[Determination of sixteen antibiotics and four β-agonists in human urine samples using ultra-performance liquid chromatography-tandem mass spectrometry based on high-throughput automatic solid-phase extraction]

[Determination of 12 prohibited veterinary drug residues in pig urine by ultra high performance liquid chromatography-tandem mass spectrometry]

A method was established for the simultaneous detection of 12 prohibited veterinary drugs, including β2-receptor agonists, nitrofuran metabolites, nitroimidazoles, chlorpromazine, and chloramphenicol, in pig urine. The sample was pretreated by enzymolysis, acid hydrolysis/derivatization, and liquid-liquid extraction combined with solid-phase extraction. Detection was performed using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). Ammonium acetate solution (0.2 mol/L, 4.5 mL) and β-glucuronidase/aryl sulfatase (40 μL) were added to the sample, which was subsequently enzymolized at 37 ℃ for 2 h. Then, 1.5 mL of 1.0 mol/L hydrochloric acid solution and 100 μL of 0.1 mol/L o-nitrobenzaldehyde solution were added to the sample. The mixture was incubated at 37 ℃ for 16 h, and the analytes were extracted with 8 mL of ethyl acetate by liquid-liquid extraction. The lower aqueous phase obtained after extraction was extracted and purified using a mixed cation-exchange solid-phase extraction column. The extracts were combined, the extraction solution was blow-dried with nitrogen, and the residue was redissolved for determination. The samples were analyzed under multiple-reaction monitoring mode with both positive and negative electrospray ionization, and quantified using an isotope internal standard method. The correlation coefficients (r) of the 12 compounds were >0.99. The limits of detection (LODs) and quantification (LOQs) of chloramphenicol were 0.05 and 0.1 μg/L, respectively, and the LODs and LOQs of the other compounds were 0.25 and 0.5 μg/L, respectively. The mean recoveries and RSDs at 1, 2, and 10 times the LOQ were 83.6%-115.3% and 2.20%-12.34%, respectively. The proposed method has the advantages of high sensitivity, good stability, and accurate quantification; thus, it is suitable for the simultaneous determination of the 12 prohibited veterinary drug residues in pig urine.

Fluorimetric determination of tetracycline antibiotics in animal derived foods using boron and nitrogen co-doped ceria-based nanoparticles

An innovative synthesis of boron and nitrogen co-doped ceria-based nanoparticles (B/N-CeFNPs) with bright blue fluorescence emission is reported using the hydrothermal method. Based on the aggregation-induced emission enhancement (AIEE) effect between B/N-CeFNPs and chlortetracycline (CTC), a rapid detection method for CTC through fluorescence enhancement was developed. In addition, through the electron transfer process (ET), fluorescence resonance energy transfer (FRET) effect and static quenching between B/N-CeFNPs and oxytetracycline (OTC), a ratio fluorescence strategy for detecting OTC was generated. The fluorescence of B/N-CeFNPs at 410 nm can be effectively quenched by OTC, and new fluorescence emission appears at a wavelength of 500 nm. B/N-CeFNPs showed good linear responses with CTC and OTC in the range 0.1-1 µM and 1-40 µM, respectively. This system was used to simultaneously detect the CTC and OTC in milk and honey, realizing multi-residues detection of TCs in actual samples by using the same ceria-based fluorescence nanomaterial.

[Determination of 35 antibiotics and four β-receptor agonists in teenagers and analysis of exposure status]

Antibiotics are mainly used for disease treatment and prevention, and β-receptor agonists are mainly used in the clinical treatment of respiratory diseases. Both types of drugs are also widely used in animal husbandry and aquaculture to promote animal growth and prevent disease. These drugs enter the human body through many routes and cause harm to human health. Teenagers are in a critical period of growth and development, and long-term antibiotic exposure may have adverse effects on their bodies. In this study, 442 teenagers aged 11-15 years were recruited from a middle school to investigate the body burden of various antibiotics and β-receptor agonists. The seven categories of antibiotics, including five macrolides, four tetracyclines, 10 quinolones, 11 sulfonamides, three β-lactams, one quinoxaline, and one lincosamide, and four β-receptor agonists were determined by isotope dilution and solid phase extraction coupled with ultra performance liquid chromatography-tandem mass spectrometry. Analyte levels were corrected using urine creatinine, and detection rates were used for data analysis. Pearson's chi-squared test was used to analyze the correlations between detection rate and gender, age, or body mass index (BMI). Logistic regression was used to evaluate the correlation between detection rate and different groups after adjusting for confounding factors. The results showed that 397 teenagers had at least one antibiotic or β-receptor agonist in their urine, with a total detection rate of 89.8%. A total of 29 antibiotics and β-receptor agonists were detected, and the detection rate of each compound ranged from 0.2% to 59.0%. Doxycycline, oxytetracycline, and azithromycin were the top three drugs with the highest detection rates (59.0%, 56.1%, and 34.6%, respectively). Tetracyclines and macrolides were the two antibiotic categories detected most often, with detection rates of 81.9% and 42.3%, respectively. Among the antibiotics investigated, preferred veterinary antibiotics (PVAs) had the highest detection rate (85.1%), followed by human antibiotics (HAs) (41.0%). The overall detection rate of β-receptor agonists was 2.7%. Statistical analysis showed that the male was prone to be exposed to tetracycline antibiotics (odds ratio (OR)=2.17). The detection rates of macrolides differed among the different age groups and were higher in those aged 12-13 years than in those aged 11 years. As the BMI of the teenagers increased, the detection rate of macrolides gradually increased. After adjusting for age and gender, teenagers with obesity were found to be 2.35 times more likely to be exposed to macrolides than those with a normal weight. The findings suggest that teenagers are generally exposed to low levels of antibiotics, that food and the environment may be the main sources of antibiotic exposure in teenagers, and that macrolide exposure may be associated with adolescent obesity.