超高效液相色谱-串联质谱法同时测定畜禽排泄物中20种磺胺类药物的残留

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定畜禽排泄物中20种磺胺类药物残留量的分析方法。样品经冷冻干燥后粉碎过筛,90%酸化乙腈提取,HLB固相萃取柱净化,UPLC-MS/MS检测,基质匹配校准外标法定量。结果显示,20种磺胺类药物在2～250 ng/mL浓度范围内,线性良好,相关系数均>0.99,检出限为2μg/kg,定量限为5μg/kg。在添加浓度分别为5、10、500μg/kg时,平均回收率为78.0%～117%,相对标准偏差(n=6)为1.1%～14.2%。该方法具有较低的检出限、定量限及较高的回收率和稳定性,可应用于畜禽排泄物中20种磺胺类药物残留量的监测。     

超高效液相色谱-串联质谱法同时测定鸡肝中残留的四环素类、磺胺类和喹诺酮类药物

采用超高效液相色谱-串联质谱(UPLC-MS/MS)在正离子模式下通过多反应监测(MRM)方式同时测定了鸡肝脏组织中3种四环素类药物、10种磺胺类药物以及8种喹诺酮类药物的残留。试样由McIlvaine缓冲液-乙腈(体积比为1:4)、乙腈提取,合并上清液并用氮气吹干,用0.05 mol/L磷酸三乙胺缓冲液-乙腈(体积比为85:15)溶解残余物,经正己烷脱脂后,采用UPLC-MS/MS进行定性、定量分析。该方法对测定的21种药物的检出限均为2 μg/kg,定量限均为5 μg/kg。在添加水平分别为5,10和50 μg/kg时,21种药物的加标回收率为66.8%～128.5%,日内测定的相对标准偏差(RSD)为0.8%～20.2%,日间测定的RSD为2.2%～15.3%。该方法可作为动物源性食品中这3类药物残留检测的确证方法。     

气相色谱-质谱法测定鸡肉中残留的环丙胺嗪及其代谢物三聚氰胺

建立了鸡肉中残留的环丙胺嗪及其代谢物三聚氰胺的气相色谱-质谱(GC-MS)检测方法。样品经酸化的乙腈-水溶液提取、二氯甲烷去脂、混合型的阳离子交换(MCX)固相萃取柱净化、N,O-双三甲基硅基-三氟乙酰胺(BSTFA)衍生化后进行GC-MS测定。环丙胺嗪采用外标法定量,三聚氰胺以三聚氰胺-15N3为内标定量。结果表明,环丙胺嗪与三聚氰胺的线性范围均为100～1000 μg/L,定量限为20 μg/kg。在20,40,80 μg/kg 3个添加浓度下目标化合物的平均回收率为75%～110%,批内、批间相对标准偏差分别小于10%和15%。该方法样品前处理简单,测定灵敏度高,定性准确,选择性好,可实现鸡肉中环丙胺嗪与三聚氰胺残留的同时测定。     

气相色谱-三重四极杆质谱法同时测定巴氏杀菌乳中9种香精成分

建立了气相色谱-三重四极杆质谱（GC-MS/MS）同时检测巴氏杀菌乳中9种香精成分（二氢香豆素、香兰素、香豆素、乙基香兰素、甲基香兰素、7-甲基香豆素、7-甲氧基香豆素、7-乙氧基-4甲基香豆素和环香豆素）的分析方法。巴氏杀菌乳样品用乙醇溶液萃取,低温涡旋离心,取上清液过0.22 μm滤膜,以DB-5MS色谱柱分离,在MRM模式下测定,基质曲线外标法定量。实验结果表明,9种香精成分在1~200 μg/L范围内呈良好线性,线性相关系数（R²）均大于0.997,方法的检出限为0.002~0.1 μg/kg,定量限为0.001~2 μg/kg,平均回收率为90.3%~110.6%,日内、日间精密度均小于10%。该方法前处理简单快速,检测准确度和灵敏度高,可用于巴氏杀菌乳中9种香精成分的同时检测。     

加速溶剂萃取结合气相色谱-三重四极杆质谱测定枸杞中有机磷农药多残留

建立了加速溶剂萃取与气相色谱-三重四极杆质谱联用(GC-MS/MS)法对枸杞中20种有机磷农药残留进行测定。样品经酸化乙腈-二氯甲烷(体积比4∶1)提取,Cleanert TPH固相萃取柱净化,旋转蒸发浓缩后氮吹至干,采用GC-MS/MS检测,并对萃取溶剂、温度、冲洗体积等实验条件进行了优化。结果表明,20种药物在1～500μg/kg范围内线性良好,相关系数(r~2)为0.999 0～0.999 8;在20、40、100μg/kg 3个加标水平下的回收率为70.0%～82.9%,相对标准偏差(RSD,n=5)为0.6%～8.5%,定量下限为1～15μg/kg。该方法样品前处理简单、定量准确,适用于枸杞中有机磷农药残留的检测。     

气相色谱法测定鳗鱼中残留的硫丹

建立了气相色谱检测鳗鱼中残留的硫丹（包括α-硫丹和β-硫丹）的方法。鳗鱼样品经过提取、净化,采用气相色谱-电子捕获检测法进行硫丹含量的测定。α-硫丹和β-硫丹的检测低限均为1 μg/kg;α-硫丹和β-硫丹在2～50 μg/kg范围内其含量与峰面积呈现良好的线性关系,相关系数均为0.999;α-硫丹和β-硫丹在添加水平为1.0,2.0,5.0 μg/kg时,回收率分别为74%～89%和89%~98%,相对标准偏差为3.7%~7.2%和4.7%~8.7%。表明方法的重现性和准确性都非常好。     

柱前衍生化-气相色谱-质谱法定量测定食品中丙烯酰胺的含量

建立了气相色谱-质谱(GC-MS)定量测定食品中丙烯酰胺含量的分析方法。选择13C3-丙烯酰胺作为内标物。通过超纯水提取食品中的丙烯酰胺,经正己烷脱脂两次后,在酸性条件下选用溴化钾/溴酸钾为衍生剂进行衍生化反应,再采用乙酸乙酯进行液-液萃取两次,最后用三乙胺将丙烯酰胺转化为更稳定的产物2-溴丙烯酰胺,利用质谱检测器在选择离子扫描模式下测定2-溴丙烯酰胺。该方法在0.05～2.00 mg/kg范围具有良好的线性(r2=0.9995);检出限和定量限分别达到3 μg/kg和7 μg/kg;回收率范围为62.7%～65.5%。通过与前期建立的液相色谱-串联质谱(HPLC-MS/MS)方法进行对比,该法在薯片和面包样品中丙烯酰胺的检测结果略偏高,是一种可以用于常见食品中丙烯酰胺含量测定的分析方法。     

高效液相-电喷雾串联质谱法测定动物肌肉组织中的糖皮质激素

本实验建立了肌肉组织中氢化可的松、可的松、泼尼松和地塞米松含量的高效液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)检测方法.样品经酶水解、乙酸乙酯提取、HLB固相萃取净化,C8色谱柱分离,在多反应选择性监测模式(MRM)下采用负离子模式进行信号采集和测定.4种糖皮质激素的检出限为0.13 ～0.25 μg/kg,定量限为0.25 ～ 0.5 μg/kg.在0.5～50.0 μg/L范围内具有良好的线性关系(R2＞0.99).在0.5,5.0和10.0μg/kg基质加标水平下,4种物质的平均回收率为74.0％ ～ 101.8％,相对标准偏差0.7％ ～8.6％.     

气相色谱-串联质谱多反应监测及同步子离子全扫描定性定量分析蔬菜中287种农药残留

建立了气相色谱-三重四极杆串联质谱(GC-MS/MS)多反应监测(T-SRM)及同步二级全谱同时定性定量检测蔬菜中287种农药残留的方法。基于改进的QuEChERS方式进行样品前处理,使叶绿素在乙腈-水体系中的溶解度降低而析出,经0.2μm有机相滤膜过滤,有效的去除了叶绿素,净化后采用气相色谱-三重四极杆串联质谱在多反应监测(T-SRM)模式下进行外标法定量测定。结果表明287种分析物的浓度在5.0～100μg/L范围内线性关系良好,相关系数均大于0.995,定量限为10μg/kg。进行3个水平(10,20和50μg/kg)的加标回收试验,其回收率为45%～110%,其中277个目标物回收率为60%～110%。方法的相对标准偏差(RDS)小于20%。引入了一种新的MRM监测模式(T-SRM),并且在定量限10μg/kg残留浓度下可同步获得二级全扫描质谱图。该方法已广泛应用于蔬菜中多种农药残留的快速检测与确证的日常检测工作中。     

气相色谱-串联质谱法测定贝类中指示性多氯联苯

研究并建立了测定贝类中多氯联苯残留的气相色谱-串联质谱(GC-MS/MS)方法.通过正己烷和丙酮的混合溶液超声提取,硅胶柱净化,旋转蒸发浓缩,采用GC-MS/MS多反应监测(MRM)方式测定,可同时对贝类中的7种指示性多氯联苯进行定性和定量.研究结果表明:7种指示性多氯联苯的检出限(S/N=3)为0.0066～0.0098μg/kg,定量限(S/N=10)为0.02 μg/kg;在0.1～50.0 ng/mL时峰强度与质量浓度的线性关系良好(r>0.99).方法的平均回收率为73%～113%.该法简便快捷,降低了分析成本,在一定程度上实现了持久性污染物的快速检测和确证.     

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.     

红景天苷及其酯化产物的ESI MS和MS/MS裂解途径

糖苷广泛存在于自然界中,常以糖苷酯形式存在,这有效地提高了它们的酯溶性,增加它们在肠内和胞内的吸收[1-3]。红景天苷是一种具有抗疲劳、抗辐射、抗缺氧、提高记忆、延缓衰老等药理活性的天然糖苷[4-8],在此先导化合物的基础上合成了各种红景天苷酯。本文对这类红景天苷酯的E     

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.     

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.     

Analytical performance of the various acquisition modes in Orbitrap MS and MS/MS

Quadrupole Orbitrap instruments (Q Orbitrap) permit high‐resolution mass spectrometry‐based full scan acquisitions and have a number of acquisition modes where the quadrupole isolates a particular mass range prior to a possible fragmentation and high‐resolution mass spectrometry‐based acquisition. Selecting the proper acquisition mode(s) is essential if trace analytes are to be quantified in complex matrix extracts. Depending on the particular requirements, such as sensitivity, selectivity of detection, linear dynamic range, and speed of analysis, different acquisition modes may have to be chosen. This is particularly important in the field of multi‐residue analysis (eg, pesticides or veterinary drugs in food samples) where a large number of analytes within a complex matrix have to be detected and reliably quantified. Meeting the specific detection and quantification performance criteria for every targeted compound may be challenging. It is the aim of this paper to describe the strengths and the limitations of the currently available Q Orbitrap acquisition modes. In addition, the incorporation of targeted acquisitions between full scan experiments is discussed. This approach is intended to integrate compounds that require an additional degree of sensitivity or selectivity into multi‐residue methods.     

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.     

Analysis of MS/MS fragmentation of taxoids

The fragmentation pathways of seven types of taxoids were investigated by using a LC-MS/MS method, namely: (1) neutral taxoids with a C-4(20) double bond; (2) taxoids with a C-4(20) double bond and oxygenation at C-14; (3) 5-cinnamoyl taxoids with a C-4(20) double bond; (4) a basic taxoid with a C-4(20) double bond; (5) a taxoid with a C-4(20) epoxide; (6) taxoids with an oxetane ring; and (7) taxoids with an oxetane ring and a phenylisoserine C-13 side chain. Depending on the class of core structure and the substitution pattern, each taxoid gave either the molecular adduct ion [M+NH4]+ or [M+H]+. In the MS/MS, the molecular adduct ion gave characteristic product ions corresponding to the loss of water, acetic acid, benzoic acid, and cinnamic acid or the phenylisoserine group. These could reflect the difference of the substitutions and structural modifications and should be utilized for the structure elucidation oftaxoids by LC-MS.     

Dual parallel electrospray ionization and atmospheric pressure chemical ionization mass spectrometry (MS), MS/MS and MS/MS/MS for the analysis of triacylglycerols and triacylglycerol oxidation products

Two mass spectrometers, in parallel, were employed simultaneously for analysis of triacylglycerols in canola oil, for analysis of triolein oxidation products, and for analysis of triacylglycerol positional isomers separated using reversed-phase high-performance liquid chromatography. A triple quadrupole mass spectrometer was interfaced via an atmospheric pressure chemical ionization (APCI) interface to two reversed-phase liquid chromatographic columns in series. An ion trap mass spectrometer was coupled to the same two columns using an electrospray ionization (ESI) interface, with ammonium formate added as electrolyte. Electrospray ionization mass spectrometry (ESI-MS) under these conditions produced abundant ammonium adduct ions from triacylglycerols, which were then fragmented to produce MS/MS spectra and then fragmented further to produce MS/MS/MS spectra. ESI-MS/MS of the ammoniated adduct ions gave product ion mass spectra which were similar to mass spectra obtained by APCI-MS. ESI-MS/MS produced diacylglycerol fragment ions, and additional fragmentation (MS/MS/MS) produced [RCO](+) (acylium) ions, [RCOO+58](+) ions, and other related ions which allowed assignment of individual acyl chain identities. APCI-MS of triacylglycerol oxidation products produced spectra like those reported previously using APCI-MS. APCI-MS/MS produced ions related to individual fatty acid chains. ESI-MS of triacylglycerol oxidation products produced abundant ammonium adduct ions, even for those molecules which previously produced little or no intact molecular ions under APCI-MS conditions. Fragmentation (MS/MS) of the [M+NH(4)](+) ions produced results similar to those obtained by APCI-MS. Further fragmentation (MS/MS/MS) of the diacylglycerol fragments of oxidation products provided information on the oxidized individual fatty acyl chains. ESI-MS and APCI-MS were found to be complementary techniques, which together contributed to a better understanding of the identities of the products formed by oxidation of triacylglycerols.