Determination of 24 sulfonamide antibiotics in instant pastries by modified QuEChERS coupled with ultra performance liquid chromatography-tandem mass spectrometry.

There were few reports about antibiotic residues in egg-containing products. In the study, an effective method for the simultaneous determination of 24 sulfonamide antibiotics in two instant pastries based on a modified QuEChERS sample preparation technique coupled with ultra performance liquid chromatography-tandem mass spectrometry was developed. The results show that the average recoveries of the SAs at 5, 10, and 50 µg kg-1 levels were 67.6%-103.8%, with relative standard deviations (RSD) of 0.80-9.23%. The limit of detections (LODs) and limit of quantitations (LOQs) were 0.01-0.14 µg kg-1 and 0.02-0.45 µg kg-1, respectively. This method was suitable for analysis of 24 SAs in instant pastries.

Glutamine as a Potential Noninvasive Biomarker for Human Embryo Selection.

To determine whether glutamine consumption is associated with embryo quality and aneuploidy, a retrospective study was conducted in an in vitro fertilization center. Spent embryo culture media from patients undergoing assisted reproduction treatment and preimplantation genetic testing (PGT) were obtained on day 3 of in vitro culture. Embryo quality was assessed for cell number and fragmentation rate. PGT for aneuploidy was performed using whole genome amplification and DNA sequencing. Glutamine levels in spent embryo culture media were analyzed by gas chromatography-mass spectrometry. The results demonstrated that glutamine was a primary contributor to the classification of the good-quality and poor-quality embryos based on the orthogonal partial least-squares discriminant analysis model. Glutamine consumption in the poor-quality embryos was significantly higher than that in the good-quality embryos (P < 0.05). A significant increase in glutamine consumption was observed from aneuploid embryos compared with that from euploid embryos (P < 0.01). The Pearson correlation coefficients between embryo quality and glutamine consumption, and between aneuploidy and glutamine consumption, were 0.430 and 0.757, respectively. The area under the ROC curve was 0.938 (95% CI: 0.902-0.975) for identifying aneuploidy. Animal experiments demonstrate that increased glutamine consumption may be a compensatory mechanism to mitigate oxidative stress. Our data suggest that glutamine consumption is associated with embryo quality and aneuploidy. Glutamine may serve as a molecular indicator for embryo assessment and aneuploidy testing.

Determination of higenamine in multi-matrix by gas chromatography-mass spectrometry combined with derivatization technology.

Higenamine (HG), a cardioactive component of some foods and medicines, has been listed in the doping category by the International Olympic Committee, which may lead to misuse by athletes. We report the development of a gas chromatography-mass spectrometry (GC-MS) method for determination of HG in various matrix samples (biological samples, different forms of Chinese patent medicine, Chinese herbal medicine) based on acylation derivatization of HG by heptafluorobutyric anhydride. Under optimal conditions, the linearity of HG in the range of 5-200 ng mL-1 was acceptable (R2 > 0.999), and the limit of detection (LOD) and limit of quantitation (LOQ) for HG was 1.52 ng mL-1 and 5 ng mL-1, respectively. Low, medium, and high concentrations (25, 100 and 160 ng mL-1) of HG were added to plasma, urine, oral liquid, capsule, watered bolus, honeyed bolus and Chinese herbal medicine samples, with recovery ranging from 82.70 to 109.80%, intra-day and inter-day precisions were both less than 3.39%. The results indicated that the method had sufficient sensitivity for analysis of biological samples, and Chinese patent and herbal medicine.

Simultaneous determination of lactic acid and pyruvic acid in tissue and cell culture media by gas chromatography after in situ derivatization-ultrasound-assisted emulsification microextraction.

Lactic acid and pyruvic acid are important metabolites in the tricarboxylic acid cycle that can reflect the cytoplasmic redox state and mitochondrial respiratory chain function. The combination of these acids is considered as a screening index for mitochondrial disorders. Due to their biological effects, a derivatization method was developed to simultaneously detect pyruvic acid and lactic acid in tissue and cell culture media using gas chromatography. In this work, the combined derivatization method with methoxyamine hydrochloride and isobutyl chloroformate was first proposed. To improve the efficiency of derivatization, in situ derivatization-ultrasound-assisted emulsification microextraction (USAEME) was used in this study. After optimizing the volume of reagents and reaction times, good linearity values were obtained from 50 to 1000 µmol/L and 1 to 100 µmol/L for lactic acid and pyruvic acid, respectively. The limits of detection (LODs) were 0.12 µmol/L for lactic acid and 0.29 µmol/L for pyruvic acid. The recoveries of the two analytes were between 93.60 and 102.80%, and the precisions were less than 6.20%. This method was successfully applied to quantify pyruvic acid and lactic acid in the animal and cellular hypoxia models which provided an auxiliary means for the diagnosis of mitochondrial diseases. Graphical abstract ᅟ.

Derivatization method for the quantification of lactic acid in cell culture media via gas chromatography and applications in the study of cell glycometabolism.

Lactic acid represents an important metabolite that reflects mitochondria function and may further serve as energy source for cancer cells. In light of this physiological and pathological significance, we developed a novel and sensitive gas chromatography method to detect lactic acid in cell culture media. Here, ethyl chloroformate was selected as derivative reagent and the derivatization process was further optimized in terms of number of reagents and reaction time as well as extraction reagents. Under optimal conditions, good linearity was achieved in the tested calibration range. The limit of detection (LOD) was determined to be 0.67 µmol/L, the recovery rates were 99.6%-106% and the precision rate RSD was <5.49%. Furthermore, this method has been applied to quantify the secretion of lactic acid in cells exposed to mono­2­ethylhexyl phthalate at different doses and in cancer cells over time. Taken in concert, our method proved to be both sensitive and reliable and may be applied for studies on mitochondrial function and cell glycolysis conditions.

Development of a derivatization method for the quantification of hydrogen sulfide and its application in vascular calcification rats.

Hydrogen sulfide (H2S) plays major functional and structural roles in diverse physiological functions and the pathogenesis of a variety of disorders in biological matrices. The significance of H2S has prompted the development of sensitive and selective methods to determine its concentration in biological samples. The fluorescent reagent monobromobimane (MBB) has been widely used to measure various thiol-containing species through alkylation. MBB may prevent the oxidation of sulfide and the reaction of sulfide with several different species (such as superoxide radicals, hydrogen peroxide and peroxynitrite). An isomers of MBB, 3-(bromomethyl)-2, 6, 7-trimethyl-1H, 5H-pyrazolo [1,2-a] pyrazole-1, 5-dione (MMB), is cheaper than MBB and its use in the analysis of H2S has not previously been reported. In the present study, we compared the derivatization reactions of hydrogen sulfide with MMB and MBB and developed a sensitive method to quantify H2S in blood. In our method, H2S was incubated in the dark with excess MMB in 0.1M Tris-HCl buffer (pH 10.1) at 50°C for 120min. 50µL aliquots of the derivatized product were analyzed using HPLC system with gradient elution of 0.1% (v/v) formic acid-acetonitrile. The limit of detection for the derivatized product was 0.03nmol/mL. The derivatization reaction was suitable for detecting low concentrations of H2S. The derivate product is stable over time, permitting batch storage and analysis.