超高效液相色谱-质谱法检测土壤中的羟基化多溴联苯醚

建立了土壤中8种羟基化多溴联苯醚(Hydroxylated polybrominated diphenyl ethers,OH-PBDEs)的Qu ECh ERS-超高效液相色谱串联质谱(UPLC-MS/MS)分析方法。样品前处理采用Qu ECh ERS方法,土壤样品用水浸润之后,以甲酸和乙腈提取目标物,C18填料和正丙基乙二胺(PSA)净化,C18色谱柱分离,乙腈和水梯度洗脱,多反应监测负离子模式扫描。在最佳实验条件下,8种目标物在9 min内分离良好,并在2~200μg/L范围内线性良好,相关系数范围在0.9936~0.9990,检出限范围为0.23~1.21 ng/g。在5.0和50 ng/g 2个浓度水平6次平行加标实验中,8种OH-PBDEs平均回收率为73.2%~117.7%,相对标准偏差为5.6%~19.7%。本方法操作简便,灵敏度高,适用于大批量样品的快速分析。     

超高效液相色谱-串联质谱法测定不同茶叶中草甘膦、氨甲基膦酸及草铵膦的残留

建立了超高效液相色谱-串联质谱同时快速测定不同茶叶中草甘膦、氨甲基膦酸及草铵膦的方法。样品用0.05 mol/L NaOH提取,并以HCl调节pH值,Oasis HLB小柱净化除杂,氯甲酸-9-芴基甲酯(FMOCCl)柱前衍生反应后,超高效液相色谱-串联质谱法测定。本方法在5~1000μg/L浓度范围内,不同茶叶基质中草甘膦、氨甲基膦酸、草铵膦线性关系良好(R2>0.99)。在0.1,0.4和4 mg/kg添加水平下,不同茶叶(绿茶、红茶、乌龙茶、普洱茶)中3种化合物回收率均介于72.1%~109.9%之间,相对标准偏差RSD在0.5%~9.8%之间(n=6),方法定量限(LOQ)在0.03~0.08 mg/kg之间(S/N=10)。本方法稳定,简便,灵敏,能够满足检测需求。     

高效液相色谱-同位素稀释质谱法定量分析人生长激素

建立了人生长激素( hGH)纯化分析和高效液相色谱( HPLC)与同位素稀释质谱( IDMS)联用高准确度绝对定量方法。采用快速蛋白液相色谱来分离纯化hGH,以傅里叶变换离子回旋共振质谱仪( FTICR-MS)准确地测定蛋白质的分子质量。纯化的hGH经酸水解后,采用KINETEX C18色谱柱为分析柱,以水(含0.1%三氟乙酸)和乙腈为流动相,等梯度分离,流速0.2 mL/min,温度40℃,采用电喷雾正离子模式进行电离,选择多反应监测模式进行检测,内标法定量分析。结果表明,FTICR-MS所测得的分子量实测值与理论值仅相差0.31 Da,脯氨酸、缬氨酸和苯丙氨酸在液相条件下5 min内达到基线分离,在最优条件下,hGH含量测定结果为186.80 mg/g,相对标准偏差为0.52%。利用本方法参加国际比对,比对结果与参考值等效一致。本方法具有简易、实用的特点,并且准确可靠,可作为hGH纯品标准物质的定值方法,为hGH的日常检测提供参考。     

加速溶剂萃取-凝胶色谱净化高效液相色谱法测定动物源性食品中的胆固醇

采用加速溶剂萃取-凝胶色谱净化建立了动物源性食品中胆固醇检测的高效液相色谱方法。结果表明,胆固醇浓度在1.0~40.0mg/L范围内线性关系良好,加标回收率为89.1%~99.8%,相对标准偏差为3.1%~7.8%。该方法准确、灵敏度高,适用于富含脂类的动物源性食品中胆固醇的检测。     

二氧化碳/环氧丙烷/马来酸酐三元共聚物对PPC/PHB共混物力学性能的影响

采用稀土三元催化剂制备了二氧化碳-环氧丙烷-马来酸酐三元共聚物(PPCMA).用红外和核磁谱图确定了PPCMA的结构及马来酸酐单元的含量,3 wt％马来酸酐投料量的PPCMA(共聚物中马来酸酐单元含量4.1％)的玻璃化转变温度(Tg)和起始热分解温度(Td-5％)分别为13.4℃和217℃,拉伸强度为2.88 MPa,断裂伸长率为1669％,与二氧化碳-环氧丙烷共聚物(PPC)相比,引入少量马来酸酐的PPCMA有望成为一种韧性材料,并可对PPC和聚3-羟基丁酸酯(PHB)共混体系进行改性.当在PPC/PHB共混体系中添加10 wt％的PPCMA时,所得共混材料的拉伸强度为18.2 MPa,断裂伸长率则提高到85％,较没有添加PPCMA的样品提高了4.25倍,因此PPCMA的加入能有效提高PPC/PHB共混体系的韧性,改善PPC/PHB共混体系的力学性能.偏光显微镜的研究表明PPC/PHB共混体系加入PPCMA后,很快形成大量尺寸小的PHB球晶,且结晶速度大幅度提高,因此PPCMA在一定意义上可视为一种特殊的“成核剂”.     

Feasibility of ultra-high performance liquid and gas chromatography coupled to mass spectrometry for accurate determination of primary and secondary phthalate metabolites in urine samples

Phthalates (PAEs) are ubiquitous toxic chemical compounds. During the last few years, some phthalate metabolites (MPAEs) have been proposed as appropriate biomarkers in human urine samples to determine PAE human intake and exposure. So, it is necessary to have fast, easy, robust and validated analytical methods to determine selected MPAEs in urine human samples. Two different instrumental methods based on gas (GC) and ultra-high performance liquid (UHPLC) chromatography coupled to mass spectrometry (MS) have been optimized, characterized and validated for the simultaneous determination of nine primary and secondary phthalate metabolites in urine samples. Both instrumental methods have similar sensitivity (detection limits ranged from 0.03 to 8.89 pg μL⁻¹ and from 0.06 to 0.49 pg μL⁻¹ in GC–MS and UHPLC–MS², respectively), precision (repeatability, expressed as relative standard deviation, which was lower than 8.4% in both systems, except for 5OH-MEHP in the case of GC–MS) and accuracy. But some advantages of the UHPLC–MS² method, such as more selectivity and lower time in the chromatographic runs (6.8 min vs. 28.5 min), have caused the UHPLC–MS² method to be chosen to analyze the twenty one human urine samples from the general Spanish population. Regarding these samples, MEP showed the highest median concentration (68.6 μg L⁻¹), followed by MiBP (23.3 μg L⁻¹), 5cx-MEPP (22.5 μg L⁻¹) and MBP (19.3 μg L⁻¹). MMP (6.99 μg L⁻¹), 5oxo-MEHP (6.15 μg L⁻¹), 5OH-MEHP (5.30 μg L⁻¹) and MEHP (4.40 μg L⁻¹) showed intermediate levels. Finally, the lowest levels were found for MBzP (2.55 μg L⁻¹). These data are within the same order of magnitude as those found in other similar populations.     

Tutorial review on validation of liquid chromatography–mass spectrometry methods: Part I

This is the part I of a tutorial review intending to give an overview of the state of the art of method validation in liquid chromatography mass spectrometry (LC–MS) and discuss specific issues that arise with MS (and MS/MS) detection in LC (as opposed to the “conventional” detectors). The Part I briefly introduces the principles of operation of LC–MS (emphasizing the aspects important from the validation point of view, in particular the ionization process and ionization suppression/enhancement); reviews the main validation guideline documents and discusses in detail the following performance parameters: selectivity/specificity/identity, ruggedness/robustness, limit of detection, limit of quantification, decision limit and detection capability. With every method performance characteristic its essence and terminology are addressed, the current status of treating it is reviewed and recommendations are given, how to determine it, specifically in the case of LC–MS methods.     

A new effective on chip electromembrane extraction coupled with high performance liquid chromatography for enhancement of extraction efficiency

In the present research, an effective on chip electromembrane extraction (CEME) coupled with high performance liquid chromatography was presented for analysis of nortriptyline (NOR) and amitriptyline (AMI) as basic model analytes from urine samples. The chip consists of two polymethyl methacrylate (PMMA) parts with two craved microfluidic channels in each part. These channels were used as flow path for the sample solution and a thin compartment for the acceptor phase. A porous polypropylene sheet membrane impregnated with an organic solvent was placed between two parts of chip device to separate the channels. Two platinum electrodes were mounted at the bottom of these channels that were connected to a power supply providing the electrical driving force for migration of ionized analytes from sample solution through the porous sheet membrane into the acceptor phase. This new setup provides effective and reproducible extractions with low volume of sample solution. Efficient parameters on CEME of the model analytes were optimized using one variable at a time method. Under the optimized conditions, the calibration curve was linear in the range of 10.0–500 μg L⁻¹ with coefficient of determination (r²) more than 0.9902. The relative standard deviations (RSDs %) for extraction and determination of the analytes were less than 6.8% based on six replicate measurements. LODs less than 4.0 μg L⁻¹ were obtained for both of the model analytes. The preconcentration factors higher than 17.0-fold were obtained. The results demonstrated that CEME would be used efficiently for extraction and determination of AMI and NOR from urine samples.     

Advanced analytical methods for the structure elucidation of polystyrene-b-poly(n-butyl acrylate) block copolymers prepared by reverse iodine transfer polymerisation

Reverse iodine transfer polymerisation (RITP) is a living radical polymerisation technique that has shown to be feasible in synthesising segmented styrene-acrylate copolymers. Polymers synthesised via RITP are typically only described regarding their bulk properties using nuclear magnetic resonance spectroscopy and size exclusion chromatography. To fully understand the complex composition of the polymerisation products and the RITP reaction mechanism, however, it is necessary to use a combination of advanced analytical methods. In the present RITP procedure, polystyrene was synthesised first and then used as a macroinitiator to synthesise polystyrene-block-poly(n-butyl acrylate) (PS-b-PBA) block copolymers. For the first time, these PS-b-PBA block copolymers were analysed by a combination of SEC, in situ¹H NMR and HPLC. ¹H NMR was used to determine the copolymer composition and the end group functionality of the samples, while SEC and HPLC were used to confirm the formation of block copolymers. Detailed information on the living character of the RITP process was obtained.     

Novel application of liquid chromatography/mass spectrometry for the characterization of drying oils in art: Elucidation on the composition of original paint materials used by Edvard Munch (1863–1944)

Modern oil paints, introduced at the beginning of the 20th century, differ from those classically used in antiquity in their chemical and compositional features. The main ingredients were still traditional drying oils, often used in mixtures with less expensive oils and added with several classes of additives. Consequently, detailed lipid profiling, together with the study of lipid degradation processes, is essential for the knowledge and the conservation of paint materials used in modern and contemporary art.