超高效液相色谱-电喷雾串联质谱法直接测定黄酒和葡萄酒中氨基甲酸乙酯

建立了超高效液相色谱-电喷雾串联质谱(UPLC-ESI-MS/MS)直接测定黄酒和葡萄酒中氨基甲酸乙酯含量的方法。黄酒和葡萄酒样品经蒸馏水简单稀释后,过0.22 μm微孔滤膜,直接进行UPLC-MS/MS分析检测。以Waters Acquity UPLCTMBEH C18色谱柱为分析柱,乙腈和0.1%(v/v)乙酸水溶液为流动相,采用电喷雾正离子(ESI+)模式电离,多反应监测(MRM)模式检测,以氨基甲酸丁酯(BC)作为内标进行定量。结果表明: 方法在2～500 μg/L的范围内线性关系良好(相关系数大于0.995),其对黄酒和葡萄酒的检出限为1.7 μg/L,定量限为5.0 μg/L,可达到黄酒和葡萄酒中氨基甲酸乙酯的检测要求。当添加水平为10、20和100 μg/L时,黄酒和葡萄酒中待测组分的回收率为90%～102%,日内精密度(n=6)为0.8%～4.5%,日间精密度(n=6)为1.4%～5.6%。该方法样品处理简单,前处理过程不使用有机溶剂,测定快速、准确,灵敏度高,非常适合黄酒和葡萄酒中氨基甲酸乙酯的快速检测和定量分析。     

Determination of dodine in fruit samples by liquid chromatography electrospray ionization-tandem mass spectrometry

A rapid and sensitive LC/electrospray ionization-MS/MS method has been developed for the determination of dodine in fruit samples. Based on a liquid-liquid extraction of 10 g solid fruit homogenate using an acetone-dichloromethane-hexane mixture and acetate ammonium buffer (pH 4.5), this LC/MS/MS procedure was characterized by recoveries above 50%, with good intra-assay precision (RSD < 13%) and interassay precision (RSD < 18%) for seven different matrixes (apple, apricot, cherry, peach, pear, plum, and quince). This method was validated from 5 to 500 microg/kg according to standard guidelines. Its LOD (1 microg/kg) and LOQ (5 microg/kg) were in accordance with recommendations of the European legislation defined for infant food [maximum residue level (MRL) = 10 microg/kg]. The whole procedure was finally tested on 1022 fruit samples intended for commercialization, both infant food samples and samples not intended in particular for babies. In this study, dodine was detected in 27 samples; none exhibited a concentration higher than the MRL.     

Quantitation of acrylamide in food products by liquid chromatography/mass spectrometry

A simple and inexpensive liquid chromatography/mass spectrometry (LC/MS) method was developed for the quantitation of acrylamide in various food products. The method involved spiking the isotope-substituted internal standard (1-C13 acrylamide) onto 6.00 g of the food product, adding 40 mL distilled/deionized water, and heating at 65 degrees C for 30 min. Afterwards, 10 mL ethylene dichloride was added and the mixture was homogenized for 30 s and centrifuged at 2700 x g for 30 min, and then 8 g supernatant was extracted with 10, 5, and 5 mL portions of ethyl acetate. The extracts were combined, dried with sodium sulfate, and concentrated to 100-200 microL. Acrylamide was determined by analysis of the final extract on a single quadrupole, bench-top mass spectrometer with electrospray ionization, using a 2 mm id C18 column and monitoring m/z = 72 (acrylamide) and m/z = 73 (internal standard). For difficult food matrixes, such as coffee and cocoa, a solid-phase extraction cleanup step was incorporated to improve both chromatography and column lifetime. The method had a limit of quantitation of 10 ppb, and coefficients of determination (r2) for calibration curves were typically better than 0.998. Acceptable spike recovery results were achieved in 11 different food matrixes. Precision in potato chip analyses was 5-8% (relative standard deviation). This method provides an LC/MS alternative to the current LC/MS/MS methods and derivatization gas chromatography/mass spectrometry methods, and is applicable to difficult food products such as coffee, cocoa, and high-salt foods.     

An Extraction Method for Obtaining the Maximum Non-Anthocyanin Phenolics from Grape Berry Skins

To obtain maximum non-anthocyanin phenolics from grape skins, various extraction conditions were evaluated according to the amounts of 8 non-anthocyanin phenolics. The result showed that the optimal extraction was performed in ethyl acetate solution at 25°C, with liquid/solid ratio of 10:1 (ml/g) and for 30 min. On this basis, the non-anthocyanin extracts from two red and two white grape cultivars were analyzed using high performance liquid chromatography coupled with tandem mass spectrometry (HPLC- MS/MS), and twenty-four compounds were qualified and simultaneously quantified, which indicated that the present extraction method was suitable for the study of non-anthocyanin in grape skins.     

Determination of total nitrofuran metabolites in shrimp muscle using liquid chromatography/tandem mass spectrometry in the atmospheric pressure chemical ionization mode

The method of MacMahon and Lohne for analysis of nitrofuran metabolites in shrimp was optimized to streamline the extraction processes and the LC analysis. This revised method includes 16 h of mild acid hydrolysis/derivatization followed by ethyl acetate extraction and analysis by LC/MS/MS in the atmospheric pressure chemical ionization mode. This revised method was validated in shrimp for concentrations of 0.25 to 2.0 ng/g. The LOQ was 0.25 ng/g for all metabolites. The LOD was 0.052 nglg for 1-aminohydantoin (AHD), 0.206 ng/g for 3-amino-2-oxazolidinone (AOZ), 0.108 ng/g for semicarbazide (SC), and 0.062 ng/g for 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ). The spike recoveries with RSD into negative matrix at 1 ng/g were 100.2% (3.2%) for AHD, 102.5% (1.0%) for AOZ, 103.7% (2.3%) for SC, and 104.0% (3.3%) for AMOZ. The spike recoveries at 1 ng/g into unknown samples (n=108) containing varied levels of nitrofuran metabolites were 112.6% (25.7%) for AHD, 108.1% (12.1%) for AOZ, 103.0% (12.0%) for SC, and 100.3% (6.9%) for AMOZ. Interday precision with samples containing incurred AOZ concentrations of 0.92 to 17.8 ppb performed over a year was 10.4% RSD. The method is accurate and precise for determining nitrofuran concentrations in the edible tissue of shrimp.     

实时直接分析-串联质谱法测定葡萄酒中赭曲霉毒素A

建立了葡萄酒中赭曲霉毒素A的实时直接分析-串联质谱(DART-MS/MS)方法。前处理采用乙酸乙酯提取,二甲基十八碳硅烷粉(ODS)粉分散固相萃取净化,采用DART-MS/MS检测,同位素稀释内标法定量。结果表明:在1.0、2.0、10μg/kg 3个加标水平下,回收率为88.7%~105.7%,RSD为8.5%~12.8%,定量限为0.5μg/kg。该方法具有简单、快速、灵敏度高等特点,能满足葡萄酒中赭曲霉毒素A检测的要求。     

N,N-二甲基乙醇胺三个季铵盐衍生物的合成与表征

以N，N－二甲基甲酰胺为溶剂，乙酸乙酯为催化剂，N，N－二甲基乙醇胺分别与苄基氯、十二烷基溴和十八烷基溴作用，得到了3个N，N－二甲基乙醇胺的季铵盐衍生物。标题化合物结构经IR，^1H NMR,^13C NMRt FAB-MS表征。     

Deceleration the hydrolysis reaction of ethyl acetate ester by β-cyclodextrin in basic medium: transition state analog

Electrical conductivity measurements were used to study the hydrolysis reaction of dilute aqueous solution of ethyl acetate with the presence β-cyclodextrin (β-CD) within a concentration range between 0.00 and 0.00750 M in basic medium at 25.0?°C. 0.00265 M of β-CD was chosen as typical concentration for studying the same reaction at different temperatures between 21.0 and 35.0?°C. Two different values of activation energy for the hydrolysis reaction of free ethyl acetate and ethyl acetate/β-CD complex were evaluated, and their values are 46.3 and 62.0 kJ mol^?1 respectively. The standard Gibbs energy of activation (?^?G^o), standard enthalpy of activation (?^?H^o), and standard entropy of activation (?^?S^o) for the two different cases were evaluated. β-CD plays a notable role in retarding the rate of hydrolysis of ethyl acetate in basic medium.     

LC/MS method using cloud point extraction for the determination of permitted and illegal food colors in liquid, semiliquid, and solid food matrixes: single-laboratory validation

A cloud point extraction method is reported using LC/MS for the determination of regulated water-soluble food colors (Allura Red, Sunset Yellow, erythrosine, and tartrazine) and banned fat-soluble synthetic azo dyes (Sudan I, II, III, and IV; Red B; 7B; Black B; Red G; Metanil Yellow; and Rhodamine B). The extraction of all 14 colors was carried out with cloud point extraction using the nonionic surfactant Triton X 114. Optimized conditions for cloud point extraction were 3% Triton X 114 (w/v), 0.1 M ammonium acetate, and heating at 50 degrees C for 30 min. This approach proved effective in giving quantitative recoveries from a diverse range of food matrixes, and optimized LC gave baseline chromatographic separation for all colors including Sudan IV and Red B. Single-laboratory validation was performed with spiking into liquid matrixes (wine and homemade wine), semiliquid matrixes (sauce and homemade paprika paste), and solid matrixes (spice and homemade chili powder) using the respective blank matrixes for matrix-matched calibration. The LOQ values for water-soluble colors were in the range of 15-150 mg/kg, and for the fat-soluble colors, 0.1-1.5 mg/kg. The mean recovery values were in the range of 69.6-116.0% (except Allura Red and Sunset Yellow in wine, for which recoveries were lower). The mean RSDs for colors were in the range of 4.0-14.8%. A small survey was conducted of samples of confectionery products, dried fruits, wines, bitter sodas, juices, sauces, pastes, and spices, which demonstrated the applicability of the method to a diverse selection of real food samples. Allura Red was detected in strawberry jelly and Sunset Yellow in artificial saffron.     

Optimization of detection conditions and single-laboratory validation of a multiresidue method for the determination of 135 pesticides and 25 organic pollutants in grapes and wine by gas chromatography time-of-flight mass spectrometry

This paper describes single-laboratory validation of a multiresidue method for the determination of 135 pesticides, 12 dioxin-like polychlorinated biphenyls, 12 polyaromatic hydrocarbons, and bisphenol A in grapes and wine by GC/time-of-flight MS in a total run time of 48 min. The method is based on extraction with ethyl acetate in a sample-to-solvent ratio of 1:1, followed by selective dispersive SPE cleanup for grapes and wine. The GC/MS conditions were optimized for the chromatographic separation and to achieve highest S/N for all 160 target analytes, including the temperature-sensitive compounds, like captan and captafol, that are prone to degradation during analysis. An average recovery of 80-120% with RSD < 10% could be attained for all analytes except 17, for which the average recoveries were 70-80%. LOQ ranged within 10-50 ng/g, with < 25% expanded uncertainties, for 155 compounds in grapes and 151 in wine. In the incurred grape and wine samples, the residues of buprofezin, chlorpyriphos, metalaxyl, and myclobutanil were detected, with an RSD of < 5% (n = 6); the results were statistically similar to previously reported validated methods.     

Urine drug testing for opioids,cocaine, and metabolites by direct injection liquid chromatography/tandem mass spectrometry

A sensitive and specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) method for the simultaneous quantification of opioids, cocaine, and metabolites in urine was developed and validated. A 10-microL aliquot of urine was injected directly onto the LC/MS/MS system. The lack of sample preparation substantially reduced total analysis time. Separation was performed by reversed-phase chromatography with gradient elution for all analytes in 26 min. Atmospheric pressure chemical ionization (APCI) was a rugged and efficient ionization technique for basic drugs. Identification and quantification was based on selected reaction monitoring (SRM). Calibration, with deuterated internal standards, was performed by linear regression analysis (weighting factor 1/x). Limits of quantitation (LOQ) were established between 10-100 ng/mL and linearity was obtained up to a maximum of 10 000 ng/mL with an average correlation coefficient (R(2)) > 0.99. Analytical validation criteria for specificity, precision, accuracy, dilution integrity, matrix effect, and stability were fulfilled. The method proved to be simple and time efficient, and was applicable for illicit drug use monitoring and methadone treatment compliance in clinical research projects at the National Institute on Drug Abuse (NIDA).     

Development and validation of a liquid chromatographic/ tandem mass spectrometric method for determination of chlortetracycline, oxytetracycline, tetracycline, and doxycycline in animal feeds

A selective and accurate LC/MS/MS method for the simultaneous determination of chlortetracycline (CTC), oxytetracycline (OTC), tetracycline (TC), and doxycycline (DC) in animal feeds was developed. Samples were extracted with Na2EDTA-McIlvaine buffer and further purified with Oasis HLB SPE columns. The purified extract was separated on an Xbridge C18 column and detected by LC/MS/MS with positive electrospray ionization in the multiple reaction monitoring mode. This method provided average recoveries of 80.9 to 119.5%, with CVs of 1.7 to 9.8% in the range of 0.5 to 50 mg/kg CTC, OTC, TC, and DC in feeds, except the average recovery of CTC was 76.0%, with a CV of 14.6% in pig feed spiked with 0.5 mg/kg CTC. The linear ranges for the four TCs determined by LC/MS/MS ranged from 0.005 to 2.5 microg/mL with a linear correlation coefficient (R2) >0.99. The LOD and LOQ for CTC, OTC, TC, and DC in pig and poultry feeds ranged from 0.003 to 0.02 and 0.01 to 0.05 microg/g, respectively. The method was successfully applied for the analysis of 30 real feed samples, and no illegal use was detected.     

Development and validation of a method for the quantification of milk proteins in food products based on liquid chromatography with mass spectrometric detection

The protection of allergic consumers is crucial to the food industry. Therefore, accurate methods for the detection of food allergens are required. Targeted detection of selected molecules by MS combines high selectivity with accurate quantification. A confirmatory method based on LC/selected reaction monitoring (SRM)-MS/MS was established and validated for the quantification of milk traces in food. Tryptic peptides of the major milk proteins beta-lactoglobulin, beta-casein, alphaS2-casein, and K-casein were selected as quantitative markers. Precise quantification was achieved using internal standard peptides containing isotopically labeled amino acids. For each peptide, qualifier and quantifier fragments were selected according to Commission Decision 2002/657/EC. A simple sample preparation method was established without immunoaffinity or SPE enrichment steps for food matrixes containing different amounts of protein, such as baby food, breakfast cereals, infant formula, and cereals. Intermediate reproducibility, repeatability, accuracy, and measurement uncertainty were determined for each matrix. LOD values of 0.2-0.5 mg/kg, e.g., for beta-lactoglobulin, were comparable to those obtained with ELISA kits. An LOQ of approximately 5 mg/kg, expressed as mass fraction skim milk powder, was validated in protein-rich infant cereals. The obtained validation data show that the described LC/SRM-MS/MS approach can serve as a confirmatory method for the determination of milk traces in selected food matrixes.     

Design and synthesis of new series of 3-cyanopyridine and pyrazolopyridine derivatives

Reaction of 3-cyano-4,6-dimethyl-2-pyridone with ethyl chloroacetate afforded ethyl 2-([3-cyano-4,6-dimethylpyridin-2-yl]oxy)acetate 2 and ethyl 2-(3-cyano-4,6-dimethyl-2-oxopyridin-1[2H]-yl)acetate 3 , the reaction product yield depend on the reaction condition (potassium carbonate concentration and reaction time). These compounds used as precursors to synthesize pyridine derivatives 4 , 6-10 , 15, 17-20 , furopyridines 5, 16 , pyrazolopyridine 12 , pyridopyrazolopyrimidines 14a,b . The structure of the newly synthesized compounds was confirmed by spectral data (IR, NMR, and mass spectra) and elemental analysis.     

Determination of multiclass pesticides in food commodities by pressurized liquid extraction using GC–MS/MS and LC–MS/MS

Pressurized liquid extraction (PLE) was applied to the simultaneous extraction of a wide range of pesticides from food commodities. Extractions were performed by mixing 4 g of sample with 4 g of Hydromatrix and (after optimization) a mixture of ethyl acetate:acetone (3:1, v/v) as extraction solvent, a temperature of 100°C, a pressure of 1000 psi and a static extraction time of 5 min. After extraction, the more polar compounds were analyzed by liquid chromatography (LC), and the apolar and semipolar pesticides by gas chromatography (GC); in both cases LC and GC were coupled with mass spectrometry in tandem (MS/MS) mode. The overall method (including the PLE step) was validated in GC and LC according to the criteria of the SANCO Document of the European Commission. The average extraction recoveries (at two concentration levels) for most of the analytes were in the range 70–80%, with precision values usually lower than 15%. Limits of quantification (LOQ) were low enough to determine the pesticide residues at concentrations below or equal to the maximum residue levels (MRL) specified by legislation. In order to assess its applicability to the analysis of real samples, aliquots of 15 vegetable samples were processed using a conventional extraction method with dichloromethane, and the results obtained were compared with the proposed PLE method; differences lower than 0.01 mg kg⁻¹ were found.     

Multiresidue analysis of multiclass plant growth regulators in grapes by liquid chromatography/tandem mass spectrometry

A selective and rapid multiresidue analysis method is presented for simultaneous estimation of 12 plant growth regulators (PGRs), namely, auxins (indol-3-acetic acid, indol-3-butyric acid, and naphthyl acetic acid), cytokinins (kinetin, zeatin, and 6-benzyladenine), gibberellic acid (GA3), abscisic acid, and synthetic compounds, namely, forchlorfenuron, paclobutrazole, isoprothiolane, and 2,4-dichlorophenoxy acetic acid (2,4-D) in bud sprouts and grape berries at the development stages of 2-3 and 6-8 mm diameters, which are the critical phases when exogenous application of PGRs may be necessary to achieve desired grape quality and yield. The sample preparation method involved extraction of plant material with acidified methanol (50%) by homogenization for 2 min at 15000 rpm. The pH of the extract was enhanced up to 6 by adding ammonium acetate, followed by homogenization and centrifugation. The supernatant extract was cleaned by SPE on an Oasis HLB cartridge (200 mg, 6 cc). The final extract was measured directly by LC/MS/MS with electrospray ionization in positive mode, except for 2,4-D, GA3, and abscisic acid extracts, which required analysis in negative mode. Quantification by multiple reaction monitoring (MRM) was supported with full-scan mass spectrometric confirmation using "information-dependent acquisition" triggered with MRM to "enhanced product ionization" mode of the hybrid quadrupole-ion trap mass analyzer. The LOQ of the test analytes varied between 1 and 10 ng/g with associated recoveries of 80-120% and precision RSD <25% (n = 8). Significant matrix-induced signal suppression was recorded when the responses for pre- and postextraction spikes of analytes were compared; this could be resolved by using matrix-matched calibration standards. The method could successfully be applied in analyzing incurred residue samples and would, therefore, be useful in precisely deciding the necessity and dose of exogenous applications of PGRs on the basis of measured endogenous levels.     

Synthesis and Crystal Structure of 4-（4,6-Dimethoxylpyrimidin-2-yl）- 3-thiourea Carboxylic Acid Ethyl Ester

4-（4,6-Dimethoxyl-pyrimidin-2-yl）-3-thiourea carboxylic acid ethyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at room temperature. The crystal structure was determined by X-ray diffraction analysis. Crystallographic data： C10H14N4O4S, M, = 286.31, monoclinic, space group C2/c with a = 2.5309（3）, b = 0.67682（6）, c = 1.74237（19） nm, β = 114.744（3）°, V= 2.7106（5） nm3, Dc = 1.403 g/cm3, p = 0.225 mm-1, F（000） = 1200, Z= 8, R= 0.0514 and wR= 0.1529.     

Comparison of liquid chromatography using triple quadrupole and quadrupole ion trap mass analyzers to determine pesticide residues in oranges

Liquid chromatography-triple quadrupole/mass spectrometry (LC-TQ/MS) and liquid chromatography-quadrupole ion trap/mass spectrometry (LC-QIT/MS) for determining bupirimate, hexaflumuron, tebufenpyrad, buprofezin, pyriproxyfen, and fluvalinate in fruits have been compared. The differences in the mass spectra obtained by triple and ion trap quadrupoles are discussed, showing how both of them provide interesting features. The evaluation of the two instruments was carried out by ethyl acetate extraction of oranges spiked with the studied pesticides at LOQ and 10 times the LOQ. Results obtained by LC-TQ/MS correlated well with those obtained by LC-QIT/MS. Recoveries were 70-94% by LC-TQ/MS and 72-92% by LC-QIT/MS with the R.S.D. from five replicate analysis 4-14% and 8-18%, respectively. Matrix effects were tested for both techniques by standard addition to blank extracts. Although the matrix effects are not originated in mass analyzer but in the LC/MS interface, they were, generally, more marked by LC-QIT-MS than by LC-TQ/MS. The limits of quantification (LOQs) were 0.005-0.2 mg kg(-1) by both equipments--appropriate values for determining these pesticides in orange from the regulatory point of view. The results indicate that the TQ provides higher precision, better linearity, it is more robust, and when the purpose of the analysis is quantitative determination, preferable over the QIT. However, the application of both mass spectrometers to analyze orange samples conventionally treated showed that any can be used for qualitative and quantitative purposes.     

LC–MS/MS method for the simultaneous determination of ethyl gallate and its major metabolite in rat plasma

A simple, rapid and sensitive liquid chromatography–tandem mass spectroscopy (LC–MS/MS) method was developed and validated for the determination of ethyl gallate, a pharmacologically active constituent isolated from Lagerstroemia speciosa (Linn.) Pers. This method was used to examine the pharmacokinetics of ethyl gallate and its major metabolite gallic acid in rat plasma using propyl gallate as an internal standard. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a Zorbax SB‐C₁₈ column (3.5 μm, 2.1 × 50 mm) with an isocratic mobile phase consisted of methanol–acetonitrile–10 mM ammonium acetate (10 : 25 : 65, v/v/v) containing 0.1% formic acid at a flow rate of 0.25 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple‐reaction monitoring mode using the electrospray ionization technique in negative mode. The lower limits of quantification of gallic acid and ethyl gallate of the method were 0.5 and 1.0 ng/mL. The intra‐day and inter‐day accuracy and precision of the assay were less than 8.0%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of ethyl gallate to rats. Copyright © 2009 John Wiley & Sons, Ltd.     

LC–MS–MS Determination of Rotenone, Deguelin, and Rotenolone in Human Serum

For the first time we report a rapid and sensitive LC–MS–MS method for quantification of rotenone, deguelin, and rotenolone in human serum. The analytical procedure involves extraction with ethyl acetate without further clean-up. The active ingredients were separated on a C₈ reversed-phase column by isocratic elution. Eleven simultaneous transitions of precursor ions were monitored. Excellent selectivity and sensitivity enables quantification and identification of low levels of rotenoids (LOD 2 ng mL^?1, LOQ 5 ng mL^?1) in human serum.