Chemical profiling and characterization of phenolic acids,flavonoids, terpene glycosides from Vangueria agrestis using ultra-high-performance liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry and metabolomics approach

Vangueria agrestis is a shrub indigenous to tropical Africa, belonging to family Rubiaceae and is traditionally used as a decoction for treatment of fever, pain, and malaria. This study was undertaken to investigate the chemical constituents based on precursor exact mass and fragment ion information. The chemical profiling and structural characteristics of chemical constituents from methanolic extracts of dried aerial parts and roots of V. agrestis and dietary supplements were analyzed using ultra-high-performance liquid chromatography/ion mobility quadrupole time-of-flight mass spectrometry coupled with UNIFI platform and multivariate analysis in both negative and positive ion modes. A non-targeted ultra-high-performance liquid chromatography-mass spectrometry analysis was carried out to profile the chemical constituents of crude extracts of V. agrestis, and 73 compounds, including reference compounds, were identified. The fragments of flavonoids, monoterpene, and triterpene glycosides revealed the characteristic cleavage of glycosidic linkages, and the fragmentation pattern provided the identity of the sugars. This analytical method provides a quick method for quality assessment of dietary supplements. Finally, a chemometrics approach with multivariate statistical tools was used to visualize the differences between root and aerial parts of plant samples and to find the potential chemical markers that differentiate among these parts of V. agrestis samples and dietary supplements.     

液相色谱-四极杆/ 飞行时间质谱快速筛查与确证苹果、番茄和甘蓝中的281种农药残留

建立了苹果、番茄和甘蓝中281种农药残留的QuEChERS结合液相色谱-四极杆/飞行时间质谱(LC-Q-TOF/MS)快速筛查方法。方法采用1%醋酸乙腈提取样品,经丙基乙二胺(PSA)净化,LC-Q-TOF/MS测定。281种农药在苹果、番茄和甘蓝中3个添加水平下的回收率在70%～120%范围的比例分别为98.6%、99.3%和98.2%;回收率的相对标准偏差(RSD)均≤20%(n=5);在0.25～10倍最大残留限量(MRL)的含量范围内,线性相关系数r²≥0.99的农药比例分别为95.7%、96.1%和98.2%;检出限分别为0.03～4.47、0.01～4.49和0.02～3.61 μg/kg。本方法采用精确质量数据库和谱图库检索的方式,实现了不用农药标准品对照而完成对果蔬中农药残留的快速筛查,提高了定性鉴别的准确性。应用所建立的方法对30个市售果蔬样品进行筛查,共检出13种农药残留。其中,甘蓝中甲胺磷的含量超过了GB 2763-2012《食品安全国家标准\5食品中农药最大残留限量》和欧盟的MRL;番茄中鱼藤酮的含量超出欧盟的MRL。     

液相色谱-四极杆/ 飞行时间质谱快速筛查与确证苹果、番茄和甘蓝中的281种农药残留

建立了苹果、番茄和甘蓝中281种农药残留的QuEChERS结合液相色谱-四极杆/飞行时间质谱(LC-Q-TOF/MS)快速筛查方法。方法采用1%醋酸乙腈提取样品,经丙基乙二胺(PSA)净化,LC-Q-TOF/MS测定。281种农药在苹果、番茄和甘蓝中3个添加水平下的回收率在70%～120%范围的比例分别为98.6%、99.3%和98.2%;回收率的相对标准偏差(RSD)均≤20%(n=5);在0.25～10倍最大残留限量(MRL)的含量范围内,线性相关系数r²≥0.99的农药比例分别为95.7%、96.1%和98.2%;检出限分别为0.03～4.47、0.01～4.49和0.02～3.61 μg/kg。本方法采用精确质量数据库和谱图库检索的方式,实现了不用农药标准品对照而完成对果蔬中农药残留的快速筛查,提高了定性鉴别的准确性。应用所建立的方法对30个市售果蔬样品进行筛查,共检出13种农药残留。其中,甘蓝中甲胺磷的含量超过了GB 2763-2012《食品安全国家标准\5食品中农药最大残留限量》和欧盟的MRL;番茄中鱼藤酮的含量超出欧盟的MRL。     

超高效液相色谱-四极杆-飞行时间质谱定性研究茶叶籽中的酚类化合物

采用超高效液相色谱(UHPLC)-四极杆-飞行时间质谱(Q-TOF/MS)技术定性分析茶叶籽中的酚类化合物。茶叶籽样品经乙醇水溶液提取后经反相色谱分离,通过Q-TOF/MS进行化合物的鉴定。基于山茶属及相关植物化学组成的文献,建立了一个含有106种酚类化合物的数据库。对UHPLC-Q-TOF/MS采集得到的一级质谱数据进行数据库检索,然后对检索到的化合物色谱峰进行二级质谱扫描,根据得到的碎片离子推断化合物的结构。初步推断出茶叶籽提取物中的24种酚类化合物,包括13种酚酸类、4种儿茶素类和7种黄酮类化合物,并通过与标准品比对,进一步确证了这些化合物。结果表明UHPLC-Q-TOF/MS技术可以用于对茶叶籽中酚类化合物进行快速、准确、可靠的定性分析,促进新化合物的发现与鉴别。     

Screening of antibiotics in surface and wastewater samples by ultra-high-pressure liquid chromatography coupled to hybrid quadrupole time-of-flight mass spectrometry

The potential of ultra-high-pressure liquid chromatography (UHPLC) coupled to hybrid quadrupole time-of-flight mass spectrometry (QTOF–MS) for the screening and confirmation of antibiotics in water samples is illustrated in this paper. UHPLC presents several advantages over conventional liquid chromatography as it generates narrow peaks (increasing peak height and improving sensitivity) and reduces chromatographic runs. Regarding QTOF–MS, its increased mass resolution, high sensitivity in full-spectrum acquisition mode and mass accuracy, in both MS and MS/MS modes, make this technique ideal for the detection and reliable confirmation of organic contaminants in environmental samples. After a solid-phase extraction using Oasis HLB cartridges, UHPLC–QTOF–MS has been applied in this work to several types of water samples (surface water and influent and effluent wastewaters). Several antibiotics were found in the samples, such as ofloxacin, ciprofloxacin, clarythromycin or erythromycin, among others. Moreover, the full spectrum data provided by TOF–MS acquisition has enabled searching for many other pharmaceuticals that could be present in the samples in a “post-target” way. This approach has allowed the detection and confirmation of paracetamol, omeprazole and codeine, among others. UPLC–QTOF–MS has been shown as an attractive and efficient hyphenated technique for the rapid detection and confirmation of pharmaceuticals in water with very little sample handling.     

液相色谱/四极杆-飞行时间质谱法筛查奶酪中29种禁用和限用合成色素

建立了奶酪样品中29种禁用和限用合成色素的液相色谱/四极杆-飞行时间质谱(LC/Q-TOF MS)筛查方法。样品经正己烷-水(3:1, v/v)振荡提取,得到正己烷层、水层和残渣3部分。正己烷层经旋转蒸发浓缩后,用乙酸乙酯-环己烷(1:1, v/v)溶解,经过凝胶渗透色谱(GPC)净化去除油脂。水层经乙腈振荡提取,得到乙腈-水提取液。残渣经氨水-甲醇(1:99, v/v)溶液振荡提取,得到氨水-甲醇提取液。乙腈-水提取液和氨水-甲醇提取液不需净化直接分析。结果表明: 29种不同极性范围的合成色素化合物分别得到了有效的提取,提取回收率为70%～95%。而Q-TOF MS提供的精确质量数定性功能可以将不同种类的合成色素化合物筛查出来,各化合物与精确质量质谱库中化合物的匹配度为59.66～99.47。通过Target MS/MS扫描方式进行定量,得到8种苏丹类化合物的方法检出限为0.4～2.5 μg/kg, 21种水溶性合成色素及染料化合物的检出限为20～80 μg/kg。该方法对禁用和限用合成色素的筛查范围广泛,对含有蛋白质、脂肪等基质的食品具有较好的适用性。     

A comprehensive study of celastrol metabolism in vivo and in vitro using ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry

Celastrol has attracted great attention owing to its anti-arthritis, antioxidant, and anticancer activities. Nevertheless, its metabolism in vivo (rats) and in vitro (rat liver microsomes and intestinal flora) has not been comprehensively characterized. In this study, ultra-high-performance liquid chromatography coupled with hybrid triple quadrupole time-of-flight mass spectrometry was used as a rapid and sensitive approach for studying the metabolism of celastrol in vivo and in vitro. A total of 43 metabolites were identified and characterized. These include 26 metabolites in vivo, and 28 metabolites in vitro (nine metabolites in rat liver microsomes and 24 metabolites in rat intestinal flora). Additionally, the celastrol-biotransformation capacity of the intestinal tract was confirmed to exceed that of the liver. Furthermore, the metabolic profile of celastrol is summarised. The information obtained from this study may provide a basis for understanding the pharmacological mechanisms of celastrol and will be beneficial for clinical applications.     

Assessment of benzophenone-4 reactivity with free chlorine by liquid chromatography quadrupole time-of-flight mass spectrometry

The stability of the UV filter benzophenone-4 (BP-4) in free chlorine-containing water was investigated, for the first time, by liquid chromatography quadrupole time-of-flight mass spectrometry (LC–QqTOF-MS). High mass accuracy and resolution capabilities of this hybrid mass spectrometer were used for the reliable assignation of empirical formulae and chemical structures of BP-4 derivatives. Time-course profiles of the parent compound and its by-products were simultaneously recorded by direct injection of sample aliquots, after quenching the excess of chlorine, in the LC–QqTOF-MS system. At neutral pHs, in excess of chlorine, BP-4 showed a limited stability fitting a pseudo-first-order degradation kinetics. A noticeable reduction in the half-lives of BP-4 was observed when increasing the sample pH between 6 and 8 units and also in presence of bromide traces. The reaction pathway of this UV filter involved a first electrophilic substitution of hydrogen per chlorine (or bromide) in the phenolic ring, followed by oxidation of the carbonyl moiety to an ester group, which induced a further electrophilic substitution in the same aromatic ring. Above reactions were also noticed when mixing a BP-4 containing personal care product with chlorinated tap water and in chlorinated swimming pool and sewage water, previously spiked with a BP-4 standard.     

Identification and quantitative analysis of the chemical constituents of Gandouling tablets using ultra-high-performance liquid chromatography with quadrupole time-of-flight mass spectrometry

Gandouling tablets are used in a clinical agent for the treatment of hepatocellular degeneration; however, their chemical constituents have not been elucidated. Here, we screened and identified the chemical constituents of Gandouling tablets using ultra-high-performance liquid chromatography (UHPLC)-quadrupole time of flight/mass spectrometry. A method for the quality evaluation of Gandouling tablets was developed by combining the UHPLC fingerprints and the simultaneous quantitative analysis of multiple active ingredients. For fingerprint analysis, 20 shared peaks were identified to assess the similarities among the 10 batches of Gandouling tablets and the similarity was >0.9. The levels of nine representative active ingredients were simultaneously determined to ensure consistency in quality. A total of 99 chemical components were identified, including 18 alkaloids, 20 anthraquinones, 13 flavonoids, 11 phenolic acids, 9 polyphenols, 7 phenanthrenes, 5 sesquiterpenes, 3 curcuminoids, 2 lignans, 2 isoflavones, 2 dianthranones, and 7 other components. The retention times, molecular formulae, and secondary fragmentation information of these compounds were analyzed, and the cleavage pathways and characteristic fragments of some of the representative compounds were elucidated. This systematic analysis used to identify the chemical components of Gandouling tablets lays the foundation for its further quality control and research on their pharmacodynamic substances.     

Multiresidue analysis of pesticides with hydrolyzable functionality in cooked vegetables by liquid chromatography tandem mass spectrometry

It would be preferable for pesticide residues substituted by hydrolyzable functionality to be analyzed after cooking because their structures are apt to degrade during boiling and/or heating. A liquid chromatography–tandem mass spectrometry (LC‐MS/MS) method for the quantitative determination of 44 pesticide residues with hydrolyzable functional group in five typical vegetable widely consumed in Republic of Korea is described. The sample clean‐up was carried out according to the method of Food Code No. 83 established by the Korea Food and Drug Administration (KFDA). Zorbox XDB‐C₁₈ column was selected for the analysis because of the best peak separation. The LC mobile phase consisted of water and 5 mm methanolic ammonium formate, which resulted in a peak shape with good symmetry at each run. Tandem mass spectroscopic (MS/MS) experiments were performed in ESI positive mode and the multiple reaction monitoring modes. A conventional matrix effect was modified to more comprehensive form 100γ_ij (%). A high matrix effect (相似文献   

基于超高效液相色谱-高分辨质谱的多肽组学技术用于人参不同部位多肽的差异分析

采用基于超高效液相色谱-高分辨质谱的多肽组学技术对人参主根、支根、须根和芦头的多肽谱进行全面分析,旨在评价人参不同形态区域多肽表达的异同。本研究共表征62个数据库中已收录的人参多肽。结果表明,人参不同部位均富含多肽类成分。多肽组学研究发现,人参主根和支根、芦头与须根之间多肽含量具有显著差异,从鉴定到的多肽中共发现25个稳定表达的已知潜在多肽标志物。其中多肽种类及含量在主根与其他部位间差异最显著,为主根与非主根药效差异研究提供了新思路。本研究揭示了人参多肽结构多样性及人参不同部位人参多肽表达的异同,对人参化学特征评价具有重要意义,为人参质量控制和合理应用提供了化学依据。     

Determination of priority pesticides in baby foods by gas chromatography tandem quadrupole mass spectrometry

A gas chromatography-tandem quadrupole mass spectrometry (GC-MS/MS) method for the determination of twelve priority pesticides, and transformation products (e.g. metabolites) specified in the EU Baby Food Directive 2003/13/EC is described. Prior to GC-MS/MS analysis, co-extractives were removed from acetonitrile extracts using dispersive solid phase extraction with octadecyl (200 mg) and primary secondary amine (50 mg) sorbents. The clean up proved essential for the satisfactory long-term chromatographic performance during the analysis of a range of representative commercially pre-prepared baby food samples. Extracts spiked with pesticides at 1-8 microg kg(-1), yielded average recoveries in the range 60-113% with relative standard deviations less than 28%.     

Ultra-performance liquid chromatography coupled with high-resolution quadrupole time-of-flight mass spectrometry analysis of the impact of bran-processing on the chemical profile of Radix Paeoniae Alba (Baishao)

In this study, a rapid and versatile ultra-performance liquid chromatography coupled with high-resolution quadrupole time-of-flight mass spectrometry-based chemical profiling approach was applied to evaluate chemical constitution of crude and processed Radix Paeoniae Alba (RPA) samples. A total of 44 compounds were identified, among which the contents of 9 compounds in processed samples were obviously decreased and 8 compounds were increased. Furthermore, compound 28 was not found in RPA sample after stir-frying with wheat bran. The proposed method provided a chemical basis for exploring the processed mechanism of herbal medicine.     

Quantitative liquid chromatography/time-of-flight mass spectrometry

Over the last decade, time-of-flight (TOF) instruments have increasingly been used as quantitation tools. In addition, because of their high resolving power, they can be used for verification of empirical formulas. Historically, TOF instruments have had limited quantitation capabilities because of their narrow dynamic range. However, recent advances have improved these limitations. This review covers the rationale for using TOF for LC detection, and describes the many methods currently in the literature for the quantitation of pharmaceuticals, environmental pollutants, explosives and many phytochemicals.     

基于非靶标筛查的超高效液相色谱-三重四极杆质谱法检测尿液样品中的酰基肉碱

建立了一种基于母离子扫描模式的超高效液相色谱-三重四极杆质谱检测尿液中酰基肉碱的分析方法。对酰基肉碱类化合物所共有的m/z为60、85和144的碎片离子进行选择性检测,结合化合物母离子扫描的结果及其对应的保留时间,选取一致性较好的化合物进行筛选,再利用高分辨质谱确认,最终检测到37种酰基肉碱化合物,其中有14种尚未被HMDB和LIPID MAPS数据库收录。该方法可应用于其他生物样本(如血液、组织)中酰基肉碱的定性、定量分析,可作为检测酰基肉碱化合物的新选择。     

Chemical profiling and identification of Radix Cudramiae and their metabolites in rats using an ultra-high-performance liquid chromatography method coupled with time-of-flight tandem mass spectrometry

Radix Cudramiae, known as “Chuan-Po-Shi” in China, is a herbal medicine widely used in the southwest of the country, especially applied by the Miao and Zhuang nationalities for the treatment of liver diseases, such as acute liver injury and liver fibrosis. As a kind of ethnomedicine, the report on its chemical analysis was still blank, which restricted its clinical application. Therefore, this paper aimed to illustrate the chemical characteristics of Radix Cudramiae. A rapid analytical strategy based on ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry was developed to profile the natural small-molecular compounds in Radix Cudramiae, as well as the related prototypes and their metabolites in rats after drug administration. As a result, a total of 74 compounds were detected in the aqueous exact of Radix Cudramiae. In vivo, 45 chemicals including 16 prototypes and 29 metabolites in rat serum, along with 35 chemicals including 17 prototypes and 18 metabolites in rat liver, were screened out and identified. For the first time, the chemical constituents of Radix Cudramiae and their metabolic characteristics were discovered. It was hoped that this work would be beneficial for the safe and effective application of Radix Cudramiae in a clinic.     

液相色谱-四极杆/飞行时间质谱法快速筛查测定药物中芬太尼类物质

基于液相色谱-四极杆/飞行时间质谱(LC-QTOF-MS)建立了药物中27种新型毒品芬太尼类物质(芬太尼及其类似物)的同时快速筛查、确证和定量分析方法。样品经5 mL 75%(v/v)乙腈水溶液和5 mL乙腈提取,HLB固相萃取柱净化,电喷雾电离,正离子扫描,TOF-MS和信息依赖性采集(IDA)-MS/MS采集模式检测,外标法定量;建立一级精确质量数据库、保留时间和二级质谱库,实现了固体压片、粉末、液体药物及透皮贴剂中27种芬太尼类物质的快速筛查和确证。在5.00～100μg/L范围内,27种目标化合物的线性关系良好(r²>0. 99)。27种化合物的定量限均为10.0μg/kg。在维生素C压片、头痛粉、止咳水、透皮贴剂样品中3个添加水平的平均回收率范围分别82.9%～106%、84.8%～106%、86.9%～109%和83.1%～106%,相对标准偏差(RSD)为0.38%～8.71%(n=6)。本方法操作简便,耗时短,灵敏度高,稳定性好,适用于液体和固体药物中芬太尼类物质的筛查检测及定量分析,可显著降低检测成本,具有实际应用价值。     

Simultaneous enantioselective determination of six pesticides in aqueous environmental samples by chiral liquid chromatography with tandem mass spectrometry

A robust and sensitive method was developed for the enantiomeric analysis of six chiral pesticides (including metalaxyl, epoxiconazole, myclobutanil, hexaconazole, napropamide, and isocarbophos) in aquatic environmental samples. The optimized chromatographic conditions for the quantification of all the 12 enantiomers were performed with Chiralcel OD‐RH column using mobile phase consisting of 0.1% aqueous formic acid and acetonitrile operated under reversed‐phase conditions and then analyzed using liquid chromatography with tandem mass spectrometry. Twelve enantiomers were detected in multiple reaction monitoring mode. Solid‐phase extraction and dispersive liquid–liquid microextraction were employed in this study. Response surface methodology was applied to assist in the dispersive liquid–liquid microextraction optimization. Under the optimum conditions, recoveries of pesticides enantiomers varied from 83.0 to 103.2% at two spiked levels with relative standard deviation less than 11.5%. The concentration factors were up to 1000 times. Method detection and quantification limits varied from 0.11 to 0.48 ng/L and from 0.46 to 1.49 ng/L, respectively. Finally, this method was used to determination of the enantiomers composition of the six pesticides in environmental aqueous matrices, which will help better understand the behavior of individual enantiomer and make accurate risk assessment to ecosystems.     

Characterization of synthetic nucleic acids by electrospray ionization quadrupole time-of-flight mass spectrometry

The potential of electrospray ionization quadrupole-quadrupole-time-of-flight mass spectrometry (ESI-QqTOF-MS) for the characterization of synthetic nucleic acids was evaluated. Oligonucleotides ranging in size from 12 up to 51 nucleotides were analyzed via direct infusion MS as well as via liquid chromatography (LC) online hyphenated to MS. These experiments proved the outstanding mass spectrometric performance of the TOF mass analyzer in regard of accuracy, reproducibility, resolution, and sensitivity. During a 1-min run, the monoisotopic mass of (dT)(24) was measured with a maximum relative mass deviation of 7.64 ppm proving the high mass accuracy of the TOF analyzer. Over a period of 1 h, mean deviations were determined in the range between -3.58 ppm and 3.06 ppm demonstrating the high stability of the applied external calibration. The molecular mass of a 51-mer was measured with a deviation smaller than 3.23 ppm from the theoretical value. The resolution exceeded a value of m/Deltam = 20 000 (m is the measured mass and Deltam the full peak width at half-maximum), which enabled the separation of the isotopic peaks of all investigated oligonucleotides. Because of the outstanding transmission and detection efficiency of the TOF mass analyzer, detection limits in the amol/microl to low fmol/microl range were reached. The usability of LC-ESI-QqTOF-MS for the qualitative and quantitative analysis of synthetic oligonucleotide mixtures was demonstrated.