Recognition of multiple substrate motifs by the c-ABL protein tyrosine kinase

Using a combinatorial peptide library that is based on the one-bead one-peptide approach we identified 14 peptide substrates for the c-ABL protein tyrosine kinase, which define three distinct consensus sequence groups. This is distinct from many serine/threonine kinases, which often phosphorylate only one major consensus sequence. The three consensus sequences accurately predict phosphorylation sites in cellular ABL substrates proven to play a role in cell signaling. Our data suggest that protein tyrosine kinases have evolved to recognize multiple substrate motifs.     

Rapid determination of 5-hydroxymethylfurfural by DART ionization with time-of-flight mass spectrometry

DART (direct analysis in real time), a novel technique with wide potential for rapid screening analysis, coupled with high-resolution time-of-flight mass spectrometry (TOF-MS) has been used for quantitative analysis of 5-hydroxymethylfurfural (5-HMF), a typical temperature marker of food. The DART/TOF-MS method was optimised and validated. Quantification of 5-HMF was achieved by use of a stable isotope-labelled 5-HMF standard prepared from glucose. Formation of 5-HMF from saccharides, a potential source of overestimation of results, was evaluated. Forty-four real samples (honey and caramelised condensed sweetened milk) and 50 model samples of heated honey were analysed. The possibility of using DART for analysis of heated samples of honey was confirmed. HPLC and DART/TOF-MS methods for determination of 5-HMF were compared. The correlation equation between these methods was DART?=?1.0287HPLC?+?0.21340, R ²?=?0.9557. The DART/TOF-MS method has been proved to enable efficient and rapid determination of 5-HMF in a variety of food matrices, for example honey and caramel.     

Accurate mass determination by multiple sprayers nano-electrospray mass spectrometry on a magnetic sector instrument

A new technique for accurate mass determination by using multiple sprayers nano-electrospray ionization mass spectrometry (nano-ESI-MS) on a magnetic sector instrument is described. Metal coated glass capillaries were used as nano-ESI sprayers. One of the sprayers was used for the reference compound solution, and others were used for the introduction of sample solutions. The spectra of the different compounds were obtained by shifting each sprayer's position relative to the sampling orifice. The accurate masses of several standard compounds were obtained with good accuracy, without problems arising from differences in ionization efficiency between the sample compounds and reference compound.     

同位素稀释质谱法测定蜂蜜中4种硝基呋喃代谢物

研究了蜂蜜中4种硝基呋喃代谢物:呋喃唑酮代谢物(AOZ)、呋喃它酮代谢物(AMOZ)、呋喃妥因代谢物(AHO)、呋喃西林代谢物(SEM)的同位素稀释HPLC-MS/MS分析方法,以邻硝基苯甲醛作为衍生化试剂,AOZ-d4、AMOZ-d5、AHD-13G3、SEM·HCl-(13C,15 N2)作内标,并将超声波衍生化法应用到实际样品的分析测试当中,以乙腈-0.1%甲酸为流动相,采用梯度洗脱,15 min可将4种代谢物完全分离,再以MS/MS进行定性和定量分析.加标回收率为82%～112%;定量限(LOQ)为0.05～1 μg/kg;检出限(LOD)为0.01～0.25 μg/kg.该方法满足欧盟(EU)对进出口蜂蜜中硝基呋喃代谢物的检测要求.     

Rapid determination of 237Np in soil samples by multi-collector inductively-coupled plasma mass spectrometry and gamma spectrometry

A radiochemical procedure is developed for the determination of ²³⁷Np in soil with multi-collector inductively-coupled plasma mass spectrometry (MC-ICP-MS) and gamma-spectrometry. ²³⁹Np (milked from ²⁴³Am) was used as an isotopic tracer for chemical yield determination. The neptunium in the soil is separated by thenoyl-trifluoracetone extraction from 1 M HNO₃ solution after reducing Np to Np(IV) with ferrous sulfamate, and then purified with Dowex 1 × 2 anion exchange resin. ²³⁹Np in the resulting solution is measured with gamma-spectrometry for chemical yield determination while the ²³⁷Np is measured with MC-ICP-MS. Measurement results for soil samples are presented together with those for two reference samples. By comparing the determined value with the reference value of the ²³⁷Np activity concentration, the feasibility of the procedure was validated.     

Rapid determination of fumonisins in corn-based products by liquid chromatography/tandem mass spectrometry

A simple, fast, and robust method was developed for the determination of fumonisin B1 (FB1), fumonisin B2 (FB2), and fumonisin B3 (FB3) in corn-based human food and animal feed (cornmeal). The method involves a single extraction step followed by centrifugation and filtration before analysis by ultra-performance liquid chromatographylelectrospray ionization (UPLC/ESI)-MS/MS. The LC/MS/MS method developed here represents the fastest and simplest procedure (<30 min) among both conventional HPLC methods and other LC/MS methods using SPE cleanup. The potential for high throughput analysis makes the method particularly beneficial for regulatory agencies and analytical laboratories with a high sample volume. A single-laboratory validation was conducted by testing three different spiking levels (200, 500, and 1000 ng/g for FB1 and FB2; 100, 250, and 500 ng/g for FB3) for accuracy and precision. Recoveries of FB1 ranged from 93 to 98% with RSD values of 3-8%. Recoveries of FB2 ranged from 104 to 108%, with RSD values of 2-6%. Recoveries of FB3 ranged from 94 to 108%, with RSD values of 2-5%.     

Rapid simultaneous determination of 14 sulfonamides in wastewater by liquid chromatography tandem mass spectrometry

This paper describes a rapid method for the determination of 14 kinds of sulfonamides (SAs) in wastewater using SPE, and LC-MS/MS with positive ESI (ESI(+)) and selected reaction monitoring (SRM) mode. The SPE was performed on an Oasis hydrophilic-lipophilic-balanced (HLB) cartridge. Chromatographic separation on a C18 column was achieved using a binary eluent containing methanol and water with 0.2% formic acid. Typical recoveries of the analytes ranged from 22.3 to 87.0% at a fortification level of 100 ng/L. The LODs in wastewater except sulfathiazole (3 ng/L) could be detected and quantified at levels as low as 1 ng/L. Finally, the method was applied to water from the municipal outlet and the aquaculture wastewater effluent. Sulfamethazine (SM(2)), sulfamethoxypyridazine (SMP), and sulfamethoxazole (SMZ) were most frequently found in wastewater in a concentration range between 1.2 and 31.7 ng/L.     

超高效液相色谱-串联质谱法快速测定六神曲中的米酵菌酸

基于超高效液相色谱-串联质谱法（UPLC-MS/MS），建立了快速测定六神曲中生物毒素米酵菌酸残留的检测方法。样品首先以甲醇作为提取溶剂进行超声提取，再用氨水调节pH值至8，过滤，滤液用Oasis MAX强阴离子交换固相萃取柱处理。采用Waters HSS T3色谱柱（100 mm×2.1 mm，1.8 μm）分离，以乙腈-含0.1%（体积分数）甲酸的10 mmoL/L甲酸铵溶液为流动相，采用电喷雾电离（ESI）源电离，电离模式为负离子模式，质谱检测模式为多反应监测（MRM）模式。在最佳条件下，米酵菌酸在0.5~100 μg/L范围内呈良好的线性关系，相关系数（R²）>0.99。方法的加标回收率为80.6%~85.3%，日内和日间精密度分别为4.2%~6.8%和8.2%~13.2%。方法的检出限（LOD，S/N=3）和定量限（LOQ，S/N=10）分别为0.4 μg/kg和1.2 μg/kg。实际样品测定中发现了六神曲中存在米酵菌酸残留的现象，为保健食品和中药材中生物毒素的风险监控提供了重要的科技支撑。该方法简单、快速、灵敏度高，适用于六神曲中生物毒素米酵菌酸残留量的测定。     

Rapid determination of nitroimidazole residues in honey by liquid chromatography/tandem mass spectrometry

We developed a rapid and efficient means of determining residues of four nitroimidazoles-i.e., dimetridazole, ipronidazole, metronidazole, and ronidazole-and three hydrophilic metabolites- i.e., 2-hydroxymethyl-1-methyl-5-nitroimidazole, 1 -methyl-2-(2'-hydroxyisopropyl)-5-nitroimidazole, and 1-(2-hydroxyethyl)-2-hydroxymethyl-nitroimidazole--in honey. We applied a QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) procedure improved to suit a nitroimidazole analysis, which is fast (approximately 30 min) and uses less organic solvent. The procedure involves initial single-phase extraction of 5 g of honey with acetonitrile containing 1% acetic acid, followed by liquid-liquid partitioning involving the addition of 5 g sodium chloride, 1.5 g trisodium citrate dihydrate, and 4 g magnesium sulfate. Moreover, matrix from honey was reduced by an SPE method with an alumina-N cartridge. The samples were analyzed using LC/MS/MS. Chromatographic separation of these nitroimidazoles and metabolites was performed in the gradient mode on a pentafluorophenylpropyl-bonded silica column (150x2.0 mm, 3 pm particle size) at 40 degrees C. The mobile phase consisted of a 0.01% acetic acid solution and acetonitrile, and the flow rate was 0.2 mL/min. The method was validated using honey spiked with these nitroimidazoles from 0.1 to 0.5 microg/kg. The overall recovery of the seven nitroimidazoles ranged from 76.1 to 98.5%; intra- and interassay CV values were <9.5 and <14.2%, respectively. The LOQ ranged from 0.1 to 0.5 microg/kg. LC/MS/MS coupled with the QuEChERS method showed good potential as a method for determining nitroimidazole residues in honey.     

QuEChERS-气相色谱-串联质谱法快速检测茶叶中6种禁用香精成分

建立了QuEChERS净化作为样品前处理，结合气相色谱-串联质谱（GC-MS/MS）同时检测茶叶中6种禁用香精成分（香豆素、侧柏酮、2-己基噻吩、反式-β-金合欢烯、p-薄荷-1，8（10）-二烯-9-乙酸乙酯和肉桂酸丁酯）的分析方法。茶叶样品用乙酸乙酯溶液萃取，涡旋振荡，离心后上清液中加入无水硫酸镁、十八烷基键合硅胶（C18）和乙二胺-N-丙基甲硅烷（PSA），涡旋，低温离心后过滤膜，以DB-5MS色谱柱分离，MS/MS于MRM模式下测定，基质曲线外标法定量。实验结果表明，6种禁用香精成分在1~200 μg/L线性范围内呈良好线性，线性相关系数（R²）均大于0.999。方法检出限0.005~1 μg/kg，定量限0.02~2 μg/kg，平均回收率82.3%~93.1%，日内、日间精密度均小于10%。该方法处理简单、快速，准确度和灵敏度高，可用于茶叶中6种禁用香精成分的检测。     

Rapid quality control analysis of (13)C-enriched substrate synthesis by isotope ratio mass spectrometry

There is a growing interest in the use of (13)C-enriched substrates to investigate metabolic processes in humans. The non-invasive nature of (13)C breath tests makes them attractive to clinicians, particularly because they can be safely used in children. The availability of suitable (13)C-enriched substrates can limit the application of this biotechnology. We have used isotope ratio mass spectrometry to assay the chemical purity and isotopic enrichment of substrates that were synthesised to study gut transit and colonic fermentation. Lactose ureide and lactose [(13)C]ureide were synthesised by acid-catalysed condensation of lactose and urea or (13)C urea, respectively. Glucose ureide and glucose [(13)C]ureide were synthesised by similar methods but required an additional purification step to remove urea of crystallisation. Substrates were analysed by standard analytical techniques and combustion isotope ratio mass spectrometry for carbon and nitrogen content and (13)C-enrichment. Monitoring the C/N ratio proved to be a sensitive assay of chemical purity. Analysis of the percentage composition of C and N (and hence O + H) suggested that lactose ureide crystallises as the dihydrate. It was synthesised with approximately 99% chemical purity and with the theoretical enrichment. Glucose ureide was synthesised with approximately 98% chemical purity but with lower than theoretical enrichment.     

Rapid determination of 237Np and Pu isotopes in water by inductively-coupled plasma mass spectrometry and alpha spectrometry

A new method that allows rapid preconcentration and separation of plutonium and neptunium in water samples was developed for the measurement of ²³⁷Np and Pu isotopes by inductively-coupled plasma mass spectrometry (ICP-MS) and alpha spectrometry. ²³⁸U can interfere with ²³⁹Pu measurement by ICP-MS as ²³⁸UH⁺ mass overlap and ²³⁷Np via peak tailing. The method provide enhanced removal of uranium by separating Pu and Np initially on TEVA Resin, then moving Pu to DGA resin for additional removal of uranium. The decontamination factor for uranium from Pu is almost 100,000 and the decontamination factor for U from Np is greater than 10,000. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration is performed using a streamlined calcium phosphate precipitation method. Purified solutions are split between ICP-MS and alpha spectrometry so that long and short-lived Pu isotopes can be measured successfully. The method allows for simultaneous extraction of 20 samples (including QC samples) in 4?C6 h, and can also be used for emergency response. ²³⁹Pu, ²⁴²Pu and ²³⁷Np were measured by ICP-MS, while ²³⁶Pu, ²³⁸Pu, and ²³⁹Pu were measured by alpha spectrometry.     

Rapid determination of fosetyl-aluminum residues in lettuce by liquid chromatography/electrospray tandem mass spectrometry

This paper describes a new method for the sensitive and selective determination of fosetyl-aluminum (Al) residues in vegetable samples. The method involves extraction with water by using a high-speed blender and subsequent injection of the 5-fold diluted extract into the liquid chromatograph. Fosetyl-Al is determined by liquid chromatography with electrospray tandem mass spectrometry after the addition of tetrabutylammonium acetate as the ion-pairing reagent. The method has been used to assay lettuce samples spiked at 2 and 0.2 mg/kg. Recoveries were satisfactory, with mean values of 98 and 106%, respectively, and relative standard deviations were < 10%. The limit of quantitation was 0.2 mg/kg, and the limit of detection was as low as 0.05 mg/kg. Matrix-matched calibration was used for quantitation, and the addition of an internal standard improved repeatability. The developed method allows the accurate and rapid determination of low levels of fosetyl-Al residues in lettuce with very little sample handling and good sensitivity; it was shown to be robust by the analysis of almost 100 samples.     

Rapid determination of chloramphenicol residues in milk powder by liquid chromatography-elektrospray ionization tandem mass spectrometry

A simple and rapid liquid chromatography tandem mass spectrometry (LC-ESI-MS-MS) confirmation method for the analysis chloramphenicol (CAP) in milk powder has been developed. Samples were extracted by using liquid-liquid extraction steps with ethyl acetate. Lipids were removed using hexsan. LC separation was achieved by using a Phenomenex Luna C-18 column and acetonitryle-water as a mobile phase. The mass spectrometer was operated in multiple reaction monitoring mode (MRM) with negative electro-spray interface (ESI-). The four transitions were monitored m/z 321-->257, 321-->194, 321-->152, 326-->157 (IS) and for quantification, the transition m/z 321-->152 was chosen. Validation of the method was done according to criteria of Decision Commission No 2002/657 EC. Validation includes the determination of specification, linearity, precision (within- and between-day), accuracy, decision limit (CC alpha) and detection capability (CC beta). Samples were fortified at CAP levels 0.30, 0.45 and 0.60 microg/kg with CAP-5d as internal standard. The precision within-day (RSD%) was lower than 12% and accuracy (RE%) ranged from -9.8 to -3.7%. The precision between-day (RSD%) was less than 15%. The limit of decision (CC alpha) and detection capability (CC beta) for milk powder 0.09 and 0.11 microg/kg. Value CC alpha and CC beta were calculated for the 321-->152 ion transition. This method has been successfully used for routine analysis.     

改进的QuEChERS结合超高效液相色谱-串联质谱法快速测定地表水中双酚类物质

建立了同时测定地表水中8种双酚类物质(BPs)的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法.方法 基于QuEChERS处理技术,选用乙酸乙酯为提取剂,从基质效应(ME)和萃取回收率(RE)两方面对过程效率(PE)进行优化,确定了50 mg N-丙基乙二胺(PSA)和50 mg石墨化炭黑(GCB)混合吸附剂...     

Rapid classification of enzymes in cleaning products by hydrolysis, mass spectrometry and linear discriminant analysis

A method for the rapid classification of proteases, lipases, amylases and cellulases used as enhancers in cleaning products, based on precipitation with acetone, hydrolysis with HCl, dilution of the hydrolysates with ethanol, and direct infusion into the electrospray ion source of an ion-trap mass spectrometer, has been developed. The abundances of the ([M+H]+ ions of the amino acids, from the hydrolysates of both the enzyme industrial concentrates and the detergent bases spiked with them, were used to construct linear discriminant analysis models, capable of distinguishing between the enzyme classes. For this purpose, the variables were normalized as follows: (A) the ion abundance of each amino acid was divided by the sum of the ion abundances of all the amino acids in the corresponding mass spectrum; (B) the ratios of pairs of ion abundances were obtained by dividing the ion abundance of each amino acid by each one of the ion abundances of the other 17 amino acids in the corresponding mass spectrum. Using normalization procedure B, excellent class-resolution between proteases, lipases, amylases and cellulases was achieved. In all cases, enzymes in industrial concentrates and manufactured cleaning products were correctly classified with >98% assignment probability.     

超高效液相色谱-串联质谱法快速测定鱼和虾中多类禁、限用兽药残留

建立了鱼和虾中5类(磺胺类、喹诺酮类、氯霉素类、硝基呋喃类代谢物、三苯甲烷类)28种禁、限用兽药的同时提取净化-超高效液相色谱-串联质谱(UHPLC-MS/MS)快速检测的方法。对样品前处理及色谱条件进行优化,以盐酸水解样品,待硝基呋喃类代谢物与2-硝基苯甲醛衍生化后,5类残留药物经乙腈提取,提取液经氯化钠脱水、盐析,乙腈层经正己烷净化后浓缩至近干,残留物用甲醇定容至1.0 mL,加50 mg C18、30 mg N-丙基乙二胺(PSA)、60 mg氨基键合硅胶填料(NH2)吸附剂分散固相萃取净化,最后经ZORBAX C18色谱柱(50 mm×2.1 mm, 1.8μm)分离,在正、负离子多反应监测模式下采集,同位素内标法定量。所建立的方法确保28种兽药在各自范围内线性关系良好,相关系数(r)>0.99,方法的检出限和定量限分别为0.1～0.8μg/kg和0.3～2.7μg/kg;在1、5、20倍定量限添加水平下的平均回收率为70.0%～120%,相对标准偏差为0.9%～10.0%。方法简便、快速、准确、灵敏,适用于鱼和虾中多类禁、限用药物的快速测定。     

三光气的含量的光谱快速测定

光气是一种重要的化工原料,在农药、医药、高分子材料的研究和生产中应用很广.但光气剧毒,使用不当容易发生危险.碳酸双三氯甲酯,俗称三光气或固体光气,简称BTC,是一种固体化合物,挥发性小,使用方便,可以作为光气的代用品.近年来,三光气作为光气的替代产品已经被人们广泛接受.     

超高效液相色谱-串联质谱法快速同时测定生姜中10种营养成分

建立了超高效液相色谱-串联质谱（UHPLC-MS/MS）快速同时测定生姜中姜辣素类和姜黄素类营养成分的分析方法，具体包括6-姜酚、8-姜酚、10-姜酚、6-姜烯酚、8-姜烯酚、10-姜烯酚、四氢姜黄素、姜黄素、去甲氧基姜黄素、双去甲氧基姜黄素10种目标物。采用ZORBAX RRHD Eclipse Plus C18色谱柱（100 mm×2.1 mm，1.8 μm）分离，以0.1%（v/v）甲酸水溶液和0.1%（v/v）甲酸甲醇溶液为流动相进行梯度洗脱，采用电喷雾电离（ESI）源、正离子和多反应监测（MRM）模式对目标物进行定性确证和定量分析。10种营养成分的线性相关系数（r）均≥ 0.9995，方法的定量限为0.10~7.71 μg/L，样品基质在3个水平下的平均加标回收率为82.8%~115.3%，相对标准偏差（RSD）为0.58%~11.49%。分析结果显示，生姜中10种营养成分均有检出，其中6-姜酚的含量最高且集中分布于373.35~702.48 mg/kg。该法简便快速，准确可靠，适用于生姜中姜辣素类和姜黄素类营养成分的分析，可为生姜质量鉴定和控制提供技术手段。