Quantitation of melatonin and n-acetylserotonin in human plasma by nanoflow LC-MS/MS and electrospray LC-MS/MS

Melatonin (MEL) and its chemical precursor N-acetylserotonin (NAS) are believed to be potential biomarkers for sleep-related disorders. Measurement of these compounds, however, has proven to be difficult due to their low circulating levels, especially that of NAS. Few methods offer the sensitivity, specificity and dynamic range needed to monitor MEL and its precursors and metabolites in small blood samples, such as those obtained from pediatric patients. In support of our ongoing study to determine the safety, tolerability and PK dosing strategies for MEL in treating insomnia in children with autism spectrum disorder, two highly sensitive LC-MS/MS assays were developed for the quantitation of MEL and precursor NAS at pg/mL levels in small volumes of human plasma. A validated electrospray ionization (ESI) method was used to quantitate high levels of MEL in PK studies, and a validated nanospray (nESI) method was developed for quantitation of MEL and NAS at endogenous levels. In both assays, plasma samples were processed by centrifugal membrane dialysis after addition of stable isotopic internal standards, and the components were separated by either conventional LC using a Waters SymmetryShield RP18 column (2.1?×?100 mm, 3.5?μm) or on a polyimide-coated, fused-silica capillary self-packed with 17?cm AquaC18 (3?μm, 125??). Quantitation was done using the SRM transitions m/z 233?→?174 and m/z 219?→?160 for MEL and NAS, respectively. The analytical response ratio versus concentration curves were linear for MEL (nanoflow LC: 11.7-1165 pg/mL, LC: 1165-116,500 pg/mL) and for NAS (nanoflow LC: 11.0-1095 pg/mL).     

高效液相色谱-串联质谱法测定动物血浆中罗匹尼罗的浓度

建立高效液相色谱-串联质谱(LC-MS/MS)测定动物血浆中罗匹尼罗浓度的方法。血浆经乙酸乙酯萃取后,以HPLC分离,电喷雾离子化(ESI~+)串联质谱检测。以甲醇-乙腈-0.1‰冰醋酸(36:9:55)为流动相,流速为0.2mL·min~(-1),采用Ultimate XB-C 18柱(150mm×2.1mm,3μm)分离,在三级四极杆串联质谱中经电喷雾电离源(ESI)离子化,以多反应监测(MRM)方式进行检测。盐酸罗匹尼罗、盐酸苯海拉明(内标)的扫描离子对m/Z分别为261→114和m/Z 256→167。LC-MS/MS测定血浆中罗匹尼罗线性范围为0.02—400ng·mL~(-1),范围内线性关系良好(r=0.9998);以3个浓度水平的质量控制样品求得各浓度水平日内、日间精密度(RSD)均小于15.2%。在非临床药代动力学研究中,应用此法测定了受试兔子血浆中罗匹尼罗的浓度。该法灵敏、快速、准确,操作简便,样品处理方便,线性范围宽,该方法检测快速、专一、灵敏,可满足罗匹尼罗临床前药代动力学研究和临床药动学研究的要求。     

GC-MS(n) and LC-MS/MS couplings for the identification of degradation products resulting from the ozonation treatment of Acetochlor

The degradation of the chloracetamide herbicide acetochlor has been studied under simulated ozonation treatment plant conditions. The degradation of acetochlor included the formation of several degradation products that were identified using GC/ion-trap mass spectrometry with EI and CI and HPLC/electrospray-QqTOF mass spectrometry. Thirteen ozonation products of acetochlor have been identified. Ozonation of the deuterated herbicide combined to MS(n) and high-resolution mass measurement allowed effective characterization of the degradation products. At the exception of one of them, the product B (2-chloro-2', ethyl-6', methyl-acetanilide), none of the identified degradation products has been already reported in the literature. Post-ozonation kinetics studies revealed that the concentrations of most degradation products evolved noticeably with time, particularly during the first hours following the ozonation treatment. This raises concerns about the fate of degradation products in the effluents of treatment plants and suggests the need for a better control on these products if their toxicity was demonstrated.     

固相萃取GC-MS/MS法检验家兔尿液中氯胺酮

研究了家兔尿中氯胺酮的检验方法.用1mol/L氢氧化钠溶液调正检尿液pH为9-10,上GDX-403柱,以氯仿洗脱.选取209m/Z离子碎片为母离子,进行GC-MS/MS分析,通过与氯胺酮标准品的保留时间及二级质谱图比对定性,外标定量.结果显示氯胺酮在0.02-40μg/mL范围内线性关系良好,所得校准曲线的回归方程为:y=3990.31 47045.2x,r2=0.9995.检出限为20ng/mL.平均回收率为89.36%.     

尿中MDMA和MDA的三氟乙酰化-GC/MS/MS分析法

建立了尿中MDMA和MDA的、用环己烷提取的、三氟乙酸酐衍生化的、GC/MS/MS检测的分析方法。方法操作简便快速,检测MDMA最灵敏的检出限为4ng/mL,检测MDA最灵敏的检出限为2.0ng/mL。方法的回收率为73%—94%,具有较好的线性关系。     

Determination of 13C Enrichment by Conventional GC-MS and GC-(MS)-C-IRMS

Abstract

Isotopic enrichment of branched-chain L-amino acids (BCAA) and branched-chain 2-oxo acids (BCOA) in standard preparations and in human plasma samples withdrawn after oral loads with 1-¹³C labelled BCAA were measured on a conventional GC-MS system and an on-line GC-C-IRMS employing O-TMS quinoxalinol derivatives. It was concluded that the recently introduced GC-C-IRMS, owing to its high sensitivity, is the adequate analytical tool when tracer doses of stable isotope labelled compounds of low enrichment are to be used in biomedical in vivo studies.     

Validated LC-MS/MS method for quantification of agomelatine in human plasma and its application in a pharmacokinetic study

An analytical method based on liquid-liquid extraction has been developed and validated for analysis of agomelatine in human plasma. Fluoxetine was used as an internal standard for agomelatine. A Betasil C18 (4.0?×?100?mm, 5?μm) column provided chromatographic separation of analytes followed by detection with mass spectrometry. The method involves simple isocratic chromatographic conditions and mass spectrometric detection in the positive ionization mode using an API-4000 system. The proposed method has been validated with linear range of 0.050-8.000?ng/ml for agomelatine. The intra-run and inter-run precision values are within 12.12% and 9.01%, respectively, for agomelatine at the lower limit of quantification level. The overall recovery for agomelatine and fluoxetine was 67.10% and 72.96%, respectively. This validated method was used successfully for analysis of plasma samples from a pharmacokinetic study.     

MALDI-TOF MS对难溶聚芳酰胺PA6T的分析表征

选用五种样品试剂三氟乙酸、四氢呋喃、甲酸、乙腈、60%乙腈/5%三氟乙酸和两种不同的制样方法,采用基质辅助激光解吸电离飞行时间质谱(MALDI-TOF MS)表征难溶性聚合物聚对苯二甲酸己二酰胺(PA6T)的结构和分子量。发现以60%乙腈/5%三氟乙酸为样品试剂所得谱图的分子质量范围和信噪比最大,且溶剂法一步点样优于无溶剂法制样。获得了离子液体中合成产物PA6T的链结构,表明其主链为线性,未发现环状聚合物的存在,存在三种端基结构聚合体： 两端均为氨基或羧基、或一端为氨基另一端为羧基。采用MALDI-TOF MS和SEC两种方法对比测量了PA6T的平均分子量和分子量分布指数,表明MALDI-OF MS测得的平均分子量低于SEC法,分子量分布指数也低于SEC法,这是由于MS处理数据时忽略了低分子量部分,且高分子量部分因难以离子化而无法得到引起的。对于难溶的聚芳酰胺类聚合物的结构和分子量及其分布表征,MALDI-TOF MS仍不失为一个好方法。     

Fragmentation Study of Globularin Through Positive and Negative ESI/MS,CID/MS,and Tandem MS/MS

Abstract

The structure of globularin was studied by a mass spectrometric methodology based on the combined use of positive and negative electrospray ionization, collision‐induced dissociation (CID), and tandem mass spectrometry. The mass spectrometry investigation was achieved through in‐source fragmentation of the deprotonated [M?H]^?, protonated [M+H]⁺, lithiated [M+Li]⁺, sodiated [M+Na]⁺, and potassium‐cationized [M+K]⁺ ions. This allowed collision‐induced dissociation spectra of the ionized molecular ions to be obtained to give valuable structural information regarding the nature of both the glycoside and the aglycone moieties and the effect of metal cationization on the CID spectra. Glycosidic fission and ring cleavages of both aglycone and sugar moieties were the major fragmentation pathways observed during collision‐induced dissociation, where the losses of small molecules, the cinnamoyl and the cinnamate parts were also observed. Alkali metal cationization offers additional fragmentation pathways involving cross rings cleavage under CID conditions. Unlike the dissociation of protonated molecular ions, that of metal‐cationized molecules also provides sugar fragments where the C₀ ⁺ fragment corresponding with the glucose ion was obtained as a major daughter peak for all the studied compounds. Even with low abundance, fragment ions coordinated to K⁺ were also observed from [M+K]⁺.     

三氟乙酸酐衍生化GC/MS/MS方法检验尿中吗啡

建立了人体尿中吗啡和O~6-单乙酰吗啡的衍生化GC/MS/MS定性、定量分析方法。以SKF_(525a)为内标,三氟乙酸酐为衍生化试剂,采用DB5-MS色谱柱对衍生化产物进行分析。尿中吗啡和O~6-单乙酰吗啡的质量浓度在0.05—10μg/mL范围内线性良好,线性相关系数r均为0.9901;方法回收率为65%—86%。检出限均为0.05ng/mL。该法操作简单,灵敏度高,适合作为法医毒物分析的常规方法。     

N-(反式-4-异丙基-环已烷羰基)-D-苯丙氨酸的红外光谱和质谱解析

利用红外光谱和质谱等方法研究了N-(反式-4-异丙基-环已烷羰基)-D-苯丙氨酸分子(那格列奈)的结构特征,为该化合物的结构鉴定和质量控制提供了科学依据.     

芦苇秆粉末的热脱附-气相色谱/质谱分析

采用热脱附-气相色谱/质谱联机技术（TD-GC/MS）分析了芦苇杆粉末在不同环境温度下的挥发物释放行为。结果表明：芦苇杆粉末在40℃及160℃的挥发物中,主要有益成分分别为主要有害成分的4.43倍和5.13倍,环境友好性良好;在60℃及90℃的挥发物中,主要有益成分比例也比主要有害成分高,90℃时的有益成分为有害成分的2.45倍,环境友好性较好。以芦苇杆粉末为基材,在木质素软化温度点和木质材料碳化温度点之间（150—180℃）实施高压无胶模塑成形工艺制备木质粉末基复合材料必将体现出良好的环境友好性。     

精油中挥发性成分GC/FTIR与GC/MS联合分析

采用同时蒸馏萃取(SDE)法获得了香紫苏(Salvia sclarea L.)精油,利用气相色谱/傅里叶变换红外光谱联用(GC/FTIR)和气相色谱/质谱联用(GC/MS)相结合的手段,对其挥发成分进行了定性和定量分析,着重讨论了GC/FTIR在精油分析中的应用研究。通过不同波数官能团(Gram-Schmidt)重建红外光谱图、红外光谱差谱技术及质谱等相互验证的方法,大大提高了香紫苏油挥发成分的定性分析准确性。     

六聚吡咯/丝组缀合物结构的NMR和 ESI-MS/MS表征

利用片断合成法合成了具有DNA切割能力的六聚吡咯/丝组缀合物, 检测了该化合物的¹H、¹³C NMR 和ESI-MS/ MS 图谱, 确证了该化合物的结构, 通过¹H-¹H COSY, HSQC,HMBC等2D NMR 技术对其¹H 和¹³C NMR 数据进行了归属和解析, 并探讨了其ESI-MS/ MS 质谱裂解规律.     

Importance of MS selectivity and chromatographic separation in LC-MS/MS-based methods when investigating pharmaceutical metabolites in water. Dipyrone as a case of study

Pharmaceuticals are emerging contaminants of increasing concern because of their presence in the aquatic environment and potential to reach drinking-water sources. After human and/or veterinary consumption, pharmaceuticals can be excreted in unchanged form, as the parent compound, and/or as free or conjugated metabolites. Determination of most pharmaceuticals and metabolites in the environment is commonly made by liquid chromatography (LC) coupled to mass spectrometry (MS). LC coupled to tandem MS is the technique of choice nowadays in this field. The acquisition of two selected reaction monitoring (SRM) transitions together with the retention time is the most widely accepted criterion for a safe quantification and confirmation assay. However, scarce attention is normally paid to the selectivity of the selected transitions as well as to the chromatographic separation. In this work, the importance of full spectrum acquisition high-resolution MS data using a hybrid quadrupole time-of-flight analyser and/or a suitable chromatographic separation (to reduce the possibility of co-eluting interferences) is highlighted when investigating pharmaceutical metabolites that share common fragment ions. For this purpose, the analytical challenge associated to the determination of metabolites of the widely used analgesic dipyrone (also known as metamizol) in urban wastewater is discussed. Examples are given on the possibilities of reporting false positives of dypirone metabolites by LC-MS/MS under SRM mode due to a wrong assignment of identity of the compounds detected. Copyright ? 2012 John Wiley & Sons, Ltd.     

HPLC-MS/MS检测人血浆中多潘立酮

用HPLC-MS/MS测定人血浆中多潘立酮的浓度。采用Luna C18色谱柱（150mm×2mm,5μm）,流动相为甲醇∶水（0.04%醋酸铵）=85∶15（V∶V）,采用选择反应监测（SRM）模式。多潘立酮在0.5—100ng/mL浓度范围内有良好的线性关系,日内、日间相对标准偏差（RSD）和准确度误差（RE）均小于10%。该方法灵敏、准确、快速,已用于人血浆中多潘立酮浓度的检测。     

HPLC-MS/MS测定保健食品中的镇静催眠类药物

建立了液相色谱串联质谱法测定保健食品中苯巴比妥、艾司唑仑、地西泮等13种镇静催眠类药物的方法,优化了样品前处理方法及液相色谱串联质谱测定条件.采用甲醇为提取溶剂,超声处理,液相色谱串联质谱检测.结果表明：本方法测定13种镇静催眠类药物的线性范围均为0.04-5.0μg/mL,检出限在1.0-10.0mg/kg之间,3个水平的加标回收率在82.5％-96.9％％之间.     

高效液相色谱-质谱联用法测定饮料中的苯甲酸含量

建立了高效液相色谱-质谱联用法检测饮料中的苯甲酸.选用ZORBAX XDB-C18柱(50mm×2.1mm,3.5μm)为分析柱,流动相为乙腈-水,梯度洗脱,流速为200μL·min-1;质谱条件选用气动辅助电喷雾离子源(ESI),检测方式为负离子多离子反应检测(MRM);苯甲酸校准曲线线性范围为1-500μg/L;方...     

SPME/GC/MS分析小一点红挥发性化学成分

利用固相微萃取/气相色谱/质谱(SPME/GC/MS)联用技术对小一点红挥发性成分进行研究。共鉴定出25种化学成分,占挥发性总成分的91.99%。小一点红主要挥发性化学成分是β-月桂烯(51.18%),3,7,11,15-四甲基-2-十六烯-1-醇(21.55%),β-水芹烯(8.42%),n-十六酸(2.48%)等。     

固相微萃取/气相色谱/质谱法分析金钱蒲挥发性化学成分

分析金钱蒲挥发性化学成分。利用固相微萃取/气相色谱/质谱联用技术对金钱蒲挥发性成分进行研究。共鉴定出47个化学成分,占挥发性总成分的95.64%。金钱蒲主要挥发性化学成分是爱草脑(66.9%),桉叶素(6.19%),α-石竹烯(4.01%),γ-萜品烯(2.79%),β-榄香烯(2.58%),β-水芹烯(2.22%)等。