固相萃取/超高效液相色谱-串联质谱法同时测定猪肉中14种大环内酯类兽药残留

建立了固相萃取净化/超高效液相色谱-串联质谱同时测定猪肉中14种大环内酯类药物残留的方法。样品经70%(体积分数)乙腈提取,固相萃取柱(HLB柱)富集净化后,使用BEH C_(18)色谱柱(100 mm×2.1 mm,1.7μm)分离,以乙腈和0.1%甲酸-2 mmol/L乙酸铵溶液为流动相进行梯度洗脱。在正离子模式下,采用多反应监测模式分段扫描,外标法定量。结果表明,14种大环内酯类药物在对应质量浓度范围内均呈良好的线性关系,相关系数(r~2)均大于0.995,方法检出限为0.1～0.8μg/kg,定量下限为0.5～3.0μg/kg,在低、中、高3个加标水平下的回收率为71.1%～102%,相对标准偏差(RSD)均小于6.0%。该方法准确、可靠,可用于猪肉中大环内酯类药物的检测。     

超高效液相色谱-串联质谱法同时检测口腔卫生用品中的硝基咪唑类药物

建立了采用超高效液相色谱-串联质谱同时检测口腔卫生用品(牙膏及漱口水)中甲硝唑、替硝唑、奥硝唑、二甲硝咪唑和洛硝唑的方法。试样以0.1%(体积分数)的甲酸水溶液/乙腈(95:5, v/v)稀释,经高速离心后过滤膜净化,采用Cloversil C18色谱柱(100 mm×2.1 mm, 3.5 μm)分离,以0.1%甲酸水溶液和乙腈为流动相梯度洗脱,质谱检测,外标法定量。5种硝基咪唑类化合物在1.0～60.0 μg/L质量浓度范围内线性关系良好,相关系数r均不小于0.9992;在10.0、20.0和100 mg/kg加标水平的平均回收率为91.5%～108%,相对标准偏差为1.14%～5.22%;方法的定量限(LOQ,以信噪比为10计)为2.0 mg/kg。该方法可靠、稳定,可满足口腔卫生用品中硝基咪唑类药物含量检测与确证的需要。     

超高效液相色谱-串联质谱法测定水产品中三聚氰胺残留量

建立超高效液相色谱-串联质谱(UPLC-MS/MS)快速测定水产品中三聚氰胺残留的方法.采用ACQUITY UPLC BEH HILIC色谱柱(100 mm×2.1 mm, 1.7 μm),流动相为乙腈-0.5 mmol/L乙酸铵溶液(0.1%甲酸),流速为0.3 mL/min.采用电喷雾质谱检测,以正离子模式5 min完成质谱分析.实验结果表明,三聚氰胺在水产品中的检测限为0.05 mg/kg,在0.05～0.50 mg/kg添加水平时的加标回收率为63%～90%,测定结果的相对标准偏差均小于7.2%(n=6).     

高效液相色谱-串联质谱法同时检测口腔卫生产品中抗生素类药物

采用高效液相色谱-串联质谱技术,建立了口腔卫生产品(牙膏及漱口水)中5类共13种抗生素的同时检测方法。分析物包括5种四环素类、3种大环内酯类、2种喹诺酮类、1种β-内酰胺类和2种林可胺类抗生素。样品经0.1%(体积分数,下同)甲酸溶液-乙腈(95:5, v/v)提取,高速离心并过滤,稀释后采用C18色谱柱(150 mm×2.1 mm, 5 μm)分离,以0.1%甲酸溶液-乙腈为流动相梯度洗脱,采用电喷雾离子源串联质谱,在正离子扫描方式下以多反应监测(MRM)模式检测,外标法定量。13种抗生素类药物在5.0～50.0 μg/L质量浓度范围内线性关系良好(相关系数大于0.99),定量限为10.0 mg/kg。两种基质(牙膏及漱口水)样品在10、20和100 mg/kg 3个加标水平下的平均回收率为80.1%～115%,相对标准偏差为0.94%～8.69%。该方法准确可靠、方便快捷,适用于口腔卫生产品中抗生素类药物的定性定量分析。     

超高效液相色谱-三重四极杆质谱法测定保健食品中30种非法添加壮阳类化合物

建立了超高效液相色谱-三重四极杆质谱测定保健食品中30种壮阳类化合物的方法。采用Waters CORTECS T3色谱柱(100 mm×2.1 mm,2.7μm),以0.1%(体积分数)甲酸水溶液-含0.1%(体积分数)甲酸的乙腈溶液为流动相,梯度洗脱,在电喷雾离子化正离子模式下,以多反应监测模式(MRM)检测。30种化合物在10~200μg/L范围内均呈良好的线性关系,相关系数均大于0.99;在0.1、0.2、1.0 mg/kg加标水平下的平均加标回收率为62.8%~135.2%,相对标准偏差均不大于14%(n=6);检出限为0.05 mg/kg,定量下限为0.1 mg/kg。该方法定性定量准确,操作简便,可为国家标准的建立提供参考。     

高效液相色谱-质谱法对饲料及食品添加剂中三聚氰胺的测定

建立了饲料中三聚氰胺的高效液相色谱-质谱测定方法.色谱条件:Kromasil C18柱(4.6 mm×250mm,5 μm),流动相:乙腈-0.1%(体积分数)甲酸(体积比5:95),流速0.4 mL/min.采用正离子模式的电喷雾质谱检测,以一级质谱得到的准分子离子m/z 127作为母离子,进行碰撞诱导解离(CID)二级质谱(MS2)分析,选择母离子和MS2的碎片离子m/z 85、109定性确证,提取m/z 85、109、127三个离子质量色谱峰面积定量.实验优化了质谱条件.线性范围为0.01～0.5 mg/L,检出限0.01 mg/L(S/N=3),回收率为80%～99%.     

液相色谱-串联质谱法测定化妆品中22种激素

提出了采用液相色谱-串联质谱法测定化妆品中22种激素残留量的方法。样品经乙腈超声提取,分别采用Oasis HLB固相萃取柱(方法一)和凝胶渗透色谱(方法二)两种方法净化。经净化的试液用ZORBAX Eclipse XDB-C18色谱柱(100mm×2.1mm,1.8μm)分离,15种激素用不同比例配成的含0.1%(体积分数)甲酸的水溶液和乙腈组成的流动相梯度洗脱。质谱测定中采用正离子电离方式多反应监测模式;另7种激素用不同比例配成的水和乙腈组成的流动相梯度洗脱,质谱测定中采用负离子电离方式多反应监测模式。方法一的检出限为0.01～0.40mg.kg-1;回收率在61.5%～111%之间;方法二的检出限在0.1～4.0mg.kg-1之间,回收率在60.8%～113%之间。     

动物源性食品中阿维菌素类药物残留的QuEChERS-液质联用法测定

建立了动物源性食品中阿维菌素、伊维菌素、多拉菌素、莫西菌素、埃普菌素、乙酰胺基阿维菌素6种阿维菌素类药物残留的高效液相色谱-串联质谱分析方法.样品采用乙腈提取,C18粉分散固相萃取净化,经ZORBAX Eclipse Plus C18(1.8 μm,2.1 mm×50 mm)色谱柱分离,电喷雾串联四极杆质谱在多反应离子监测方式下同时测定.6种分析物在0.002 ～0.1 mg/L范围内线性关系良好,相关系数均不低于0.991,方法的检出限(S/N≥3)为0.001 ～0.002 mg/kg;定量下限(S/N≥10)为0.002 ～0.005 mg/kg.猪肉基质中莫西菌素在0.005、0.01、0.02 mg/kg,其他化合物在0.002、0.005、0.01 mg/kg加标水平下,6种阿维菌素类药物的回收率为75% ～88%,相对标准偏差(RSD)为11.7% ～15.0%.该方法稳定、可靠,可满足动物源性食品中阿维菌素类药物残留检测与确证的需要.     

高效液相色谱-串联质谱测定猪肉中3种β-受体激动剂残留量

建立一种同时测定猪肉中3种β-受体激动剂残留量的高效液相色谱-电喷雾串联质谱(HPLC-ESI-MS/MS)确证分析方法。样品经β-葡萄糖醛酸酶/芳基硫酸酯酶酶解、乙酸铵缓冲液提取和MCX固相萃取柱净化,采用Agilent ZorbaxSB-C18(2.1mm×150mm,3.5μm)色谱柱,0.1%的甲酸水溶液、甲醇和乙腈作为流动相进行洗脱,高效液相色谱分离,电喷雾离子源电离,正离子多反应监测模式进行检测,内标法定量。3种药物在0.05～1μg/kg浓度范围内线性良好,相关系数r均大于0.999,0.05、0.1、0.5μg/kg3个浓度水平的添加回收率在89.7%～106.7%之间,相对标准偏差为2.4%～8.6%,3种药物的定量限均为0.05μg/kg。方法适用于猪肉中β-受体激动剂残留的确证分析。     

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。     

LC/MS and LC/MS/MS determination of protein tryptic digests

Tryptic digests were analyzed by means of online microbore liquid chromatography combined with mass spectrometry (LC/MS) for some common proteins. Following conventional enzymatic digestion with trypsin, the freeze-dried residues were dissolved in high-performance liquid chromatography (HPLC) eluent and subjected to gradient reversed-phase microbore HPLC separation with mass spectrometric detection. The latter was done in the full-scan single or tandem (MS/MS) mass spectrometry mode. The formation of gas-phase ions from dissolved analytes was accomplished at atmospheric pressure by pneumatically assisted electrospray (ion spray) ionization. This produced field-assisted ion evaporation of dissolved ions, which could then be mass-analyzed for molecular mass or structure. In the full-scan LC/MS mode, the masses for the peptide fragments in the tryptic digests can be determined as either their singly or multiply charged ions. When the molecular weights of the peptides lie outside the mass range of the mass spectrometer, the multiply charged feature of these experimental conditions still provides reliable molecular weight determinations. In addition, collision-activated dissociation (CAD) on selected peptide precursor ions provides online LC/MS/MS sequence information for the tryptic fragments. Results are shown for the tryptic digests of horse heart cytochrome c, bovine β-lactoglobulin A, and bovine β-lactoglobulin B.     

Exploiting the complementary nature of LC/MALDI/MS/MS and LC/ESI/MS/MS for increased proteome coverage

The goal of this work was to evaluate the improvement in proteome coverage of complex protein mixtures gained by analyzing samples using both LC/ESI/MS/MS and LC/MALDI/MS/MS. Parallel analyses of a single sample were accomplished by interfacing a Probot fractionation system with a nanoscale LC system. The Probot was configured to perform a post-column split such that a fraction (20%) of the column effluent was sent for on-line LC/ESI/MS/MS data acquisition, and the majority of the sample (80%) was mixed with a matrix solution and deposited onto the MALDI target plate. The split-flow approach takes advantage of the concentration sensitive nature of ESI and provides sufficient quantity of sample for MALDI/MS/MS. Hybrid quadrupole time-of-flight mass spectrometers were used to acquire LC/ESI/MS/MS data and LC/MALDI/MS/MS data from a tryptic digest of a preparation of mammalian mitochondrial ribosomes. The mass spectrometers were configured to operate in a data dependent acquisition mode in which precursor ions observed in MS survey scans are automatically selected for interrogation by MS/MS. This type of acquisition scheme maximizes the number of peptide fragmentation spectra obtained and is commonly referred to as shotgun analysis. While a significant degree of overlap (63%) was observed between the proteins identified in the LC/ESI/MS/MS and LC/MALDI/MS/MS data sets, both unique peptides and unique proteins were observed by each method. These results demonstrate that improved proteome coverage can be obtained using a combination of these ionization techniques.     

Reliable peak-finding for MS/MS

A fast, reliable routine has been developed for dynamically reducing the peak-shaped sequential intensity data, normally obtained in a scanning mass spectrometer, to a mass/intensity pair for each peak in the scan. The algorithm is specifically designed for applications such as MS/MS having large dynamic range as well as overlapping and irregular peak shapes. A method of testing the accuracy of real-time peak-finding algorithms is also described and applied to this algorithm.     

High-throughput quantitative bioanalysis by LC/MS/MS

This review article discusses the most recent significant advances in the sample preparation and mass spectrometry aspects of high-throughput bioanalysis by LC/MS/MS for the quantitation of drugs, metabolites and endogenous biomolecules in biological matrices. The introduction and implementation of automated 96-well extraction has brought about high-throughput approaches to the biological sample preparation techniques of solid-phase extraction, liquid-liquid extraction and protein precipitation. The fast-flow on-line extraction technique is a different high-throughput approach that has also significantly speeded up analysis by LC/MS/MS. The use of pierceable caps for biological tubes further enhances the analysis speed and improves the safety in handling biological samples. The need for adequate chromatographic separation in order to eliminate interferences due to metabolites and/or matrix effects in LC/MS/MS is discussed. To highlight our limited understanding of atmospheric pressure ionization mass spectrometry, results from recent investigations that appear to be counter-intuitive are presented. Looking ahead to the future, multiplexed LC/MS/MS systems and capillary LC are presented as areas that can bring about further improvements in analysis speed and sensitivity to quantitative bioanalysis by LC/MS/MS.     

Selective detection and identification of phosphopeptides by dansyl MS/MS/MS fragmentation

Protein phosphorylation regulates many cellular processes and pathways, such as cell cycle progression, signal transduction cascades and gene expression. Selective detection of phosphopeptides from proteolytic digests is a challenging and highly relevant task in many proteomics applications. Often phosphopeptides are present in small amounts and need selective isolation or enrichment before identification. Here we report a novel approach to label selectively phospho-Ser/-Thr residues by exploiting the features of a novel linear ion trap mass spectrometer. Using dansyl labelling and MS3 fragmentation, we developed a method useful for the large-scale proteomic profiling of phosphorylation sites. The new residues in the sequence were stable and easily identifiable under general conditions for tandem mass spectrometric sequencing.     

MS/MS: Cloned mass spectrometers

Coupling mass spectrometers in tandem (MS/MS) can greatly increase the specificity of MS analysis without significantly decreasing its unusual sensitivity and speed, particularly for trace levels of preselected compounds in complex organic mixtures. MS/MS also gives more detailed structural information for larger organic molecules in submicrogram quantities.     

Determination of estrogens and progestogens by mass spectrometric techniques (GC/MS, LC/MS and LC/MS/MS)

Steroid sex hormones and related synthetic compounds have been shown to provoke alarming estrogenic effects in aquatic organisms, such as feminization, at very low concentrations (ng/L or pg/L). In this work, different chromatographic techniques, namely, gas chromatography/mass spectrometry (GC/MS), liquid chromatography/mass spectrometry (LC/MS) and liquid chromatography/tandem mass spectrometry (LC/MS/MS), are discussed for the analysis of estrogens, both free and conjugated, and progestogens, and the sensitivities achieved with the various techniques are inter-compared. GC/MS analyses are usually carried out after derivatization of the analytes with bis(trimethylsilyl)trifluoroacetamide (BSTFA). For LC/MS and LC/MS/MS analyses, different instruments, ionization techniques (electrospray (ESI) and atmospheric pressure chemical ionization (APCI)), ionization modes (negative ion (NI) and positive ion (PI)) and monitoring modes (selected ion monitoring (SIM) and selected reaction monitoring (SRM)) are generally employed. Based on sensitivity and selectivity, LC/ESI-MS/MS is generally the method of choice for determination of estrogens in the NI mode and of progestogens in the PI mode (instrumental detection limits (IDLs) 0.1-10 ng/mL). IDLs achieved by LC/ESI-MS in the SIM mode and by LC/ESI-MS/MS in the SRM mode were, in general, comparable, although the selectivity of the latter is significantly higher and essential to avoid false positive determinations in the analysis of real samples. Conclusions and future perspectives are outlined.     

LC/MS/MS方法筛查新生儿苯丙酮尿症

苯丙酮尿症 [1～ 4 ] ( PKU )发病原因是患者基因缺陷使肝脏不能合成苯丙氨酸羟化酶而导致体内苯丙氨酸 ( Phe)不能正常代谢为酪氨酸 ( Tyr) ,前者在体内大量堆积并氧化为对人体有害的苯丙酮酸 . PKU是目前筛查范围最广的氨基酸代谢遗传疾病 ,在全世界每年 [5]约有一千万婴儿接受 PKU筛查 ;在我国 ,PKU也是卫生部要求重点筛查的病种 .Chace[5]等在 1 993年报道了 MS/ MS方法筛查新生儿PKU:直接使用 MS/ MS的中性碎片丢失扫描方式检测 Phe和 Tyr,通过氘代内标与待测氨基酸的质谱峰高比来定量 .MS/ MS方法速度快、准确性好、可以…     

Coupling techniques in LC/MS and SFC/MS

Summary Techniques and applications of analytical instruments combining a chromatographic technique, including liquid chromatography and supercritical fluid chromatography, with mass spectrometry (LC/MS and SFC/MS), that have appeared over the past five years, are reviewed and discussed. It is shown that still many different methods co-exist and have both specific advantages and limitations. SFC/MS appears easier to run for many compounds so far analysed by conventional LC/MS methods. On the other hand, new LC/MS methods that use fast atom bombardment or electrospray ionization have the greater potential for the investigation of polar biopolymers.