An untargeted and pseudotargeted metabolomic combination approach to identify differential markers to distinguish live from dead pork meat by liquid chromatography-mass spectrometry.

An untargeted and pseudotargeted metabolomic combination approach was developed to identify reliable and stable differential markers which can distinguish between pork meat from live pigs conventionally butchered and pork meat from dead pigs butchered immediately after death from diseases or other abnormalities. In this study, 24 differential metabolites of interest were screened by the UHPLC-Triple-TOF-MS-based untargeted metabolomic method, and 14 differential markers were detected by the UHPLC-QTRAP-MS-based pseudotargeted metabolomic method after performing statistical analysis to remove false-positive differential metabolites. Among the possible differential markers identified using the Metlin database and references were carnosine, l-carnitine, l-histidine, N-acetylhistidine, acetylcholine, l-acetylcarnitine and two phosphatidylcholines. The results of the principal component analysis (PCA) and the hierarchical clustering analysis (HCA) indicate that 14 differential markers could be potentially used to distinguish live and dead pork meat. This reliable and stable approach not only could detect the unknown differential markers, but also accurately quantify them.

A method for determining glyphosate and its metabolite aminomethyl phosphonic acid by gas chromatography-flame photometric detection.

As a globally popular herbicide, glyphosate (GLY) and its metabolite aminomethylphosphonic acid (AMPA) pose potential hazards to the ecological environment. In this study, a sensitive and reliable method for detecting GLY and AMPA was utilized to facilitate exposure risk assessment of the analytes in environmental systems such as water and soil. GLY and AMPA were extracted from the sample using a solid-phase extraction (SPE) procedure, derivatized by heptafluorobutyric anhydride and heptafluorobutanol, and detected by gas chromatography-flame photometric detection (GC-FPD). The linearities of GLY and AMPA in the range of 10-1000 ng/mL were good (r=0.9998, r=0.9991), and the limits of quantitation (LOQ) for GLY and AMPA were 0.37 and 0.81 ng/mL, respectively. The method has been successfully applied for detecting GLY and AMPA in water, soil and monitoring the degradation of GLY under different environmental conditions. Simulated migration characteristics of GLY and AMPA in soil were investigated for evaluating the potential hazards of GLY and AMPA to the ecological environment.

Studies on the metabolism and degradation of vancomycin in simulated in vitro and aquatic environment by UHPLC-Triple-TOF-MS/MS.

Vancomycin is one of the most commonly used glycopeptide antiobiotics, and as such is an important emerging environmental contaminant. Pharmaceuticals and personal care products (PPCPs), such as antibiotics, are problematic since wastewater treatment processes are not completely effective at removing these chemical compounds. Since wastewater treatment processes are not completely effective, vancomycin occurs in surface water. Vancomycin and its metabolites in vivo and degradation products in aquatic environment may lead to undesirable ecological effects that threaten the environment or cause undesirable reactions that affect human health. We aimed to study vancomycin metabolism in vitro and its natural degradation in aquatic environment, as well as explore for related metabolites and degradation products. Accordingly, we established four systems, using a constant temperature oscillator at 37 °C for 10 days for vancomycin in activated rat liver microsomes (experimental system), inactivated rat liver microsomes (control system), phosphate buffer saline (PBS system) and pure water (pure water system), as well as an additional system of activated rat liver microsomes without vancomycin (blank system). The metabolism and degradation of vancomycin were studied using a high resolution and high sensitivity ultra-high performance liquid chromatography (UHPLC)-Triple-time of flight (TOF)-mass spectrometry (MS) method in positive ion mode. The compared result of activated rat liver microsomes system and inactivated rat liver microsomes system confirms that vancomycin is not metabolized in the liver. Vancomycin was degraded in the four non-blank incubation systems. The MetabolitePilot 2.0 software was used for screening the probable degradation products, as well as for establishing its associated degradation pathways. Eventually, four degradation products were identified and their chemical structures were deduced. The results of this study provide a foundation for evaluation of the effects of vancomycin and its degradation products on environmental safety and human health in the future.

Development of a Method for Rapid Determination of Morpholine in Juices and Drugs by Gas Chromatography-Mass Spectrometry.

A reliable derivatization method has been developed to detect and quantify morpholine in apple juices and ibuprofen with gas chromatography-mass spectrometry. Morpholine can react with sodium nitrite under acidic condition to produce stable and volatile N-nitrosomorpholine derivative. In this experiment, various factors affecting the derivatization and extraction process were optimized, including volume and concentration of hydrochloric acid, quantity of sodium nitrite, derivatization temperature, derivatization time, extraction reagents, and extraction time. The derivative was extracted with dichloromethane and determined by gas chromatography-mass spectrometry. The linearity range of morpholine was 10-500 µg·L-1 with good correlation, and limits of detection (LOD) and limits of quantification (LOQ) were 7.3 µg·L-1 and 24.4 µg·L-1, respectively. Low, medium, and high concentrations of morpholine were added in apple juices and ibuprofen samples to evaluate standard recovery rate and relative standard deviation. The spiked recovery rate ranged from 94.3% to 109.0%, and the intraday repeatability and interday reproducibility were 2.0%-4.4% and 3.3%-7.0%, respectively. The developed method has good accuracy and precision. This quantitative method for morpholine is simple, sensitive, rapid, and low cost and can successfully be applied to analyze the residual morpholine in apple juices and drug samples.

Trace level determination of 5-hydroxytryptamine and its related indoles in amniotic fluid by gas chromatography-mass spectrometry.

5-hydroxytryptamine (5-HT) and its derivatives are endogenously active substances involved in multiple physiological and pathological processes. A novel method of detetermining 5-hydroxyindole ethanol (5-HTOL), 5-hydroxyindole acetic acid (5-HIAA), 5-hydroxytryptophan (5-HTP) and 5-HT in amniotic fluid by gas chromatography-mass spectrometry (GC-MS) was established based on a modified method of derivatization by silanization, in combination with solid-phase extraction pretreatment. Good linearity was achieved in the tested calibration range. The limits of detection (LOD) were 0.05, 0.08, 0.56, 0.43µg/L for 5-HTOL, 5-HIAA, 5-HTP and 5-HT, respectively. Accuracy (92.4-103.3) and precision (RSD <5.4%) for all analytes was also determined. Then the method was used to analyze samples of amniotic fluid from 12 patients carrying foetuses with trisomy 21 and 12 healthy controls. Compared with normal fetuses, the levels of 5-HTOL, 5-HTP and 5-HT in the amniotic fluid were significantly altered in the fetuses with trisomy 21 (P<0.01); the level of 5-HIAA showed no significant difference between the two groups (P>0.05). This is a rapid, sensitive and reliable method for the determination of 5-HTOL, 5-HIAA, 5-HTP and 5-HT, and the study provide both potential trisomy 21 markers and elucidation of the physiological and pathological roles of 5-HT.

[Quantitative risk assessment of the polycyclic aromatic hydrocarbons dietary exposure from edible fats and oils in China].

OBJECTIVE: To assess the quantitative risk of the polycyclic aromatic hydrocarbons (PAHs) dietary exposure from edible fats and oils in China. METHODS: One hundred samples of edible fats and oils were collected from the supermarkets and the farmers markets in 11 provinces of China from December in 2013 to May in 2014. Then they were tested for EU15+1 PAHs (16 PAHs were controlled in priority by European Food Safety Authority) by two test methods which were QuECHERS-GC-MS-MS and GPC-HPLC-FLD. Data of PAHs concentration and edible fats and oils consumption which were from Chinese National Nutrition and Health Survey in 2002 were combined to evaluate carcinogenic risk of PAHs in edible fats and oils by the method of margin of exposure (MOE). In this process, we divided the population into 6 groups, namely male adults (older than 18 years old), female adults (older than 18), male youths (13-17), female youths (13-17), school-agers (6-12) and preschoolers (2-5), and thought carcinogenicity as the critical toxicity end point of PAHs. Two quantitative risk assessment methods, i.e. point assessment and probability assessment, were used to evaluate the dietary exposure and MOEs. RESULTS: EU15+1 PAHs in one of 100 samples were not detected, other samples were polluted in different degrees; the detection rates were 3%-98% and the average contents were 0.26-3.26 µg/kg. The results of PAHs dietary exposure from both of point assessment and probability assessment were the same. The average exposures of PAH8 were as the following: male adults were 10.03 and (9.34 ± 12.61) ng·kg(-1)·d(-1)(The former was from point assessment and the latter from probability assessment, the same below), female adults were 9.95 and (9.60 ± 15.04) ng · kg(-1)·d (-1), male youths were 11.09 and (10.84 ± 16.54) ng·kg(-1)·d(-1), female youths were 10.06 and (9.58 ± 12.87) ng·kg(-1)·d(-1),school-agers were 15.29 and (15.62 ± 25.54) ng·kg(-1)·d(-1), preschoolers were 19.27 and (19.22 ± 28.91) ng·kg(-1)·d(-1). MOEs of mean and 50% exposure levels in different group of people were more than 10,000, while MOEs of 95% exposure levels in school-agers and preschoolers were less than 10,000. CONCLUSION: For general consumers, the health risk of PAHs exposure is very low. However, for high-end consumers (95% exposure level) from the sensitive groups (school-ager and preschooler) has a potential health risk.