Analytical Strategy for Determination of Chloramphenicol in Different Biological Matrices by Liquid Chromatography - Mass Spectrometry

Development of a method for the determination of sedatives in bovine and porcine urine and kidneys by liquid chromatography-tandem mass spectrometry

Introduction

Sedatives have been used for a long time as animal tranquillisers to prevent stress and weight loss during their transportation. The proper determination of these substances in food of animal origin is essential for consumer safety.

Material and Methods

A 1 g portion of pig or cow urine or homogenised kidney was mixed with acetonitrile, sodium chloride was added, and the solution was further mixed and then centrifuged. The supernatant was transferred to a new centrifuge tube with primary and secondary amine, octadecylsilane and ZrO2, and mixed rapidly. The filtered solution was evaporated under a nitrogen stream. The residue was dissolved in 200 μL of acetonitrile, centrifuged with filters and then transferred to vials. Samples were analysed by high-performance liquid chromatography-tandem mass spectrometry.

Results

The decision limit for confirmation was calculated at 2.5 μg kg-1 for all sedatives with relative standard deviation repeatability and reproducibility below 20%.

Conclusion

The validation results showed that this method meets the pertinent EU criteria for such methods and is suitable for sedative analysis in urine and kidney matrices.

Adsorptive stripping voltammetric determination of chloramphenicol residues in milk samples using reduced graphene oxide sensor

In this paper, the electrochemical response of chloramphenicol (CHL) was investigated on a bare glassy carbon electrode (GCE) and after modification with reduced graphene oxide (GCE/rGO). Preliminary studies by cyclic voltammetry demonstrated an adsorption-controlled mass transport regime of CHL species and a pH-dependent behavior on both electrode surfaces. An adsorptive stripping differential pulse voltammetry (AdSDPV) method was proposed and under optimized instrumental conditions, a comparison of the analytical characteristics of both sensors was performed. The GCE/rGO sensor showed an increase in sensitivity (10-fold), and an anticipation of the reduction potential (200 mV), compared to the bare electrode, due to the adsorptive character (pre-concentration of the CHL species) and the electrocatalytic effect of the nanomaterial. The method was applied to skimmed and whole milk samples, which were simply diluted (50-fold) in supporting electrolyte. The results by AdSDPV using GCE/rGO showed adequate detectability (0.22 μmol L^-1), good precision with a 6% relative standard deviation (RSD) and satisfactory recovery ranging from 93 to 108%. The obtained results were statistically similar (95% confidence level) with those performed through ultra-fast liquid chromatography (UFLC). Furthermore, the sensor showed an improvement in the analytical performance for CHL detection, when compared to other sensors reported in the literature. Therefore, the developed method is reliable and promising for implementation in monitoring CHL residues in milk samples.

QuEChERS and HPLC-MS/MS Combination for the Determination of Chloramphenicol in Twenty Two Different Matrices

A simple method for the determination of chloramphenicol in 22 matrices was prepared based on the QuEChERS and HPLC-MS/MS combination. Following a hydrolysis step, the homogenized samples were extracted and partitioned after adding sodium chloride with acetonitrile. Chloramphenicol was analysed by HPLC-MS/MS in negative electrospray mode by monitoring the daughter ions m/z: 321→194 and 321→152. The limit of decision (CCα) was calculated at the range of 0.10 μg kg⁻¹ to 0.15 μg kg⁻¹ and detection capability (CCβ) from 0.12 μg kg⁻¹ to 0.18 μg kg⁻¹. Validation results showed that this method is suitable for the determination and confirmation of chloramphenicol in various matrices.