Research on the Upper Limit of Accuracy for Predicting Theoretical Tandem Mass Spectrometry

In recent years, numerous theoretical tandem mass spectrometry prediction methods have been proposed, yet a systematic study and evaluation of their theoretical accuracy limits have not been conducted. If the accuracy of current methods approaches this limit, further exploration of new prediction techniques may become redundant. Conversely, a need for more precise prediction methods or models may be indicated. In this study, we have experimentally analyzed the limits of accuracy at different numbers of ions and parameters using repeated spectral pairs and integrating various similarity metrics. Results show significant achievements in accuracy for backbone ion methods with room for improvement. In contrast, full-spectrum prediction methods exhibit greater potential relative to the theoretical accuracy limit. Additionally, findings highlight the significant impact of normalized collision energy and instrument type on prediction accuracy, underscoring the importance of considering these factors in future theoretical tandem mass spectrometry predictions.

Determination of Voriconazole in Human Plasma by Liquid Chromatography Tandem Mass Spectrometry: Application in Therapeutic Drug Monitoring

A sensitive, accurate and robust Liquid Chromatography Tandem Mass Spectrometry method has been developed and validated to measure voriconazole trough levels in human plasma. The plasma samples were mixed with fluconazole as an Internal Standard and directed to protein precipitation and drug extraction. An aliquot of 1 μl was injected into the chromatographic system and separated by the Acquity BEH C18 column at a flow rate of 0.30 ml/min in a gradient mobile phase consisting of acetonitrile, Ultrapure water (UPW), methanol and formic acid. Voriconazole was detected by a Triple Quadrupole Detector (TQD) operating on Multiple Reaction Monitoring (MRM) and a positive ion mode Electrospray ionization (ESI) Q1 mass: 350.1 m/z, Q3 mass: 281.1 m/z. Method linearity of the calibration curve (0.10 - 8.00 μg/ml) indicated a correlation coefficient r ≥ 0.99. The intra and inter-assay accuracy was within 85% - 115% and the intra and inter-assay precision was ≤5.76%. Voriconazole recovery percentage was between 97.69 - 119.62%. The method was successively applied in routine voriconazole TDM.

Determination of Oleuropein in Cosmetics by Ultra Performance Liquid Chromatography-Triple Quadrupole Tandem Mass Spectrometry

An ultrahigh performance liquid chromatography-triple quadrupole tandem mass spectrometry(UPLC-MS/MS)was established to quickly and accurately determine the content of oleuropein in cosmetics.The samples were extracted with methanol-aqueous solution,and the mobile phase with methanol-formic acid solution(0.1 mol/L)=40∶60 was separated by Agilent ZORBAX Eclipse Plus C18(2.1 mm×50 mm×1.8μm-Micron)column temperature 30℃,flow rate 0.3 mL/min.The MS end was detected by electrospray negative mode ionization(ESI-)and multiple reaction monitoring(MRM)mode.The results show a good linear relationship in the range of 0.002~5 mg/L,with a correlation coefficient R2 of 0.999,5.Method recovery range from 84.2%~107.6%and the relative standard deviation RSD is 5.8%.The detection time is 5 min,the detection limit is 0.000,6 mg/L,and the limit of quantification is 0.002 mg/L.This method has the advantages of convenient operation,low quantification limit,high precision and good repeatability,and is suitable for measuring the content of oleuropein in many kinds of cosmetics.

Liquid Chromatography-tandem Mass Spectrometry for Analysis of Acylcarnitines in Dried Blood Specimens Collected at Autopsy from Neonatal Intensive Care Unit

Objective To investigate the feasibility of analyzing acylcarnitine in dry filter-paper blood spots by liquid chromatography-tandem mass spectrometry(LC-MS/MS) which could be applied to detect inborn errors of metabolism in neonates.Methods We obtained filter-paper blood from 26 dead infants from a neonatal intensive care unit(NICU) between October 1,2008 and September 30,2009.Acylcarnitine and amino acid profiles were obtained with LC-MS/MS.Four infants underwent routine autopsy.The postmortem blood specimens were compared with newborn blood specimens,and with specimens obtained from older infants with metabolic disorders.Results Of all the 26 patients,5(19.2%) were diagnosed as having different kinds of diseases:3 with methylmalonic acidemia(the concentration of C3,and the ratio of C3/C16,C3/C2 increased),1 with maple syrup urine disease(the concentration of leucine and isoleucine increased),and 1 with isovaleric aci-demia(the concentration of C5 increased).Conclusions Postmortem metabolic test can explain infant deaths and provide estimates of deaths attributable to inborn errors of metabolism in NICU.LC-MS/MS is suitable for analysis of postmortem specimens and can be considered for routine application in NICU autopsy.

Modernization of Chinese herbal compound and the high performance liquid chromatography tandem mass spectrometry (HPLC-MS)

Chinese herbal compound is playing an important role on curing human diseases.And it has been a trend that Chinese herbal compound is being used all over the world in 21 century.However,our Chinese herbal compound is facing serious challenge for the lack of canonical system of quality criterion for Chinese herbal compound so it has been a urgent problem to set up the quality control standards and reveal therapeutic basis of Chinese herbal compound.In order to give full play to the advantages of Chinese herbal compound,modern scientific and technological is used to research of Chinese herbal compound,especially the high performance liquid chromatography tandem mass spectrometry(HPLC-MS),because it is high sensitive,rapid,and obtain more information.It is very necessary that HPLC-MS is uesed to elucidate the effective components of basic substances of Chinese Herbal Compound,and endow traditional Chinese medicine with modern scientific connotation.

Determination of Impurities and Degradation Products/Causes for <i>m</i>-Iodobenzylguanidine Using HPLC-Tandem Mass Spectrometry

m-Iodobenzylguanidinium hemisulfate (MIBGHS) is a precursor in the preparation of radioiodine-labeled m-iodobenzylguanidine (MIBG), which is used as a radio-imaging and therapy agent for neuroendocrine tumors and myocardial sympathetic nerve function. To ensure the quality and efficacy of the medicine and prevent side effects, the precursor purity, source of impurity, and derivatives have to be determined. In this study, the purity of synthesized MIBGHS and the amount of contaminants therein were determined by high-performance liquid chromatography and ultraviolet detection, gradient eluted by ammonium formate aqueous solution and acetonitrile mobile phase on both C8 and phenyl type column. The impurities were identified on the basis of molecular and fragmented ion mass spectra using of electrospray ionization triple quadrupole tandem mass spectrometry. The results revealed the presence of process-related impurities including m-bromobenzylguanidine (MBrBG) and overreacted byproducts. Stress test results indicated that MIBGHS is stable under acidic and dry thermal conditions for at least 72 h but MIBG aqueous solution was deteriorated slowly when exposed to UV light, thermal, oxidative and alkaline environments. Thus, m-iodobenzylamine, the starting material intended for the synthesis of MIBGHS should be analyzed to ensure that it is free from m-bromobenzylamine impurity. Stored under normal condition (-18°C), MIBGHS is stable for at least 12 months. The chemically labile guanidine and amine groups in MIBGHS are the major causes of its instability, while iodide loss from the phenyl group is a minor cause.

基于不确定度评估研究ID-LC-MS/MS法检测鸡蛋中氟虫腈砜残留量的关键控制点

为了控制检测结果准确性,以鸡蛋粉中氟虫腈砜残留分析标准物质[GBW(E)100779]为测试样,采用“自下而上”法对基于多功能净化柱(PAC柱)净化的同位素稀释液相色谱串联质谱(ID-LC-MS/MS)法进行测量不确定度评估。“鱼骨图”分析表明,不确定度分量主要来源有样品称样量、内标溶液添加体积、标准工作溶液浓度及其移取体积。内标溶液添加体积引入的不确定度最大,对检测结果不确定度的贡献率为68.59%;万分之一天平称量引入的不确定度可忽略不计。同位素内标的添加过程是ID-LC-MS/MS法检测的关键控制点,参考基准的合理选择和目标物的完全提取是准确测量的前提。进一步用LC-MS/MS法对参考物质、稀释剂和内标溶液的适用性进行了评估,并基于国家有证标准物质[GBW(E)100779]对提取方法进行了优化。研究结果有利于提升鸡蛋食品安全的检测质量和质控水平,为精准检测质控方案的设计提供新思路。

自动QuEChERS结合UPLC-MS/MS测定莲雾中苯并咪唑类农药残留

为了建立自动QuEChERS结合高效液相色谱-串联质谱法测定莲雾中多菌灵、噻菌灵、苯菌灵及甲基硫菌灵4种苯并咪唑类农药残留量的检测方法。将莲雾样品采用混合试剂(5.5 g硫酸镁+1.5 g氯化钠+1.0 g柠檬酸钠+0.5 g柠檬酸二钠)进行净化,经QuEChERS自动样品制备系统进行制备后,应用超高效液相色谱-三重四级杆串联质谱法进行分析。结果表明,4种农药在1.00~10.00 ng/mL质量浓度范围内线性关系良好,决定系数(R2)均大于0.99;0.1、1.0、5.0 mg/kg 3个添加水平下,在莲雾基质中添加回收率为84%~105%,相对标准偏差为0.8%~9.5%(n=3),方法检出限和定量限分别为0.1~0.5μg/kg和0.5~10.0μg/kg。综上,该方法简便省时,净化效果好,灵敏度及准确度高,可用于同时测定莲雾中多菌灵、噻菌灵、苯菌灵及甲基硫菌灵4种苯并咪唑类农药的残留量。

HPLC及LC-MS测定榛子中氯吡苯脲和多菌灵残留

本文采用高效液相色谱法(HPLC)和液相色谱-质谱法(LC-MS)对干果榛子中氯吡苯脲和多菌灵残留量进行含量测定.HPLC和LC-MS均使用C18色谱柱,含量测定采取等度洗脱,流动相:甲醇-水(55∶45,体积比);体积流量:1.0 mL·min-1;测定波长:260 nm;柱温:30℃.LC-MS采取电喷雾离子源,梯度洗脱,体积流量:0.6 mL·min-1,柱温:30℃.结果表明,榛子中氯吡苯脲与多菌灵存在残留,氯吡苯脲质量浓度在1.00~10.00μg·mL-1范围内线性关系良好,加样回收率在95.58%~100.58%;多菌灵质量浓度在1.005~15.075μg·mL-1范围内具有良好的线性关系,加样回收率在95.61%~104.39%.实验证明,HPLC与LC-MS相结合的方法具有操作简便、灵敏度高、检出限低等优点,能有效地检测到榛子样品中膨大剂氯吡苯脲及杀菌剂多菌灵的残留,并确定其残留量,线性关系和回收率结果均令人满意.根据被检测的8批样品中氯吡苯脲和多菌灵两项农药残留量推断,作为一般干果食用榛子是安全的.

UPLC-MS/MS法检测3种食品中松仁过敏原

基于食品基质中松仁过敏原Pin k 2建立了一种超高效液相色谱-串联质谱法。将松仁经过研磨、脱脂、浸提、酶解后经Easy-nLC 1000-QExactive高分辨质谱仪进行分离分析,结合Uniprot蛋白数据库以及ProteinPilotTM软件对质谱图进行数据处理,经BLAST验证特异性,最终筛选3条松仁特异性肽段。方法学验证结果表明,方法在0.001~50mg/mL范围内线性关系良好,定量限为1mg/kg;在饼干、巧克力和饮料3种空白基质中的平均回收率为88.50%~107.57%,相对标准偏差不高于6.08%,基质效应为89.77%~96.13%。该方法具有灵敏度高、特异性好的优势,可应用于饼干、巧克力、饮料等食品样品中松仁过敏原的检测,为我国食品标签真实性检验及食品中隐性过敏原的检测提供技术支持。

自动化磁珠法提取血清脂溶性维生素应用LC-MS/MS检测的性能评价

目的评估自动化磁珠法提取血清脂溶性维生素应用液相色谱串联质谱法(liquid chromatography-tandem mass spectrometry,LC-MS/MS)检测的性能。方法收集200例临床剩余血清样本,采用自动化磁珠法提取血清中脂溶性维生素A,D_(2),D_(3),E和K;同时联合LC-MS/MS检测脂溶性维生素A,D_(2),D_(3),E和K的线性、定量限、精密度、正确度、携带污染率等性能指标以及基质效应。并比较此方法与传统萃取法检测结果的一致性。结果自动化磁珠法提取脂溶性维生素A,D_(2),D_(3),E和K线性相关系数均>0.99;五种物质的定量限分别为5,0.25,0.25,125和0.025ng/ml;批内精密度和批间精密度分别为0.66%~4.83%,0.15%~3.70%;平均加标回收率为87.05%~111.11%;基质效应为95.43%~99.07%;高-低值样本循环进样结果均值与低-低值样本循环进样结果均值之差,均小于低-低值样本循环进样结果均值的3s;统计学结果显示自动化磁珠法和传统萃取法提取的脂溶性维生素结果相关性良好(r>0.99),两种方法的检测结果无显著偏倚。结论自动化磁珠法提取脂溶性维生素的检测性能良好,有望提高样品通量和分析效率。

Tandem Mass Tag-based proteomics analysis reveals the vital role of inflammation in traumatic brain injury in a mouse model

Proteomics is a powerful tool that can be used to elucidate the underlying mechanisms of diseases and identify new biomarkers.Therefore,it may also be helpful for understanding the detailed pathological mechanism of traumatic brain injury(TBI).In this study,we performed Tandem Mass Tag-based quantitative analysis of cortical proteome profiles in a mouse model of TBI.Our results showed that there were 302 differentially expressed proteins in TBI mice compared with normal mice 7 days after injury.Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses showed that these differentially expressed proteins were predominantly involved in inflammatory responses,including complement and coagulation cascades,as well as chemokine signaling pathways.Subsequent transcription factor analysis revealed that the inflammation-related transcription factors NF-κB1,RelA,IRF1,STAT1,and Spi1 play pivotal roles in the secondary injury that occurs after TBI,which further corroborates the functional enrichment for inflammatory factors.Our results suggest that inflammation-related proteins and inflammatory responses are promising targets for the treatment of TBI.

基于LC-MS/MS测定人体类固醇激素的研究进展

类固醇激素是一类具有环戊烷多氢菲结构的化合物,由细胞色素P450酶催化形成,在调节机体代谢、促进性器官发育等方面起着重要作用。临床上将类固醇激素水平作为肾上腺疾病、精神类疾病等的诊断指标。液相色谱-串联质谱(LC-MS/MS)联用技术因具有高灵敏度、高通量和高专属性的特点,已成为类固醇临床测定的首选方法。本文综述了LC-MS/MS在内源性类固醇激素测定中的应用,特别是在样品前处理、色谱条件和质谱条件优化等方面的研究进展,为临床上类固醇激素的诊断检测提供参考。

Analysis of Norditerpenoid Alkaloids Extracted from Aconitum sinomantanum Nakai by Electrospray Ionization Tandem Mass Spectrometry

Electrospray ionization mass spectrometry（ESI-MS） was applied simultaneously in determining norditerpenoid alkaloids from the roots of Aconitum sinomantanum Nakai （RAS） based on molecular mass information. The tandem mass spectra（ ESI-MS^n） provided the alkaloidal structural information, through which the existence of these alkaloids was further confirmed. Accordingly, six known norditerpenoid alkaloids were simultaneously determined on the basis of their ESI-MS^n spectra. Furthermore, based on the diagnostic fragmentation pathways of alkaloidal MS^n, a rapid method for direct detection and characterization of alkaloids from an ethanolic extract of RAS was described.

Determination of urine catecholamines and metanephrines by reversed-phase liquid chromatography-tandem mass spectrometry

The measurement of urine catecholamine and metanephrine concentrations is important for biochemical screening and diagnosis of pheochromocytoma.The goal of this work was to develop a simple liquid chromatography-tandem mass spectrometry(LC-MS/MS)method for determining catecholamines and metanephrines in urine to replace an existing liquid chromatographic method using electrochemical detection.Urine samples were prepared using Oasis weak-cation-exchange cartridges.The eluate was analyzed on an Agilent ZORBAX Eclipse Plus Phenyl-Hexyl column in 3 min.Adrenaline,noradrenaline,dopamine,metanephrine,normetanephrine,and their deuterated internal standards were monitored in positive electrospray ionization mode by multiple reaction monitoring(MRM).No evidence of ion suppression was observed.The assay was linear up to 5μmol/L for adrenaline,5μmol/L for noradrenaline,6.1μmol/L for dopamine,5.6μmol/L for metanephrine,and 34.6μmol/L for normetanephrine,with lower limits of quantification of 5,5,12,6 and 7nmol/L,respectively.The intra-day and inter-day precisions for all analytes ranged from 0.59%to 4.64%and1.98%to 4.80%,respectively.External quality assurance samples were assayed and showed excellent agreement with the target values.This simple method provides an improved assay for determining urine catecholamines and metanephrines.

Rapid analysis of fifteen sulfonamide residues in pork and fish samples by automated on-line solid phase extraction coupled to liquid chromatography–tandem mass spectrometry

The aim of this work was to develop an automated on-line solid phase extraction(SPE)with liquid chromatography-tandem mass spectrometry method for the detection of fifteen sulfonamides in pork and fish samples.Samples were extracted with 0.2%formic acid acetonitrile solution,purified by on-line SPE device with HLB column,then separated by XBridge C18 column,using 0.1%formic acid solution and acetonitrile as the mobile phase.Mass spectrometric data was acquired under multiple reaction monitoring(MRM)mode using positive ionization electrospray.Internal standard method was used in the quantification,good linear relationship was got in range of 0.1–100 ng/mL and correlation coefficient was higher than 0.9990.The limits of detection were in the range of 0.125–2.00g/kg and the limits of quantitation were in the range of 0.250–5.00g/kg.Recoveries of the method were in range of 78.3%–99.3%,relative standard deviation were lower than 10%.The method was simple,sensitivity,and could be used for routine supervision and analysis of fifteen sulfonamides in pork and fish.

A liquid chromatography with tandem mass spectrometry method for quantitating total and unbound ceritinib in patient plasma and brain tumor

A rapid, sensitive, and robust reversed-phase liquid chromatography with tandem mass spectrometry method was developed and validated for the determination of total and unbound ceritinib, a secondgeneration ALK inhibitor, in patient plasma and brain tumor tissue samples. Sample preparation involved simple protein precipitation with acetonitrile. Chromatographic separation was achieved on a Waters ACQUITY UPLC BEH C_(18) column using a 4-min gradient elution consisting of mobile phase A(0.1% formic acid in water) and mobile phase B(0.1% formic acid in acetonitrile), at a flow rate of 0.4 m L/min. Ceritinib and the internal standard([^(13)C_6]ceritinib) were monitored using multiple reaction monitoring mode under positive electrospray ionization. The lower limit of quantitation(LLOQ) was 1 n M of ceritinib in plasma. The calibration curve was linear over ceritinib concentration range of 1–2000 n M in plasma. The intra-and interday precision and accuracy were within the generally accepted criteria for bioanalytical method( o15%).The method was successfully applied to assess ceritinib brain tumor penetration, as assessed by the unbound drug brain concentration to unbound drug plasma concentration ratio, in patients with brain tumors.

Detection of 36 antibiotics in coastal waters using high performance liquid chromatography-tandem mass spectrometry

Among pharmaceuticals and personal care products released into the aquatic environment, antibiotics are of particular concern, because of their ubiquity and health effects. Although scientists have recently paid more attention to the threat of antibiotics to coastal ecosystems, researchers have often focused on relatively few antibiotics, because of the absence of suitable analytical methods. We have therefore developed a method for the rapid detection of 36 antibiotic residues in coastal waters, including tetracyclines (TCs), sulfanilamides (SAs), and quinolones (QLs). The method consists of solid-phase extraction (SPE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis, using electrospray ionization (ESI) in positive mode. The SPE was performed with Oasis HLB and Oasis MCX cartridges. Chromatographic separation on a C18 column was achieved using a binary eluent containing methanol and water with 0.1% formic acid. Typical recoveries of the analytes ranged from 67.4% to 109.3% at a fortification level of 100 ng/L. The precision of the method, calculated as relative standard deviation (RSD), was below 14.6% for all the compounds. The limits of detection (LODs) varied from 0.45 pg to 7.97 pg. The method was applied to determine the target analytes in coastal waters of the Yellow Sea in Liaoning, China. Among the tested antibiotics, 31 were found in coastal waters, with their concentrations between the LOD and 212.5 ng/L. These data indicate that this method is valid for analysis of antibiotics in coastal waters. The study first reports such a large number of antibiotics along the Yellow Sea coast of Liaoning, and should facilitate future comprehensive evaluation of antibiotics in coastal ecosystems.

固相萃取-UPLC-MS/MS法测定环境水体中多种抗生素

采用固相萃取-超高效液相色谱串联质谱法测定环境水样中25种磺胺类和喹诺酮类抗生素,通过优化试验条件,使方法在2.00μg/L~200μg/L范围内线性良好,方法检出限为1.01 ng/L~2.85 ng/L,7次测定结果的RSD为2.3%~8.0%。将该方法用于自来水和地表水测定,结果均为未检出,高、低质量浓度水平的加标回收率为61.2%~102%。

Liquid Chromatography-electrospray Ionization Tandem Mass Spectrometry for Simultaneous Determination of Metformin and Glimepiride in Beagle Dog Plasma and Bioequivalence Study

A sensitive and selective liquid chromatography-electrospray ionization tandem mass spectrometry（LC- ES1-MS/MS） was used for the simultaneous determination of metformin and glimepiride in beagle dog plasma with glipizide as internal standard（IS）. After simplified protein precipitation with methanol, both the analytes and IS were chromatographed on a Zorbax CN column via gradient elution with methanol（containing 5 mmol/L ammonium ace- tate） and 5 mmol/L aqueous ammonium acetate as the mobile phase. Detection was performed by multiple reaction monitoring（MRM） scanning via ESI source operated in positive ionization mode. Specificity, linearity, accuracy, pre- cision, recovery, matrix effect and stability were validated for metformin and glimepiride in beagle dog plasma. The calibration curves were linear in a concentration range of 10-10000 ng/mL for metformin and 4-4000 ng/mL for glimepiride with both correlation coefficients higher than 0.99. The recoveries obtained for the analytes and IS were all between 82.7% and 101.2%. The method exhibited excellent performance in terms of selectivity, robustness, short analytical time and simplicity of sample preparation. Finally, the proposed method was applied to a bioequivalence study of self-made bilayer tablet and commercial formulation containing 500 mg of metformin and 1 mg of glimepi- ride in beagle dogs.