1, menaquinone-4 (which is one of the K2 vitamins) and vitamin K1 2,3-epoxide in human plasma was developed, based on high-performance liquid chromatography with coulometric reduction and fluorimetric detection, following extraction from plasma and purification on a Sep-Pak silica cartridge. The detection limits of vitamin K1, menaquinone-4 and vitamin K1 2,3-epoxide were 5, 5 and 8 pg per injection for the standard substances and 30, 30 and 50 pg/ml in human plasma, respectively.     

Matrix solid-phase dispersion extraction versus solid-phase extraction in the analysis of combined residues of hexachlorocyclohexane isomers in plant matrices

This paper describes a method based on matrix solid-phase dispersion (MSPD) to determine the presence of combined residues of hexachlorocyclohexane (HCH) isomers (alpha-, beta-, gamma- and delta-) in various plant matrices including vegetables, fruits, leaves, grains and roots, by gas chromatography with (63)Ni electron-capture detection. The MSPD method consists of sample homogenization, cellular disruption, exhaustive extraction, fractionation and clean up by simple processes in which a small amount of sample (5 g) was blended with Florisil and the mixture passed into a small chromatographic column and eluted with 10 ml of n-hexane-ethyl acetate solvent mixture (70:30; v/v) and repeated with another 10 ml of the same solvent mixture. A comparison with classical solid-phase extraction (SPE) showed MSPD to be efficient, fast, simple and easy to perform. The detection limit of various HCH isomers was found to be in the range of 2.15-5.68 ng and method detection limit varied from 0.465 to 1.136 ng g(-1). Mean recoveries were found in the range of 91-98%. Till date, there are no official methods or standards by Central Pollution Control Board or Bureau of Indian standards that take into account India's real life conditions in the analysis of pesticide residues in plant matrices and the MSPD method described herein has proved to be a feasible one for the analysis of combined residues of HCH isomers in various plant materials.     

Liquid chromatographic analysis of vitamin K1 in milk-based infant formula with matrix solid-phase dispersion.

A liquid chromatographic method for vitamin K1 in milk-based infant formula is described. The vitamins are extracted from infant formula by matrix solid-phase dispersion and quantitated by reversed-phase chromatography with fluorescence detection. Vitamin K1 is converted to the fluorescent hydroquinone with a postcolumn zinc reductive reactor. The limit of detection is 12 pg, and the limit of quantitation is 38 pg on-column. Linear responses were obtained in the range 0.55-22.1 ng/ml (r2 = 0.9998). Recoveries of vitamin K1 from an analyte-fortified blank material for milk-based infant formula averaged 91.7% (n = 25). The method provides a rapid, specific, and easily controlled assay for vitamin K1 in fortified infant formula.     

Rapid monitoring of carvacrol in plants and herbal medicines using matrix solid-phase dispersion and gas chromatography flame ionisation detector

Matrix solid-phase dispersion (MSPD) method coupled with gas chromatography flame ionisation detector as a quick and easy extraction technique has been developed to extract carvacrol from plants and herbal medicines. Influence of important parameters on the MSPD method efficiency, such as the sorbent material, the ratio of sample to sorbent material, elution solvent and volume of the elution solvent has been evaluated and optimised. Carvacrol was successfully extracted by diatomaceous earth as sorbent with 350 μL of dichloromethane as elution solvent. The calibration curve showed good linearity (r² = 0.9965) and precision (RSD < 8.16%) in the concentration range of 0.5–100 μg mL^? 1 for carvacrol. The limit of detection and limit of quantification were 0.1 and 0.5 μg mL^? 1, respectively. The recoveries were in the range of 74.4–80.5% with relative standard deviation (RSD) values ranging from 8.4% to 9.8%. The reported MSPD extraction method revealed to be simpler and faster than conventional methods used to quantify carvacrol from plants and herbal medicines.     

Comparison of extraction techniques for quantitative analysis of pendimethalin from soil and rice grain

The paper exploits the development, optimization, and comparison of fast, efficient, quantitative analytical extraction techniques such as ultrasonic-assisted extraction (UAE) and matrix solid-phase dispersion (MSPD) for proficient extraction of pendimethalin from soil and rice samples. Residues of pendimethalin were quantified using high-performance liquid chromatography. Impact of several experimental parameters of UAE and MSPD techniques on extraction of pendimethalin from soil and rice samples was also evaluated. Under the optimized conditions, the mean percent recoveries obtained from both methods were in the range of 80.3–101.3 and 81.7–103.1, respectively, with relative standard deviation <10. Linearity was in the range of 0.003–5.0?µg?mL^?1 with limit of detection and limit of quantification as 0.001 and 0.003?µg?g^?1, respectively. MSPD method was found superior in terms of low solvent consumption, small sample size, and reduced matrix coextracts due to simultaneous extraction and cleanup steps. Both extraction methodologies were successfully applied in monitoring routine soil and rice samples, in which pendimethalin residues (0.003–0.007?µg?g^?1) were detected in few rice samples while residues in soil samples were below the quantification limit.     

食品中维生素D与25-羟基维生素D检测技术及含量分布研究进展

维生素D是一种对于维持人体健康具有重要作用的脂溶性维生素,25-羟基维生素D是其在人体内循环和存储的主要形式。食品中维生素D和25-羟基维生素D前处理的通常采用碱皂化、有机溶剂提取、固相萃取或者半制备色谱净化;其测定方法多为放射免疫法和液相色谱法。液相色谱串联质谱凭借高灵敏度和高准确度,目前在食品中维生素D和25-羟基维生素D测定中发挥重要作用。近年来二维液相色谱和超高效超临界流体色谱由于其强大的分离能力,在食品中维生素D和25-羟基维生素D的分析中表现出强大的潜力。该文综述了近年来食品中维生素D和25-羟基维生素D的检测方法及二者在动物食品和植物食品中的含量分布研究,以期为建立适合不同食物样品的测定方法,指导居民合理膳食,进行膳食摄入量评估等研究工作提供参考。     

Matrix solid-phase dispersion extraction of carbadox and olaquindox in feed followed by hydrophilic interaction ultra-high-pressure liquid chromatographic analysis

A new method involving matrix solid-phase dispersion (MSPD) extraction and hydrophilic interaction ultra-high-pressure liquid chromatography (HILIC-UHPLC) with photodiode array detection was developed for the determination of carbadox and olaquindox in feed. Separation of carbadox and olaquindox was achieved within 1 min on the 1.7 microm Acquity UPLC BEH HILIC column by using isocratic elution with a mobile phase consisting of 10 mmol L(-1) ammonium acetate in acetonitrile-water (95:5, v/v) at a flow rate of 0.5 mL min(-1). Optimization of MSPD extraction parameters, such as type of solid sorbent and elution solvent were carried out. Optimal conditions selected for MSPD extraction were: 0.25 g of feed sample, 0.5 g of octadecylsilica as solid sorbent and 10 mL of acetonitrile-methanol (8:2, v/v) as eluting solvent. Both analytes provided average recoveries from spiked feed samples ranging from 89.1 to 98.4% with relative standard deviations less than 10%. Obtained performance characteristics are comparable to those achieved by liquid-liquid extraction-HPLC with the advantages of being simpler and significantly faster.     

Determination of phenolic compounds in wines by novel matrix solid-phase dispersion extraction and gas chromatography/mass spectrometry

A novel matrix solid-phase dispersion (MSPD) extraction method was developed to extract simultaneously 23 phenolic compounds from wine samples prior to determination by gas chromatography with mass spectrometric detection in the selected ion monitoring mode. Different parameters of the MSPD technique such as dispersant solid-phase, eluting solvent, and sample ionic strength and pH were optimized. The optimized MSPD procedure requires a small volume of wine (1 mL), commercial silica gel (1.5 g) as dispersant solid-phase and a small volume of ethyl acetate (5 mL) as eluting solvent. Under these conditions, the extraction of the studied compounds was almost complete (mean values of recoveries between 87 and 109%) in a short time (15 min). Moreover, satisfactory standard deviations of repeatability (RSD<9% in most cases), linear regression coefficients (r(2)>0.993) and detection limits (<8 microg/L) confirm the usefulness of the methodology for routine monitoring of the concentration of individual phenolic antioxidants in wines. Application was illustrated by analysis of different wine samples.     

Determination of menadione in an animal feed using supercritical fluid extraction and HPLC with electrochemical detector

Menadione (vitamin K3) is extracted from spiked rat chow using supercritical fluid carbon dioxide at 8000 psi and 60 degrees C. Quantitative extraction requires only 20 min. The extraction does not suffer from the problems associated with conventional solvent extraction of lipophilic materials from animal feeds. Menadione is determined in the extract, which does not require further cleanup, using reversed-phase high-performance liquid chromatography (HPLC) with reductive mode electrochemical detection at a silver electrode at -0.75 V vs. calomel. The minimum detectable quantity by the detector is 125 pg of menadione, and the response is linear over at least 4 orders of magnitude; however, the minimum quantity extractable is about 20 micrograms/g of feed. Repetitive extracts of a spiked feed sample over a five-day period show an average recovery of 90.5% with a relative standard deviation of 2.2% at the 1 mg/g level.     

快速溶剂萃取–凝胶渗透色谱净化–气相色谱质谱法测定土壤中邻甲苯胺含量

以快速溶剂萃取–凝胶渗透色谱净化–气相色谱质谱法测定土壤中邻甲苯胺的含量。土壤样品经ASE–350快速溶剂萃取仪萃取,萃取液用凝胶渗透色谱净化浓缩后,用全扫描模式(SCAN)采集气相色谱–质谱法测定土壤中的邻甲苯胺含量。该方法检出限为0.01 mg/kg,加标回收率为78.3%~95.5%,测定结果的相对标准偏差为2.35%~14.9%(n=6)。该方法具有分离效果好、灵敏度高、重现性好、前处理操作简便及纯化效果好等优点,可用于测定土壤中邻甲苯胺的含量。     

液相色谱-串联质谱法测定小型家用电器塑料部件中全氟辛酸

建立了高效液相色谱-串联质谱(HPLC-MS/MS)结合加速溶剂萃取测定小型家用电器塑料部件中全氟辛酸(PFOA)的分析方法。样品冷冻粉碎后采用甲醇作溶剂进行快速溶剂萃取,萃取液经C18固相萃取柱富集净化后,以C18柱为分离柱,以甲醇-水为流动相,梯度洗脱,电喷雾负离子模式下多反应监测(MRM))模式检测。PFOA在0.5～100.0μg/L范围内线性关系良好(r2=0.998 9),回收率为93%～107%,相对标准偏差为2.9%～7.6%,检出限(S/N=3)为0.5μg/kg。该方法操作简便、灵敏度高,适用于小型家用电器塑料部件中全氟辛酸残留分析。     

Analysis of Cembranoids in Flue‐cured Tobacco by Accelerated Solvent Extraction and Gas Chromatography‐Mass Spectrometry‐Selected Ion Monitoring

An efficient and sensitive analytical method based on accelerated solvent extraction (ASE) and gas chromatography‐mass spectrometry‐selected ion monitoring (GC‐MS‐SIM) was developed and validated for analysis of cembranoids in flue‐cured tobacco leaves. Extraction efficiency of different pretreatment methods including liquid‐solid extraction (LSE), ultrasound‐assisted extraction (UAE), Soxlet extraction and accelerated solvent extraction (ASE) was compared and ASE was chosen as the optimal extraction method. During ASE procedure, effect of four parameters on extraction efficiency was considered and the experimental conditions were selected as follows: extraction solvent: dichloromethane; oven temperature: 50 °C; static time: 5 min and number of cycles: 2. Working standards of cembranoids were isolated by silica gel column chromatography and the identification was performed by mass spectrometry. Performance characteristics such as linearity, limit of detection (LOD), limit of quantitation (LOQ), precision and recovery were studied. The LOD and LOQ values were ranging from 5.0 × 10^?3 to 6.9 × 10^?3 μg/mL and 1.7 × 10^?2 to 2.3 × 10^?2 μg/mL for all analytes. At three different spiked levels, recoveries for CBT‐ol, α‐CBT‐diol and β‐CBT‐diol were 94.6%‐105.1%, 93.0%‐97.2% and 88.7%‐107.5% while the relative standard deviations (RSDs) were in the ranges of 3.9%‐6.2%, 1.8%‐8.7% and 1.7%‐6.0%, respectively. The proposed analytical methodology was successfully applied in the analysis of cembranoids in tobacco samples.     

Pharmacokinetics of isofraxidin in rat plasma after oral administration of the extract of Acanthopanax senticosus using HPLC with solid phase extraction method

High-performance liquid chromatography coupled with solid phase extraction method was developed for determination of isofraxidin in rat plasma after oral administration of Acanthopanax senticosus extract (ASE), and pharmacokinetic parameters of isofraxidin either in ASE or pure compound were measured. The HPLC analysis was performed on a Dikma Diamonsil RP(18) column (4.6 mm x 150 mm, 5 microm) with the isocratic elution of solvent A (acetonitrile) and solvent B (0.1% aqueous phosphoric acid, v/v) (A : B = 22 : 78) and the detection wavelength was set at 343 nm. The calibration curve was linear over the range of 0.156-15.625 microg/ml. The limit of detection was 60 ng/ml. The intra-day precision was 5.8%, and the inter-day precision was 6.0%. The recovery was 87.30+/-1.73%. When the dosage of ASE is equal to pure compound caculated by the amount of isofraxidin, it has been found to have two maximum concentrations in plasma while the pure compound only showed one peak in the plasma concentration-time curve. The determined content of isofraxidin in plasma after oral administration of ASE is the total contents of free isofraxidin and its precursors in ASE in vitro. The pharmacokinetic characteristics of ASE showed the priority of the extract and the properities of traditional Chinese medicine.     

加速溶剂萃取/离子色谱法测定菊花中的SO_2残留

采用碱性溶液加速溶剂萃取(ASE)/离子色谱(IC)法测定,建立了菊花中SO2残留的分析方法。粉碎后的样品以碱性溶液为萃取溶剂,经加速溶剂萃取仪提取,C18固相萃取(SPE)净化后,以碳酸盐为淋洗液,IonPac AS9-HC离子色谱柱分离,电导检测器进行检测。结果表明,SO2(以SO2-3计)在0.5~50 mg·L-1范围内线性关系良好(r2=0.999 7),检出限(LOD)为0.05 mg·L-1,定量下限(LOQ)为0.17 mg·L-1。以空白菊花样品为基体,在低、中、高3个浓度水平下的平均加标回收率为82.9%~92.6%,RSD(n=6)小于5.0%。与传统方法相比,该方法具有自动化程度和提取效率高的优点,适合于批量测定菊花中的SO2残留。     

Application of matrix solid-phase dispersion to the determination of a new generation of fungicides in fruits and vegetables

A method based on matrix solid-phase dispersion (MSPD) and gas chromatography to determine eight fungicides in fruits and vegetables is described. Fungicide residues were identified and quantified using nitrogen-phosphorus detection and electron-capture detection connected in parallel and confirmed by mass spectrometric detection. The method required 0.5 g of sample, C18 bonded silica as dispersant sorbent, silica as clean-up sorbent and ethyl acetate as eluting solvent. Recoveries from spiked orange, apple, tomato, artichoke, carrot and courgette samples ranged from 62 to 102% and relative standard deviations were less than 15% in the concentration range 0.05-10 mg kg(-1). Detection and quantitation limits ranged 3-30 microg kg(-1) and 10-100 microg kg(-1), respectively, with linear calibration curves up to 10 mg kg(-1). The analytical characteristics of MSPD compared very favourably with the results of a classical multiresidue method, which uses ethyl acetate and anhydrous sodium sulphate for the extraction.     

快速溶剂萃取–高效液相色谱法测定禽蛋中磺胺嘧啶

建立快速溶剂萃取–高效液相色谱法测定禽蛋中磺胺嘧啶残留的方法。用单因素和正交试验对禽蛋中磺胺嘧啶的萃取条件进行优化,确定了最佳萃取条件:以甲醇为萃取剂,在130℃循环萃取4次,冲洗体积分数为80%,萃取时间为25 min。色谱柱为Hypersil ODS2柱(4.6 mm×250 mm,5μm),流动相为甲醇–0.5%冰乙酸(25∶75),流量为1.0 m L/min,检测波长为265 nm。磺胺嘧啶的质量浓度在0.025~0.500 mg/m L范围内与色谱峰面积呈良好的线性关系,相关系数r=0.999 5,检出限为0.5μg/kg。加标回收率在83.0%~88.2%之间,测定结果的相对标准偏差为2.2%(n=9)。方法的精密度、准确度和基质效应均符合禽蛋样品检测要求,可用于禽蛋中磺胺嘧啶含量的测定。     

Development of a matrix solid-phase dispersion method for the determination of polycyclic aromatic hydrocarbons in sewage sludge samples

A new, single-step extraction and purification method based on matrix solid-phase dispersion (MSPD) was developed to determine 17 polycyclic aromatic hydrocarbons (PAHs) in sewage sludge samples. The MSPD method consists of sample homogenisation, exhaustive extraction and clean-up by a single process. The different operational parameters of the method, such as the type of dispersant, type and amount of additives, clean-up co-sorbent and extractive solvent were evaluated. Reversed-phase (C18) and polymeric (Oasis HLB and Oasis MAX) materials, as well as normal phase sorbents (Florisil, silica, neutral alumina) and an inert support (sand) were tested to assess the sorbents effect on the yield and selectivity of the MSPD process. Analysis of extracts was performed by high performance liquid chromatography (HPLC) coupled with fluorescence detection.Quantification limits obtained for all of these considered compounds (between 0.0001 and 0.005 μg g⁻¹ dry mass) were well below of the limits recommended in the EU. The extraction yields for the different compounds obtained by MSPD ranged from 76.3% to 103.6%. On the other hand, the extraction efficiency of the optimised method is compared with that achieved by microwave-assisted extraction and the method was applied to the analysis of real sewage sludge samples. A certified reference material (sewage sludge (BCR 088)) and a reference material (sewage sludge (RTC-CNS312-04)) were used to validate the proposed method.     

Analysis of isotope ratios in vitamin K1 (phylloquinone) from human plasma by gas chromatography/mass spectrometry

Vitamin K(1) is a fat-soluble vitamin required for the gamma-carboxylation of vitamin K-dependent proteins. Recent work has suggested an important role for vitamin K(1) in bone health beyond its more established function in the control and regulation of blood coagulation. However, current UK recommended intakes do not reflect this recent evidence. The use of stable isotopes provides a powerful tool to investigate vitamin K kinetics, turnover and absorption in man, although published methods have reported difficulties in the extraction and analysis of isotope ratios of vitamin K in human plasma. In this paper, we report a new methodology for the extraction and measurement of isotope ratios in vitamin K(1). Sample clean-up is achieved with liquid-liquid extraction, enzyme hydrolysis with lipase and cholesterol esterase, and solid-phase extraction. Isotopic analysis of the pentafluoropropionyl derivative of vitamin K(1) is performed by gas chromatography/mass spectrometry (GC/MS). The limit of quantitation is equivalent to at least 0.3 nmol/L and the method is demonstrated to be linear over a range of enrichments. This method provides a robust alternative to previous work requiring the use of semi-preparative high-performance liquid chromatography (HPLC).