Determination of 3-nitropropionic acid in sugarcane using dispersive solid-phase extraction and gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry.

A method for accurately determining 3-nitropropionic acid in sugarcane was established for the first time using gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry (GC - APCI-MS/MS). Under acidic conditions, 3-nitropropionic acid is methylated to obtain methyl 3-nitropropionate. The derivative product was purified using dispersive solid-phase extraction (d-SPE) method and analyzed using GC - APCI-MS/MS. The recovery experiments were conducted at three concentrations: low, medium, and high. The recovery rates ranged from 75.1% to 90.2%, the relative standard deviations were <8.2%, and the limit of quantification was 2.0 µg/kg. The method offers the advantage of being accurate, sensitive, and specific, meeting the requirements of the determination of 3-nitropropionic acid in sugarcane.

[Immunomodulatory effect of low relative molecular mass seleno-aminopolysaccharide in Acanthopagrus schlegelii by hepatic metabolomics analysis].

To investigate the immunomodulatory mechanism of low relative molecular mass seleno-aminopolysaccharide, a metabolomics method based on liquid chromatography-time-of-flight mass spectrometry (LC-TOF-MS) was used to analyze the endogenous metabolites changes in the liver of Acanthopagrus schlegelii. The potential biomarkers were screened using non-targeted mass spectrometry with the XCMSplus software, and the related metabolic pathways were analyzed using MetaboAnalyst3.0 website. The results showed that the liver metabolites in the low relative molecular mass seleno-aminopolysaccharide-fed group were significantly different from those in the blank group. Also, 32 biomarkers were identified. Additionally, low relative molecular mass seleno-aminopolysaccharide could enhance the immune function of Acathopagrus schlegelii via amino acid, nucleotide, and nitrogen metabolism, aminoacyl-transfer ribonucleic acid (tRNA) biosynthesis, and other metabolic pathways. This study therefore provides a scientific basis for elucidating the immunoenhancement mechanism of low relative molecular mass seleno-aminopolysaccharide.

[Rapid screening of pesticide residues in imported grains by ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry].

A fast sample pretreatment method by fast pesticide extraction (FaPEx) method combined with ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry was developed for screening of unknown pesticide residues in imported grains. The samples were extracted with 1% (v/v) acetic acid acetonitrile solution, cleaned-up by solid phase extraction column with FaPEx cartridges, and determined by UPLC-Q-TOF. The data was compared with the library with the accurate mass, isotopic distribution, fragmentation information and retention time. The results showed that this method can be used for the rapid screening of pesticide residues in imported grains without the reference standards, and it was applied to the actual screening of imported grain samples. The method is high efficiency, sensitivity and accuracy, which can meet the requirement for the rapid screening of pesticide residues in imported grains.

Determination of vanillin, ethyl vanillin, and coumarin in infant formula by liquid chromatography-quadrupole linear ion trap mass spectrometry.

A simple, precise, accurate, and validated liquid chromatography-quadrupole linear ion trap mass spectrometry method was developed for the determination of vanillin, ethyl vanillin, and coumarin in infant formula samples. Following ultrasonic extraction with methanol/water (1:1, vol/vol), and clean-up on an HLB solid-phase extraction cartridge (Waters Corp., Milford, MA), samples were separated on a Waters XSelect HSS T3 column (150 × 2.1-mm i.d., 5-µm film thickness; Waters Corp.), with 0.1% formic acid solution-acetonitrile as mobile phase at a flow rate of 0.25 mL/min. Quantification of the target was performed by the internal standard approach, using isotopically labeled compounds for each chemical group, to correct matrix effects. Data acquisition was carried out in multiple reaction monitoring transitions mode, monitoring 2 multiple reaction monitoring transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the enhanced product ion modus of the linear ion trap. The novel liquid chromatography-quadrupole linear ion trap mass spectrometry platform offers the best sensitivity and specificity for characterization and quantitative determination of vanillin, ethyl vanillin, and coumarin in infant formula and fulfills the quality criteria for routine laboratory application.

Microwave-assisted extraction and determination of dicyandiamide residue in infant formula samples by liquid chromatography-tandem mass spectrometry.

A simple, precise, accurate, and validated liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the determination of dicyandiamide residue in infant formula samples. Following microwave-assisted extraction with 5% formic acid and clean-up on a Sep-Pak AC-2 SPE cartridge, samples were separated on a ZIC-HILIC HPLC column (150 × 2.1mm i.d., 5-µm film thickness; Merck KGaA, Darmstadt, Germany) with 20mM ammonium acetate solution-acetonitrile as mobile phase at a flow rate of 0.25 mL/min. A linear calibration curve was obtained in the concentration range from 1.0 to 50 ng/mL. Infant formula samples were fortified with dicyandiamide at 3 levels, producing average recovery yields of 83.6 to 95.7%. The limits of detection and quantification of dicyandiamide were 3 and 10 µg/kg, respectively. Due to its simplicity and accuracy, the straightforward method is particularly suitable for routine dicyandiamide detection.

Determination of three capsaicinoids in Capsicum annuum by pressurized liquid extraction combined with LC-MS/MS.

A new method based on pressurized liquid extraction followed by LC-MS/MS analysis has been developed for the identification and quantification of three capsaicinoids (capsaicin, dihydrocapsaicin, and nordihydrocapsaicin) in extracts of Capsicum annuum. For the recovery of three capsaicinoids, the efficiency levels of ultrasonic-assisted extraction, microwave-assisted extraction, Soxhlet extraction, and pressurized liquid extraction were compared under different conditions. Pressurized liquid extraction resulted in higher yields. Pressurized liquid extractions were performed using methanol; temperature was set at 100°C and pressure at 1500 psi. LC analysis was performed on a Waters XBridge™ C18 column (150 × 2.1 mm, id 3.5 µm) eluted by a mobile phase of 0.1% formic acid and ACN. Data acquisition was carried out in multiple reaction monitoring transitions mode, monitoring two-reaction monitoring transitions to ensure an accurate identification of target compounds in the samples. The proposed method is rapid, simple, and could be utilized for the routine analysis of three capsaicinoids in C. annuum samples.

Rapid quantification of four major bioactive alkaloids in Corydalis decumbens (Thunb.) Pers. by pressurised liquid extraction combined with liquid chromatography-triple quadrupole linear ion trap mass spectrometry.

A new method based on pressurised liquid extraction (PLE) followed by liquid chromatography-triple quadrupole linear ion trap mass spectrometry (LC-QTrap-MS) analysis has been developed for the identification and quantification of four major alkaloids in extracts of Corydalis decumbens (Thunb.) Pers. PLE extractions were performed using 90% ethanol; temperature was set at 100°C and pressure at 1500 psi. HPLC analysis was performed on a Waters XBridge™ C(18) column (150 mm × 2.1mm i.d., 3.5 µm) eluted by a mobile phase of acetonitrile and 0.2% acetic acid. Data acquisition was carried out in multiple reaction monitoring transitions (MRMs) mode, monitoring two MRM transitions to ensure an accurate identification of target compounds in the samples. Additional identification and confirmation of target compounds were performed using the enhanced product ion modus (EPI) of the linear ion trap. The novel LC-QTrap-MS platform offers the best sensitivity and specificity for characterization and quantitative determination of the four alkaloids in C. decumbens (Thunb.) Pers. and fulfils the quality criteria for routine laboratory application.

Excretion of enrofloxacin in pigs and its effect on ecological environment.

The concentration of enrofloxacin and its metabolite, ciprofloxacin, in feces and urines were investigated in healthy pigs after oral administration (p.o.) of a single dose of 5.0mg/kgbw and an indoor soil model was set to study the effects of enrofloxacin and ciprofloxacin through biological and chemical metrics including changes to edaphon, edaphic ammonification and nitrification and the soil bacterial community. The results showed that the concentrations of entofloxacin and ciprofloxacin in feces and urines fluctuated, the maximum concentrations of enrofloxacin and ciprofloxacin in the urine were 22.74 and 48.04µg/ml, respectively, 24.68 and 30.98µg/g in the feces, respectively. The effect of enrofloxacin and ciprofloxacin on edaphon, edaphic ammonification and nitrification and the soil bacterial community differed at different time points. And the model can be used to evaluate environmental safety of enrofloxacin and develop possible procedures for the safe handling and utilization of animal excrement.