Residue analysis for halofuginone in sturgeon muscle by immunoaffinity cleanup and liquid chromatography

A high-performance liquid chromatography (LC) method was developed for the determination of halofuginone (HFG) in sturgeon muscle. The extracted samples were cleaned up by an immunoaffinity chromatography column that was prepared by covalently coupling polyclonal antibodies against HFG to cyanogen bromide (CNBr) activated Sepharose 4B. The eluate was evaporated to dryness, and residues were determined by LC with absorbance detection at 243 nm. Recoveries of HFG from samples fortified at 20-200 microg/kg levels ranged 74.6-81.1%, with coefficients of variation of 0.7-8.6%. The detection limit was estimated to be 10 microg/kg in a 2 g sample.     

Stereoselective separation and determination of triadimefon and triadimenol in wheat, straw, and soil by liquid chromatography-tandem mass spectrometry

A sensitive and rapid analytical method was developed for simultaneous determination of triadimefon (TF) and triadimenol (TN) stereoisomers in wheat, straw, and soil by liquid chromatography coupled with triple quadrupole mass spectrometry (LC-MS/MS). The direct enantioseparation of TF and TN was performed on a Lux cellulose-1 column packed with cellulose-tris-(3,5-dimethylphenylcarbamate). The effects of mobile-phase composition on the separation were investigated and stereoisomeric elution orders were confirmed with a polarimeter detector. The pesticides were extracted from samples with acetonitrile and cleaned up by solid-phase extraction or activated carbon. Based on the developed stereoselective LC-MS/MS method, for TF and TN stereoisomers, good linearities were obtained over the concentration range of 0.003-4 mg/L; recoveries were 84.2-102.7% in wheat, 84.0-104.0% in straw, and 85.2-106.8% in soil at spiked concentrations of 0.007-2.0 mg/kg; intra-day and inter-day assay precisions were below 12.2%. Limits of detection (LODs) and limits of quantification (LOQs) in wheat, straw, and soil were 0.001-0.005 mg/kg and 0.007-0.02 mg/kg, respectively. Finally, the method was successfully applied to detect TF and TN stereoisomers in wheat, straw, and soil samples from residual trials in farm.     

Determination of fludioxonil and famoxadone in processed fruits and vegetables by liquid chromatography/electrospray tandem mass spectrometry

The feasibility of using liquid chromatography/ electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) for determining 2 fungicides (fludioxonil and famoxadone) in tomato pulp, pear purée, and concentrated lemon juice has been evaluated. A miniaturized extraction-partition procedure requiring small amounts of nonchlorinated solvents was used. The extracts (5 microL) were analyzed by LC/ESI-MS/MS without previous cleanup. Chromatographic determination was performed using a C18 column with isocratic elution. Four MS/MS transitions of precursor ions were monitored simultaneously (2 for each pesticide) by means of negative ESI. Mean recoveries from samples at fortification levels of 0.002-0.020 mg/kg (fludioxonil) and 0.010-0.100 mg/kg (famoxadone) ranged from 77.1 to 96.5%, with associated relative standard deviations between 4.2 and 11.5%.     

Liquid chromatographic determination of imazosulfuron in drinking water and in soil using ultraviolet detection.

Reversed-phase liquid chromatography (LC) is used to determine a relatively new sulfonylureic herbicide, imazosulfuron, 1-(2-chloroimidazo-[1,2-a] pyridin-3-ylsulfonyl)-3-(4,6-dimethoxy-2-pyrimidinyl)-urea (TH-913), in drinking water and in soil. TH-913 is extracted from water using solid-phase extraction on C18 bonded silica. Soil samples (20 g) are extracted with 300 ml of methanol-water (50:50) and the acidified extracts are transferred onto Sep-Pak C18 and processed as described for water samples. Off-line desorption is done with 20 ml of methanol-water (50:50). The eluate is evaporated to dryness, the residue dissolved in acetonitrile and analysed by LC with UV detection at 238 nm. The recoveries of TH-913 from water were over 95% (at 0.05 microg/l level) and from soil over 90% (at 0.005 mg/kg level).     

固相萃取/高效液相色谱-串联质谱法测定黄瓜及土壤中的春雷霉素残留

建立了测定黄瓜和土壤中春雷霉素残留的固相萃取/高效液相色谱-串联质谱(SPE/HPLC-MS/MS)方法。黄瓜和土壤样品分别经1%甲酸的甲醇、0.5%甲酸水提取后,采用MCX固相萃取柱净化,以Waters Xbridge BEH Amide色谱柱分离,0.2%甲酸水-乙腈溶液进行梯度洗脱,电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测,基质匹配标准曲线外标法定量。该方法灵敏、准确、简单快速、重复性好,在2~250μg/L浓度范围内,不同基质中春雷霉素的线性相关系数均大于0.999,检出限为0.002 mg/kg,定量下限为0.008 mg/kg;在0.008、0.040、0.200、0.400 mg/kg 4个加标水平下,春雷霉素在黄瓜和土壤样品中的平均回收率为77.5%~97.0%,相对标准偏差为2.6%~10.7%,能够满足黄瓜及土壤中春雷霉素残留的检测需求。应用该法对田间样品进行检测,结果表明,春雷霉素在黄瓜中的残留量不超过0.053 mg/kg,小于我国规定的黄瓜中最大残留限量(0.2 mg/kg);土壤中春雷霉素的残留量不超过0.013 mg/kg。     

高效液相色谱法拆分苯霜灵对映体

以高效液相色谱手性固定相法在对映体水平上建立了苯霜灵的分析方法。采用OD手性色谱柱,正己烷/异丙醇流动相,流速为1.0 mL/m in,检测波长206 nm,以圆二色检测器对两对映体进行出峰顺序确证并考察了其圆二色特性。结果显示,苯霜灵单一对映体在0.52~259.2 mg/L浓度范围内具有较好的线性,线性相关系数均大于0.9994,最低检出限为0.26 mg/L,在240 nm处的出峰顺序为( )/(-)。同时建立了苯霜灵对映体在土壤、水、葡萄中的残留分析方法。土壤和葡萄样品分别用丙酮和乙腈提取,水样用固相萃取法(SPE)富集净化。土壤中两对映体在0.025~2.5 mg/kg范围内的回收率为93.67%~108.95%之间;水样品在0.005~0.5 mg/L浓度范围的回收率在85.13%~100.79%之间,葡萄样品在0.04~1 mg/kg浓度范围的回收率在83.22%~106.62%之间;相对标准偏差RSD均小于6%。     

液相色谱-串联质谱法检测食品中的多种易滥用着色剂

建立了硬糖、果酱、液态奶、果汁中酸性红52、红色2G、喹啉黄、专利蓝、酸性红26、柠檬黄、靛蓝、胭脂红、诱惑红、日落黄、亮蓝、苋菜红等12种易滥用着色剂残留量的液相色谱-串联质谱分析方法。样品用水溶液稀释提取,经聚酰胺固相萃取柱净化后,在Agilent XDB-C18色谱柱分离,以20 mmol/L乙酸铵溶液和乙腈为流动相进行梯度洗脱。质谱采用电喷雾负离子(ESI~)模式电离,多反应监测(MRM)模式检测,基质匹配标准溶液外标法定量。易滥用着色剂在0.5～50 mg/L范围内呈线性相关,相关系数(r)均大于0.99,其定量限(信噪比大于10)为0.5 mg/kg,检出限(信噪比大于3)为0.1 mg/kg。各种基质样品在0.5、5和50 mg/kg添加水平时,易滥用着色剂的回收率范围为62.6%～115.3%,相对标准偏差(RSDs)为2.6%～26.3%,可以满足食品中易滥用着色剂含量的检测需要。     

Liquid chromatographic determination of fosthiazate residues in environmental samples and application of the method to a fosthiazate field dissipation study

A method was developed and validated for the determination of residues of the organophosphorus nematicide fosthiazate in soil and water by using reversed-phase liquid chromatography with UV detection. Good recoveries (>85%) of fosthiazate residues were obtained from water samples (drinking water, groundwater, and liquid chromatography water) after passage of 0.5-2 L water through solid-phase extraction (SPE) C-18 cartridges and subsequent elution with ethyl acetate. Residues in soil were extracted with methanol-water (75 + 25, v/v) on a wrist-action shaker, and the extract was cleaned up on C-18 SPE cartridges before analysis. The method was validated by analysis of a range of soils with different physicochemical characteristics; recoveries exceeded 87% at fortification levels ranging from 0.02 to 5.0 mg/kg. The precision values obtained for the method, expressed as repeatability and reproducibility, were satisfactory (<11%). Fosthiazate detection limits were 0.025 microg/L and 0.005 mg/kg for water and soil samples, respectively. The decline in the levels of fosthiazate residues in soil was measured after application of fosthiazate to protected tomato cultivation. The dissipation of fosthiazate residues followed first-order kinetics with a calculated half-life of 21 days.     

Determination of linuron and related compounds in soil by microwave-assisted solvent extraction and reversed-phase liquid chromatography with UV detection

The combination of microwave-assisted solvent extraction (MASE) and reversed-phase liquid chromatography (RPLC) with UV detection has been investigated for the efficient determination of phenylurea herbicides in soils involving the single-residue method (SRM) approach (linuron) and the multi-residue method (MRM) approach (monuron, monolinuron, isoproturon, metobromuron, diuron and linuron). Critical parameters of MASE, viz, extraction temperature, water content and extraction solvent were varied in order to optimise recoveries of the analytes while simultaneously minimising co-extraction of soil interferences. The optimised extraction procedure was applied to different types of soil with an organic carbon content of 0.4-16.7%. Besides freshly spiked soil samples, method validation included the analysis of samples with aged residues. A comparative study between the applicability of RPLC-UV without and with the use of column switching for the processing of uncleaned extracts, was carried out. For some of the tested analyte/matrix combinations the one-column approach (LC mode) is feasible. In comparison to LC, coupled-column LC (LC-LC mode) provides high selectivity in single-residue analysis (linuron) and, although less pronounced in multi-residue analysis (all six phenylurea herbicides), the clean-up performance of LC-LC improves both time of analysis and sample throughput. In the MRM approach the developed procedure involving MASE and LC-LC-UV provided acceptable recoveries (range, 80-120%) and RSDs (<12%) at levels of 10 microg/kg (n=9) and 50 microg/kg (n=7), respectively, for most analyte/matrix combinations. Recoveries from aged residue samples spiked at a level of 100 microg/kg (n=7) ranged, depending of the analyte/soil type combination, from 41-113% with RSDs ranging from 1-35%. In the SRM approach the developed LC-LC procedure was applied for the determination of linuron in 28 sandy soil samples collected in a field study. Linuron could be determined in soil with a limit of quantitation of 10 microg/kg.     

长江沿岸某化工园区土壤、底泥中酚类化合物的污染现状

建立了同时测定土壤（底泥）样品中12种酚类化合物的检测方法。采用加速溶剂萃取（ASE）与凝胶渗透色谱（GPC）协同净化进行前处理,气相色谱和质谱联用技术（GC-MS）进行定性定量分析。方法检出限为0.410~13.1 μg/kg（干重）,回收率在70.7%~122%之间,相对标准偏差（RSD）为1.2%~16%。基于上述分析方法研究了长江沿岸某化工园区土壤及长江底泥中12种酚类化合物的污染水平。17个土壤样品和7个底泥样品中除对苯二酚外的11种酚类化合物均有检出。土壤和底泥中酚类污染物总含量范围分别为10.16~30.66 mg/kg和18.00~29.83 mg/kg,平均含量分别为18.26 mg/kg和22.51 mg/kg。土壤和底泥中最主要的酚类污染物为4-硝基苯酚和4-氯-3-甲酚,其次为邻氯对苯二酚、4,6-二硝基邻甲基苯酚和2,4,6-三氯酚。该化工园区周边土壤及长江底泥中12种酚类污染物污染水平较低、环境风险较小。     

水果蔬菜中多种杀菌剂的基质固相分散液相色谱测定方法研究

采用基质固相分散(MSPD)代替液液分配和固相萃取,从蔬菜水果中提取、净化10种常用杀菌剂农药残留,用C18硅胶交联剂作为固相吸附剂,乙酸乙酯作为洗脱液,用HPLC/PDA和LC-MS进行分析检测。10种杀菌剂在0.5~5 mg/kg含量的添加回收率在65%~110%之间,相对标准偏差小于10%,使用HPLC、PDA和LC-MS的检出限分别在0.02~0.2 mg/kg和0.002~0.01 mg/kg之间。该方法节省溶剂,提取和净化一步完成,适用于新鲜水果和蔬菜中10种杀菌剂的残留分析。     

Reversed-phase liquid chromatographic determination of riboflavin in feeds

A method for determination of riboflavin in animal feeds using liquid chromatography (LC) was developed for feed samples fortified with riboflavin at 1 mg/lb or greater (up to 10,000 mg/lb). Feed samples were extracted in 0.1 N HCl with heating on a steam bath for 30 min, followed immediately by mechanical shaking for 30 min. Sample extracts were diluted to target volume with 2% acetic acid and filtered; riboflavin was determined by LC on a reversed-phase C18 column with 2% acetic acid-acetonitrile (85 + 15) mobile phase for separation and fluorescence detection with excitation at 460 nm and emission at 530 nm. The extraction was compared with that of the AOAC Official Method for riboflavin in food and feed premixes. The 2 method extractions were not significantly different from each other at the 95% confidence level. The developed method also had good linearity over 4 orders of magnitude, recovery of 95-99% from spiked feed samples, a limit of detection of riboflavin at 0.00034 microg/mL in solution, a limit of quantitation of 0.023 mg/lb in feed, and good ruggedness.     

Liquid chromatographic determination of triasulfuron in soil

Two extraction methods were developed for the determination of triasulfuron in soil. Method I included extraction with methanol-phosphate buffer at pH 7 (2 + 1, v/v), liquid-liquid partition with dichloromethane, and cleanup on a liquid chromatographic Si adsorption solid-phase extraction tube. In Method II, Extrelut was added and the sample was then extracted with acetonitrile. In both cases, the extracts were analyzed by liquid chromatography (LC) with UV detection and the LC peak was confirmed by LC/mass spectrometry (MS). The 2 methods were tested on 3 soils having different physicochemical characteristics. Method I gave 83% average recovery and a determination limit of 0.4 microg/kg soil. Method II gave 67% average recovery and a determination limit of 2 microg/kg soil. Examples of application of Method I to field samples are reported.     

高效液相色谱-串联质谱法测定食品中硝磺草酮

1 引 言 硝磺草酮(Mesotrione),化学名2-(4-甲磺酰基2硝基苯甲酰基)环己烷1,3二酮,又名甲基磺草酮、硝磺酮,是瑞士先正达公司发明的玉米田芽前和苗后广谱选择性除草剂,因具有低毒性、高活性、对环境友好等特点[1,2],是近几年广泛使用的除草剂.但最近研究发现,硝磺草酮具有高效的起始活性和残留活性,长期食用含有硝磺草酮残留的食物会对人畜产生致癌作用,或引起胎儿畸形[3,4].欧盟和世界贸易组织对浆果、亚麻籽、越橘、栗草料等物质中硝磺草酮的限量为0.05 mg/kg.而美国、加拿大等国对芦笋、草杆、草料等物质中硝磺草酮的限量为0.01 mg/kg[10-13].     

Amnesic shellfish poisoning toxins in shellfish: estimation of uncertainty of measurement for a liquid chromatography/tandem mass spectrometry method

A liquid chromatography/mass spectrometry (LC/MS) method for amnesic shellfish poisoning toxins in shellfish was developed and validated. Tissue homogenate (4 g) was extracted with 16 mL methanol-water (1 + 1, v/v). Dilution into acetonitrile-water (1 + 9, v/v) was followed by C18 solid-phase extraction cleanup. Domoic acid (DA) and epi-domoic acid were determined by LC/MS/MS with electrospray ionization and multiple reaction monitoring. External calibration was performed with dilutions of a certified reference standard. Advantages of this method include speed, lower detection limits, and a very high degree of specificity. The LC/MS response was highly linear, and there were no significant interferences to the determination of DA. Formal method validation was performed on 4 shellfish species. Fortification studies gave recoveries (mean +/- SD; n = 24) of 93 +/- 14% at 1 mg/kg, and 93.3 +/- 7.6% at 20 mg/kg over all the species. Analysis of a mussel certified reference material showed the bias as < 5%. The limits of detection and quantitation were 0.15 and 0.5 mg/kg, respectively. Routine application of the method over 4 months gave a recovery for the QC sample (1 mg/kg fortified blank mussel homogenate) run with each batch of 88.9 +/- 5.5% (mean +/- SD; n = 37). The total uncertainty of measurement results were estimated as 0.12 (12%) at 0.25-5 mg/kg and 0.079 (7.9%) at 5-50 mg/kg. The major contribution to the uncertainty was the repeatability of the LC/MS determination, probably arising from subtle matrix effects.     

Quantitative determination of coenyzme Q10 by liquid chromatography and liquid chromatography/mass spectrometry in dairy products

The dietary sources of CoQ10 and the evaluation of CoQ10 in dairy products were characterized. For quantitation of CoQ10 in food samples, 2 liquid chromatography (LC) methods with UV and mass spectrometry (MS) detections were developed. LC with UV detection was performed at 25 degrees C on a Hyperclone ODS 5 microm 150 x 4.6 mm column with mobile phase consisting of methanol-ethanol-2-propanol (70 + 15 + 15, v/v/v). Flow rate was 1.0 mL/min. Retention time of CoQ10 was 10.9 +/- 0.1 min. The method was sensitive [limit of detection (LOD) = 0.2 mg/kg], reproducible [relative standard deviation (RSD) = 3:0%), and linear up to 25 mg/kg (R > 0.999). LC/MS analysis was performed on a LUNA C18 3 microm, 150 x 4.6 mm column, using mobile phase consisting of ethanol-dioxane-acetic acid (9 + 1 + 0.01, v/v/v), flow rate was 0.6 mL/min, and the retention time of CoQ10 was 4.1 +/- 0.1 min. Identification and quantitation were performed with a Finnigan-LCQ mass detector in positive atmospheric pressure chemical ionization mode. Mass spectra were obtained in selected-ion monitoring mode; molecular mass (M+H)+ m/z 863.4 +/- 1 was used for quantitative determination. MS detection is more sensitive than UV detection (LOD = 0.1 mg/kg), less reproducible (RSD = 4.0%), and linear in selected range. Analytical recoveries are 75-90% and depend on the ratio between the amount of fat in the matrix and the concentration of CoQ10 in the sample. Some soybean milk products were analyzed together with different cow, goat, and sheep milk products. Concentrations obtained with LC and LC/MS were compared with a few accessible results available from the literature. Concentrations varied from 0 ppm in soybean milk to nearly 2 ppm in fresh milk from local farms.     

Determination of tridemorph and other fungicide residues in fruit samples by liquid chromatography-electrospray tandem mass spectrometry

A rapid and sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method for the determination of tridemorph and other pre- and post-harvest fungicides (carbendazim, thiabendazole, imazalil, propiconazole and bitertanol) in banana and orange samples has been developed and validated. The sample preparation was a simple extraction step with acetone using a high-speed blender prior to the injection of the five-fold diluted extract into the LC system with no other previous sample pre-treatment. Quantification was carried out using a matrix matched calibration curve which was linear in the range of 1-100 ng ml(-1) for all the compounds. The limit of quantification was 0.05 mg kg(-1) for all studied compounds, whereas limits of detection ranged between 0.005 and 0.025 mg kg(-1) (0.01 mg kg(-1) for tridemorph). Recoveries for tridemorph from spiked banana and orange samples at 0.05 and 1 mg kg(-1) were satisfactory, with values between 83 and 99% and relative standard deviations (R.S.D.s) lower than 13% (n = 5). For the other fungicides, recoveries between 75 and 95% with R.S.D.s lower than 12% were obtained. The developed method has been applied to the determination of selected fungicides in real samples of bananas and oranges from different origin. Thiabendazole and imazalil have been detected in almost all orange samples analyzed, and in around of 30% of banana samples. Bitertanol residues exceeded the maximum residue level (0.05 mg kg(-1)) in three banana samples while tridemorph was only detected in one sample.     

液相色谱串联质谱法快速测定牛奶与鸡蛋中的维吉霉素M_1残留量

建立了牛奶和鸡蛋样品中维吉霉素M_1残留的液质联用确证方法.用乙腈萃取样品中的维吉霉素M1残留,水稀释后,正己烷脱脂,以YMC-Pack Pro C_(18)色谱柱为分离柱,在正离子模式下以电喷雾电离串联质谱仪进行测定.方法的线性范围为2.5 ～25 μg/L,定量下限为50 μg/kg.在50、100、200 μg/kg 3个浓度水平进行加标回收实验,回收率为72% ～99%,相对标准偏差为2.7% ～6.1%.该方法简便、快速、准确,各项技术指标满足国内外法规的要求,可用于牛奶和鸡蛋样品中维吉霉素M1残留的快速确证检测.     

Assessment of performance of laboratories in determining acrylamide in crispbread

A proficiency testing round was undertaken to assess the performance of laboratories to measure acrylamide in a sample of crispbread. Retail samples of crispbread were ground to a fine powder and after thorough mixing were packed in 40 g units for distribution. Ten samples were selected at random and analyzed in duplicate for acrylamide by liquid chromatography/mass spectrometry (LC/MS). Standard statistical tests showed that the material was homogeneous for the purposes of proficiency testing. Test samples were distributed to 55 laboratories in 16 countries in Europe, North America, Australia, and the Middle East. The results were analyzed by standard proficiency testing statistical procedures, and laboratories were awarded z-scores on the basis of their reported results. Based on a target standard deviation (sigmap value) taken from the Horwitz equation, for a robust mean value of 1.2 mg/kg acrylamide, satisfactory results (z-score within +/- 2 for those between 0.8 and 1.6 mg/kg) were obtained by 86% of the 37 laboratories that returned results. Only 1 laboratory was unsatisfactory and 4 had questionable results. About equal numbers of laboratories used gas chromatography (GC)/MS and LC/MS procedures with about 25% using MS/MS and one using GC with electron capture detection. There was no evident trend in performance or bias in results. GC/MS and LC/MS data were evenly distributed across the population of laboratories reporting results.     

A sensitive confirmatory method for aflatoxins in maize based on liquid chromatography/electrospray ionization tandem mass spectrometry

A liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for measurement of aflatoxins B1, B2, G1, and G2 in maize is described. Aflatoxins (AFs) were extracted from 1 g samples by using tri-portions of acetonitrile/water (80:20, v/v) (10 + 7 + 7 mL), and 2/5 of the extract diluted to 500 mL by water was cleaned up with a 100 mg Carbograph-4 cartridge. After the addition of the internal standard AFM1, the final extract was analyzed by LC/ESI-MS/MS in positive ion mode using multiple reaction monitoring with a triple-quadrupole instrument. A C(18) column thermostatted at 45 degrees C with a mobile phase gradient of acetonitrile/water with 2 mmol/L ammonium formate was used. Although the matrix suppression effect was negligible, quantitation was achieved by an external calibration procedure using matrix-matched standard solutions to improve accuracy. Sample recoveries at four spiking levels ranged from 81 to 101% (relative standard deviation (RSD) 相似文献