Determination of Chloramphenicol Residues in Milk and Milk-products Using LC/MS/MS

Abstract

The aim of the present investigation was to demonstrate the presence of chloramphenicol residues in milk and milk products of dairy animals by performing liquid chromatographic mass spectrometric (LC/MS/MS) method for quantification. LC/MS/MS was used for quantitative detection of chloramphenicol in milk and milk products because it can determine very low concentration of antibiotics at about parts per million (ppm)/parts per billion (ppb) levels. Injection of 10% chloramphenicol prepared in sterile water and 2 mg/kg body weight was administered in livestock (food producing animal). Milk samples (with product prepared from it) were collected after 24 h of dermal administration of antibiotic, analyzed using LC/MS/MS and compared with commercially available milk samples for human consumption. It was found that considerable residue of the active substance is present in milk and milk products of the treated animal. Analysis in LC/MS/MS was conducted by extracting milk with ethyl acetate. Chloramphenicol was eluted from the C18 LC column at about 0.57 min using ammonium acetate-methanol as a mobile phase. The mass spectrometer was operated in the negative ion mode using selective reaction monitoring (SRM). The peak area was used for quantification. The milk fortified with chloramphenicol at 50, 100, 500 and 1000 ng/mL was used as standard.