Extraction-ultra Performance Liquid Chromatography-tandem Mass Research Articles

Determination of four phenolic endocrine-disrupting chemicals in water by dispersive solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry based on metal-organic skeleton porous carbon materials

Phenolic endocrine-disrupting chemicals (EDCs) are exogenous substances that interfere with the endocrine system and disrupt normal cell functions upon entering a living organism, leading to reproductive and developmental toxicity. Therefore, the development of a rapid and efficient analytical method for detecting phenolic EDCs in environmental waters is crucial. Owing to the low concentration of phenolic EDCs in environmental water, appropriate sample pretreatment methods are necessary to remove interferences caused by the sample matrix and enrich the target analytes before instrumental analysis. Dispersive solid-phase extraction (DSPE) has gained considerable attention as a simple and rapid sample pretreatment method for environmental-sample analysis. In this method, an adsorbent material is uniformly dispersed in a sample solution and the target analytes are extracted through processes such as vortexing. Compared with traditional solid-phase extraction (SPE), DSPE increases the contact area between the adsorbent and sample solution, reduces the required amounts of adsorbent and organic solvents, and improves the extraction efficiency. The adsorbent material plays a critical role in DSPE because it determines the extraction efficiency of the method. Metal-organic frameworks (MOFs) are porous framework materials composed of metal clusters and multifunctional organic ligands. They possess many excellent properties such as tunable pore sizes, large surface areas, and good thermal and chemical stability, rendering them ideal adsorbent materials for sample pretreatment. MOF-derived porous carbon materials obtained through high-temperature carbonization not only increase the density of MOF materials for better separation but also retain the advantages of a large surface area, highly ordered porous structure, and high porosity. In this study, a porous carbon material derived from an MOF, named as University of Oslo-66-carbon (UiO-66-C), was synthesized using a solvothermal method and applied as an adsorbent to enrich four phenolic EDCs (bisphenol A, 4-tert-octylphenol, 4-nonylphenol, and nonylphenol) in water. A method combining DSPE with ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established to analyze these phenolic EDCs in water. The UiO-66-C dosage, pH of water sample, adsorption time, eluent type and volume, elution time, and ion strength were optimized. Gradient elution was performed using methanol-water as the mobile phase. The target analytes were separated on an ACQUITY UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm), and multiple reaction monitoring (MRM) was conducted in negative electrospray ionization mode. The method exhibited a linear correlation within the range of 0.5-100 μg/L for the four phenolic EDCs. The limits of detection (LODs) and quantification (LOQs) of the four phenolic EDCs were 0.01-0.13 μg/L and 0.03-0.42 μg/L, respectively. The precision of the method was evaluated through intra- and inter-day relative standard deviations (RSDs), with values ranging from 1.5% to 10.6% and from 6.1% to 13.2%, respectively. When applied to the detection of phenolic EDCs in tap and surface water, the spiked recoveries of the four phenolic EDCs were 77.1%-116.6%. Trace levels of 4-nonylphenol and nonylphenol were detected in surface water at levels of 1.38 and 0.26 μg/L, respectively. The proposed method exhibits good accuracy and precision; thus, it provides a new rapid, efficient, and sensitive approach for the detection of phenolic EDCs in environmental water.

Target analysis, occurrence and cytotoxicity of halogenated polyhydroxyphenols as emerging disinfection byproducts in drinking water

Halogenated aromatic disinfection byproducts (DBPs) in drinking water, such as halogenated phenols, have received widespread attention due to their high toxicity and ubiquitous occurrence in recent years. This study identified a group of emerging halogenated aromatic DBPs, known as halogenated polyhydroxyphenols (HPPs), and investigated their occurrence and cytotoxicity. We developed a highly sensitive solid-phase extraction ultra-performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) method under multiple reaction monitoring (MRM) mode, with recoveries ranging from 86 to 115% and method detection limits (MDLs) ranging from 0.10 to 1.87 ng/L for the analysis of 15 HPPs. Eleven of these HPP DBPs were detected in collected drinking water samples using this method with detection frequencies ranging from 14 to 100% and a maximum concentration of 24 ng/L. The IC50 of the 15 HPPs in Chinese hamster ovary (CHO-K1) cells were ranged from 15.13 µM to 6.08×103 µM. The tested HPPs with -CHO substitution exhibited higher cytotoxicity compared to those with -COOH substitution. The TIC-Tox values of HPPs were calculated to be higher than those of HPs, indicating a potential necessity to pay attention to HPP DBPs. A quantitative structure−activity relationship (QSAR) model was developed for the cytotoxicity of HPPs, which was shown to be significantly associated with acid dissociation constant (pKa) and total valence connectivity (TVCon). To the best of our knowledge, this study reported the analysis, occurrence, and cytotoxicity of HPP DBPs in drinking water for the first time.

Determination of beauvercin and enniatins in rice flour and wheat flour by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry

To develop a method for the determination of beauvercin(BEA), enniatin A(ENNA), enniatin A1(ENNA1), enniatin B(ENNB) and enniatin B1(ENNB1) in rice flour and wheat flour by ultra performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS). Samples were extracted by acetonitrile-water, purified by Oasis Prime HLB solid-phase extraction column. The sample solution was separated by waters BEH C_(18) column(2.1 mm×100 mm, 1.8 μm). The detection was performed in the electrospray positive ionization(ESI+) under multiple reaction monitoring(MRM) mode. The internal standard method and the matrix-matched calibrations were used for quantification. The linear relationships of BEA and 4 kinds of enniatins(ENNs) were good in the range of 0.1-50.0 ng/mL(r>0.999). The average recoveries of BEA and ENNs in rice flour and wheat flour were 96.4%-105.4% and 99.1%-109.2%, with the relative standard deviations(RSD) of 1.01%-7.42% and 1.09%-9.69%(n=6). The detection limits(LOD) of BEA and ENNs were 0.03 μg/kg. The quantitative limits(LOQ) of BEA and ENNs were 0.1μg/kg. The matrix induced suppression or enhancement effect were 72.7%-99.3% and 60.8%-100.4%, respectively. The levels of emerging BEA and ENNs in wheat flour were higher than rice flour. The detection rate of enniatin B was highest in wheat flour and rice flour, the contents were 0.03-9.57 μg/kg and 0.03-0.56 μg/kg, the positive percentage were 98.5% and 36.4%. The method is quick, easy, accurate and sensitive, which is suitable for the determination of BEA and 4 kinds of ENNs in rice flour and wheat flour.

Sulfonated magnetic graphite carbon nitride solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry for screening malachite green and leucomalachite green in freshwater fish

Malachite green (MG) and its metabolite, leucomalachite green (LMG), exert toxic effects on the human body. The use of these dyes is illegal, but they are still detected in aquatic products. Freshwater fish are aquatic products with the high non-qualified rates. Therefore, the sensitive screening of MG and LMG in freshwater fish is of great importance to ensure the safety of aquatic products. Owing to the low contents of MG and LMG in fish and the complex matrix of actual samples, sample preparation is required before detection to purify impurities and enrich the target compounds. Graphite carbon nitride (GCN), a polymer material composed of C, N, and H, has good chemical and thermal stability, a large specific surface area, and a large number of active sites. It has a wide range of application prospects in adsorption and can be used in food safety testing when compounded with Fe3O4 to form magnetic graphite carbon nitride (MGCN). In this study, sulfonated magnetic graphite carbon nitride (S-MGCN) was prepared by further functionalizing MGCN with sulfonic acid. After characterization by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), and vibrating sample magnetometry (VSM), a magnetic solid-phase extraction (MSPE) method based on S-MGCN was established to extract MG and LMG from freshwater fish. The targets were screened using ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Following sulfonic acid functionalization, S-MGCN showed increased electrostatic interactions based on the MGCN adsorption mechanism, which includes hydrogen bonds and π-π interactions; thus, its adsorption efficiency was significantly improved. The matrix effects were -42.21% and -33.77% before functionalization, -11.40% and -7.84% after functionalization, thus confirming that S-MGCN has significant matrix removal ability. Given that S-MGCN demonstrated excellent efficiency as an MSPE adsorbent, the adsorption conditions for S-MGCN were optimized. The optimal conditions were as follows: adsorbent dosage, 15 mg; adsorption time, 2 min; solution pH, 5; and ionic strength, not adjusted. Under these conditions, the adsorption efficiency of S-MGCN could reach 94.2%. Different organic solvents were used to elute adsorbed MG and LMG, and the desorption efficiency peaked when 1%(v/v) ammonia acetonitrile was used as the elution solvent. The elution volume was also optimized, and a maximum desorption efficiency of 93.2% was obtained when 1 mL of 1%(v/v) ammonia acetonitrile was added to S-MGCN. The limits of detection (LODs) and quantification (LOQs) of the two targets were determined at signal-to-noise ratios (S/N) of 3 and 10, respectively. The LODs and LOQs were 0.075 μg/kg and 0.25 μg/kg, respectively. The linear ranges of the two target compounds were 0.25-20.0 μg/kg with correlation coefficients (r) greater than 0.998. To assess accuracy and precision, we prepared spiked samples at three levels (low, medium, and high) with six parallel samples per level (n=6). The recoveries ranged from 88.8% to 105.9%. The intra- and inter-day relative standard deviations were 5.4%-13.7% (n=6) and 3.3%-11.1% (n=3), respectively. Compared with the national standard method, the proposed method features simpler sample pretreatment procedures, less use of organic reagents (5 mL), and a shorter extraction time (2 min); moreover, the method does not require complicated elution steps, and the eluent can be directly analyzed by UPLC-MS/MS. The test results of actual samples were consistent with those obtained via the national standard method, thus confirming the practical feasibility of the developed method. The proposed MSPE method based on S-MGCN is an efficient and environmentally friendly method that could provide a new methodological reference for the sensitive screening of MG and LMG in actual samples.

Simultaneous determination of 43 antibacterials from nine categories in water using automatic sample loading-solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry

Antibacterials represent a pharmaceutical class that is extensively used and consumed worldwide. The presence of a large number of antibacterial agents in water could result in antibiotic resistance. Thus, the development of a fast, accurate, and high-throughput method to analyze these emerging contaminants in water is necessary. Herein, a method was developed to achieve the simultaneous determination of 43 antibacterials from nine pharmaceutical categories (i.e., sulfonamides, quinolones, fluoroquinolones, tetracyclines, lincosamides, macrolides, nitroimidazoles, diterpenes, and dihydrofolate reductase inhibitors) in water using automatic sample loading-solid phase extraction (SPE)-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Because the properties of these 43 antibacterials are quite different, the main objective of this work is to develop an extraction procedure that would enable the simultaneous analysis of a wide range of multiclass antibacterials. Given this context, the work presented in this paper optimized the SPE cartridge type, pH, and sample loading amount. Multiresidue extraction was performed as follows. The water samples were filtered through 0.45 μm filter membranes, added with Na2EDTA and NaH2PO4, and pH-adjusted to 2.34 using H3PO4. The solutions were then mixed with the internal standards. An automatic sample loading device fabricated by the authors was used for sample loading, and Oasis HLB cartridges were used for enrichment and purification. The optimized UPLC conditions were as follows: chromatographic column, Waters Acquity UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm); mobile phases, methanol-acetonitrile (2∶8, v/v) solution containing 0.1% formic acid and 0.1% formic acid aqueous solution; flow rate, 0.3 mL/min; injection volume, 10 μL. The compounds were step scanned using an electrospray ionization source in the positive and multiple-reaction monitoring (MRM) modes, and analyzed by internal and external standard methods. The results showed that the 43 compounds achieved high linearity in their respective linear ranges, with correlation coefficients (r2) greater than 0.996. The limits of detection (LODs) of the 43 antibacterial agents ranged from 0.004 ng/L to 1.000 ng/L, and their limits of quantification (LOQs) ranged from 0.012 ng/L to 3.000 ng/L. The average recoveries ranged from 53.7% to 130.4%, and the relative standard deviations (RSDs) were between 0.9% and 13.2%. The method was successfully applied to the determination of six tap water samples from different districts and six water samples obtained from the Jiangyin section of the Yangtze River and Xicheng Canal. No antibacterial compound was detected in any of the tap water samples, but a total of 20 antibacterial compounds were detected in the river and canal water samples. Among these compounds, sulfamethoxazole showed the highest mass concentrations, ranging from 8.92 to 11.03 ng/L. The types and contents of antibacterials detected in the Xicheng Canal were greater than those found in the Yangtze River, and two kinds of diterpenes, namely tiamulin and valnemulin, were found easily and commonly in water sample. The findings indicate that antibacterial agents are widespread in environmental waters. The developed method is accurate, sensitive, rapid, and suitable for the detection of the 43 antibacterial compounds in water samples.

Determination of kojic acid in fermented foods by solid-phase extraction coupled with ultra performance liquid chromatography-tandem mass spectrometry

Kojic acid naturally appears in fermented foods and can be formed during the aerobic fermentation process induced by Aspergillus and Penicillium fungi. It is widely used in the food industry because it exhibits antibacterial and antifungal properties and does not affect food taste. However, recent studies indicate that kojic acid may be a potential carcinogen. Therefore, assessing the health risks of kojic acid in fermented foods are of great importance, and developing a sensitive and accurate analytical method for this compound is a significant endeavor. Much efforts have been devoted to the detection of kojic acid using electrochemistry, high performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). HPLC and HPLC-MS/MS are the analytical techniques most often employed for this purpose. Of these two methods, HPLC-MS/MS displays excellent sensitivity and is the optimal selective technique. Pretreatment is usually necessary for kojic acid determination because of the complex matrix effects of fermented foods. However, few researches on the determination of kojic acid in food are available, and, to the best of our knowledge, the determination of kojic acid using solid-phase extraction (SPE) pretreatment has not been reported yet. Herein, a convenient, sensitive, and accurate method was developed to determine kojic acid in fermented foods using solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). The pretreatment conditions, such as the extraction solvent, cartridge, rinse solvent, and eluent, were systematically optimized. The samples, including soy sauce, vinegar, liquor, sauce, fermented soya bean, and fermented bean curd, were extracted with 0.1% formic acid-absolute ethyl alcohol and purified using a PRiME HLB cartridge. Kojic acid was separated using an ACQUITY UPLC® BEH C18 column (100 mm×2.1 mm, 1.7 μm) with formic acid-acetonitrile (1∶999, v/v) and formic acid-5 mmol/L ammonium acetate (1∶999, v/v) solutions as the mobile phases under gradient elution mode. MS was performed in electrospray positive ionization (ESI+) and multiple reaction monitoring (MRM) modes. An internal standard method was used for quantification. Under optimized conditions, good linearity was achieved at mass concentrations of 5.0-100.0 μg/L, with a correlation coefficient (r) of 0.9994. The limits of detection and quantification of the method for kojic acid were 2-5 μg/kg and 6-15 μg/kg, respectively. Good recoveries of 86.8%-111.7%, intra-day precisions of 1.0%-7.9% (n=6), and inter-day precisions of 2.7%-10.2% (n=5) were also obtained. The matrix effect was evaluated by establishing a matrix-matching calibration curve, and weak inhibitory effects were found in vinegar and liquor; moderate inhibitory effects in fermented bean curd, fermented soya bean, and soy sauce; and a strong inhibitory effect in sauce. The developed method was used to detect kojic acid in 240 fermented foods, and the results showed that the detection rate of vinegar was the highest, followed by liquor, sauce, soy sauce, fermented soya bean, and fermented bean curd, the contents were 5.69-2272 μg/kg. Matrix interferences can be significantly reduced by optimizing the pretreatment and detection procedures. The proposed method is sensitive, accurate, and can be used to analyze kojic acid in fermented foods.

Uncovering an Emerging Group of Halogenated Nucleobase-Derived Disinfection Byproducts in Drinking Water: Prioritization of the Highly Cytotoxic 2-Chloroadenine.

Constant efforts have been devoted to exploring new disinfection byproducts in drinking water causally related to adverse health outcomes. In this study, five halogenated nucleobases were identified as emerging disinfection byproducts in drinking water, including 5-chlorouracil, 6-chlorouracil, 2-chloroadenine, 6-chloroguanine, and 5-bromouracil. We developed a solid phase extraction-ultraperformance liquid chromatography-tandem mass spectrometry method with the limits of detection (LOD) and recoveries ranging between 0.04-0.86 ng/L and 54-93%, respectively. The detection frequency of the five halogenated nucleobases ranged from 73 to 100% with a maximum concentration of up to 65.3 ng/L in the representative drinking water samples. The cytotoxicity of the five identified halogenated nucleobases in Chinese hamster ovary (CHO-K1) cells varied with great disparity, in which the cytotoxicity of 2-chloroadenine (IC50 = 9.4 μM) is appropriately three times higher than emerging DBP 2,6-dichloro-1,4-benzoquinone (IC50 = 42.4 μM), indicating the significant toxicological risk of halogenated nucleobase-DBPs. To the best of our knowledge, this study reports the analytical method, occurrence, and toxicity of halogenated nucleobase-DBPs for the first time. These findings will provide a theoretical basis for further research on probing the relationship between its mutagenicity and human health risk.

Determination of three penicillin residues in milk by solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry using a covalent triazine framework sorbent

A method based on solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) was established for the determination of gpenicillin, cloxacillin, ampicillin residues in milk. Using self-made covalent triazine frameworks (CTFs) as the solid-phase extraction sorbents, the main factors influencing the efficiency of the solid-phase extraction columns, such as the sorbent amount, eluent type, eluent volume, and flow rate, were optimized. The extraction and purification conditions for the samples were also investigated. The optimal extraction effect was achieved at a flow rate of 3 mL/min with 60 mg CTFs and 6 mL eluent solution (acetonitrile). Separation was carried out on a Waters ACQUITY UPLC BEH C18 column, and 0.1% formic acid aqueous solution-acetonitrile was used as the mobile phases for gradient elution. The filtrate was detected by ultra performance liquid chromatography-tandem mass spectrometry, identified by electrospray ionization (ESI) in the positive mode using multiple reaction monitoring, and quantified using external standards. The calibration curves of the three penicillins showed good linearity and the correlation coefficients of the linear regression equations for the three target analytes were all greater than 0.999. The limits of detection (LODs) and limits of quantification (LOQs) were 0.05-0.10 μg/kg and 0.1-0.4 μg/kg, respectively. The average recoveries of the three analytes were 84.9%-94.1%, and the relative standard deviations (RSDs, n=5) were 1.66%-3.27%. Moreover, the mechanism of interaction between the CTFs and the target analytes was analyzed. The results revealed the existence of π-π and hydrogen-bond interactions between the CTFs and analytes. The results further indicated that the CTFs could be successfully used for the enrichment and purification of penicillins in milk. The proposed method has the advantages of high precision, good reproducibility, high resolution, and short analysis time, and it is suitable for the qualitative and quantitative determination of trace targets in complex matrices.

Determination of five nonsteroidal anti-inflammatory drugs in water by dispersive solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry based on metal-organic framework composite aerogel

非甾体类抗炎药(NSAIDs)能在环境水体中长期稳定存在,不仅对生物有慢性毒性还能增加病原体的耐药性,开发可靠的测定水样中痕量非甾体抗炎药的分析方法至关重要。该文制备新型金属有机骨架/壳聚糖复合气凝胶材料Co-UiO-67(bpy)/CS分散固相萃取吸附剂,将其用于环境水体中酮洛芬、萘普生、氟比洛芬、双氯芬酸、布洛芬5种非甾体类抗炎药的富集,结合超高效液相色谱-串联质谱法(UPLC-MS/MS),建立了基于金属有机骨架材料(MOFs)复合气凝胶环境水体中药物残留检测的新方法。为获得最佳的萃取效率,对影响萃取效果的主要因素(材料类型、MOFs用量、萃取时间、水样pH值、离子强度、甲酸体积分数、洗脱时间、洗脱剂体积)进行条件考察及优化。优化结果显示,吸附剂5 min内就可实现目标化合物的完全吸附,用总体积为5 mL的1%甲酸甲醇溶液洗脱6 min,目标化合物就能充分解吸。在最优的固相萃取条件下建立分析方法,结果表明,5种非甾体类抗炎药在各自范围内线性关系良好,线性相关系数均大于0.9937,方法的检出限(LOD)和定量限(LOQ)分别为0.32~2.06 ng/L和1.05~6.78 ng/L。在40、250和1500 ng/L 3个加标水平下进行加标回收试验,5种待测物的平均回收率为74.5%~114.1%。日内、日间相对标准偏差分别为1.3%~12.3%和1.3%~11.5%。将该方法用于实际水样的检测,市政污水检测出微量的酮洛芬和氟比洛芬,含量分别为14.52 ng/L和10.05 ng/L。该方法具有良好的灵敏度、准确度和精密度,操作简便,耗时短,为环境水体中痕量非甾体抗炎药富集检测提供了新方法。

Determination of seven phenoxy acid herbicides in water by dispersive solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry based on cationic metal-organic framework mixed matrix membrane

离子型金属有机骨架材料(iMOFs)对离子型化合物具有良好的选择吸附性,利用水热法合成了一种金属有机骨架材料MIL-101-NH2,以聚偏二氟乙烯(PVDF)为交联剂将其制备成混合基质膜(MMM),然后用三氟甲烷磺酸甲酯进行季胺基功能化改性,最终得到阳离子型金属有机骨架膜材料MIL-101-$NMe_{3}^{+}$-PVDF MMM,采用分散固相萃取方式富集水中的苯氧羧酸类除草剂,建立了一种基于阳离子型MOF混合基质膜的分散固相萃取-超高效液相色谱-串联质谱(UPLC-MS/MS)测定水体中7种苯氧羧酸类除草剂的分析方法。通过傅里叶变换红外光谱和扫描电子显微镜对制备的混合基质膜进行表征,结果表明季胺基功能化改性是成功的,得到了阳离子型MOF膜。对影响萃取效果的主要因素(吸附剂用量、水样pH值、萃取时间、洗脱剂种类、洗脱剂体积及洗脱时间)进行了优化,确定了最佳萃取条件。以0.01%(v/v)甲酸水溶液和乙腈作为流动相进行梯度洗脱,目标化合物在ACQUITY UPLC BEH C18色谱柱(100 mm×2.1 mm, 1.7 μm)上分离,在电喷雾电离源、负离子模式下进行多反应监测(MRM),外标法定量。结果表明,7种苯氧羧酸类除草剂在各自范围内线性关系良好,线性相关系数均大于0.997,方法的检出限(LOD)和定量限(LOQ)分别为0.00010~0.00090 μg/L和0.00033~0.00300 μg/L。在0.005、0.05和0.2 μg/L 3个加标水平下进行加标回收率试验,7种待测物的平均回收率为80%~102%,日内、日间相对标准偏差分别为1.4%~9.4%和4.2%~12.6%。该方法操作简单、快速,灵敏度高,适用于环境水体中7种苯氧羧酸类除草剂的检测。

Determination of nine ginsenosides in health foods by solid extraction phase-ultra performance liquid chromatography-tandem mass spectrometry

建立了以固相萃取结合超高效液相色谱-串联质谱(UPLC-MS/MS)同时检测保健食品中9种原人参二醇型和原人参三醇型人参皂苷的方法。保健食品中人参皂苷经过提取后,通过Alumina-N/XAD-2 SPE柱净化,在Hypersil Gold C18色谱柱(100 mm×2.1 mm, 1.9 μm)上分离,利用乙酸铵溶液(含0.1%甲酸)和乙腈作为流动相进行梯度洗脱,采用负离子扫描,多反应监测模式测定,外标法定量。研究通过对不同填料的固相萃取小柱的考察,最终选择了Alumina-N/XAD-2复合填料,其能对保健食品复杂基质中的人参皂苷进行有效富集和净化;通过考察人参皂苷的电离裂解过程,确定人参皂苷一级质谱准分子离子和相应的碎片离子,并经过色谱条件的优化,使质谱条件下一级质谱准分子离子和相应的碎片离子均一致的3种原人参二醇型人参皂苷Rb2、Rb3、Rc同分异构体实现完全分离。结果表明,9种人参皂苷在0.005~0.5 μg/mL范围内具有很好的线性关系,相关系数均大于0.9950。方法的加标回收率为81.1%~114.2%,相对标准偏差为0.4%~8.0%。所建立的方法采用XAD-2大孔吸附树脂和中性氧化铝的复合固相萃取材料,保健食品经过简单提取可直接作为固相萃取的上样溶液进行人参皂苷的富集和净化,通过超高效液相色谱-串联质谱不仅缩短了分析时间,也能对复杂基质样品中含量相对较低的人参皂苷进行准确定性和定量。该方法通量高,简单快速,重复性好,适用于保健食品中9种人参皂苷的定性和定量分析。

Determination of 18 pesticide residues in environmental water by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry

A method was developed for the simultaneous determination of 18 pesticide residues in environmental water by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). The samples were purified and enriched by a large-volume SPE apparatus through a Cleanrt®-PEP SPE column at a rate of 2 mL/min. After being concentrated 50-fold, the samples were detected by UPLC-MS/MS and quantified by the external standard method. The target compounds showed good linearity in the range of 0.5-50 μg/L, with linear correlation coefficients (R2) ≥0.995. At spiked levels of 10, 100 and 1000 ng/L, the average recoveries of the 18 pesticides in the three different environmental water samples were 71.3%-105.9%, and the relative standard deviations (RSDs, n=5) were 1.3%-9.9%. LOQs of the 18 pesticides were 10 ng/L. The method was applied to the detection of the water environment around Tai'an City, and no pesticide residues were detected at any of the collection sites. The method has the advantages of good purification effect, high versatility, sensitivity, and accuracy, and operational simplicity. The method is suitable for the determination of the 18 pesticides in environmental water.

Determination of diazepam in aquatic products by ultra performance liquid chromatography-tandem mass spectrometry with pass-through solid phase extraction

A method was developed for the determination of diazepam in aquatic products by pass-through solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The analyte was extracted with acetonitrile directly and purified on a Prime HLB solid phase extraction column (60 mg/3 mL). The separation was performed on an Acquity UPLC BEH C18 column (100 mm×2.1 mm, 1.7 μm)using methanol-0.1% (v/v) formic acid aqueous solution as the mobile phase in gradient elution mode. Qualitative analysis was performed in the multiple reaction monitoring (MRM) mode. The analyte was quantified by matrix-matched external standard curves. The results showed good linear relationship in the range of 0.1-10 ng/mL, and the correlation coefficient (r2) was greater than 0.99. The spiked recoveries of diazepam were 88.2%-101.1% at the spiked levels of 1.5, 3.0 and 15.0 μg/kg, and both the intra-and inter-day precisions were less than 10%. The developed method is simple, rapid and accurate, and it can meet the requirements for diazepam determination in aquatic product samples.

Determination of 3,5-Dinitrosalicylic Acid Hydrazide in Honey by Solid-Phase Extraction–Ultraperformance Liquid Chromatography–Tandem Mass Spectrometry

3,5-Dinitrosalicylic acid hydrazide (DNSAH) is the metabolite of the antibacterial nitrofuran nifursol. A simple and accurate analytical method to determine DNSAH levels in honey by solid-phase extraction-ultraperformance liquid chromatography-tandem mass spectrometry has been established. The honey sample was hydrolyzed under acidic conditions and derivatized with 2-nitrobenzaldehyde in the dark for 16 h, followed by solid-phase extraction and column chromatography. Detection was performed with an electrospray ionization source and multiple reaction monitoring mode and was quantified by the internal standard method. The detection and quantitative limits of DNSAH in honey were 0.1 and 0.3 μg/kg, respectively. Good linear relationships between peak areas and mass concentrations of the analyte were achieved in the range of approximately 0.1 to 200 μg/L, with the correlation coefficient >0.9991. Under the concentration levels of 0.2, 0.5, 1.0, and 2.0 μg/kg, the average recovery rate were between 98.5 and 102.3%, and the relative standard deviations were between 1.1 and 5.4%. The results indicate that the method is simple, rapid, sensitive, and reproducible and can be used to determine DNSAH levels in different types of honey.

Determination of the Residue Behavior and Risk Assessment of Chlorfluazuron in Chinese Cabbage, Kale, Lettuce and Cauliflower by UPLC-MS/MS.

Chlorfluazuron is used as a highly effective insect growth regulator to control a variety of crop pests. However, residues of this pesticide have been shown to be harmful to human health. To evaluate the residual dissipation pattern and risk for dietary intake of chlorfluazuron in various vegetables, a solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry method was established to analyze chlorfluazuron residues in Chinese cabbage, Chinese kale, Chinese lettuce, and cauliflower. The sample was extracted with acetonitrile and purified using an SPE amino column. The average recovery of the target sample in the analyzed four vegetables was between 75.0% and 104.1%, and the relative standard deviation was between 2.5% and 9.6%. The precision and accuracy of the analysis met the requirements of residue analysis standards. Dissipation kinetic testing of chlorfluazuron in different vegetables showed a half-life of 2.4–12.6 days, with a rapid dissipation rate. The estimated daily intake of the chlorfluazuron was 0.753–1.661 μg/(kg bw·d), and the risk quotient was 0.15–0.35. It showed that chlorfluazuron had a low risk of chronic dietary intake from vegetables in different populations in China. The results of this study has described the degradation rate of chlorfluazuron in four vegetables, evaluated the risk of dietary exposure to Chinese residents. Therefore, it provides supporting data and empirical basis for guiding the reasonable use of chlorfluazuron in vegetable production and in evaluating its dietary intake risk in vegetables.

Occurrence and ecological risk of pharmaceuticals and personal care products (PPCPs) and pesticides in typical surface watersheds, China

To evaluate the occurrence and ecological risk of organic contaminants in aquatic environment in China, a method for simultaneously detecting 130 pharmaceuticals and personal care products (PPCPs) and 35 pesticides has been established using solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) method. In the present survey, a total of 122 target compounds (103 PPCPs and 19 pesticides) were detected in seven major watersheds in China, with average concentrations ranged from 0.02 ng/L (sulfamerazine) to 332.75 ng/L (bisphenol A), revealing that PPCPs and pesticides were widely distributed in surface water of China. Antibiotics and organophosphorus were the most ubiquitously PPCPs and pesticides, respectively; quinolones were the predominant antibiotics, most of which were detected in more than 96% sampling sites, with average concentrations ranged from 2.14 to 309.67 ng/L; six pesticides including isoprocarb, fenobucarb, acetamiprid, imidacloprid, acetochlor and bentazone were detected in more than 80% sampling sites, with average concentrations ranged from 5.62 to 225.93 ng/L; more than half of the non-antibiotic pharmaceuticals were hormones; and diethyltoluamide (DEET) was predominant personal care products; The risk assessment showed that each watershed was at potential medium ecological risk based on their mean concentration (RQTotal > 1), and pesticides were the main compounds arising risks.

Rapid determination of ultra-trace levels of atrazine in surface water by on line solid phase extraction coupled with ultra-performance liquid chromatography-tandem mass spectrometry

A method for the determination of ultra-trace atrazine in surface water was developed based on on line solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (on line SPE-UPLC-MS/MS). The water sample was directly injected into an on line SPE system after filtering using a 0.22 μm filter membrane. An HLB Direct Connect HP column was used for the enrichment and purification of the water sample and eluted using a methanol solution. The analyte was separated on an Acquity BEH 130 column, and then detected by tandem mass spectrometry. The analyte was quantified with external standard method. There was a good linear relationship in the range of 1.0-5000 ng/L. The correlation coefficient (r) was 0.9989. The method detection limit was 0.2 ng/L. The recoveries of atrazine ranged from 83.0% to 105.1%. The relative standard deviation was 1.6%-5.3% (n=7), which met the requirements of trace analysis. The method is sensitive, fast and effective, and it is suitable for the determination of atrazine in surface water. It is important to ensure the safety of the water environment, provide timely pollution information, and effectively respond to environmental emergencies.

Dietary Epicatechin Is Available to Breastfed Infants through Human Breast Milk in the Form of Host and Microbial Metabolites

Polyphenols play an important role in human health. To address their accessibility to a breastfed infant, we planned to evaluate whether breast milk (BM) (colostrum, transitional, and mature) epicatechin metabolites could be related to the dietary habits of mothers. The polyphenol consumption of breastfeeding mothers was estimated using a food frequency questionnaire and 24 h recalls. Solid-phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) was applied for direct epicatechin metabolite analysis. Their bioavailability in BM as a result of dietary ingestion was confirmed in a preliminary experiment with a single dose of dark chocolate. Several host and microbial phase II metabolites of epicatechin were detected in BM among free-living lactating mothers. Interestingly, a modest correlation between dihydroxyvalerolactone sulfate and the intake of cocoa products was observed. Although a very low percentage of dietary polyphenols is excreted in BM, they are definitely in the diet of breastfed infants. Therefore, evaluation of their role in infant health could be further promoted.

Method development and validation: solid Phase extraction-ultra performance liquid chromatography-tandem mass spectrometry quantification of pirlimycin in bovine feces and urine.

Pirlimycin, a lincosamide antibiotic, is one of the most commonly used antibiotics for the treatment of mastitis in dairy cows. Assessment of pirlimycin loadingto the environment via fecal and urinary excretion is critical to develop efficient management strategies to reduce environmental pollution by the livestock industry. Therefore, the aim of this study was to develop and validate an analytical method to identify and quantify pirlimycin in bovine feces and urine. Samples were extracted with methanol- phosphate buffer and cleaned up by SPE before analysis for pirlimycin using UPLC-MS/MS. This method was sensitive (LOQ 1.47 ng/g wet feces, 0.90 ng/mL urine), accurate (recovery, 80-108%), and precise (repeatability, 2.3-13%; reproducibility, 2.3-14%) for both bovine feces and urine. With the application of this method to samples collected in the first 10 h and then every 24 h for 120 h following intramammary dosing (50 mg/cow; n = 3 cows), pirlimycin was detected at 40.5-287 ng/g and 46.1-254 ng/mL in feces and urine, respectively. This robust, sensitive, and accurate method can be used to assess the fate and environmental impact of antibiotics used on farms.

Simultaneous determination of three estrogens in feed by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry

A method was developed for the simultaneous determination of three estrogens (17β-estradiol, estradiol benzoate, estradiol valerate) in feed by solid phase extraction-ultra performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS). After the sample was extracted by acetonitrile and cleaned-up on a Heaion C18 solid phase extraction (SPE) column, the three estrogens were separated by an ACQUITY UPLC BEH C18 column (50 mm x 2.1 mm, 1.7 μm) with gradient elution using acetonitrile and 0.1% ammonia solution as mobile phases and finally confirmed and quantified in multiple reaction monitoring (MRM) mode. The internal standard calibration curves were used for the quantification. The results showed that all the estrogens were determined with excellent linear relationships from 10 μg/L to 200 μg/L for 17β-estradiol and estradiol valerate, and from 5 μg/L to 200 μg/L for estradiol benzoate. The correlation coefficients (r) of the three estrogens were not lower than 0. 996. The limits of detection for 17β-estradiol, estradiol benzoate and estradiol valerate were 7 μg/kg, 5 μg/kg and 7 μg/kg, respectively. The average recoveries were 96.5%-102.0%. The results demonstrated that the developed method can simultaneously determine the three estro- gens in feed with advantages of simple pretreatment, rapid analysis, low limit of detection and high accuracy.