Simple derivatization of aldehydes with d-cysteine and their determination in beverages by liquid chromatography–tandem mass spectrometry

We describe a simple derivatization method to determine aldehydes. This method is based on derivatization with d-cysteine and consecutive liquid chromatography–tandem mass spectrometry (LC–MS/MS). The optimum derivatization conditions of aldehydes with d-cysteine were 10 min at 50 °C and pH 7.0. The formed alkyl thiazolidine-4-carboxylic acid derivatives were directly injected in LC–MS/MS. In the established condition, the method was used to detect eight aldehydes in beverages. The limit of detection (LOD) and limit of quantification (LOQ) of the aldehydes were 0.2–1.9 μg L⁻¹ and 0.7–6.0 μg L⁻¹ and the relative standard deviation was less than 2.0% at concentrations of 0.1 mg L⁻¹ and 1.0 mg L⁻¹ with the exception of octanal. All the beverage samples had detectable levels of methanal (0.033–0.145 mg L⁻¹), ethanal (0.085–2.12 mg L⁻¹), propanal (ND to 0.250 mg L⁻¹), butanal (ND to 0.003 mg L⁻¹), pentanal (ND to 0.471 mg L⁻¹), hexanal (ND to 0.805 mg L⁻¹), heptanal (0.019–3.91 mg L⁻¹) and octanal (0.029–0.118 mg L⁻¹).     

Simple and sensitive determination of nisoldipine in plasma using liquid chromatography-tandem mass spectrometry.

A simple and rapid quantification method was developed for determining nisoldipine in plasma. After a simple protein precipitation with a mixture of 10% of zinc sulfate and methanol, the analytes were chromatographed on a reversed-phase C(18) column, and detected by MS/MS. The assay precision was less than 10.7%, and the accuracy ranged from 86 to 112%. The limit of quantification was 0.1 ng/ml. This method was used to measure the plasma concentration of nisoldipine from healthy subjects after a single 5-mg oral dose of nisoldipine.     

柱前衍生-超高效液相色谱-串联质谱法同时检测茶叶中草甘膦和草铵膦的残留量

采用超高效液相色谱-串联质谱建立了茶叶中草甘膦和草铵膦残留同时快速测定的方法。茶样经超纯水、二氯甲烷提取和C₁₈固相萃取柱净化后,在硼酸盐缓冲液中与9-芴甲氧羰酰氯(FMOC-Cl)进行衍生反应,衍生后产物在C₁₈色谱柱上进行超高效液相色谱分离;质谱检测采用电喷雾正离子化模式和多反应监测模式。结果表明,在0.003125~0.1 mg/L范围内,草甘膦和草铵膦均有良好的线性关系(r> 0.990),检出限(LOD)均为0.03 mg/kg;在添加浓度为0.375、1.5和4.5 mg/kg时,草甘膦的平均回收率为87.37%~99.11%,相对标准偏差(RSD)(n=6)为0.68%~1.35%;草铵膦的平均回收率为81.44%~86.17%,RSD(n=6)为1.01%~2.33%。该方法样品前处理简单,分析时间短,回收率和精密度等均符合农药多残留检测技术的要求,适用于茶叶中草甘膦和草铵膦残留的同时检测。     

柱前衍生化液相色谱-串联质谱法测定茶叶中草铵膦的残留量

建立了茶叶中草铵膦残留检测的液相色谱-串联质谱分析方法。样品经水超声提取,C18固相萃取小柱净化,9-芴基氯甲酸酯(FMOC-Cl)溶液在硼酸盐缓冲溶液下衍生2 h后,用Kinetex C18色谱柱分离,以乙腈和5 mmol/L乙酸铵水溶液(含0.2%(v/v)甲酸)作为流动相进行梯度洗脱,电喷雾负离子模式电离(ESI~),多反应监测(MRM)模式检测,外标法定量。方法的线性范围为2.5～50.0 μg/L,相关系数r2大于0.999;定量限为0.10 mg/kg。在不同基质中,草铵膦在0.10、0.50、1.00 mg/kg添加水平下的平均回收率为61.6%～81.4%,相对标准偏差为3.2%～8.4%。该方法具有快速简便、灵敏度高、准确性强等特点,适用于茶叶中草铵膦残留量的检测。     

Simultaneous quantification of fatty acids in serum with dual derivatization by liquid chromatography-tandem mass spectrometry

Fatty acids have multitudinous biological functions and play a crucial role in many biological processes, but due to poor ionization efficiency and lack of appropriate internal standards, the comprehensive quantification of fatty acids by liquid chromatography-tandem mass spectrometry is still challenging. In this study, a new, accurate, and reliable method for quantifying 30 fatty acids in serum using dual derivatization was proposed. Indole-3-acetic acid hydrazide derivants of fatty acids were used as the internal standard and indole-3-carboxylic acid hydrazide derivants of them were used to quantify. The derivatization conditions were systematically optimized and the method validation results showed good linearity with R² > 0.9942, low detection limit (0.03–0.6 nM), precision (1.6%–9.8% for intra-day and 4.6%–14.1% for inter-day), recovery (88.2%–107.2% with relative standard deviation < 10.5%), matrix effect (88.3%–105.2% with the relative standard deviation < 9.9%) and stability (3.4%–13.8% for fatty acids derivants in 24 h at 4°C and 4.2%–13.8% for three freeze-thaw cycles). Finally, this method was successfully applied to quantify fatty acids in serum samples of Alzheimer's patients. In contrast to the healthy control group, nine fatty acids showed a significant increase in the Alzheimer's disease group.     

Identification and determination of glucuronides and their aglycones in Erigeron breviscapus by liquid chromatography-tandem mass spectrometry

A novel, speedy and reliable LC-MS-MS method for the search, identification and quantitation of O-glycosides and their aglycones from plant resources was established by analyzing the extract of Erigeron breviscapus. The extract was directly infused to a triple-quadrupole MS-MS and major glucuronides in the extract were screened out with high confidence by a neutral loss scan for the loss of a gluconic acid. The identity of these glucuronides and their aglycones was further confirmed with LC-MS-MS. In addition to scutellarin, apigenin 7-O-glucuronide, quercetin-3-O-glucuronide and their aglycones that were previously reported by others, we also confirmed by LC-MS-MS that remarkable amount of baicalin, an isomer of apigenin 7-O-glucuronide, presented in the extract of this plant, which had not been reported before. A satisfying quantitation of three glucuronides was also made by LC-MS-MS.     

高效液相色谱-串联质谱法检测牛奶中多种苯并咪唑兽药残留

采用正交试验优化的QuEChERS方法处理样品,建立了牛奶中包括前体药物和代谢物在内12种苯并咪唑类(BZs)兽药残留的高效液相色谱-串联质谱检测方法.方法在1～500μg/kg范围内线性良好,相关系数为0.9980～0.9996,平均回收率72.4%～108.3%,RSD为1.4%～9.7%,检出限低于0.5μg/k...     

Aflatoxin M1 determination in cheese by liquid chromatography-tandem mass spectrometry

A new method for determining aflatoxin M1 (AFM1) in cheese by liquid chromatography-tandem mass spectrometry has been developed. Two methodologies were compared for sample extraction. The first one involves sample extraction with dichloromethane for hard, aged cheese or acetone for fresh cheese and includes a preliminary matrix solid-phase dispersion-extraction step before solid-phase extraction (SPE) clean-up by a Carbograph-4 cartridge. The second method uses a water/methanol solution (90:10, v/v) extraction at 150 degrees C before clean-up. The average recoveries of AFM1 from samples spiked at levels of 0.25-0.45 microg/kg, were 81-92% and the precision (RSD) ranged from 3 to 7% with the first method, whilst the average recoveries were 79-84%, and RSD ranged from 7 to 15% for the second method. Due to different matrix effect, the quantification limits were 0.019-0.025 microg/kg in the first case and 0.048-0.143 microg/kg in the second one, depending on cheese typology.     

柱前衍生-液相色谱-串联质谱法测定葡萄和樱桃中单氰胺残留

建立了丹磺酰氯（DNS）柱前衍生-液相色谱-串联质谱（LC-MS/MS）测定葡萄和樱桃中单氰胺的方法。样品经破壁机匀浆,乙酸乙酯超声提取,无水硫酸钠除水,提取液经减压浓缩,在碱性条件下与丹磺酰氯进行衍生反应。色谱柱为岛津Shim-pack XR-ODS色谱柱（75 mm×2.0 mm,1.6 μm）,流动相为甲醇和含0.05%（体积分数）甲酸的2 mmol/L醋酸铵水溶液,梯度洗脱,采用电喷雾离子源正离子多反应监测模式进行质谱检测。单氰胺在0.01~1.0 mg/L范围内,峰面积与质量浓度之间线性关系良好,相关系数不小于0.9990。在0.01、0.05和1.0 mg/kg的添加水平下,葡萄和樱桃中单氰胺的平均回收率为75%~81%,精密度为6.5%~9.8%,定量限为0.01 mg/kg。该方法简便、快速、可靠,可用于批量检测葡萄和樱桃中单氰胺残留。     

Sensitive determination of phloroglucinol in human plasma by liquid chromatography-tandem mass spectrometry

Summary A sensitive and selective liquid chromatographic method coupled with tandem mass spectrometry (LC-MS-MS) was developed for the quantification of phloroglucinol in human plasma. Resorcinol was used as internal standard, with plasma samples extracted using ethyl acetate. A centrifuged upper layer was then evaporated and reconstituted with mobile phase. The reconsituted samples were injected into a C₁₈ XTerra MS column (2.1×100 mm) with 3.5 μm particle size. The analytical column lasted for at least 500 injections. The mobile phase was 15% acetonitrile (pH 3.0), with a flow rate at 100 μL min¹. The mass spectrometer was operated in positive ion mode using electrospray ionization. Using MS-MS in multiple reaction monitoring (MRM) mode, phloroglucinol was detected without severe interferences from the plasma matrix. Phloroglucinol produced a parent molecule ([M+H]⁺) atm/z 127 and a corresponding product ion atm/z 8l. Detection of phloroglucinol in human plasma was accurate and precise, with quantification on limit at 0.5 ng mL¹. The method has been successfully applied to a study of phloroglucinol in human specimens.     

Multi-class determination of antimicrobials in meat by pressurized liquid extraction and liquid chromatography-tandem mass spectrometry

A multi-residue method using pressurized liquid extraction (PLE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for determining trace levels of 31 antimicrobials, including beta-lactams, lincosamides, macrolides, quinolones, sulfonamides, tetracyclines, nitroimidazoles and trimethoprim. The extraction method required pre-homogeneization of the meat with EDTA-washed sand and subsequent one-static-cycle extraction for 10 min with 40 ml of water at 1500 psi and 70 degrees C. The effect of operation temperature, pressure, flush volume, and static cycles on PLE performance was studied. Average recoveries ranged from 75 to 99% with relative standard deviations <18%. The method was validated according to the European Union requirements (2002/657/EC). In addition to the quality parameters included in that decision, the limits of detection (LODs) and quantification (LOQs) were determined. The use of LC-MS/MS provided LODs (between 3 and 15 microg kg(-1)) and LOQs (between 10 and 50 microg kg(-1)), by far lower than half of their maximum residue limits (MRLs) (between 50 and 1200 microg kg(-1)). Confirmation of the presence of any of the studied compounds was accomplished in 1h after sample receipt. This methodology has been successfully applied to the analysis of cattle and pig tissue samples from local markets and slaughterhouses of the Valencian Community (Spain). The results showed the presence of some antimicrobials at different concentrations. Quinolones and tetracyclines were the antimicrobials most detected in cattle and pig samples, respectively. Sulfonamides were also frequently detected in both types of samples.     

柱前衍生-超高效液相色谱-串联四极杆质谱法测定茶叶中乙撑硫脲的残留

建立了茶叶中乙撑硫脲残留的柱前衍生-超高效液相色谱-串联四极杆质谱检测方法。样品采用乙腈提取,提取液经QuEChERS基质分散固相萃取净化后采用9-芴基甲基氯甲酸酯（FMOC-CL）柱前衍生;衍生溶液经BEH-C18色谱柱（100 mm×2.0 mm,1.7 μm）分离后进入串联四极杆质谱仪检测,采用同位素内标法定量;流动相为0.1%（v/v）甲酸-乙腈。该方法对茶叶样品检出限为1.3 μg/kg,定量限为4.2 μg/kg;加标回收率在97.7%~107.5%之间,相对标准偏差（RSD,n=6）在2.1%~10.0%之间;在1.0~203.4 μg/L范围内线性回归系数r为0.9993。该方法灵敏度高,重现性好,定性定量准确,可有效满足对茶叶中乙撑硫脲残留检测的要求。     

液相色谱-串联质谱法测定猪肉中咪唑类药物及其代谢物

建立了高效液相色谱-串联质谱同时测定猪肉中29种咪唑类药物及其代谢物残留的检测方法。样品采用乙酸乙酯提取,浓缩复溶后加入乙腈饱和正己烷净化除脂,以0.3%(体积分数)甲酸水溶液和乙腈为流动相,反相C_(18)色谱柱梯度洗脱分离,采用电喷雾正离子(ESI+)源多反应监测(MRM)模式进行检测。29种化合物在0.05~20.0μg/L范围内线性关系良好,相关系数r~20.99。在1.0~5.0μg/kg添加范围内,平均回收率为65.4%~103%,相对标准偏差(RSD)为1.3%~6.8%。方法检出限为0.02~0.3μg/kg,定量限为0.1~1μg/kg。该方法简便、快速、灵敏,适用于猪肉中咪唑类及其代谢物残留的检测。     

Multi-residue determination of veterinary drugs in milk by ultra-high-pressure liquid chromatography-tandem mass spectrometry

Stir bar sorptive extraction with polyurethane (PU) and polydimethylsiloxane (PDMS) polymeric phases followed by high-performance liquid chromatography with diode array detection [SBSE(PU or PDMS)/HPLC-DAD] was studied for the determination of six acidic pharmaceuticals [o-acetylsalicylic acid (ACA), ibuprofen (IBU), diclofenac sodium (DIC), naproxen (NAP), mefenamic acid (MEF) and gemfibrozil (GEM)], selected as non-steroidal acidic anti-inflammatory drugs and lipid regulators model compounds in environmental water matrices. The main parameters affecting the efficiency of the proposed methodology are fully discussed. Assays performed on 25 mL of water samples spiked at the 10 microg L(-1) level under optimized experimental conditions, yielded recoveries ranging from 45.3+/-9.0% (ACA) to 90.6+/-7.2% (IBU) by SBSE(PU) and 9.8+/-1.6% (NAP) to 73.4+/-5.0% (GEM) by SBSE(PDMS), where the former polymeric phase presented a better affinity to extract these target analytes from water matrices at the trace level. The methodology showed also excellent linear dynamic ranges for the six acidic pharmaceuticals studied, with correlation coefficients higher than 0.9976, limits of detection and quantification between 0.40-1.7 microg L(-1) and 1.5-5.8 microg L(-1), respectively, and suitable precision (RSD <15%). Moreover, the developed methodology was applied for the determination of these target analytes in several environmental matrices, including river, sea and wastewater samples, having achieved good performance and moderate matrix effects. In short, the PU foams demonstrated to be an excellent alternative for the enrichment of the more polar metabolites from water matrices by SBSE, overcoming the limitations of the conventional PDMS phase.     

同位素内标-液相色谱-串联质谱法同时测定粮食及其制品中的5种真菌毒素

建立了同位素内标-液相色谱-串联质谱快速测定粮食及其制品中玉米赤霉烯酮(ZON)、雪腐镰刀菌烯醇(NIV)、脱氧雪腐镰刀菌烯醇(DON)及其衍生物3-乙酰基脱氧雪腐镰刀菌烯醇(3-ACDON)和15-乙酰基脱氧雪腐镰刀菌烯醇(15-ACDON)5种真菌毒素的分析方法。以乙腈-水(84∶16,v/v)为提取液,采用多功能净化柱净化,同位素内标法定量。5种真菌毒素在各自的线性范围内线性关系良好,相关系数(r2)均大于0.99,检出限(LOD,S/N=3)为5~20μg/kg。大麦、小麦、燕麦、玉米等9种代表性粮食及其制品在3个不同添加水平下的加标回收率为84.2%~114.5%,相对标准偏差(RSD)为0.4%~9.9%(n=6)。该法操作简单,成本低,准确可靠,灵敏度高,可同时检测粮食及其制品中的5种真菌毒素。     

Simultaneous determination of seven flavonoids in Epimedium by liquid chromatography-tandem mass spectrometry method

In this paper, a sensitive and specific liquid chromatography-electrospray ionisation-mass spectrometry （LC-ESI-MS） method has been developed and validated for the identification and determination of seven flavonoids, namely epimedin A, epimedin B, epimedin C, icariin, sagittatoside B, 2＂-O-rhamnosyl icariside II, and baohuoside I in Epimedium from different sources.     

液相色谱-串联质谱法检测水产品中15种喹诺酮类药物残留量

建立了液相色谱-串联质谱技术同时检测水产品中15种喹诺酮类药物(氟罗沙星、氧氟沙星、依诺沙星、诺氟沙星、环丙沙星、恩诺沙星、洛关沙星、单诺沙星、奥比沙星、双氟沙星、沙拉沙星、司帕沙星、口恶喹酸、萘啶酸、氟甲喹)残留量的方法.试样中残留的喹诺酮类药物采用乙腈提取,提取液经正已烷液液分配脱脂后,以强阳离子固相萃取小柱净化,液相色谱.串联质谱法测定.对液/质分离条件与样品前处理条件进行了优化,并对喹诺酮类药物在分析过程的稳定性进行了研究.15种喹诺酮类药物在1.0～100 μg/L范围内线性关系良好,相关系数为0.9924～0.9992.在0.002～0.04 mg/kg浓度范围内,平均加标回收率在79.9%～93.8%;相对标准偏差为4.8%～14.6%.方法可满足水产品中喹诺酮类药物多残留检测与确证的需要.     

Simultaneous determination of paracetamol and chlorpheniramine in human plasma by liquid chromatography-tandem mass spectrometry

An analytical method for the determination of paracetamol and chlorpheniramine in human plasma has been developed, validated and applied to the analysis of samples from a phase I clinical trial. The analytical method consists in the extraction of paracetamol and chlorpheniramine with diethyl ether, followed by the determination of both drugs by an LC–MS–MS method, using 2-acetamidophenol as internal standard. The intra-assay and inter-assay precision and accuracy of this technique were good and the limit of quantitation was 0.5 μg/ml of plasma for paracetamol and 0.2 ng/ml for chlorpheniramine. The concentration working range was established between 0.5 μg/ml and 25 μg/ml for paracetamol and between 0.2 ng/ml and 50 ng/ml for chlorpheniramine. This method has been used for analyzing more than 1200 human plasma samples from a clinical study with 24 volunteers.     

Simultaneous determination of chlorpheniramine and pseudoephedrine in human plasma by liquid chromatography-tandem mass spectrometry

A sensitive and specific procedure for simultaneous quantitation of chlorpheniramine and pseudoephedrine in human plasma has been developed and validated. Analytes were extracted from plasma samples by liquid-liquid extraction, separated on a Diamonsil C18 column (250 x 4.6 mm i.d.) and detected by tandem mass spectrometry with an atmospheric pressure chemical ionization interface. Diphenhydramine was used as the internal standard. The method has a lower limit of quantitation of 0.2 and 2.0 ng/mL for chlorpheniramine and pseudoephedrine, respectively. The intra- and inter-day relative standard deviation, calculated from quality control (QC) samples were below 4.3% for chlorpheniramine and below 9.5% for pseudoephedrine. The inter-day relative error as determined from QC samples was within 4.7% for each analyte. The overall extraction recoveries of chlorpheniramine and pseudoephedrine were 77 and 61% on average, respectively. The method was successfully applied to pharmaockinetic study of chlorpheniramine and pseudoephedrine in volunteers receiving formulations containing 4 mg of chlorpheniramine maleate and 60 mg of pseudoephedrine hydrochloride.     

QuEChERS结合液相色谱-串联质谱法快速测定奶酪中多类兽药残留

建立了一种快速测定奶酪中大环内酯类、磺胺类、喹诺酮类和四环素类共50种兽药残留的分析方法。方法采用改进后的QuEChERS对奶酪进行前处理。样品在加入Na₂EDTA缓冲液和陶瓷均质子后,在5%(v/v)醋酸乙腈条件下进行振荡提取,氯化钠和无水硫酸钠用于盐析,经C₁₈吸附剂净化后,供液相色谱-串联质谱(LC-MS/MS)测定。目标化合物经ZORBAX-SB-C₁₈柱梯度分离,在正离子动态多反应监测模式下进行检测。结果表明,奶酪中50种兽药的定量限(LOQ)为0.05~20 μg/kg;在3个添加浓度(20、50、100 μg/kg)下(n=6),平均回收率在70%~120%范围内的比例分别为94%、92%和96%,相对标准偏差(RSD)为1%~14%。对市售的7个样品进行测定,其中两个样品分别检出了微量的罗红霉素和氟甲喹兽药残留。该方法快速简便,适用于奶酪中兽药残留的快速检测和日常监控。