Determination of 4-hydroxycoumarin rodenticides in animal products, fishery products, and honey by liquid chromatography-tandem mass spectrometry

A sensitive and selective method for the determination of 4-hydroxycoumarin-type rodenticides (warfarin, coumatetralyl, bromadiolone, and brodifacoum) in animal products, fishery products, and honey was developed. 4-Hydroxycoumarin rodenticides were extracted with acidified acetone, and the crude extract was purified by liquid-liquid partitioning followed by PSA column cleanup. Gradient liquid chromatographic separation was performed by using an Inertsil ODS-4 column, with methanol and water containing ammonium acetate as the mobile phase. Detection was carried out on a tandem mass spectrometer with electrospray ionization in the negative mode. Average recoveries from bovine muscle, bovine liver, bovine fat, swine muscle, salmon, eel, freshwater clam, egg, milk, and honey spiked at 0.0005-0.001 mg/kg were in the range of 79-108%, and the relative standard deviations were 2-8%. The limits of quantitations of the developed method were 0.0005 mg/kg for brodifacoum, 0.001 mg/kg for warfarin, coumatetralyl, and bromadiolone.     

Determination of pindone in agricultural products by LC-MS/MS

A sensitive and selective analytical method for the determination of pindone in agricultural products by LC-MS/MS was developed. Pindone was extracted with acetone, and an aliquot of the crude extract was re-extracted with hexane. For lipid-rich samples, the crude extract was further cleaned up by acetonitrile-hexane partitioning. The extract was cleaned up on a tandem graphitized carbon-silica gel column. For brown rice, soybean, and tea, PSA column cleanup was added prior to LC-MS/MS determination. Average recoveries of pindone from brown rice, soybean, potato, spinach, cabbage, apple, orange, tomato, cucumber, and tea fortified at 0.001 mg/kg were 81-93%, and the relative standard deviations were 2-7%. The limit of quantitation (S/N ≥ 10) of the developed method was 0.001 mg/kg for all the tested agricultural products.     

Determination of vedaprofen in livestock products and seafoods by liquid chromatography-tandem mass spectrometry

A novel liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the trace residue determination of vedaprofen (VPF) in livestock products and seafoods. VPF was extracted from each sample with acidified acetone, and the crude extract was re-extracted with ethyl acetate and NaCl solution. Clean-up was performed using a weak anion exchange cartridge (Bond Elut DEA). The LC separation was performed on a C18 column using acetonitrile-0.0025 mol/L formic acid (3 : 2) as the mobile phase and MS was run in the negative ion electrospray ionization mode. The calibration curve was linear in the range of 0.001-0.1 μg/mL VPF. The mean recoveries from equine muscle, cattle muscle, cattle liver, cattle fat, salmon, eel, corbicula, milk, egg and buckwheat honey were 72-94%, and the relative standard deviations (RSDs) were 1.1-2.0%. Limits of quantitation (LOQs) ranged from 0.001 to 0.007 μg/g.     

气相色谱-质谱联用法快速检测乳制品中维生素E含量

目的建立正己烷涡旋辅助提取-气相色谱-质谱联用法(gas chromatography-mass spectrometry,GC-MS)快速检测乳制品中α-生育酚和α-醋酸生育酚的分析方法。方法样品经甲醇沉淀蛋白后,采用正己烷涡旋提取,提取液以HP-5MS色谱柱分离,GC-MS选择离子监测模式测定。结果α-生育酚和α-醋酸生育酚在0.05~10 mg/L浓度范围内线性关系良好,相关系数均大于0.999;α-生育酚和α-醋酸生育酚检出限(S/N=3)分别为0.51 mg/kg和0.25 mg/kg,定量限(S/N=10)分别为1.70 mg/kg和0.83 mg/kg。质控样NIST SRM 1849a检测值与参考值偏差为-3.75%,日内相对标准偏差(RSD,n=5)为1.38%~2.25%,日间相对标准偏差为1.83%。结论该方法快速、准确、灵敏,适用于乳制品中维生素E含量的快速测定。     

气相色谱-质谱法测定粮油制品中的二甲基黄和二乙基黄含量

目的建立气相色谱-质谱法测定粮油制品中二甲基黄和二乙基黄的含量的分析方法。方法试样以1%醋酸的乙腈提取,采用油基质萃取管净化和HP-5MS色谱柱分离,质谱采用全扫描和选择离子模式测定,以外标法定量。同时考察了不同的提取溶剂及净化方式对回收率的影响。结果在添标水平为1、10和25 mg/kg时,二甲基黄和二乙基黄的平均回收率为76.3%~89.3%,相对标准偏差为3.0%~8.7%,二甲基黄的方法检出限为0.002 mg/kg,二乙基黄的检出限为0.001 mg/kg,符合检测方法参数的确认要求。结论该方法快速、准确,适用于粮油制品中的二甲基黄和二乙基黄含量。     

Determination of dimetridazole, metronidazole and ronidazole in salmon and honey by liquid chromatography coupled with tandem mass spectrometry

A liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed to determine the residues of dimetridazole (DMZ), metronidazole (MNZ) and ronidazole (RNZ) in salmon and honey. These compounds were extracted with ethyl acetate from samples and cleaned up using a silica solid phase extraction (SPE) cartridge. These compounds were determined by reversed-phase LC using a C18 column with distilled water-methanol as the mobile phase, and MS detection in the positive mode by applying selected reaction monitoring (SRM). DMZ-d(3), MNZ-(13)C(2),(15)N(2) and RNZ-d(3) were used as internal standards. The method was validated in salmon and honey spiked with these compounds at 0.4-2 μg/kg, and average recoveries were in the range of 91.2-107.0%. Repeatability was 1.7-17.1% and intermediate precision was less than 20%. The detection limits of DMZ, MNZ and RNZ in salmon and honey were 0.05-0.2 μg/kg. The method was applied to 3 salmon and 20 honey samples. The concentrations of these compounds in all samples were lower than the detection limits established by the Ministry of Health, Labour and Welfare in Japan.     

Analysis of tetracyclines in honey and royal jelly by LC/MS/MS

A simple and accurate method using liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) was developed for the determination of tetracyclines (TCs), i.e., oxytetracycline (OTC), chlortetracycline (CTC) and tetracycline (TC), in honey and royal jelly. Mass spectral acquisition was performed in the positive mode. In LC separation, L-column ODS and 0.01% formic acid-acetonitrile were used as the column and mobile phase, respectively. TCs in a honey sample were diluted with water, while TCs in royal jelly were extracted with 2% metaphosphoric acid-methanol (6:4). They were cleaned up with Oasis HLB and Sep Pak C18 cartridges, respectively. The quantification limits of TC, OTC, and CTC were 5, 5, and 10 ng/g, respectively, while those in royal jelly were 25, 25, and 50 ng/g, respectively. The recoveries of TCs from both honey and royal jelly were 75-120%.     

Analysis of chloramphenicol in honey and royal jelly by LC/MS/MS

A sensitive and selective method using liquid chromatography coupled with electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was developed for the determination of chloramphenicol (CAP) in honey and royal jelly. Mass spectral acquisition was performed in the negative mode by applying multiple reaction monitoring. In LC separation, Mightyl RP-18GP and 10 mmol/L ammonium acetate-acetonitrile were used as the column and mobile phase, respectively. CAP in honey samples was diluted with water, while CAP in royal jelly was extracted with 1% metaphosphoric acid-methanol (4 : 6). The solutions were cleaned up with an Oasis HLB cartridge. The quantification limits of CAP in honey and royal jelly were 0.3 ng/g and 1.5 ng/g, respectively. The recoveries of CAP from both honey and royal jelly at the quantification limits were over 92%. Twenty honey products and seven royal jelly products were analyzed by the developed method. CAP was detected in one honey product at 0.6 ng/g and in six royal jelly products at the level of 1.5-17.8 ng/g. These results show that the developed method has satisfactory sensitivity selectivity and is useful for the determination of CAP residues in honey and royal jelly.     

Total determination of residual flutolanil and its metabolites in livestock products and seafood using liquid chromatography-tandem mass spectrometry

ABSTRACT

We have developed a simple and sensitive LC-MS/MS analytical method for the determination of residual flutolanil and its principal metabolites, including α,α,α-trifluoro-3′-hydroxy-o-toluanilide (M-4) and its conjugates, in livestock and seafood products. Both flutolanil and its metabolites contain the 2-(trifluoromethyl)benzoic acid (2-TFMBA) moiety. In this method, flutolanil and its metabolites are converted to 2-TFMBA by hydrolysis. The method involves direct hydrolysis with sodium hydroxide at 200°C, acidification, partitioning into a mixture of ethyl acetate-n-hexane (1:9, v/v), clean-up using a strong anion exchange cartridge (InertSep SAX), and then quantification using LC-MS/MS. The optimal conditions for the complete hydrolysis of flutolanil to 2-TFMBA are an incubation time of 6 h and a temperature of 200°C. The developed method was evaluated using seven types of food: bovine samples of muscle, fat, liver and milk, as well as egg, eel, and freshwater clam. Samples were spiked both at 0.01 mg/kg and at the Japanese maximum residue limit (MRL) established for each food type. The validation results show excellent recoveries (88–107%) and precision (< 10%) for flutolanil and M-4. The limit of quantification (S/N ≥ 10) of the developed method is 0.01 mg/kg. The developed method is applicable to the definition of residual flutolanil for animal-based food commodities and MRLs established by the Codex Alimentarius, and will be useful for the regulatory monitoring of residual flutolanil and its metabolites in food products.     

Analytical method of hydramethylnon in agricultural products by LC-MS/MS

A simple determination method of hydramethylnon in agricultural products by liquid chromatography-tandem mass spectrometry (LC-MS/MS) was developed. The sample was homogenized with phosphoric acid and extracted with acetone. An aliquot of crude extract was re-extracted with hexane and sat. NaCl solution. In the case of tea leaf, solidification processing using ammonium chloride and phosphoric acid was performed before re-extraction with hexane. Clean-up was performed using a silica-gel mini column (500 mg). The LC separation was performed on a C18 column using methanol-water (8 : 2) containing 10 mM ammonium acetate as the mobile phase and MS detection with positive ion electrospray ionization. The calibration curve was linear between 0.002-0.2 μg/mL of hydramethylnon. Recoveries (n=5) of hydromethylnon from 10 kinds of agricultural products fortified at 0.01 μg/g (0.05 μg/g for pineapple) were 82-110%, and their relative standard deviations were 2-12%.     

Simultaneous determination of polyether antibiotics and macrolide anthelmintics in livestock products by liquid chromatography/tandem mass spectrometry

A method using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed for the simultaneous determination of polyether antibiotics and macrolide anthelmintics in livestock products. The polyether antibiotics and macrolide anthelmintics were extracted from livestock products with acetonitrile and cleaned up with dispersive solid-phase extractions and a silica gel column. The quantification limits of polyether antibiotics and macrolide anthelmintics were 0.00005-0.0005 μg/g. Except for narasin and lasalocid in bovine liver and milk, the recoveries were 70 to 117%. The relative standard deviations met the required guideline. The developed method was applied to six kinds of livestock products.     

超高效液相色谱测定蜂蜜及其制品中的苯甲酸、山梨酸

研究蜂蜜及其制品中的山梨酸与苯甲酸两种防腐剂的提取净化及其超高效液相色谱检测方法。样品用水溶解,超声波辅助提取样品中的山梨酸与苯甲酸。样液经高速离心,滤膜过滤后,采用超高效液相色谱梯度洗脱与二极管阵列检测器测定样品中的山梨酸与苯甲酸的含量。以BEH Shield RP18(2.1mm × 100mm,1.7μm)为色谱柱,以0.02mol/L 乙酸铵溶液和乙醇为流动相梯度洗脱,两种防腐剂在4min 中内实现较好的分离。方法检出限：苯甲酸为2.5mg/kg,山梨酸为2.0mg/kg。以加标样品做添加回收率测定,苯甲酸与山梨酸的回收率分别为94.1%～102.3% 和96.2%～99.8%,相对标准偏差均小于5%。方法简单、快速准确、灵敏度高是一种较好的定性和定量方法。     

Analysis of imidocarb in livestock and seafood products using LC-MS/MS

A simple method using high-performance liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was investigated for the detection of the antiprotozoal drug imidocarb in 10 livestock and seafood products. Liquid chromatographic separation employed a TSK VMpak-25 column with ammonium acetate-acetonitrile as a mobile phase. Mass spectral acquisition was performed in the ESI positive-ion mode. Imidocarb was extracted from all samples using liquid extraction with acetonitrile under basic conditions. For samples other than honey, fat-soluble impurities were removed by acetonitrile-hexane partitioning. The salting-out technique was used for extraction from honey in order to improve the separation of the organic solvent and water added to the honey sample. The limit of quantitation was 0.005 μg/g (expressed as concentration in samples). The recoveries from all samples were 76-109%, and the repeatability and reproducibility were also satisfactory.     

液相色谱- 串联质谱法同时测定蜂蜜中4种四环素族抗生素及其3 种差向异构体

采用液相色谱-质谱联用技术,建立同时测定蜂蜜样品中4种四环素族抗生素及其3种差向异构体的方法。蜂蜜样品中残留的药物用EDTA-McIlvaine缓冲液提取,提取液依次经OASIS HLB及羧酸弱阳离子柱固相萃取柱富集、净化后,用流动相洗脱。洗脱液经微孔滤膜过滤,用流动相甲酸水-乙腈梯度分离,电喷雾-串联质谱进行测定。在多反应监测模式下,22min内7种药物基本实现分离以及定性定量。样品在10～500μg/kg添加范围内,回收率均在64.9%～91.0%之间,相对标准偏差(RSD)不大于10.5%。土霉素及差向土霉素、四环素及差向四环素的检测限为1μg/kg,金霉素及差向金霉素、强力霉素的检测限为2μg/kg。本方法灵敏、可靠,可用于蜂蜜中7种四环素类抗生素的同时检测(其中包括3种毒性代谢产物)。     

同位素稀释-超高效液相色谱-串联质谱法检测蜂蜜中泛酸含量

建立了同位素稀释-超高效液相色谱-串联质谱法（UPLC-MS/MS）检测蜂蜜中泛酸（维生素B5）的快速定量和确证方法。样品经0.1%氨水（V/V）提取,MAX固相萃取柱净化后,以0.1%甲酸乙腈-0.1%甲酸水为流动相梯度洗脱,使用HSS T3色谱柱进行分离,电喷雾正离子多反应监测（MRM）模式检测,同位素内标法定量。在优化条件下,泛酸在0.500～500 μg/L范围内线性良好,相关系数（R2）为0.999 6;方法检出限为1.0 μg/kg（S/N=3）,定量限为3.0 μg/kg（S/N=10）;回收率在98.3%～98.7%之间,相对标准偏差（RSD）为2.4%～3.1%。通过市售蜂蜜样品测试表明,该方法操作简单、检测结果准确,可用于蜂蜜中泛酸的快速检测。     

Analytical method of clofencet in animal fishery products by LC/MS

A method for the determination of clofencet in animal and fishery products was developed, using liquid chromatography with electrospray ionization mass spectrometry (LC/ESI-MS). The sample was homogenized with water and hexane, and the homogenate was extracted with acetonitrile, then acetonitrile-water (4 : 1). An aliquot of the crude extract was passed through a C18 cartridge column (1,000 mg), and the eluate was concentrated. A solution of 10% sodium chloride and 1% sodium hydrogen carbonate, and ethyl acetate were added to the residue, and the mixture was shaken. After shaking, the aqueous phase was recovered and acidified with hydrochloric acid, and then clofencet was extracted with ethyl acetate. The extract was evaporated to dryness and the residue was dissolved in methanol-water (3 : 7). Clofencet was analyzed by LC/MS. The recoveries of clofencet from ten kinds of animal and fishery products were 77.8-97.8%, and the relative standard deviations were 0.6-5.8% (n=5). S/N of the peak of clofencet was >10 and no interfering peak was found in animal and fishery products fortified at 0.01 mg/kg.     

固相萃取一在线凝胶渗透色谱一气相色谱质谱联用测定蔬菜干制品中的18种有机磷和拟除虫菊酯残留

建立了蔬菜干制品中18种有机磷农药和拟除虫菊酯农药残留的在线凝胶渗透色谱一气相色谱／质谱（GPC-GC／MS）分析方法。样品以乙腈为提取剂超声波高速匀浆提取,提取液经ENVI．Carb固相萃取柱净化,除去样品中大部分的色素等干扰基质,再经在线GPC进一步净化除去大分子干扰物质,有效降低了样品基质带来的背景干扰。采用外标法定量,在质量浓度为0．02mg／kg,-0．5mg／kg有良好的线性关系,加标水平为0．4mg／kg时,18种农药的回收率基本都在80％-130％,相对标准偏差小于10％,检出限为0．001mg／kg-0．026mg／kg。经实验证明,该方法是一种快速,准确,灵敏度高的同时检测梅菜干中多种农药残留的检测方法。     

Simultaneous determination of sedecamycin and terdecamycin in livestock products by LC/MS

A simple and rapid LC/MS method for simultaneous determination of sedecamyin (SCM) and terdecamycin (TDM) in livestock products has been developed. SCM and TDM were extracted with acetonitrile. The extract was washed with n-hexane and then evaporated to dryness. The residue was dissolved in methanol, and injected into the LC/MS. The mass spectrometer was operated in the positive electrospray ionization (ESI) mode. LC separation was performed on a high-pH-resistant C18 column with 10 mmol/L carbonic acid-ammonia buffer (pH 10.0)-acetonitrile as a mobile pahse. The recoveries from swine muscle and liver fortified at the levels of 0.01 and 0.05 microg/g were 77-88%, and those from poultry muscle and liver fortified at the levels of 0.01 and 0.3 microg/g were 51-93%. The quantitation limits of SCM and TDM were 0.008 microg/g and 0.005 microg/g, respectively.     

Determination of carbendazim, thiophanate, thiophanate-methyl and benomyl residues in agricultural products by liquid chromatography-tandem mass spectrometry

A simple and reliable liquid chromatographic-tandem mass spectrometric (LC-MS/MS) method was developed for carbendazim (MBC), thiophanate (TE), thiophanate-methyl (TM) and benomyl (BM) in agricultural products. These compounds were extracted from agricultural products with methanol after addition of sodium L-ascorbate. BM was hydrolyzed to MBC during the extraction with methanol. TE and TM were cyclized to ethyl 2-benzimidazole carbamate (EBC) and MBC by refluxing at 120 °C for 30 min with copper acetate in 50% acetic acid. MBC and EBC were cleaned up by an n-hexane wash and extraction with ethyl acetate and determined by LC-MS/MS. The mean recoveries from 10 agricultural products were in the range of 75.8-100.0%, and the relative standard deviations of 5 experiments were in the range of 1.5-9.2% at concentrations equal to the maximum residue limits (MRLs). The calibration curves were made by using commercial MBC and EBC as reference analytical standards without refluxing. The quantification limits were 0.01 mg/kg (as MBC), which is the uniform limit in the positive list system for agricultural chemical residues in foods in Japan.     

基质分散固相萃取-高效液相色谱法测定水果中的异菌脲残留量

以PSA(乙二胺基-N- 丙基硅烷)和ODS(十八烷基硅胶键合硅胶填料)为混合固相基质分散剂萃取净化,液相色谱柱分离,建立了水果中异菌脲残留量的测定方法。异菌脲在0.1～5.0μg/ml 的浓度范围内,峰面积和浓度的相关系数为0.9994。在香蕉、柑橘和芒果中分别添加0.5、1.0、2.0mg/kg 三个浓度异菌脲,回收率在82.70%～108.62% 之间,RSD 值在1.8%～5.3% 之间,方法的检出限为0.036mg/kg。此方法具有灵敏、准确、简便、重现性好等优点。