气相色谱/质谱联用测定大鼠脑部的神经甾体

应用气相色谱 质谱联用技术建立了大鼠脑部神经甾体的测定方法。游离型甾体和甾体硫酸酯分两步萃取。第一步用乙酸乙酯提取游离型甾体,第二步用氯仿/2 丁醇提取甾体硫酸酯,然后经固相萃取纯化。甾体硫酸酯进行溶剂解形成游离型甾体。游离型甾体和甾体硫酸酯分别经七氟丁酸酐衍生化后进行气相色谱 质谱分析。经初步研究雄性大鼠脑部游离型神经甾体孕烯醇酮(PREG)、黄体酮(PROG)、别孕烯醇酮(AP)和脱氢表雄酮(DHEA)的含量分别为（8.53±1.11） ng/g ,（ 7.01±2.60） ng/g ,（ 1.     

6-羟基-3-硫酸酯钠甾体化合物的合成及生理活性研究

甾醇硫酸酯钠化合物由于其独特的结构特征和特殊的生理活性正引起人们越来越多的关注.从天然存在的甾醇1a～1b出发,经过PCC氧化得到4-烯-3,6-二羰基甾体化合物2a～2b,然后在Ni2+存在的条件下用硼氢化钠还原2a～2b,得到3-羟基-6-酮甾体化合物3a～3b.利用三乙胺-三氧化硫复合物对3a～3b进行硫酸酯化得到4a～4b,然后通过阳离子(钠型)交换树脂对4a～4b进行Na+交换得到6-氧代-3β-硫酸酯钠盐5a～5b,5a～5b进一步通过NaBH4还原得到6-羟基-3β-硫酸酯钠(6a～6b).另外,采用类似的方法合成了6-羟基胆甾-4-烯-3β-硫酸酯钠(10a).并对化合物5a～5b和6a～6b进行抗肿瘤活性试验,结果表明6a在体外对卵巢癌(Hey-1B)细胞株具有较好的细胞毒性,IC50值为48 nmol/mL.     

固相萃取-高效液相色谱/串联质谱法测定水产品中硫酸新霉素残留量

建立了一种分析水产品中硫酸新霉素残留量的固相萃取-高效液相色谱/串联质谱法。样品经三氯乙酸水溶液提取,固相萃取小柱净化。用带加热电喷雾离子源的高效液相色谱/串联质谱以选择反应离子监测(SRM)正离子模式检测,基质标准曲线定量。结果显示,在草鱼、斑点叉尾鮰、鳗鲡、南美白对虾和甲鱼空白肌肉中添加硫酸新霉素水平为25~1 000μg/kg时,其加标回收率为91.04%~114.57%,相对标准偏差为1.91%~9.62%。硫酸新霉素的检测限为10μg/kg,定量限为25μg/kg。方法适用于水产品中硫酸新霉素残留量的测定,也适用于硫酸新霉素在水产动物体内组织分布和消除研究。     

液相色谱-串联质谱法检测血清中15种甾体激素的动态变化

建立了用液相色谱-串联质谱检测血清中15种甾体激素的方法。在血清样品中加入含内标的乙腈沉淀蛋白质后,用100 mmol/L盐酸羟胺衍生,经Agilent-C18柱(50 mm×3.0 mm,2.7μm)分离,内标法定量。质谱分析采用电喷雾电离(ESI)正离子扫描,多反应监测(MRM)模式检测。数据显示,13种激素在0.05~20 ng/mL范围内线性关系良好(相关系数(R2)不小于0.995 6),检出限不大于1 ng/mL;皮质醇及脱氢表雄酮硫酸酯在50~2 000ng/mL范围内线性关系良好(R2不小于0.997 9),检出限不大于0.5 ng/mL。将该方法应用于女性月经周期激素变化规律的研究,结果表明,15种甾体激素在一个完整的月经周期内有不同特征的动态变化,其中雄激素在滤泡期的后期达到最高值,孕(雌)激素在黄体期达到最高值,而皮质激素则波动不明显。该方法灵敏度高、重复性好,为临床诊疗提供了参考。     

液相色谱-电喷雾离子阱质谱分析土壤中四溴双酚-A

建立了固相萃取-高效液相色谱-电喷雾离子阱质谱(SPE-HPLC-MS-Trap)分析环境土壤样品中四溴双酚-A(Tetrabromobisphenol-A,TBBP-A)的方法.样品用正己烷索氏提取,用固相萃取C18小柱富集纯化,外标法定量.结果表明:土壤中不同加标浓度(11.9 pg/g～11.9 ng/g)四溴双酚-A的回收率分别为:(88.9±1.4)%、(98.7±9.9)%、(97.3±10.2)%、(100.6±2.0)%、(97.7±7.4)%和(99.96±4.73)%;不同浓度平行测量的相对标准偏差为0.83%～6.81%.应用建立的方法对环境土壤样品进行了测定,土壤样品中TBBP-A浓度为(25.2±2.7) ng/g (n=4).     

小鼠血浆中染料木素水溶性代谢产物和染料木素脂肪酸酯的分离及测定

本文建立了小鼠灌胃染料木素单体后血浆中水溶性染料木素代谢产物和染料木素脂肪酸酯的分离及测定方法。血浆样品经乙酸乙酯萃取后上Sephadex LH-20柱,分别用体积比1∶1的正己烷/氯仿和甲醇洗脱,染料木素脂肪酸酯用脂肪酶酶解后转化成染料木素,水溶性代谢产物用葡萄糖醛酸酶及硫酸酯酶水解成染料木素,然后采用液相色谱串联飞行时间质谱(Q-TOF LC/MS)检测染料木素。血浆中染料木素在10～10000 ng/mL范围内线性关系良好,检测限为1 ng/mL。10批次小鼠血浆中水溶性代谢产物平均为526.006 ng/mL,染料木素脂肪酸酯平均为58.976 ng/mL。采用SephadexLH-20柱具有良好的分离效果,脂肪酶水解染料木素脂肪酸酯稳定、专一性强,用Q-TOF LC/MS检测染料木素快速、灵敏。     

全自动在线顶空固相微萃取-气相色谱-串联质谱法测定鱼塘投毒案件水样中硫丹和硫丹硫酸酯

鱼塘水样采用全自动在线顶空固相微萃取进行萃取:萃取温度为75℃;萃取时间为60 min;氯化钠加入量为0.3 kgL-1;样品体积为2.0 mL.采用气相色谱-串联质谱法测定水样中硫丹(α-硫丹、β-硫丹)和硫丹硫酸酯的含量,在气相色谱分离中采用DB-5 m s毛细管色谱柱,在串联质谱分析中采用多反应监测模式.α-硫丹...     

亚临界水萃取及气相色谱-串联质谱法检测红茶中多种农药残留

建立了亚临界水萃取及气相色谱-串联质谱(GC-MS/MS)检测红茶中21种有机氯和拟除虫菊酯农药残留的方法。在萃取压力为5 MPa条件下,样品经150 ℃的亚临界水提取15 min后,将目标物转移至丙酮-正己烷(1:1, v/v)中,经ENVI-Carb固相萃取净化小柱净化,DB-5毛细管气相色谱柱分离,在多反应监测(MRM)模式下进行MS/MS检测,基质匹配溶液内标法定量。各目标物在5.0～320.0 μg/L范围内线性关系良好,相关系数均大于0.99,其定量限(信噪比(S/N)＞10)为50 ng/g,检出限(S/N＞3)为10 ng/g。茶叶基质中添加50、100和200 ng/g的标准品时,21种农药的回收率为70.18%～119.98%,相对标准偏差(RSD)为5.01%～11.76%。该方法的灵敏度、准确度和精密度均符合农药残留测定的技术要求,适用于红茶中有机氯和拟除虫菊酯农药残留的检测。     

固相萃取-气相色谱-质谱法分析尿液中邻苯二甲酸单酯和双酯

建立了固相萃取-气相色谱-质谱测定尿液中邻苯二甲酸单酯和双酯的分析方法。尿液经 β-葡萄糖苷酸酶酶解后进行固相萃取净化,用乙腈、乙酸乙酯和乙醚-正己烷(1: 19, v/v)分别洗脱,合并洗脱液,氮气吹干后,用N,O-双三甲基硅基三氟乙酰胺(BSTFA)对邻苯二甲酸单酯进行硅烷化处理,使用气相色谱-质谱法检测。邻苯二甲酸单酯和双酯的线性范围为5~1000 μ g/L,检出限为0.3~1.1 μ g/L,回收率为77.9%~97.7%,相对标准偏差为3.7%~10.9%。应用该方法对50份尿液进行检测,检出邻苯二甲酸二(2-乙基己基)酯(DEHP)等7种邻苯二甲酸单酯和双酯类物质,平均质量浓度为6.0~142.7 μ g/L。该方法准确、可靠、灵敏度高,适用于尿液中邻苯二甲酸单酯和双酯的同时测定。     

超声萃取-高效液相色谱-串联质谱法测定大气颗粒物中甾醇类化合物

采用超声萃取与液相色谱-串联质谱联用,建立了快速测定大气颗粒物中甾醇类化合物的方法.甾醇类化合物用甲醇超声萃取,浓缩后使用液相色谱-串联质谱分析.采用Waters公司Atlantis C18色谱柱(100mm× 2.1 mm,3μm),以乙腈和水混合流动相梯度洗脱,实现了胆甾醇、豆甾醇、菜油甾醇及β-谷甾醇的分离.并在APCI-MS/MS MRM模式下定量检测.在选取的实验条件下,方法回收率在80.3％～97.7％之间,检出限0.015 ng/m3,相对标准偏差小于15％,日内及日间测定精密度小于20％.本方法具有较好的准确性及精密度,实际样品的测试结果表明,方法可以满足大气颗粒物中甾醇类化合物的定量分析要求.     

Quantification of glucuronidated and sulfated steroids in human urine by ultra-high pressure liquid chromatography quadrupole time-of-flight mass spectrometry

The urinary steroid profile is constituted by anabolic androgenic steroids, including testosterone and its relatives, that are extensively metabolized into phase II sulfated or glucuronidated steroids. The use of liquid chromatography coupled to mass spectrometry (LC-MS) is an issue for the direct analysis of conjugated steroids, which can be used as urinary markers of exogenous steroid administration in doping analysis, without hydrolysis of the conjugated moiety. In this study, a sensitive and selective ultra high-pressure liquid chromatography coupled to quadrupole time-of-flight mass spectrometer (UHPLC-QTOF-MS) method was developed to quantify major urinary metabolites simultaneously after testosterone intake. The sample preparation of the urine (1 mL) was performed by solid-phase extraction on Oasis HLB sorbent using a 96-well plate format. The conjugated steroids were analyzed by UHPLC-QTOF-MS^E with a single-gradient elution of 36 min (including re-equilibration time) in the negative electrospray ionization mode. MS^E analysis involved parallel alternating acquisitions of both low- and high-collision energy functions. The method was validated and applied to samples collected from a clinical study performed with a group of healthy human volunteers who had taken testosterone, which were compared with samples from a placebo group. Quantitative results were also compared to GC-MS and LC-MS/MS measurements, and the correlations between data were found appropriate. The acquisition of full mass spectra over the entire mass range with QTOF mass analyzers gives promise of the opportunity to extend the steroid profile to a higher number of conjugated steroids.     

LC-ESI/MS/MS method for rapid screening and confirmation of 44 exogenous anabolic steroids in human urine

A sensitive and rapid method based on liquid chromatography-triple-quadrupole tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI) has been developed and validated for the screening and confirmation of 44 exogenous anabolic steroids (29 parent steroids and 15 metabolites) in human urine. The method involves an enzymatic hydrolysis, liquid-liquid extraction, and detection by LC-MS/MS. A triple-quadrupole mass spectrometer was operated in positive ESI mode with selected reaction monitoring (SRM) mode for the screening and product ion scan mode for the confirmation. The protonated molecular ions were used as precursor ions for the SRM analysis and product ion scan. The intraday and interday precisions of the target analytes at concentrations of the minimum required performance levels for the screening were 2-14% and 2-15%, respectively. The limits of detection for the screening and confirmation method were 0.1-10 ng/mL and 0.2-10 ng/mL, respectively, for 44 steroids. This method was successfully applied to analysis of urine samples from suspected anabolic steroid abusers.     

Studies on neurosteroids XXII. Liquid chromatography-tandem mass spectrometric method for profiling rat brain 3-oxo-4-ene-neuroactive steroids

A sensitive liquid chromatography-electrospray ionization-tandem mass spectrometric (LC-ESI-MS/MS) method for the simultaneous determination of five 3-oxo-4-ene-neuroactive steroids, i.e. androstenedione, testosterone (T), progesterone (PROG), 20alpha-dihydroprogesterone and 20beta-dihydroprogesterone, in rat brain has been developed and validated. The brain steroids were extracted with methanol-acetic acid, purified using solid-phase extraction cartridges and subjected to LC-ESI-MS/MS. The method does not require derivatization. Deuterium-labeled T and PROG were used as the internal standards, and quantification was based on the selected reaction monitoring mode. This method allowed the reproducible and accurate quantification of the brain neuroactive steroids using 100 mg of tissue; the intra- and inter-assay relative standard deviations were below 4.7 and 4.3%, respectively, and the accuracy values were 97.6-103.2% for all the steroids. The limits of quantitation were 0.1 ng/g tissue for all the steroids. The application of this developed method for the analysis of changes in the brain neuroactive steroid levels by immobilization stress is also presented.     

Simultaneous determination of salidroside and its aglycone metabolite p-tyrosol in rat plasma by liquid chromatography-tandem mass spectrometry

Salidroside and its aglycone p-tyrosol are two major phenols in the genus Rhodiola and have been confirmed to possess various pharmacological properties. In our present study, p-tyrosol was identified as the deglycosylation metabolite of salidroside after intravenous (i.v.) administration to rats at a dose of 50 mg/kg, but was not detectable after intragastric gavage (i.g.) administration through HPLC-photodiode array detection (PDA) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Next, an accurate and precise LC-MS/MS method was developed to quantitatively determine salidroside and p-tyrosol in rat plasma samples. Samples were analyzed by LC-MS/MS on a reverse-phase xTerra MS C18 column which was equilibrated and eluted with an isocratic mixture of acetonitrile-water (1:9, v/v) at a flow rate of 0.3 mL/min. The analytes were monitored by multiple reaction monitoring (MRM) under the negative electrospray ionization mode. The precursor/product transitions (m/z) were 299.0 → 118.8 for salidroside, 137.0 → 118.9 for p-tyrosol and 150.1 → 106.9 for the internal standard (IS), paracetamol, respectively. The calibration curve was linear over the concentration ranges of 50-2,000 ng/mL for salidroside and 20-200 ng/mL for p-tyrosol. The inter- and intra-day accuracy and precision were within ± 15%. The method has been successfully applied to the pharmacokinetic study and the oral bioavailability was calculated.     

Liquid chromatography-mass spectrometry method for the determination of venlafaxine in human plasma and application to a pharmacokinetic study

A sensitive and selective liquid chromatographic-mass spectrometric (LC-MS) method for the determination of venlafaxine in human plasma has been developed. Samples were prepared using liquid-liquid extraction and analyzed on a C(18) column interfaced with a triple quadrupole mass spectrometer. Positive electrospray ionization was employed as the ionization source. The mobile phase was methanol-water containing 10 mmol/L ammonium acetate, pH 7.9 adjusted with aqueous ammonia (80:20, v/v) at the flow rate of 1.0 mL/min. The analyte and internal standard clozapine were both detected by use of selected ion monitoring mode. The method was linear in the concentration range of 1.0-200.0 ng/mL. The lower limit of quantification (LLOQ) was 1.0 ng/mL. The intra- and inter-day relative standard deviation across three validation runs over the entire concentration range was less than 10.1%. The accuracy determined at three concentrations (5.0, 50.0 and 150.0 ng/mL for venlafaxine) was within +/-10.0% in terms of relative error (RE). The method was successfully applied for the evaluation of pharmacokinetic profiles of venlafaxine capsule in 20 healthy volunteers. The results show AUC, T(max), C(max) and T(1/2) between the testing formulation and reference formulation have no significant difference (p > 0.05). Relative bioavailability was 103.4 +/- 14.1%.     

液相色谱-串联质谱法测定尿液中的内源性类固醇激素

建立了液相色谱-串联质谱(LC-MS/MS)测定尿液中的内源性类固醇激素的方法。尿样经葡萄糖醛酸甙酶酶解后进行液-液提取,以甲醇-0.1%甲酸缓冲液(含0.02 mol/L乙酸铵)(体积比为68:32)为流动相,采用Cosmosil C18色谱柱分离,并以三重四极杆串联质谱多反应监测扫描方式对尿样中的脱氢表雄酮(DHEA)、睾酮、表睾酮、雄酮和苯胆烷醇酮等5种激素进行检测。方法的最低检出限为0.01～10 ng/mL,平均回收率为96.7%～106.5%,日内和日间相对标准偏差(RSD)分别小于7%和11%。应用所建立的方法测定了健康志愿者口服DHEA后尿液中内源性类固醇激素的变化情况,结果表明该方法样品处理简便,色谱分离完全,结果准确可靠,可替代气相色谱-质谱法用于体液中内源性类固醇激素兴奋剂的常规分析。     

LC-MS/MS profiling for detection of endogenous steroids and prostaglandins in tissue samples

Roles of steroid hormones, and compounds that can influence their levels in cells, are of increasing interest in e.g. cancer research, partly because resistance to hormone therapies often complicates treatment. To elucidate the processes involved, the hormones and related compounds need to be accurately measured. Reversed-phase liquid chromatography with dynamic multiple reaction monitoring mass spectrometric detection in electrospray mode is capable of providing such measurements. Therefore, LC-MS/MS was developed for sensitive, selective analysis of 11 steroid hormones, cholesterol and two prostaglandins. The effects of the tissue matrix, and solid-phase extraction (SPE) sample clean-up, on the LC-MS/MS signals of the hormones were also investigated. The results show that the developed LC-MS/MS method, following SPE clean-up to reduce matrix interference, can detect selected steroids in extracts of mouse tissues. The method provides linear measurements of the steroids at concentrations up to few ng/μL, and limits of detection in the range 0.03-0.2 pg/μL (for some compounds lower than those of previously reported methods).     

Determination of darusentan enantiomers in rat plasma by enantioselective liquid chromatography with tandem mass spectrometry using cellulose-based chiral stationary phase

A sensitive, specific and rapid liquid chromatography-mass spectrometry (LC-MS/MS) method has been developed and validated for enantioselective determination of darusentan enantiomers, orally active potent endothelin-A receptor antagonist, in rat plasma. The plasma samples were pretreated by protein precipitation with methanol and baseline chromatographic separation was performed on a Chiralcel OD-RH column with a mobile phase consisting of acetonitrile/water/formic acid (50:50:0.1, v/v/v) at a flow rate of 0.5 mL/min. The detection was accomplished by multiple-reaction monitoring (MRM) scanning via electrospray ionization (ESI) source operating in the negative ionization mode. The calibration curve was linear over the investigated concentration from 0.500 to 2500 ng/mL (r≥0.995) for each enantiomer using 50 μL of rat plasma. The lower limit of quantitation (LLOQ) for each enantiomer was 0.500 ng/mL. The intra- and inter-day precisions were not more than 10.2% and the accuracy was within the range from -5.4 to 6.3% for darusentan enantiomers. No chiral inversion was observed during the plasma preparation, storage and analysis. The method proved adequate for enantioselective pharmacokinetic studies of darusentan enantiomers after oral administration of three different doses of racemic darusentan.     

A liquid chromatography-mass spectrometry method for the quantitation of aristololactam-I in rat plasma

A sensitive method with liquid chromatography-electrospray ionization mass spectrometry has been developed and validated for the determination of aristololactam-I in rat plasma after oral administration of aristolochic acid-I using finesteride as the internal standard. Chromatographic separation was achieved on a Lichrospher C(18) column using methanol:0.05% acetic acid in water (71:29, v/v) as a mobile phase delivered at a flow rate of 1 mL/min. The assay was linear for aristololactam-I over the range 0.3-300 ng/mL. The analysis of quality control samples demonstrated precision with coefficient of variation less than 20% (n = 5). Absolute recovery of aristololactam-I was 90.4-97.3%. The LC-MS method for the determination of aristololactam-I is sensitive, specific and can be used to investigate the toxicokinetics of aristololactam-I.