Multi-class/residue method for determination of veterinary drug residues, mycotoxins and pesticide in urine using LC-MS/MS technique.

BACKGROUND: Veterinary drugs are widely used in animals to prevent diseases and are a complex set of drugs with very different chemical properties. Multiclass and multi-residue methods for simultaneous detection of residues from veterinary drugs and contaminants in urine are very rare or non-existent. Therefore, the aim of this study was to develop and validate a sensitive and reliable quantitative LC-MS/MS method for simultaneous determination of a wide range of veterinary drug and pesticide residues and mycotoxins in bovine urine. This involved 42 veterinary drug residues (4 thyreostats, 6 anabolic hormones, 2 lactones, 10 beta agonists, 15 antibiotics, 5 sulphonamides), 28 pesticides and 2 mycotoxins. Stable isotopically labelled internal standards were used to facilitate effective quantification of the analytes. Analysis was performed in both positive and negative ionization modes with multiple reaction monitoring transitions over a period of 12 min. RESULTS: The parameters validated included linearity, limit of detection (LOD), limit of quantification (LOQ), detection capability (CCß), decision limit (CCα), stability, accuracy and precision. The process followed guidelines of the regulation 2021/808/EC. The calibration curves were linear with coefficient of correlation (R2) from 0.991 to 0.999. The LODs were from 0.01 to 2.71 µg/L, while the LOQs were from 0.05 to 7.52 µg/L. The CCα and CCß were in range 0.05-12.11 µg/L and 0.08-15.16 µg/L. In addition, the average recoveries of the spiked urine samples were from 71.0 to 117.0% and coefficient of variation (CV) < 21.38% (intraday and interday). CONCLUSION: A new isotopic LC-MS/MS method has been developed, validated and applied for identification and quantification of 72 residues of veterinary drugs and pesticides and other contaminants such as mycotoxins in bovine urine. The most appropriated sample preparation procedures involved sodium acetate buffer, enzymatic hydrolysis using ß-glucuronidase and cleanup solid phase extraction with OASIS SPE cartridges. The parameters were satisfactorily validated fulfilling requirements under Regulation 2021/808/EC. Consequently, the method could be used in routine analysis of bovine urine samples for simultaneous detection of veterinary drug and pesticide residues as well as contaminants such as mycotoxins.

D-galactose induced inflammation lipid peroxidation and platelet activation in rats.

BACKGROUND: To investigate events possibly related to the development of D-galactose induced senescence, we examined whether 8-iso PGF(2α) formation, a marker of in vivo lipid peroxidation is altered and whether its biosynthesis is associated with 11-dehydro-TXB(2) excretion rate, as a marker of in vivo platelet activation. In this setting, we also investigated the relationship between proinflammatory mediators (IL-6 and TNF-α from one, and lipid peroxidation and platelet activation, from another aspect. METHODS AND RESULTS: Forty animals were divided, depending on treatment with d-galactose into: placebo and D-galactose treated rats. 8-iso-PGF(2α), IL-6 and TNF-α were measured in plasma, while 11-dehydro-TXB(2) was determined in the urine after a six week treatment with d-galactose. Compared to placebo, d-galactose treated animals showed significantly higher levels of all measured parameters. CONCLUSIONS: D-galactose induced changes in the rate of F(2)-isoprostane formation are associated with the changes in the excretion rate of 11-dehydro-TXB(2).

Determination of Multi-Class Antimicrobial Residues and Antimicrobial Resistance in Cow Milk and Feces Samples during Withdrawal Period.

The use of antimicrobials in livestock production and their effect on the development of antimicrobial resistance (AMR) is a global health problem for humans, animals and the environment. The aim of this study was to determine antimicrobial residue levels in milk and feces samples during the withdrawal period in dairy cattle administrated with a single dose of the drug, as well as to characterize the antimicrobial resistance patterns of Escherichia coli cultured from feces samples. In the study, dairy cows from three different farms in North Macedonia were included. Raw milk and feces samples were collected before drug administration (0 day) and on the 1st, 2nd, 3rd, 7th and 21st day after drug administration. The antimicrobial residues of oxytetracycline, enrofloxacin, amoxicillin, trimethoprim and procaine-benzylpenicillin were determined using a validated liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) method involving stable isotopes. According to results obtained, the highest levels of analyzed antimicrobial residues were determined on the first day after drug administration, which then gradually decreased until their elimination (7th day). The highest AMR of E. coli (100%) was found in ß-lactam antimicrobials. Less exposure to broad-spectrum antimicrobials could be an important factor for reduction of AMR on dairy farms.

Determination of Veterinary Drug Residues, Mycotoxins, and Pesticide Residues in Bovine Milk by Liquid Chromatography Electrospray Ionisation -tandem Mass Spectrometry.

Introduction: Multi-class and multi-residue analyses are very complex procedures because of the physico-chemical properties of veterinary drug residues and other contaminants. The purpose of the study was to develop an analytical method for the sensitive determination of 69 analytes in bovine milk by liquid chromatography electrospray ionisation-tandem mass spectrometry. Material and Methods: Antimicrobial, anabolic hormone, lactone, ß-agonist, mycotoxin and pesticide residues were analysed in 120 raw milk samples from different dairy farms in North Macedonia. Stable isotopically labelled internal standards were used to facilitate effective quantification of the analytes. Results: The linear regression coefficients were higher than 0.99, the limits of detection ranged from 0.0036 to 47.94 µg/L, and the limits of quantification ranged from 0.053 to 59.43 µg/L. The decision limit values ranged from 0.062 to 211.32 µg/L and the detection capability from 0.080 to 233.71 µg/L. Average recoveries of the analytes spiked in raw milk were in the range of 70.83% to 109%, intra-day coefficient of variation (CV) values from 2.41% to 22.29%, and inter-day CV values from 3.48% to 23.91%. The method was successfully applied in the testing of bovine milk samples. In five samples residues were detected. They were sulfadimethoxine (in two samples), enrofloxacin, tetracycline and oxytetracycline and were at concentrations below the EU maximum residue limit. Conclusion: The method is useful for routine testing for this group of chemical hazards in bovine milk.

A new LC-MS/MS method for multiple residues/contaminants in bovine meat.

A multi-class and multi-residue/contaminant method for the determination of veterinary drug and pesticide residues and mycotoxins in bovine meat has been developed and validated. The veterinary drug residues/contaminants included antimicrobials, anabolic hormones, lactones, ß-agonists, mycotoxins, and pesticides. Isotopic labeled internal standards were included to compensate residual matrix effects. The calibrators used in the method demonstrated linearity with the R2 > 0.98. The decision limit (CCα) values were in the range from 0.067 to 2103.84 µg/kg, while the range for detection capability (CCß) was from 0.083 to 2482.13 µg/kg. The limit of detection (LOD) and limit of quantification (LOQ) were in the range from 0.059 to 291.36 µg/kg, and 0.081 to 328.13 µg/kg, respectively. The recovery of analytes ranged from 61.28% to 116.20%. The intra-day coefficient of variation (CV) was from 0.97 to 25.93% and the inter-day CV was 2.30-34.04%. The method has been used for the determination of 49 residues/contaminants in bovine meat. Application of the method in routine analysis in bovine samples, revealed in limited samples the presences of enrofloxacin, oxytetracycline and sulfadiazine at the concentration of 35.22 µg/kg, 27.35 µg/kg, and 36.20 µg/kg, respectively.

Erythrocyte glucose-6-phosphate dehydrogenase activity in laboratory rats treated with amoxiclav, lidaprim and 1-chloro-2,4-dinitrobenzen.

The enzyme glucose-6-phosphate dehydrogenase (G6P-DH, EC.1.1.1.49) catalyzes the oxidation of glucose-6-phosphate in 6-phosphogluconat which is indispensable in the defence of erythrocytes from oxidative insult. The aim of this study was to examine the influence of commonly used drugs in our medical practice, amoxiclav (amoxicillin-clavulanate combination) and lidaprim (trimethoprim-sulfamethrole combination) respectively, upon the erythrocyte G6P-DH activity in experimental rats. In addition, the effect of the toxic drug 1-chloro-2,4-dinitrobenzen (CDNB) on the activity of G6P-DH was examined. The experiment was conducted in fresh blood haemolysates of white laboratory rats, Wistar type, of both genders (n=80). The enzyme activity was determined by "Boehringer-Mannheim" diagnostic assay kits (Kornberg et al., 1955). However, the measured enzyme activity in the control group of rats was found to be a statistically insignificant difference between the genders (140.2 +/- 21.2 mU/10(9)Er in male rats, 144.3 +/- 20.6 mU/10(9) in the female group). Hence, the established enzyme activity does not differ from the activity of the same enzyme in healthy human subjects. The administered dose of lidaprim did not affect the activity of G6P-DH in the treated group of rats, thus attaining levels similar to the control group. By contrast, amoxiclav administration provoked a significant reduction in enzyme activity of 13.6% in male and 19.5% in female rats (p < 0.001), while the treatment with CDNB significantly increased the activity of the latter to 49.7% in male and 30.1% in female rats (p < 0.001) in comparison with the control ones. Testing of haemolitical potential is strongly recommended prior to the use of new drugs, particularly in the Mediterranean region, were this enzymopathy is found to be frequent bearing in mind that there is an established list of drugs which affect the G6P-DH activity in the erythrocytes. The above-mentioned method may be used in experimental animal models allowing for administration of a wider selection of drugs in this type of research.