Quantitative Analysis of TAG in Oils Using Lithium Cationization and Direct‐Infusion ESI Tandem Mass Spectrometry

This study was undertaken to determine whether triple‐stage mass spectrometry (MS³) could be employed to obtain quantitative and regioisomeric data from complex oil samples without the need for a chromatographic step in the analysis protocol. Lithium‐7 trifluoroacetate and electrospray ionization were used to form lithium adducts of the triacylglycerols (TAG) in a fish oil sample. The first‐generation precursor ion was the lithium‐TAG adduct, the second‐generation precursor ion was formed by loss of a neutral acid side chain in the first fragmentation. The ions used for analysis were formed in the second fragmentation by loss of the lactones of the acid side chains remaining after the first fragmentation. This analysis scheme provided quantitative and regioisomeric data without interference from TAG in the sample other than TAG with the same acyl carbon number, one more double bond, and two acyl side chains in common with the analyte. Even in this case a majority of the interferences could be estimated and compensated. Analysis of synthetic samples containing the fish oil matrix indicated that both absolute and relative quantitative data could be obtained with average errors of approximately 5 %. The method proved well suited to routine analyses of complex oil samples.     

液相色谱-串联质谱法测定化妆品中米诺地尔的含量

提出了液相色谱-串联质谱联用法测定化妆品中米诺地尔含量的方法。样品经甲醇超声提取,用高效液相色谱分离后,采用电喷雾串联质谱进行定性和定量检测。线性范围为2～100ng·mL-1,线性相关系数r大于0．99,方法的检出限为2g·kg-1（S／N=10）,高、中、低3个浓度水平的加标回收率在90％～110％o之间,测定值的相对标准偏差（n=6）小于10％。     

Mass Spectrometry of the Lithium Adducts of Diacylglycerols Containing Hydroxy FA in Castor Oil and Two Normal FA

Castor oil can be used in industry. The molecular species of triacylglycerols containing hydroxy fatty acids (FA) in castor oil have been identified. We report here the identification of twelve diacylglycerols (DAG) containing hydroxy FA in castor oil using positive ion electrospray ionization mass spectrometry of the lithium adducts. They were RR (diricinolein, R is ricinoleate), RL, RS, R‐diOH18:0, R‐diOH18:1, R‐diOH18:2, R‐triOH18:0, R‐triOH18:1, R‐triOH18:2, diOH18:0‐diOH18:1, diOH18:1‐diOH18:1 and diOH18:1‐diOH18:2. The MS² fragment ions, [M + Li ? FA]⁺ and [FA + Li]⁺, from the lithium adducts of DAG containing hydroxy FA (one or two hydroxy FA), were used for the identification. The additional fragment ions from the neutral losses of FA lithium salts [M + Li ? FALi]⁺ were used for the identification of eleven DAG containing two normal FA in a soybean oil bioconversion product. The MS² fragment ions from the neutral losses of FA lithium salts [M + Li ? FALi]⁺ were not detected from the DAG containing hydroxy FA. The DAG containing FA with more hydroxyl groups than the other FA on the same DAG molecule tended to have a prominent fragment ion [FA + Li]⁺ and an undetectable fragment ion [M + Li ? FA]⁺ while the FA was the more hydroxylated FA. Also the less hydroxylated FA of a DAG tended to have a prominent fragment ion [M + Li ? FA]⁺ and an undetectable fragment ion [FA + Li]⁺ while the FA was the less hydroxylated FA.     

Direct Synthesis and Characterization of Site-Specific Deoxyguanosyl and Deoxyadenosyl Adducts Derived from the Binding of Pah Diol Epoxides to Oligonucleotides

The direct synthesis method is a relatively simple approach for generating modified oligonucleotides of defined base sequence with site-specifically placed polycyclic aromatic hydrocarbon diol epoxide-modified deoxyguanosyl and deoxyadenosyl residues. Up to 5–10 mg quantities of several different modified oligonucleotides have been synthesized for detailed NMR structural studies. Smaller amounts of modified oligonucleotides containing a single modified guanosyl residue in oligonucleotides 10–11 bases long containing up to three other unmodified guanine residues can be readily generated in smaller quantities for site-directed mutagenesis and other studies.     

超高效液相色谱/串联质谱法测定水中戊唑醇

建立了固相萃取(SPE)-超高效液相色谱/串联质谱法(UPLC/MS/MS)检测水中戊唑醇的方法。本方法对戊唑醇的检出限为0.05 ng/L,平均回收率为95.3%,相对标准偏差(RSD)为6.4%,线性范围为0.01～10μg/L。应用该法分析了某地表水,取得满意结果,表明本方法具有一定的实用性。     

液相色谱-电喷雾串联四极杆质谱测定水果中的丁酰肼

建立了4种水果中丁酰肼残留量的液相色谱-电喷雾串联四极杆质谱检测方法.样品经匀浆提取净化后.采用LC-MS/MS法,ESI(+)电离方式,多反应监测(MRM)定量,用Vensil HILIC色谱柱,以含0.1%甲酸的水和乙腈为流动相进行洗脱.结果表明:丁酰肼在0.01～1.0 mg/L质量浓度范围内呈现良好的线性,相关系数为0.999 1,方法的检出限为2.5 μg/kg,当添加质量分数为0.01、0.1、0.5 mg/kg时,4种水果中丁酰肼的平均回收率为77.7%～103.7%,相对标准偏差为2.0%～9.3%.     

Characterization of Polyglycerol Polyricinoleate Formulations Using NMR Spectroscopy, Mass Spectrometry and Dynamic Light Scattering

Three different analytical techniques, namely NMR spectroscopy, mass spectrometry and dynamic light scattering, were used to unravel the structure and morphology of polyglycerol polyricinoleate (PGPR). This material is used as an emulsifier in the preparation of chocolate and other confectionary products. The use of 1D and 2D NMR techniques led to the distinction of two separate entities in commercial ricinoleic acid (RA) and PGPR samples, namely the monomeric and oligomeric RA (estolides). ¹H and ¹³C spectra of PGPR confirmed the presence of polyglycerol moieties of various lengths being esterified by RA and estolides and to a lesser extent by oleic and linoleic acids. ¹³C-NMR DOSY experiments demonstrated the occurrence of several species in PGPR. Electrospray Ionization and tandem Mass Spectrometry succeeded in identifying the presence of over 30 glycerol/polyglycerol species containing n glycerol moieties with n = 1–6 esterified by monomeric and oligomeric RA molecules. Dynamic light scattering contributed to the characterization of PGPR morphology. The PGPR mixture contains relatively small-sized entities (monomers, dimmers, trimmers) and larger aggregates resulted from chain association. The percentage of larger aggregates is minimal compared to small-sized species.     

凝胶渗透色谱净化/气相色谱-串联质谱法同时测定大豆中23种酰胺类除草剂残留量

[目的]建立一种同时测定大豆中23种酰胺类除草剂残留量的分析方法.[方法]采用乙腈提取目标物,结合凝胶渗透色谱净化方法,通过气相色谱-串联质谱多反应监测模式,采用基质匹配外标法定量.[结果]在0.0050～0.50 mg/L范围内,黄豆和黑豆基质中23种酰胺类除草剂的质量浓度与对应的峰面积成良好的线性关系.在0.010...     

气相色谱-质谱法测定纺织品中的二辛基锡

构建了气相色谱-质谱(GC-MS)测定纺织品中二辛基锡的方法。应用液液萃取法提取纺织品中的二辛基锡,通过四乙基硼化钠衍生后,使用用GC-MS总离子流图和选择离子进行定性检测,使用选择离子的质谱峰进行定量测定。该方法样品前处理简单,使用外标标准曲线法对二辛基锡检测,在0.3～2.0μg/mL范围内呈良好的线性关系,加标回收率在93.1%～102.4%之间,可应用于纺织品中有机锡的检测。     

超高压液相色谱-串联质谱法测定含硫蔬菜中烟碱类农药残留

[目的]为快速准确测定复杂基质样品中烟碱类农药残留,建立了含硫蔬菜中烯啶虫胺等烟碱类农药多残留的液相色谱-电喷雾串联质谱测定方法.[方法]样品经乙腈提取,用PSA、C18填料净化后,以BEH C18超高效液相色谱柱,以电喷雾离子源正离子多反应监测模式下进行测定.[结果]烯啶虫胺等7种农药在10-500 μg/L的范围内均成线性,回收率范围在70%～120%之间,方法的检出限在0.2～2.5 μg/kg之间.[结论]方法具有操作简便、重现性好和灵敏度高的特点,可满足含硫蔬菜中烟碱类农药残留限量检测的需要.     

超高效液相色谱-串联质谱法测定化妆品中的9种性激素成分

采用超高效液相色谱-串联质谱（UPLC-MS/MS）检测技术,建立了化妆品中睾酮等9种性激素成分的检测方法。样品经质量分数50%乙腈提取,经流动相（水+乙腈）提取过滤后,采用C18柱（100 mm×2.1 mm×3.0μm）进行分离,用电喷雾离子源、正负离子模式进行扫描,在多反应离子监测模式下检测,基质匹配标准曲线外标法定量。结果表明,9种性激素在5～115 ng/mL范围内线性关系良好,相关系数大于0.999;加标回收率为80%～120%,RSD小于5%(n=3),检出限均低于0.03μg/g。该方法简单、快速、灵敏,能够满足化妆品中睾酮等9种性激素的检测需求。     

Determination of Bile Acids in Piglet Bile by Solid Phase Extraction and Liquid Chromatography-Electrospray Tandem Mass Spectrometry

An LC/MS/MS‐based method was developed for the determination of individual bile acids (BA) and their conjugates in porcine bile samples. The C18‐based solid‐phase extraction (SPE) procedure was optimized so that all 19 target BA and their glycine and taurine conjugates were collected with high recoveries for standards (89.1–100.2 %). Following this, all 19 compounds were separated and quantified in a single 12 min chromatographic run. The method was validated in terms of linearity, sensitivity, accuracy, precision, and recovery. An LOD in the low ppb range with measured precisions in the range of 0.5–9.3 % was achieved. The recoveries for all of the 19 analytes in bile samples were all >80 %. The validated method was successfully applied to the profiling of BA and their conjugates in the bile from piglets treated with exogenous glucagon‐like peptide‐2 (GLP‐2) in a preclinical model of neonatal parenteral nutrition‐associated liver disease (PNALD). The method developed is rapid and could be easily implemented for routine analysis of BA and their conjugates in other biofluids or tissues.     

植物源性食品中噻酰菌胺残留的液相色谱串联质谱法检测

建立了植物源性食品中噻酰菌胺残留量的检测方法.样品用乙酸乙酯提取,凝胶渗透色潜和同相萃取法联用去除杂质.高效液相色谱-质谱/质谱仪测定,电喷雾电离,多反应离子监测模式检测.对噻酰菌胺的检出限为0.01 mg/kg,线性范围为0.01～0.10 mg/kg,选用了9种样本进行0.01、0.02、0.05 mg/kg三个水平的添加回收验证实验,回收率范围为71.8%～117.0%,标准偏差为3.46%～9.49%.     

Identification of Tetraacylglycerols in Lesquerella Oil by Electrospray Ionization Mass Spectrometry of the Lithium Adducts

Tetraacylglycerol (an acylglycerol estolide) contains an acyl chain attached to the hydroxyl group of another acyl chain attached to the glycerol backbone. Lesquerolic acid (Ls, OH¹⁴20:1¹¹) is the main fatty acid in lesquerella oil and may be used industrially for the manufacture of biodegradable industrial products. Electrospray ionization mass spectrometry of the lithium adducts of acylglycerols in the high-performance liquid chromatography fractions from the seed oil of lesquerella (Physaria fendleri) was used to identify thirteen tetraacylglycerols. They were LsLsLsLn, LsLsLsL, LsLs-OH20:2-O, LsLsLsO, LsLsLnLn, LsLsLLn, LsLsOLn, LsLsLL, LsLsOL, LsLsOP, LsLsOO, LsLsLS and LsLsOS. The OH20:2 was auricolic acid (OH¹⁴20:2^11,17). For the four tetraacylglycerols containing one normal fatty acid (non-hydroxy fatty acid), LsLsLsLn, LsLsLsL, LsLs-OH20:2-O and LsLsLsO, the normal fatty acids were all directly attached to the glycerol backbone, not to the hydroxyl group of fatty acids. We propose that the biosynthetic precursors (triacylglycerol acyltransferase) of these four tetraacylglycerols were LsLsLn, LsLsL, LsLsO (Ls-OH20:2-O) and LsLsO individually. LsLsO and Ls-OH20:2-O were equally active as the biosynthetic precursors for LsLs-OH20:2-O. For LsLsLS, linoleate were all attached to the glycerol backbone and LsLsL was proposed to be the biosynthetic precursor. For LsLsOS, stearate were all attached to the glycerol backbone and LsLsS was proposed to be the biosynthetic precursor. For the other seven tetraacylglycerols containing two normal fatty acids, LsLsAB, the biosynthetic precursors could be both LsLsA and LsLsB.     

Tandem Mass Spectrometry for the Analysis of Ginsenosides in a Phytoadaptogene Composition with Antitumor Properties

Theoretical Foundations of Chemical Engineering - The results of an analysis for ginsenosides in the Multiphytoadaptogene (MPA) phytoadaptogene composition with antitumor properties by...     

Stability of the Gossypol-Amine Adducts Used for Chromatographic Measurement of Total and Isomeric Gossypol

The stability of the gossypol amine adducts used for chromatographic determination of gossypol was studied. After extraction and complexation with R-(−)-2-amino-1-propanol, the samples were diluted into an acetonitrile/phosphate buffer solution as described in AOCS Recommended Practice Ba 8a-99. The solutions were then stored under different conditions before being analyzed by reverse-phase chromatography. Samples stored in the dark at −80 °C or at −20 °C showed little change in peak size over 30 days. Samples stored in the dark at −4 °C or at room temperature showed a measurable reduction in gossypol peak size over the study period. Samples stored in the light at room temperature showed the greatest reduction with only 25% of the initial gossypol detectable after 30 days. The rate of degradation followed first-order kinetics. The rate of decrease in gossypol peak size did not differ for the different gossypol matrices studied, i.e., cottonseed kernels, cottonseed meal, or pure gossypol-acetic acid; nor did it differ for the individual gossypol enantiomers. The results indicate that these gossypol Schiff's base adducts can be transported on dry ice before chromatography with minimal concern for their stability.     

Assessment of Isoprostanes in Human Plasma: Technical Considerations and the Use of Mass Spectrometry

Oxygenated lipid mediators released from non‐enzymatic peroxidation of polyunsaturated fatty acids (PUFA) are known to have functional roles in humans. Notably, among these lipid mediators, isoprostanes molecules are robust biomarkers of oxidative stress but those from n‐3 PUFA are also bioactive molecules. In order to identify and assess the isoprostanes, the use of mass spectrometry (MS) for analysis is preferable and has been used for over two decades. Gas chromatography (GC) is commonly coupled to the MS to separate the derivatized isoprostanes of interest in biological samples. In order to increase the accuracy of the analytical performance, GC–MS/MS was also applied. Lately, MS or MS/MS has been coupled with high‐performance liquid chromatography to assess multiple isoprostane molecules in a single biological sample without derivatization process. However, there are limitations for the use of LC–MS/MS in the measurement of plasma isoprostanes, which will be discussed in this review.     

Metabolic Alteration Analysis of Steroid Hormones in Niemann–Pick Disease Type C Model Cell Using Liquid Chromatography/Tandem Mass Spectrometry

Niemann–Pick disease type C (NPC) is an autosomal recessive disease caused by a functional deficiency of cholesterol-transporting proteins in lysosomes, and exhibits various clinical symptoms. Since mitochondrial dysfunction in NPC has recently been reported, cholesterol catabolism to steroid hormones may consequently be impaired. In this study, we developed a comprehensive steroid hormone analysis method using liquid chromatography/tandem mass spectrometry (LC–MS/MS) and applied it to analyze changes in steroid hormone concentrations in NPC model cells. We investigated the analytical conditions for simultaneous LC–MS/MS analysis, which could be readily separated from each other and showed good reproducibility. The NPC phenotype was verified as an NPC model with mitochondrial abnormalities using filipin staining and organelle morphology observations. Steroid hormones in the cell suspension and cell culture medium were also analyzed. Steroid hormone analysis indicated that the levels of six steroid hormones were significantly decreased in the NPC model cell and culture medium compared to those in the wild-type cell and culture medium. These results indicate that some steroid hormones change during NPC pathophysiology and this change is accompanied by mitochondrial abnormalities.     

Native Mass Spectrometry for the Study of PROTAC GNE-987-Containing Ternary Complexes

PRO teolysis TA rgeting C himeras (PROTACs) promote the degradation, rather than inhibition, of a drug target as a mechanism for therapeutic treatment. Bifunctional PROTAC molecules allow simultaneous binding of both the target protein and an E3-Ubiquitin ligase, bringing the two proteins into close spatial proximity to allow ubiquitinylation and degradation of the target protein via the cell's endogenous protein degradation pathway. We utilized native mass spectrometry (MS) to study the ternary complexes promoted by the previously reported PROTAC GNE-987 between Brd4 bromodomains 1 and 2, and Von Hippel Lindeau E3-Ubiquitin Ligase. Native MS at high resolution allowed us to measure ternary complex formation as a function of PROTAC concentration to provide a measure of complex affinity and stability, whilst simultaneously measuring other intermediate protein species. Native MS provides a high-throughput, low sample consumption, direct screening method to measure ternary complexes for PROTAC development.