Occurrence and concentrations of residues of tetracyclines, polyether ionophores and anthelmintics in livers of chickens sold in the informal market in Gauteng province, South Africa

The occurrence, concentrations and variables associated with tetracycline, polyether ionophore and anthelmintic residues in the livers of chickens sold in the informal market in South Africa were determined. An ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS) was used to simultaneously analyze for four tetracyclines, five polyether ionophores and six anthelmintic residues. The study determined the presence of residues in liver samples at both the limit of quantifications (LoQ) and concentrations over the maximum residue limit (MRLs), i.e. non-compliant. Doxycycline (tetracycline group) was detected in 24.5% (24/98) of chicken livers and 15.3% (15/98) were non-compliant. The mean±SD concentration of 919.04±1081.30 (LoQ) and 1410.57±108.89 ppb (MRL) were obtained. Maduramycin was detected in 27.6% (27/98) of chicken livers and 19.4% (19/98) were non-compliant. The mean±SD for LoQ was 117.96±84.56 and MRL was 153.21±76.29 ppb. The concentrations of residues of doxycycline and maduramycin in chicken livers varied significantly across townships. Lasalocid was quantified in 31.6% (31/98) of the samples, of which 5.1% (5/98) contained concentrations above the MRL. The mean±SD concentrations of Lasalocid was 62.90±170.84 for samples in which Lasalocid was quantified and 310.16±356.68 ppb for non-compliant samples. The frequencies of chicken livers that contained detectable concentrations of the three anthelmintic residues were 3.1% (3/98), 1.0% (1/48) and 2.0% (2/98) for praziquantel, closantel and rafoxanide, respectively. The presence of three classes of veterinary drugs residues in chicken liver poses food safety implications to consumers and indicates a need for enhanced regulatory enforcement in controlling these drugs in South Africa.