Simultaneous determination of metformin and glipizide in human plasma by liquid chromatography-tandem mass spectrometry

A method has been developed for the simultaneous quantification of metformin (I) and glipizide (II) in human plasma. It is based on high-performance liquid chromatography with electrospray ionization tandem mass (LC-ESI-MS/MS) spectrometric detection in positive ionization mode. Phenformin (III) and gliclazide (IV) were used as internal standards for I and II, respectively. The MS/MS detection was performed in multiple reaction monitoring (MRM) mode. The precursor-product ion combinations of m/z 130 --> 71, 446 --> 321, 206 --> 60 and 324 --> 127 were used to quantify I, II, III and IV, respectively. This method was validated in the concentration ranges of 0.02-4 microg/mL for I and 0.004-0.8 microg/mL for II. It was utilized to support a clinical pharmacokinetic study after single dose oral administration of a combination of I and II.     

Multiresidue analysis of plant growth regulators in grapes by triple quadrupole and quadrupole-time of flight-based liquid chromatography/mass spectrometry

A selective and sensitive LC-MS/MS method is presented for simultaneous determination of 12 plant growth regulators, viz., indol-3-acetic acid, indol-3-butyric acid, kinetin, zeatin, 6-benzyl aminopurine, gibberellic acid, abscisic acid, chlormequat chloride, forchlorfenuron, paclobutrazole, daminozide, and 2,4-dichlorophenoxy acetic acid, in bud sprouts and grape berries. The sample preparation method involved extraction of homogenized sample (5 g) with 40 mL methanol (80%), and final determination was by LC-MS/MS in the multiple reaction monitoring (MRM) mode with time segmentation for quantification supported by complementary analysis by quadrupole-time of flight (Q-TOF) MS with targeted high-resolution MS/MS scanning for confirmatory identification based on accurate mass measurements. The recovery of the test compounds ranged within 90-107% with precision RSD less than 5% (n = 6). The method could be successfully applied in analyzing incurred residue samples, and the strength of accurate mass analysis could be utilized in identifying the compounds in cases where the qualifier MRM ions were absent or at an S/N less than 3:1 due to low concentrations.     

Detection of buffalo mozzarella adulteration by an ultra‐high performance liquid chromatography tandem mass spectrometry methodology

Over the past years, LC–MS‐based approaches have gained a growing interest in food analysis by using different platforms and methodologies. In particular, enhanced selectivity and sensitivity of multiple reaction monitoring (MRM) scan function offer powerful capabilities in detecting and quantifying specific analytes within complex mixtures such as food matrices. The MRM approach, traditionally applied in biomedical research, is particularly suitable for the detection of food adulteration and for the verification of authenticity to assure food safety and quality, both recognized as top priorities by the European Union Commission. Increasingly stringent legislation ensure products safety along every step ‘from farm to fork’, especially for traditional foods designed with the Protected Designation of Origin certification. Therefore, there is a growing demand of new methodologies for defining food authenticity in order to preserve their unique traits against frauds. In this work, an ultra performance liquid chromatopgraphy‐electrospray ionization‐tandem mass spectrometry (MS/MS) methodology based on MRM has been developed for the sensitive and selective detection of buffalo mozzarella adulteration. The targeted quantitative analysis was performed by monitoring specific transitions of the phosphorylated β‐casein f33‐48 peptide, identified as a novel species‐specific proteotypic marker. The high sensitivity of MRM‐based MS and the wide dynamic range of triple quadrupole spectrometers have proved to be a valuable tool for the analysis of food matrices such as dairy products, thus offering new opportunities for monitoring food quality and adulterations. Copyright © 2012 John Wiley & Sons, Ltd.     

Isotope coded protein label quantification of serum proteins—Comparison with the label-free LC-MS and validation using the MRM approach

Protein quantification based upon mass spectrometry is gaining ground in diverse applications of biological and clinical relevance. The present article focuses on one of the most complex biological fluids - serum - and provides a novel ICPL based quantification protocol. The results are compared to a label-free (data independent alternate scanning) absolute quantification method. The validation is performed using MRM based protein quantification technique. Regarding the ICPL approach, serum samples used in this study were depleted of high abundant proteins, labeled with ICPL and fractionated according to their respective pI (3-5, 5-7 and 7-12). The samples were further subjected to tryptic digestion followed by treatment with the Glu-C enzyme. The peptides were analyzed on a 2D-nano-LC system using four different concentrations of salt injections (45, 75, 150 and 500 mM ammonium acetate). The LC system was connected on-line with the electrospray ion-trap mass spectrometer. For the label-free quantification the serum samples were depleted and digested with trypsin. A proteome-wide comparison was performed using highly reproducible LC and data independent alternate scanning in conjunction with a high mass accuracy orthogonal time-of-flight mass spectrometer. Selected proteins, found by both methods, were validated using the MRM approach. For this purpose non-depleted tryptically digested serum samples were analyzed by LC coupled with a triple-quadrupole MS. The relative protein quantification using ICPL and mass spectrometry allowed for the detection of approximately 200 proteins, whereas about 2/3 of those contained the ICPL label and could therefore be quantified. Label-free approach used no fractionation, less sample and was able to identify and quantify over 110 proteins. The identified proteins covered generally 3-4 orders of magnitude of protein concentration in human serum. Changes in relative abundance of eight proteins were validated using MRM. This study, for the first time, shows the ability of the relative protein quantification based upon ICPL and 2D-LC-MS/MS to quantify serum biomarkers. It provides two additional label-free approaches that could validate and bring additional value to the label-based results, offering a starting point for comprehensive proteomics studies aiming at revealing biomarkers of clinical relevance.     

Development of a sample preparation procedure of sewage sludge samples for the determination of polycyclic aromatic hydrocarbons based on selective pressurized liquid extraction

An automated, simple and sensitive method based on selective pressurized liquid extraction (SPLE) was developed for the analysis of polycyclic aromatic hydrocarbons in sewage sludge samples. The new sample preparation procedure consists of on-line clean-up by inclusion of sorbents in the extraction cell, and combines elevated temperatures and pressures with liquid solvents to achieve fast and efficient removal of target analytes from complex sewage sludge matrices. The effects of various operational parameters (e.g. sample pretreatment, extraction solvent, temperature, pressure, static time, etc.) on the performance of SPLE procedure were carefully investigated, obtaining the best results when SPLE conditions were fixed at 140 °C, 1500 psi, static time of 5 min and n-hexane as extraction solvent. A new programmed temperature vaporization–gas chromatography–tandem mass spectrometry method based on large volume injection (PTV–LVI–GC–MS/MS) was also developed and analytical determinations were performed by high performance liquid chromatography coupled with fluorescence detection and GC–MS/MS. The extraction yields for the different compounds obtained by SPLE ranged from 84.8% to 106.6%. Quantification limits obtained for all of these studied compounds (between 0.0001 and 0.005 μg g⁻¹, dry mass) were well below the regulatory limits for all compounds considered. To test the accuracy of the SPLE technique, the optimized methodology was applied to the analysis of a certified reference material (sewage sludge (BCR088)) and a reference material (sewage sludge (RTC-CNS312-04)), with excellent results.     

Determination of caudatin-2,6-dideoxy-3-O-methy-beta-d-cymaropyranoside in rat plasma using liquid chromatography-tandem mass spectrometry

A selective, sensitive and rapid liquid chromatography-tandem mass spectrometry method has been developed for the determination of caudatin-2,6-dideoxy-3-O-methy-beta-d-cymaropyranoside (CDMC) in rat plasma. This method involves a plasma clean-up step using liquid-liquid extraction, followed by LC separation and positive electrospray ionization mass spectrometry detection (LC/ESI-MS/MS). Chromatographic separation of the analytes was achieved using a C(18) column with a mobile phase of acetonitrile and water (70:30, v/v) at a flow rate of 1.0 mL/min. Low energy collision tandem mass spectrometric analysis (CID-MS/MS) using the multiple reaction monitoring (MRM) mode was used for analyte quantification. For the MRM analysis of CDMC, the following transition at m/z 658.4 --> 529.6 derived from the protonated molecule [M + Na](+). A calibration curve was linear in the 5-500 ng/mL range for CDMC, and the limit of detection was 5 ng/mL. The inter- and intra-day precisions (RSD) were 相似文献   

Versatility of tandem mass spectrometry for focused analysis of oxylipids

Liquid chromatography‐tandem mass spectrometry (LC‐MS/MS) in the multiple reaction monitoring (MRM) scan mode has been the primary MS method applied for the target identification of specific and minor oxylipids in complex matrices, such as eicosanoids and docosanoids, which are potent lipid mediators derived from polyunsaturated fatty acid oxygenation. However, the high specificity of MRM can limit the detection of species with m/z MRM transitions not covered by the method. In addition to MRM, tandem‐quadrupole mass analyzers enable other experiments to be conducted, by fragmenting ions via collision‐induced dissociation process (CID). This paper presents the potential of tandem mass spectrometry for the focused analysis of oxylipids. We have successfully developed an LC‐MS/MS method for the identification of precursor ions of m/z 115, a diagnostic product ion of 5‐hydroxy‐ and 5‐epoxy‐fatty acids. As a proof of concept, the developed method was used to discover several oxylipids oxidized at C5 derived from arachidonic acid (C20 : 4) oxygenation in a hypothalamus rat extract that were not identified using the target MRM methodology. The proposed focused MS/MS‐based approach in a tandem mass analyzer has proven to be a powerful strategy to accelerate the identification of oxylipids with structural similarities and assist the field of lipidomic research. Copyright © 2015 John Wiley & Sons, Ltd.     

A rapid liquid chromatography-tandem mass spectrometry method for quantification of a biologically active molecule camboginol in the extract of Garcinia cambogia

A liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the determination of camboginol in the extract of fruit rinds of Garcinia cambogia has been developed. Separation was achieved isocratically on an RP C(18) column using a solvent system consisting of a mixture of acetonitrile-water (9:1) and methanol-acetic acid (99.5:0.5) in the ratio of 30:70 as mobile phase at a flow rate of 0.4 mL/min. A multiple reaction monitoring (MRM) method was developed for quantification of camboginol in the fruit rinds extract of G. cambogia using MRM transitions of m/z 601.4 --> m/z 176.7 and m/z 601.4 --> m/z 448.9, respectively. The calibration curve based on peak area against concentration was linear up to 50 ng/mL with a detection limit of 0.5 ng/mL. The method showed satisfactory reproducibility with a coefficient of variation of less than 6%. The method was successfully applied for quantification of camboginol in different Garcinia extracts.     

Identification and determination of the major constituents in Kai‐Xin‐San by UPLC‐Q/TOF MS and UFLC‐MS/MS method

In order to have overall chemical material information of Kai‐Xin‐San (KXS), the reliable ultra‐high‐performance liquid chromatography quadrupole time‐of‐flight mass spectrometer (UHPLC–Q‐TOF‐MS) and ultra‐fast liquid chromatography mass spectrometer (UFLC‐MS/MS) methods were developed for the identification and determination of the major constituents in KXS. Moreover, the UHPLC–Q‐TOF‐MS method was also applied to screen for multiple absorbed components in rat plasma after oral administration of KXS. The UHPLC–Q‐TOF‐MS method was achieved on Agilent 6520 Q‐TOF mass and operated in the negative ion mode. Good separation was performed on a ZORBAX Eclipse Plus C18 column with a gradient elution at a flow rate of 0.2 ml/min. A total of 92 compounds in KXS were identified or tentatively characterized based on their exact molecular weights, fragmentation patterns, and literature data. A total of 26 compounds including 23 prototype components and three metabolites were identified in rat plasma after oral administration of KXS. Then, 16 major bioactive constituents were chosen as the benchmark substances to evaluate the quality of KXS. Their quantitative analyses were performed by a triple quadrupole tandem mass spectrometer (MS/MS) operating in multiple‐reaction monitoring mode(MRM). The analysis was completed with a gradient elution at a flow rate of 0.4 ml/min within 35 min. The simple and fast method was validated and showed good linearity, precision, and recovery. Furthermore, the method was successful applied for the determination of 16 compounds in KXS. All results would provide essential data for identification and quality control of active chemical constituents in KXS. Copyright © 2016 John Wiley & Sons, Ltd.     

The Rapid Analysis of Antibiotics in Animal Meat and Egg Using a Novel SEP Method and UPLC–MS/MS

A simple and sensitive method for the determination of 39 antibiotics, including sulfonamides and quinolones, in pork, chicken, fish tissues and eggs, has been developed. The sample preparation included ultrasound-assisted extraction (UAE) with 0.1% formic acid in 90:10 acetonitrile/water (v:v) and a final clean-up with Oasis PRiME HLB, a new reversed phase SPE without traditional pre-equilibration and washing steps before eluting SPE. Analysis was performed by ultra-performance liquid chromatography coupled to tandem quadrupole mass spectrometry (UPLC–MS/MS). The positive ionization in multiple reaction monitoring mode (MRM) and product ion confirmation scan (PICs) were used in the method. The PICs provides additional confirmation for compound identification through acquisition of MS/MS spectra in the same injection and a means of verifying that the signal from the MRM peak is from the compound of interest. In particular, single test is simultaneously able to gain both quantitative MRM and qualitative full-scan MS/MS data without the need for long analysis times or repeat injection. All solvent and matrix-matched calibration curves showed excellent correlation coefficient >0.990, with the dynamic range 0.2–100 ng mL^?1. For over 90% of the analytes, the recoveries were between 60 and 120% in all matrices studied at three spiked levels of low, medium, and high concentrations, with the intra-day precision values in the range of 2.7–20.0% and the inter-day precision values in the range of 6.2–21.3%. The limits of detection (LODs) and limits of quantification (LOQs) of all drugs were 0.05–2.6 and 0.12–5.6 μg kg^?1, respectively. A weak matrix effect was observed for most of the compounds in four complex samples. The proposed method was proven very simple, fast, sensitive, and selective and has been successfully applied in real samples from local markets and farms.     

Determination of lovastatin in human plasma by ultra-performance liquid chromatography/electrospray ionization tandem mass spectrometry

A fast and sensitive ultra-performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) method was developed for the determination of lovastatin in human plasma. With simvastatin as internal standard, sample pretreatment involved one-step extraction with n-hexane-methylene dichloride-isopropanol (20:10:1, v/v/v) of 0.5 mL plasma. Chromatographic separation was carried out on an Acquity UPLC BEH C(18) column with mobile phase consisting of acetonitrile-water (containing 5 mmol/L ammonium acetate; 85:15, v/v) at a flow-rate of 0.35 mL/min. The detection was performed on a triple-quadrupole tandem mass spectrometer by multiple reaction monitoring (MRM) via electrospray ionization source with positive mode. The analysis time was shorter than 1.7 min per sample. The standard curve was linear (r2>or=0.99) over the concentration range 0.025-50.0 ng/mL with a lower limit of quantification of 0.025 ng/mL. The intra- and inter-day precision values were below 11% and the accuracy (relative error) was within 6.0% at three quality control levels. This is the first method of MS with MRM coupled to UPLC for the determination of lovastatin, which showed great advantages of high sensitivity, selectivity and high sample throughput. It was fully validated and successfully applied to the pharmacokinetic study of lovastatin tablets in healthy Chinese male volunteers after oral administration.     

超高效液相色谱-串联质谱法测定纺织助剂中双(氢化牛脂基)二甲基季铵化合物

建立了快速测定纺织助剂中双(氢化牛脂基)二甲基季铵化合物(DHTDMAC)的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法.样品经5%(v/v)甲酸甲醇超声波提取、稀释后,采用Eclipse Plus C18柱(50 mm×2.1 mm, 1.8 μm)分离,甲醇和0.1%(v/v)甲酸水溶液为流动相梯度洗脱,电喷雾离子源正离子多反应监测模式进行定性和定量分析.实验结果表明,DHTDMAC在10~280 μg/L范围内与峰面积呈良好的线性关系,相关系数(r²)为0.9991;以不低于3倍信噪比计算方法检出限(LOD, S/N=3)为3 mg/kg;方法定量限(LOQ, S/N=10)为10 mg/kg.3种纺织助剂基质中DHTDMAC在3个不同加标水平的平均回收率为97.2%~108.3%,相对标准偏差(RSD)为1.5%~4.6%.该方法灵敏度高、操作简便、快速准确,适用于纺织助剂中DHTDMAC的分析测定.     

On-line solid-phase extraction LC-MS/MS for the determination of Ac-SDKP peptide in human plasma from hemodialysis patients

We developed a high-throughput method based on on-line solid-phase extraction liquid chromatography tandem mass spectrometry (SPE-LC-MS/MS) to determine N-terminal thymosin-β fragment peptide (N-acetyl-seryl-aspartyl-lysyl-proline, Ac-SDKP) in human plasma samples. Quantification of Ac-SDKP was performed using direct injection for on-line SPE based on C(18), reversed-phase LC separation and stable isotope dilution electrospray ionization-MS/MS in multiple reaction-monitoring (MRM) mode. The Ac-SDKP-(13)C(6), (15)N(2) (m/z 496 → 137) was synthesized for the internal standard. The MRM ion for Ac-SDKP was m/z 488 → 129 (quantitative ion)/226. The limit of detection and lower limit of quantitation were 0.05 and 0.1 ng/mL in standard solution, respectively. Recovery values were 98.3-100.4% with inter-day (relative standard deviation, RSD, 0.4-14.1%) and intra-day (RSD, 0.8-19.7%) assays. This method was applied to the measurement of Ac-SDKP levels in plasma from hemodialyzed subjects. Concentrations were 0.59 ± 0.23 ng/mL (pre-hemodialyzed subjects, n = 9) and 0.44 ± 0.19 ng/mL (post-hemodialyzed subjects, n = 9). All plasma Ac-SDKP levels were decreased by dialysis. Thus, plasma Ac-SDKP was decreased through dialysis in chronic kidney disease. The findings in this study will be useful for the treatment of anemia in chronic kidney disease with dialysis.     

固相萃取-超高效液相色谱-串联质谱法检测粮食及其制品中的玉米赤霉烯酮类真菌毒素

建立了粮食及其制品中6种玉米赤霉烯酮类物质(α-玉米赤霉醇、β-玉米赤霉醇、α-玉米赤霉烯醇、β-玉米赤霉烯醇、玉米赤霉酮和玉米赤霉烯酮)的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。样品用84%(体积分数)乙腈水溶液提取,通过ENVI-Carb石墨化炭黑(GCB)固相萃取柱进行富集净化,用6 mL二氯甲烷-甲醇(7:3, v/v)溶液洗脱,采用UPLC-MS/MS进行测定。在ACQUITY UPLCTM BEH C18反相柱上分离,梯度洗脱,流动相为水和乙腈;质谱采集模式为电喷雾负离子多反应监测模式。以α-玉米赤霉烯酮-d4为内标,6种目标物的线性范围为0.1～50 μg/L,相关系数(R2)大于0.99,检出限为0.1～0.2 μg/kg, 3个不同水平的加标平均回收率为79.9%～104.0%,相对标准偏差不大于10%。应用该方法对北京市的粮食及相关产品进行了分析,结果发现玉米赤霉烯酮的检出率最高,含量为0.42～220.7 μg/kg;此外还检出了α-和β-玉米赤霉烯醇。该方法具有操作简单、灵敏度高、重现性好等特点,符合食品样品中痕量污染物的检测要求。     

An improved high-throughput liquid chromatographic/tandem mass spectrometric method for terbinafine quantification in human plasma, using automated liquid-liquid extraction based on 96-well format plates

A fully automated high-throughput liquid chromatography/tandem mass spectrometry (LC-MS/MS) method was developed for terbinafine quantification in human plasma. The plasma samples were treated by liquid-liquid extraction (LLE) in 2.2 mL 96-deepwell plates. Terbinafine and the internal standard (IS) N-methyl-1-naphthalenemethylamine were extracted from human plasma by LLE, using a mixture of methyl t-butyl ether (MTBE)-hexane (70:30, v/v) as the organic solvent. All liquid transfer steps, including preparation of calibration standards and quality control samples, as well as the addition of the IS, were performed automatically by using robotic liquid handling workstations. After vortexing, centrifugation and freezing, the supernatant organic solvent was evaporated and reconstituted in a small volume of a reconstitution solution. Sample analysis was performed by reversed-phase LC-MS/MS, with positive ion electrospray ionization, using multiple reaction monitoring (MRM). The method had a very short sample preparation time and a chromatographic run time of 2.2 min. It was proved to have excellent sensitivity, specificity, accuracy as well as inter- and intraday precision for the quantification of terbinafine in human plasma. The calibration curve was linear for the range of concentrations 5.0-2000.0 ng/mL. The proposed method was applied to the rapid and reliable determination of terbinafine in a bioequivalence study after per os administration of 250 mg tablet formulations of terbinafine.     

Multi-residue method for trace level determination of pharmaceuticals in solid samples using pressurized liquid extraction followed by liquid chromatography/quadrupole-linear ion trap mass spectrometry

A simple and sensitive method for simultaneous analysis of 43 pharmaceutical compounds in sewage sludge and sediment samples was developed and validated. The target compounds were extracted using pressurized liquid extraction (PLE) and then purified and pre-concentrated by solid phase extraction (SPE) using a hydrophilic-lipophilic balanced polymer. PLE extraction was performed on temperature of 100 °C, with methanol/water mixture (1/2, v/v) as extraction solvent. The quantitative analysis was performed by liquid chromatography tandem mass spectrometry using a hybrid triple quadrupole-linear ion trap mass spectrometer (LC-QqLIT-MS). Data acquisition was carried out in selected reaction monitoring (SRM) mode, monitoring two SRM transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the Information Dependent Acquisition (IDA) function. The method was validated through the estimation of the linearity, sensitivity, repeatability, reproducibility and matrix effects. The internal standard approach was used for quantification because it efficiently corrected matrix effects. Despite the strong matrix interferences, the recoveries were generally higher of 50% in both matrixes and the detection and quantification limits were very low. Beside the very good sensitivity provided by LC-QqLIT-MS, an important characteristic of the method is that all the target compounds can be simultaneously extracted, treated and analysed. Hence, it can be used for routine analysis of pharmaceuticals providing large amount of data. The method was applied for the analysis of pharmaceuticals in river sediment and wastewater sludge from three treatment plants with different treatment properties (i.e. capacity, secondary treatment, quality of influent waters). The analysis showed a widespread occurrence of pharmaceuticals in the sludge matrices.     

改良QuEChERS方法快速测定果蔬中8种新型琥珀酸脱氢酶抑制剂类杀菌剂

建立了一种同时测定果蔬中啶酰菌胺、吡噻菌胺、吡唑萘菌胺、氟唑菌酰胺、联苯吡菌胺、氟唑环菌胺、氟唑菌苯胺和氟吡菌酰胺8种新型琥珀酸脱氢酶抑制剂类杀菌剂残留量的液相色谱-串联质谱方法。通过比较乙二胺-N-丙基硅烷（PSA）和十八烷基键合硅胶吸附剂（C₁₈）两种分散固相萃取剂不同添加剂量下的吸附作用和净化效果,优化QuEChERS方法净化过程,以乙腈-0.1%（体积分数）甲酸水溶液为流动相进行梯度洗脱,使8种目标化合物在Poroshell 120 EC-C₁₈色谱柱上分离,经电喷雾正/负双离子扫描、多反应监测模式质谱检测,外标法定量。8种目标化合物在0.5~500.0 μg/L范围内线性关系良好,相关系数均大于0.998,方法检出限为0.2~1.7 μg/kg,定量限为0.5~5.0 μg/kg。各种目标化合物在8种基质中3个添加水平（5.0、25.0和125.0 μg/kg）下的回收率为71.4%~121.3%,相对标准偏差（RSD,n=6）为0.8%~17.2%。该方法操作简单、净化效果好,适用于果蔬中新型琥珀酸脱氢酶抑制剂类杀菌剂的快速检测。     

气相色谱-三重四极杆串联质谱法快速测定蔬菜水果中129种农药的残留量

采用QuEChERS方法结合气相色谱-串联质谱法(GC-MS/MS)建立了蔬菜、水果中129种农药残留同时检测的分析方法。试样用1%乙酸乙腈均质提取,采用混合型固相分散萃取剂净化后,用GC-MS/MS在多反应离子监测(MRM)模式下进行检测,外标法定量。结果表明,129种药物在一定的含量范围内线性关系良好,相关系数(r2)均大于0.98;不同基质在10 μg/kg添加水平下大部分农药的平均回收率为66.2%～124.7%,相对标准偏差(RSD)为0.9%～24.4%;方法的定量限(LOQ)为0.03～16.7 μg/kg。结果表明,该方法简便快速、灵敏可靠、经济有效,适用于蔬菜、水果中农药多残留的同时快速筛查测定。     

Quantitative analysis of costunolide and dehydrocostuslactone in rat plasma by ultraperformance liquid chromatography–electrospray ionization–mass spectrometry

Costunolide and dehydrocostuslactone are well‐known sesquiterpene lactones contained in many plants used as popular herbs, such as Saussurea lappa and Laurus novocanariensis, and have been considered as potential candidates for the treatment of various types of tumor. In the present work, a sensitive UPLC‐MS/MS for the quantification of costunolide and dehydrocostuslactone in biological matrices has been developed. The method is based on protein precipitation with acetonitrile followed by isocratic ultraperformance liquid chromatographic separation using methanol–formic acid (0.1% in water; 70:30, v/v) mobile phase. Detection was performed by ESI mass spectrometry in MRM mode with the precursor‐to‐product ion transitions m/z 233–187 and m/z 231–185, respectively. The calibration curves of analytes showed good linearity within the established range 0.19–760 ng/mL for costunolide and 0.23–908 ng/mL for dehydrocostuslactone. The lower limits of quantification of costunolide and dehydrocostuslactone were found to be 0.19 and 0.23 ng/mL, respectively. The intra‐day and inter‐day presicions of this method for the entire validation were less than coefficient of variation of 7% and the accuracy was within ±8% (relative error). The mean extraction recoveries were 73.8 and 75.3%, respectively. The method was found to be precise, accurate and specific during the study, and was successfully used to analyze the pharmacokinetics of costunolide and dehydrocostuslactone. Copyright © 2010 John Wiley & Sons, Ltd.     

Selective determination of alkylmercury compounds in solid matrices after subcritical water extraction,followed by solid‐phase microextraction and GC–MS

A method for the extraction and determination of methylmercury (MeHg) in solid matrices is presented. Combining the advantages of two extraction techniques—subcritical water extraction (subWE) and solid‐phase microextraction (SPME)—selective separation of MeHg from soils is possible. The procedure is based on extraction with subcritical water without using organic solvents, followed by in situ aqueous‐phase derivatization with sodium tetraethylborate and headspace SPME with a silica fiber coated with poly(dimethylsiloxane). The optimization of the extraction parameters is described. The identification and quantification of the extracted alkylmercury compounds from spiked soil samples is performed by GC–MS after thermal desorption. Copyright © 2000 John Wiley & Sons, Ltd.