Studies on occurrence of tetracycline and aminoglycoside residues in milk
Abstract
In the present study, High Performance Liquid Chromatography with Ultra-Violet detector
(HPLC-UV) technique and with florescence detector (HPLC-FL) was standardized and validated for
the detection and quantitation of tetracyclines (oxytetracycline, tetracycline and chlortetracycline) and
aminoglycoside (kanamycin and gentamicin) in milk respectively. The validation procedure showed
that the values for the system precision (% RSD for all analytes were less than 12.68% for area and
1.12 % for retention time). Linearity (R2>0.99), specificity and accuracy (70-110%) and precision
(<10%) were within accepted range and demonstrated the system and method suitability for analysis of
milk samples. The standardized and validated method was used to detect tetracycline and
aminoglycoside residues in 100 milk samples collected randomly from local market of Hisar
(Haryana). A total of 33 samples were found to be containing antimicrobial residues, out of which 18
samples were positive for tetracycline residues and 15 samples for aminoglycoside residues. Maximum
positive samples were associated with vendor milk followed by dairy and pasteurized milk. Mean
concentrations of oxytetracycline, tetracycline and chlortetracycline antimicrobial residues in market
milk samples were 12.45, 1.11 and 7.69 μg/kg, respectively, while that of kanamycin and gentamicin
were 1.27 and 65.06 μg/kg, respectively. Comparison of antimicrobial concentration in each positive
sample of milk with international MRLs showed that gentamicin and oxytetracycline were responsible
for maximum violations. The risk assessment based on per capita availability of milk in Haryana and
India by calculating hazard quotient for each analyte under study revealed no risk due to dietary
exposure to tetracycline and aminoglycoside residues through milk.