液相色谱和液质联用技术在水产品安全检测中的应用

介绍了近年来高效液相色谱和色质联用技术在水产品安全检测中的应用进展。本文介绍了高效液相色谱和液质联用技术(LC-MS)的特点,及其在水产品中渔药、抗生素及赤潮藻毒素类有毒有害物质残留分析中的应用。     

高速逆流色谱分离纯化氧化葵花油中三亚油酸甘油酯单氢过氧化物

该文为了获得较高纯度的三亚油酸甘油酯单氢过氧化物,用于"脂肪调控氧化-热反应"制备肉味香精机理的研究。葵花油在70℃下通空气0.72 m3/(kg.h)氧化70 h制备含三亚油酸甘油酯单氢过氧化物的氧化产物,采用液-质联机定性及液相色谱-蒸发光散射检测器面积归一化定量,氧化产物中三亚油酸甘油酯单氢过氧化物质量分数为1.95%。高速逆流色谱分离该氧化产物中的三亚油酸甘油酯单氢过氧化物,较佳的两相溶剂系统为V(正己烷)∶V(二氯甲烷)∶V(乙腈)=4∶1∶3。以上相为固定相,下相为流动相,正向洗脱,流速1.5 mL/min,转速850 r/min,上样5 g,分离时间195 min,一次性得三亚油酸甘油酯单氢过氧化物53 mg,液相色谱-蒸发光散射检测器分析纯度为96.3%,回收率52.3%。     

Efficient electrochemical decomposition of perfluorocarboxylic acids by the use of a boron-doped diamond electrode

The electrochemical decomposition of environmentally persistent perfluorooctanoic acid (PFOA) was achieved by the use of a boron-doped diamond (BDD) electrode. The PFOA decomposition follows pseudo-first-order kinetics, with an observed rate constant (k₁) of 2.4 × 10^− 2 dm³ h^− 1. Under the present reaction conditions, k₁ increased with increasing current density and saturated at values over 0.60 mA cm^− 2. Therefore, the rate-limiting step for the electrochemical decomposition of PFOA was the direct electrochemical oxidation at lower current densities. In the proposed decomposition pathway, direct electrochemical oxidation cleaves the C-C bond between the C₇F₁₅ and COOH in PFOA and generates a C₇F₁₅ radical and CO₂. The C₇F₁₅ radical forms the thermally unstable alcohol C₇F₁₅OH, which undergoes F⁻ elimination to form C₆F₁₃COF. This acid fluoride undergoes hydrolysis to yield another F⁻ and the perfluorocarboxylic acid with one less CF₂ unit, C₆F₁₃COOH. By repeating these processes, finally, PFOA was able to be totally mineralized to CO₂ and F⁻. Moreover, whereas the BDD surface was easily fluorinated by the electrochemical reaction with the PFOA solution, medium pressure ultraviolet (MPUV) lamp irradiation in water was able to easily remove fluorine from the fluorinated BDD surface.     

Determining estrogenic steroids in Taipei waters and removal in drinking water treatment using high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry

River water and wastewater treatment plant (WWTP) effluents from metropolitan Taipei, Taiwan were tested for the presence of the pollutants estrone (E1), estriol (E3), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) using a new methodology that involves high-flow solid-phase extraction and liquid chromatography/tandem mass spectrometry. The method was also used to investigate the removal of the analytes by conventional drinking water treatment processes. Without adjusting the pH, we extracted 1-L samples with PolarPlus C18 Speedisks under a flow rate exceeding 100 mL/min, in which six samples could be done simultaneously using an extraction station. The adsorbent was washed with 40% methanol/60% water and then eluted by 50% methanol/50% dichloromethane. The eluate was concentrated until almost dry and was reconstituted by 20 microL of methanol. Quantitation was done by LC-MS/MS-negative electrospray ionization in the selected reaction monitoring mode with isotope-dilution techniques. The mobile phase was 10 mM N-methylmorpholine aqueous solution/acetonitrile with gradient elution. Mean recoveries of spiked Milli-Q water were 65-79% and precisions were within 2-20% of the tested concentrations (5.0-200 ng/L). The method was validated with spiked upstream river water; precisions were most within 10% of the tested concentrations (10-100 ng/L) with most RSDs<10%. LODs of the environmental matrixes were 0.78-7.65 ng/L. A pre-filtration step before solid-phase extraction may significantly influence the measurement of E1 and EE2 concentrations; disk overloading by water matrix may also impact analyte recoveries along with ion suppression. In the Taipei water study, the four steroid estrogens were detected in river samples (ca. 15 ng/L for E2 and EE2 and 35-45 ng/L for E1 and E3). Average levels of 19-26 ng/L for E1, E2, and EE2 were detected in most wastewater effluents, while only a single effluent sample contained E3. The higher level in the river was likely caused by the discharge of untreated human and farming waste into the water. In the drinking water treatment simulations, coagulation removed 20-50% of the estrogens. An increased dose of aluminum sulfate did not improve the performance. Despite the reactive phenolic moiety in the analytes, the steroids were decreased only 20-44% of the initial concentrations in pre- or post-chlorination. Rapid filtration, with crushed anthracite playing a major role, took out more than 84% of the estrogens. Except for E3, the whole procedure successfully removed most of the estrogens even if the initial concentration reached levels as high as 500 ng/L.     

液相色谱-串联质谱法测定蜂王浆中新型烟碱类药物及其代谢物残留量

采用QuEChERS净化-液相色谱-串联质谱法（QuEChERS-LC-MS/MS）测定蜂王浆中新型烟碱类药物吡蚜酮、呋虫胺、烯啶虫胺、噻虫嗪、氟啶虫酰胺及代谢物4-（三氟甲基）烟酰胺、吡虫啉、噻虫胺、氯噻啉、啶虫脒及代谢物N-去甲基啶虫脒和噻虫啉的残留量。样品经水稀释,甲醇沉淀蛋白并提取,以N-丙基乙二胺（PSA）、C18和无水硫酸镁作为分散剂进行QuEChERS净化,采用液相色谱-串联质谱法进行检测（电喷雾离子源,正离子模式,多反应监测模式）,以同位素内标法和外标法进行定量分析。结果表明,该方法定量限以S/N=10计,吡呀酮、呋虫胺为2.5 μg/kg,烯啶虫胺、氯噻啉、啶虫脒、噻虫啉为5.0 μg/kg,噻虫嗪、氟啶虫酰胺、吡虫啉、噻虫胺、4-（三氟甲基）烟酰胺、N-去甲基啶虫脒为12.5 μg/kg。线性相关系数大于0.996。对空白蜂王浆进行添加回收实验,回收率为81.2%~119%;相对标准偏差为1.7%~12.2%。该方法简便、快捷,定量限能够满足目前国内外最大残留限量的要求,可作为蜂王浆中新型烟碱类药物及其代谢物残留量的测定方法。     

液相色谱串联质谱法测定食品中红曲色素

采用液相色谱串联质谱法测定了食品中红曲红胺、红曲红素、红曲素、红曲黄素的含量,并选择离子检测进行阳性确证。液体试样用水超声提取,离心定容后,固体和半固体样品采用水溶解定容,提取液再经固相萃取柱净化,样液经洗脱定容后,供液相色谱-质谱/质谱仪测定和确证,外标法定量。该方法的最低检出限、线性范围和方法回收率分别为:1.0 mg/kg、1.0～100.0 mg/kg和89.3%～94.3%。     

Chemical Profile and Biological Activities of Two Edible Plants: Chemical Investigation and Quantitative Analysis Using Liquid Chromatography Tandem Mass Spectrometry and Gas Chromatography Mass Spectrometry

The objectives of this study were to define the phenolic and fatty acid profiles, anticholinesterase, antioxidant, antimicrobial activities, and total phenolic-flavonoid contents of Lycopsis orientalis and Tragopogon latifolius var. angustifolius which have been used as food source and food supplement in Anatolia and have never been examined before. Rosmarinic and quinic acids (21.11 and 11.46 mg g^–1 extract, respectively) were found to be the most abundant constituents in L. orientalis and T. latifolius var. angustifolius among the studied 27 compounds by liquid chromatography tandem mass spectrometry. In the fatty acid compositions of L. orientalis and T. latifolius var. angustifolius that were determined by gas chromatography mass spectrometry, oleic (29.1%) and palmitic (28.7%) acids were identified as the major components, respectively. The high antioxidant activity of the methanol extract of L. orientalis shows parallelism to its rosmarinic acid content. Besides, this extract showed medium anticholinesterase activity. The results of the present study proves that the L. orientalis might also be used as a food source due to its high phenolic acid content and strong antioxidant property.     

Investigating the chlorination of acidic pharmaceuticals and by-product formation aided by an experimental design methodology

The degradation of seven acidic drugs and two metabolites during chlorination was investigated by liquid chromatography-mass spectrometry (LC-MS). A triple-quadrupole (QqQ) system was used to follow the time course of the pharmaceuticals and by-products, while a quadrupole time-of-flight (Q-TOF) system was also used for the identification of the by-products. Under strong chlorination conditions (10 mg/L Cl₂, 24 h), only four of the target compounds were significantly degraded: salicylic acid, naproxen, diclofenac and indomethacine. The degradation kinetics of these four compounds were investigated at different concentrations of chlorine, bromide and pH by means of a Box-Behnken experimental design. Depending on these factors, measured pseudo-first order half-lives were in the ranges: 23-573 h for salicylic acid, 13-446 min for naproxen, 5-328 min for diclofenac and 0.4-13.4 min for indomethacine. Also, it was observed that chlorine concentration was the overall most significant factor, followed by the bromide concentration (except for indomethacine), resulting in increased degradation kinetics as they are increased. The degradation path of salicylic acid, naproxen and diclofenac consisted of aromatic substitution of one or two hydrogens by chlorine and/or bromide. Moreover, for diclofenac, two other by-products corresponding to a decarboxylation/hydroxylation pathway from the monohalogenated products were also identified. On the other hand, indomethacine degradation did not lead to halogenation products but to oxidation ones. The investigation of these by-products in real samples by LC-MS/MS (QqQ) showed that the halogenated derivates of salicylic acid occurred in all the drinking water and wastewater samples analysed.     

Degradation Products of Tryptophan in Cell Culture Media: Contribution to Color and Toxicity

Biomanufacturing processes may be optimized by storing cell culture media at room temperature, but this is currently limited by their instability and change in color upon long-term storage. This study demonstrates that one of the critical contributing factors toward media browning is tryptophan. LC-MS technology was utilized to identify tryptophan degradation products, which are likely formed primarily from oxidation reactions. Several of the identified compounds were shown to contribute significantly to color in solutions but also to exhibit toxicity against CHO cells. A cell-culture-compatible antioxidant, a-ketoglutaric acid, was found to be an efficient cell culture media additive for stabilizing components against degradation, inhibiting the browning of media formulations, and decreasing ammonia production, thus providing a viable method for developing room-temperature stable cell culture media.