Residue depletion of gentamicin in swine tissues after intramuscular administration

Determination of four main components of gentamicin in animal tissues after solid-phase extraction by high-performance liquid chromatography/tandem mass spectrometry

RATIONALE

An analytical method for gentamicin in animal tissues was developed and validated. An alkaline mobile phase with an HPH C₈ column was selected so that all the four gentamicin components were retained and eluted without using fluorinated ion-pairing reagents.

METHODS

The method is sufficiently sensitive and highly selective, using a strong cation-exchange solid-phase extraction cartridge (PCX) to clean up the samples. Different types of solid-phase extraction columns and membranes were considered to obtain a high recovery. The method was validated on spiking samples, recovery, inter- and intra-assay variation, to ensure its accuracy and precision.

RESULTS

The LOQ (S/N ≥ 10) for gentamicin in goat meat, liver, kidney and adipose tissue was 25, 50, 30 and 30 ng/g, respectively; the LOD (S/N ≥ 3) was 5, 10, 10 and 10 ng/g, respectively. The recoveries were between 88% and 106%. The method in all animal tissues was calibrated from 10 to 1000 μg/L in the matrix-assisted standard solution.

CONCLUSIONS

The novelty of this method is that the commonly used fluorinated ion-pairing reagent was not used in the mobile phase in our analysis, greatly reducing the contamination of the ESI source in negative mode. Moreover, the four gentamicin components were clearly separated via chromatographic separation.

Development of indirect competitive ELISA using egg yolk-derived immunoglobulin (IgY) for the detection of Gentamicin residues

Gentamicin (Gent) is an aminoglycoside antibiotic being used in livestock sector. Gent residues could cause some genetic disorders by nonsense mutations. This study aimed to develop IgY-based ELISA for the detection of Gent in animal products. Gent was conjugated with Bovine serum albumin (BSA) by carbodiimide method for further immunization in the laying chickens. PEG-6000 extraction method was employed to extract IgY from the egg yolk. The titer of anti-Gent-IgY attained the peak of 1:256,000 after the 5(th) booster immunization. Checkerboard titration confirmed that, anti-Gent IgY in 1:2,000 dilution could give an Optical Density (OD) 1.0 at 2 µg mL(-1) of Gent-OVA coating concentration. IgY-based indirect competitive ELISA (Ic-ELISA) showed that, the IC50 value of anti-Gent IgY was 2.69 ng mL(-1) and regression curve equation was y = -16.27x + 56.97 (R(2) = 0.95, n = 3), confirming that, the detection limit (LOD, IC10 value) was 0.01 ng mL(-1). Recoveries from fresh milk, pork and chicken samples were ranged from 69.82% to 94.32%, with relative standard deviation lower than 10.88%. Our results suggested that generated anti-Gent IgY antibodies can be used in routine screening analysis of Gent residues in food samples.