Analysis of primary aromatic amines in the mainstream waterpipe smoke using liquid chromatography-electrospray ionization tandem mass spectrometry

In recent years waterpipe smoking has spread worldwide and emerged as global health issue. Yet only little is known on the composition of waterpipe smoke. Here, we present a study on the identification and quantification of primary aromatic amines (PAAs) in this complex environmental matrix. Smoking of the waterpipe was conducted with a smoking machine and particulate matter was collected on glass fiber pads. We developed a fast, simple and specific liquid chromatography-electrospray ionization tandem mass spectrometry (LC-MS/MS) approach to simultaneously detect 31 different PAAs in this matrix. The detection limits comprised a range of 0.45-4.50 ng per smoking session, represented by 2-aminobiphenyl and 3,4,5-trichloroaniline, respectively. Intra- and inter-day precision were determined and proved excellent. We detected 31.3 ± 2.2 ng aniline and 28.0 ± 1.6 ng 4,4'-oxydianiline in the smoke of one waterpipe session. The water in the bowl exerted a small but considerable filter effect on PAAs. The method worked-out showed excellent sensitivity and specificity and is thus highly suited for the determination of PAAs in mainstream waterpipe smoke.     

液相色谱-电喷雾串联质谱法同时检测鸡组织中5种抗病毒类药物的残留量

建立了鸡组织中抗病毒类药物多残留检测的液相色谱-电喷雾串联质谱法(LC-ESI-MS/MS)。采用三氯乙酸-乙腈溶液提取鸡组织中的金刚烷胺、金刚乙胺、美金刚、咪喹莫特和吗啉胍,离心过滤后经强阳离子交换柱(SCX)净化,色谱柱Xamide(100 mm×2.1 mm, 5 μm)分离,多反应监测(MRM)正离子扫描方式进行质谱检测。结果表明,鸡组织与鸡肝中5种药物的检出限为0.06～0.30 μg/kg,定量限为0.2～1.0 μg/kg。当5种药物的添加水平为0.2～10.0 μg/kg时,在鸡肉中的平均回收率为72.3%～94.2%,相对标准偏差(RSD)(n=6)为3.5%～11.3%;在鸡肝中的平均回收率为70.8%～92.7%, RSD(n=6)为5.3%～12.6%。该方法选择性好,抗干扰能力强,可作为鸡肉和鸡肝中抗病毒药物残留检测的确证方法。     

超高效液相色谱-电喷雾串联质谱法测定生活饮用水中49种药物及5种代谢物

建立了超高效液相色谱-电喷雾串联质谱(UPLC-ESI MS/MS)分析生活饮用水中54种药物的方法。采用HLB固相萃取柱对水样中的目标化合物进行富集净化,以5 mL甲醇洗脱;洗脱液用氮气吹至近干,用0.4 mL 0.1%甲酸水溶液定容,上机分析;ACQUITY UPLC^TMBEH C₁₈柱用作色谱分离,以0.1%甲酸水溶液-甲醇为流动相进行梯度洗脱;多反应监测(MRM)模式进行检测;目标药物使用基质外标法定量。54种药物在自备井水、市政末梢水和地表水中的加标回收率分别为58.7%~104.4%、53.1%~109.5%和50.7%~118.8%,相对标准偏差(n=6)分别为0.3%~12.8%、1.0%~15.5%和0.4%~19.3%;方法定量限为0.002~5.000 ng/L。将建立的方法应用于北京部分自备井水、市政末梢水和地表水样品的分析,结果在自备井水样中检出26种药物。     

Quantification of zolpidem in human plasma by liquid chromatography-electrospray ionization tandem mass spectrometry

A simple and robust method for quantification of zolpidem in human plasma has been established using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI MS/MS). Es-citalopram was used as an internal standard. Zolpidem and internal standard in plasma sample were extracted using solid-phase extraction cartridges (Oasis HLB, 1 cm3/30 mg). The samples were injected into a C8 reversed-phase column and the mobile phase used was acetonitrile-ammonium acetate (pH 4.6; 10 mm) (80:20, v/v) at a flow rate of 0.7 mL/min. Using MS/MS in the selected reaction-monitoring (SRM) mode, zolpidem and Es-citalopram were detected without any interference from human plasma matrix. Zolpidem produced a protonated precursor ion ([M+H]+) at m/z 308.1 and a corresponding product ion at m/z 235.1. The internal standard produced a protonated precursor ion ([M+H]+) at m/z 325.1 and a corresponding product ion at m/z 262.1. Detection of zolpidem in human plasma by the LC-ESI MS/MS method was accurate and precise with a quantification limit of 2.5 ng/mL. The proposed method was validated in the linear range 2.5-300 ng/mL. Reproducibility, recovery and stability of the method were evaluated. The method has been successfully applied to bioequivalence studies of zolpidem.     

Analysis of OSPAR priority pharmaceuticals using high-performance liquid chromatography-electrospray ionisation tandem mass spectrometry

The occurrence and potential adverse effects of pharmaceutical compounds in the aquatic environment have received much scientific interest. Presented are analytical methodologies for the determination of 10 of the pharmaceuticals listed on the Oslo and Paris Commission for the protection of the Marine Environment of the North East Atlantic (OSPAR) hazardous substances website. In addition to these 10 substances, the chemical fluoxetine (Prozac) was also investigated. The performance characteristics of a combined solid phase extraction (SPE) isolation and high-performance liquid chromatography-electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS) procedure have been determined. Extraction efficiencies were obtained for a variety of SPE sorbents, following this initial investigation. Strata-X (Phenomenex, UK) was selected for further development. The extraction method performed satisfactorily for the majority of the 11 compounds analysed, with recoveries of over 60% for most of the compounds and relative standard deviations of between 4 and 13%. The recoveries of chloroquine and closantel were below 50% but the method provides semi-quantitative information regarding the occurrence of these compounds. Separation of the analytes was made using a C18 Luna analytical column (Phenomenex, UK) and mass spectra were obtained using an ion trap mass spectrometer operated in both positive and negative electrospray ionisation modes. Limits of detection for all compounds ranged from 1 to 20 ng/l, making the method suitable for low level environmental analysis. Of the selected surface water and treated sewage effluent samples (n = 6) analysed, chlorpromazine, fluoxetine and miconazole were detected in concentrations ranging from 7 to 34 ng/l. The chemicals determined using this procedure fall into a variety of pharmaceutical classes including antipsychotics and tranquilisers resulting in an analytical method that contains compounds from diverse chemical classes.     

高效液相色谱-电喷雾串联质谱法检测环境水样中22种抗生素类药物

建立了高效液相色谱-电喷雾串联质谱(HPLC-ESI MS/MS)分析环境水样中22种抗生素类药物的方法。采用HLB固相萃取柱对环境水样中的目标化合物进行富集、净化,然后以6 mL氨水-甲醇(5:95, v/v)溶液洗脱。收集的洗脱液经氮气吹干至1 mL,然后进行HPLC-ESI MS/MS分离分析。色谱流动相A相为甲醇-乙腈(1:1, v/v), B相为0.3%(体积分数)甲酸水溶液(含0.1%(体积分数)甲酸铵,pH 2.9);色谱柱为XTerra MS C18柱。质谱检测采用正离子扫描,多反应监测模式。分别以自来水和污水作为基质,22种抗生素类药物的加标平均回收率分别为54.9%～130%和57.4%～138%,相对标准偏差(n=3)分别为2.85%～28.6%和2.02%～23.2%;方法的检出限为0.05～0.5 ng/L。将建立的方法应用于北京市高碑店湖和小清河水样的分析,结果表明在两个水样中均有部分抗生素类药物检出。     

Analysis of sulfophthalimide and some of its derivatives by liquid chromatography-electrospray ionization tandem mass spectrometry.

A system was developed for the separation of sulfophthalimide (SPI), sulfophthalamide (SPAM), sulfophthalamic acid (SPAA) and sulfophthalic acid (SPA) by ion-pair liquid chromatography and their detection by electrospray ionization tandem mass spectrometry (ESI-MS-MS). Except for SPAM, the 3- and 4-sulfo-isomers of the analytes were separated by HPLC using volatile tributylamine as ion-pairing agent. Initial fragmentations of the analytes in the negative mode involve losses of CO2 or HNCO or condensation via H2O or NH3 elimination. ortho-Effects of the sulfonate group were recognized in the fragmentation of the respective 3-sulfo-isomers and allowed us to assign the order of elution of the SPAA isomers. Quantitative analysis of these sulfonated aromatic compounds with MRM detection was elaborated and resulted in detection limits ranging from 1 pg for SPA to 13 pg for SPAA isomers and in limits of quantification of 2-10 microg/L for 5 microL volumes of injected tap water, municipal wastewater or industrial effluents up to salt contents of 0.5-1 g/L. The method was applied to study the isomer-specific chemical and microbial transformations of SPI, which was previously shown to be formed by white-rot fungi from sulfophthalocyanine textile dyes.     

超高效液相色谱-电喷雾串联四极杆质谱法同时测定配合饲料中29种兽药

建立了同时测定配合饲料中喹诺酮类、磺胺类、大环内酯类和硝基呋喃类共计29种兽药的超高效液相色谱-电喷雾串联四极杆质谱(UPLC-ESI-MS/MS)检测方法。饲料样品用甲醇-乙腈(1:1, v/v)混合溶液提取,提取液经Oasis HLB固相萃取柱净化,采用UPLC-ESI-MS/MS检测。以甲醇和含0.1%(v/v)甲酸的水溶液作为流动相,进行梯度洗脱,用C18色谱柱分离,正离子模式扫描,多反应监测模式检测。29种兽药在0.01～5.0 mg/L范围内线性关系良好,相关系数(r)均大于0.99;在复合预混饲料、全价配合饲料、浓缩饲料中4个添加水平下29种兽药的平均回收率在61.2%～94.3%范围内,相对标准偏差(RSD)为2.2%～15.0%;方法的检出限(以信噪比大于10计)为0.01 mg/kg或0.05 mg/kg。该方法简便、快速、准确,重现性好,灵敏度高,适用于配合饲料中多种兽药的同时检测。     

Bacterial response to eukaryotic cells. Analysis of differentially expressed proteins using nano liquid chromatography-electrospray ionization tandem mass spectrometry

Host-bacteria interactions have mostly been investigated with regard to the host response or to activities of pathogenic bacteria. In contrast, we aim to identify reactions of non-pathogenic bacteria that result from their contact with host cells of the gastrointestinal tract. In a proteomic approach, the response of non-pathogenic human Escherichia coli bacteria on gut epithelial cells (rat IEC-6) was investigated in an in vitro co-culture model. For this purpose, a sensitive analytical procedure was developed based on the identification of two-dimensional polyacrylamide gel electrophoresis separated proteins by online nanoLC-electrospray ionization MS/MS using a quadrupole time-of-flight tandem mass spectrometer for accurate mass determination. We demonstrate here the efficiency of this technique by the identification of a total of 43 differentially expressed proteins, out of which 25 were up-regulated and 18 were down-regulated. They represent a wide range of molecular weight and different metabolic and physiological functions.     

液相色谱-电喷雾串联质谱法检测鸡组织中5种聚醚类药物残留

建立了鸡组织中聚醚类药物多残留检测的高效液相色谱-电喷雾串联质谱方法。采用甲醇提取鸡组织中的拉沙洛菌素、盐霉素、莫能菌素、甲基盐霉素和马杜霉素,经硅胶柱净化,以乙腈(含0.1%甲酸)-0.1%甲酸水溶液(体积比为97:3)为流动相,Symmetry Shield RP18作为色谱分析柱,多反应监测(MRM)正离子扫描方式进行质谱检测。当5种聚醚类药物的添加水平为鸡肉0.1～1500 μg/kg、鸡肝0.2～4500 μg/kg时,平均回收率为71.6%～99.1%,日内测定的相对标准偏差(RSD)(n=5)为3.2%～10.7%,日间RSD(n=3)为4.6%～14.7%。2种鸡组织中5种聚醚类药物的定量限为0.1～1.0 μg/kg。该方法的灵敏度、准确度和精密度均符合兽药残留分析技术的要求,适用于鸡肉和鸡肝中5种聚醚类药物的多残留检测。     

Application of liquid chromatography-electrospray ionization tandem mass spectrometry to the detection of 10 sulfonamides in honey

Liquid chromatography (LC) in combination with tandem mass spectrometry (MS-MS) has been applied to the separation and detection of 10 different sulfonamides in honey. The methodology encompasses a simple hydrolysis of the honey sample to liberate sugar-bound sulfonamides followed by liquid-liquid extraction of the 10 analytes, filtration, and analysis by LC-MS-MS. Conditions for reversed-phase LC and electrospray ionization (ESI) MS-MS in the positive ion mode were optimized for the 10 compounds under study, monitoring two characteristic mass transitions simultaneously for each analyte. The procedure is a qualitative confirmatory method for 10 sulfonamides at the low microg/kg level in honey. Typical recoveries of the analytes in honey ranged from 44 to 73% at a fortification level of 50 microg/kg. This study also addresses the issue of matrix-induced suppression of ionization, an effect often encountered in trace residue analysis of food matrices using LC-ESI-MS-MS based methods.     

超高效液相色谱-串联质谱法同时测定调味料中的17种防腐剂和抗氧化剂

建立了超高效液相色谱-串联质谱(UPLC-MS/MS)同时测定调味料中11种防腐剂和6种抗氧化剂的定性、定量分析方法。低脂肪和中等脂肪含量的调味料样品用饱和NaCl水溶液(用磷酸调pH为2～3)稀释混合均匀,然后用乙腈提取,正己烷液-液萃取净化(中等脂肪含量的样品提取液还需经C8固相萃取柱进一步的净化处理);脂肪含量高的样品先用正己烷稀释,再用饱和NaCl水溶液(用磷酸调pH为2～3)溶解样品,然后用乙腈提取,提取液进一步经C8固相萃取柱净化处理。提取液经C18反相色谱柱(150 mm×2.1 mm, 1.7μm)分离,流动相为20 mmol/L乙酸铵水溶液和乙腈,梯度洗脱,以电喷雾离子源负离子多反应监测(MRM)模式进行MS/MS检测。17种分析物在线性范围内具有较好的线性关系,相关系数r≥0.9955,其定量限(LOQ,信噪比为10)为0.05～5 mg/kg;空白样品中的添加回收率为79.7%～118%,精密度(以相对标准偏差计)为0.57%～13.1%。该方法适用于调味品中防腐剂和抗氧化剂的检测。     

同位素稀释液相色谱-串联质谱法准确测定猪肉中的氯霉素

建立了同位素稀释质谱测定猪肉中氯霉素残留的方法,对影响溶剂提取、萃取净化、液相色谱-质谱检测方法准确度的因素进行了量化与优化。猪肉样品经液氮冷冻粉碎,加入氯霉素-D5同位素内标和0.1 mol/L醋酸钠缓冲溶液(pH 5),用乙酸乙酯提取4次,正己烷脱脂,HLB固相萃取小柱净化后采用负离子多反应监测模式下的液相色谱-质谱技术检测。方法的线性范围为0.01～0.5 ng/g,相关系数r2大于0.999;检出限和定量限分别为0.004 ng/g和0.02 ng/g;在0.02 ng/g和1.0 ng/g加标水平的回收率(n=3)分别为95.2%～109.1%和99.7%～102.5%;日内和日间相对标准偏差均小于2%。研究了氯霉素及氯霉素-D5的基体效应,测得不同流动相和稀释溶剂组成时基体效应因子k的范围在0.950～1.015之间。研究结果对同位素稀释质谱痕量残留检测结果准确度的控制、方法的建立与验证具有参考意义。     

Optimization of a trypsin-bioreactor coupled with high-performance liquid chromatography-electrospray ionization tandem mass spectrometry for quality control of biotechnological drugs

The optimization of a silica-based trypsin bioreactor and its use in the quality control of biotechnological drugs like peptides and proteins is described. Five bioreactors based on monolithic material have been prepared, with different amount of bound trypsin. The performances of these bioreactors were compared to the proteolytic activity of a bioreactor based on silica material. The trypsin-based chromatographic columns were coupled on-line with an LC/ESI/MS/MS system for digestion and identification of proteins. First, human serum albumin has been used as test protein to compare the ability of the bioreactors to hydrolyse high-molecular-weight proteins. The best chromatographic material (epoxy monolithic silica) and the optimum amount of enzyme bound (7.13 mg) have been identified to obtain the highest protein recovery and an analytical reproducibility of the whole digestion, separation and identification process. The optimized enzyme-reactor has been used for the on-line digestion of some biotechnological drugs such as somatotropin. Somatotropin for parentheral use has been analyzed, without sample pre-treatment, with both an on-line procedure and the traditional off-line procedure described in the European Pharmacopoeia. It was found that the cleavage efficiency (aminoacidic recovery, %AA) achieved within minutes by the developed protocol is at least comparable or even better than the conventional 4h consuming method.     

Validated method using liquid chromatography-electrospray ionization tandem mass spectrometry for the determination of contamination of the exterior surface of vials containing platinum anticancer drugs

Contamination of the exterior surface of vials of cytostatic drugs by the drugs themselves is a potential hazard to human health. This study developed a validated method using liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) for the determination of contamination of the exteriors of vials of cisplatin and carboplatin. Large Alpha^® sampling swabs were employed to wipe the vial exterior. Cisplatin or carboplatin and gold(III) as an internal standard were derivatized by N,N-diethyldithiocarbamate (DDTC). Pt(DDTC)₃⁺ and Au(DDTC)₂⁺ were monitored by the respective transitions of m/z 639.3-490.9 and 493.0-345.0, respectively. Each separation was completed within 9 min using a 3 μm particle ODS-column. Calibration curves for cisplatin and carboplatin were linear over concentration ranges of 30-10,000 and 30-30,000 pg vial⁻¹, respectively. The accuracies and precisions were 96.1-102.5% and within 8.2% for intra-assay and 99.6-103.3% and within 7.6% for inter-assay, respectively. Their lower limit of quantification was 30 pg vial⁻¹. Amounts of 0.17-17.0 ng vial⁻¹ as cisplatin and 0.48-794 ng vial⁻¹ as carboplatin were detected from the exterior surface of the vials. This validated method using LC-ESI-MS/MS for the determination of platinum anticancer drugs is helpful for monitoring contamination of the exterior surface of drug vials.     

液相色谱-电喷雾离子阱串联质谱同时分析烟草中的20种游离氨基酸

建立了液相色谱-电喷雾离子阱串联质谱(LC-ESI-IT-MS/MS)同时分析烟草中20种游离氨基酸的方法。烟草样品经萃取后过滤直接进样,无需进行衍生和固相萃取等其他前处理步骤。液相色谱采用HyPURITY C18反相色谱柱(200 mm×2.1 mm, 5 μm),采用1%(体积分数,下同)乙腈水溶液(含0.1%九氟戊酸)和90%乙腈水溶液(含0.1%九氟戊酸)为流动相进行梯度洗脱。结果表明,20种氨基酸的检出限(LOD)为0.01～0.05 μmol/L (S/N=3),线性相关系数均大于0.9977,峰面积测定的相对标准偏差(RSD)为0.78%～4.93%。该方法分析效率、灵敏度和选择性高,已成功应用于多种烟草样品中氨基酸的分析测定。     

高效液相色谱-串联质谱测定猪肉中3种β-受体激动剂残留量

建立一种同时测定猪肉中3种β-受体激动剂残留量的高效液相色谱-电喷雾串联质谱(HPLC-ESI-MS/MS)确证分析方法。样品经β-葡萄糖醛酸酶/芳基硫酸酯酶酶解、乙酸铵缓冲液提取和MCX固相萃取柱净化,采用Agilent ZorbaxSB-C18(2.1mm×150mm,3.5μm)色谱柱,0.1%的甲酸水溶液、甲醇和乙腈作为流动相进行洗脱,高效液相色谱分离,电喷雾离子源电离,正离子多反应监测模式进行检测,内标法定量。3种药物在0.05～1μg/kg浓度范围内线性良好,相关系数r均大于0.999,0.05、0.1、0.5μg/kg3个浓度水平的添加回收率在89.7%～106.7%之间,相对标准偏差为2.4%～8.6%,3种药物的定量限均为0.05μg/kg。方法适用于猪肉中β-受体激动剂残留的确证分析。     

Development of sensitive derivatization method for aldosterone in liquid chromatography-electrospray ionization tandem mass spectrometry of corticosteroids

A highly sensitive quantification method of aldosterone by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) was investigated in a positive mode using recently developed picolinyl derivatization. Aldosterone was smoothly and quantitatively converted to the ethyl ether-picolinyl derivative by treatment with HCl-ethanol followed by the esterification with picolinic acid in the presence of 2-methyl-6-nitrobenzoic anhydride and 4-dimethylaminopyridine. The positive ion-ESI mass spectrum of the ethyl ether-picolinyl derivative was characterized by an appearance of protonated molecule ([M+H](+)) as a base peak. The ethyl ether-picolinyl derivatization gave a successful result in a separation of aldosterone from corticosterone, dehydrocorticosterone and cortexolone, and also provided an approximately 10-fold higher ESI response in the positive-LC-ESI-MS/MS (selected reaction monitoring; SRM) when compared to that of underivatized molecule (negative mode). The limit of quantification of aldosterone by SRM using ethyl ether-picolinyl derivatization (m/z 494-->m/z 448) was 1 pg/0.2 ml serum with accuracy and precision of 92.6% and 5.6%, respectively.     

Determination of the antibiotic chloramphenicol in meat and seafood products by liquid chromatography-electrospray ionization tandem mass spectrometry

A confirmatory method based on isotope dilution liquid chromatography-electrospray ionization tandem mass spectrometry is described for the determination of the antibiotic chloramphenicol (CAP) in foods. The method is quantitative and entails liquid-liquid extraction followed by a clean-up step on a silica gel solid-phase extraction cartridge. Mass spectral acquisition is done in the negative ion mode applying multiple reaction monitoring of two diagnostic transition reactions for CAP (m/z 321 --> 257 and m/z 321--> 152). In addition, the presence of two chlorine atoms in the CAP molecule provides further analyte certainty by assessing the 37Cl/35Cl ratio using the transition reactions m/z 323 --> 257 and m/z 323 --> 152. Validation of the method in chicken meat is conducted according to the latest European Union criteria for the analysis of veterinary drug residues at levels of 0.05, 0.10, and 0.20 microg/kg, employing [2H5]-chloramphenicol as internal standard. The decision limit and the detection capability were calculated at 0.01 microg/kg and 0.02 microg/kg, respectively. At the lowest fortification level (i.e. 0.05 microg/kg), precision values below 14 and 17% were achieved under repeatability and within-laboratory reproducibility conditions, respectively. The accuracy of the method was within 20, 15, and 5% of the target values at the 0.05, 0.10, and 0.20 microg/kg fortification levels, respectively. The applicability of this procedure was demonstrated by the analysis of other meat (turkey, pork, beef) and seafood (fish, shrimps) products. The method is robust and suitable for routine quality control operations, and more than 200 sample injections were performed without excessive pollution of the mass spectrometer or loss of LC column performance.     

Monitoring the metabolism of moexipril to moexiprilat using high-performance liquid chromatography-electrospray ionization mass spectrometry

High-performance liquid chromatography combined with a UV absorbance detector and electrospray ionization mass spectrometer is used for the simultaneous analysis of moexipril and moexiprilat in biological samples. Moexipril and moexiprilat are determined in samples metabolized by rat and human liver microsomal preparations, and also in rat urine. The calibration curve is linear in the ng/mL and microg/mL concentration range of the injected moexipril.