Metal Ion–Enhanced Quantification of Chloramphenicol in Milk Using Imipramine Hydrochloride as Diazo-Coupling Agent

Abstract

Chloramphenicol is a broad-spectrum antibiotic that is administered to cattle, fish, poultry, and honeybees among other animals. Consumption of food from such sources leads to non-regenerative anaemia, aplastic anaemia, and bone marrow suppression in humans. It is therefore a pressing necessity to detect chloramphenicol in food items through a convenient, accurate, and rapid method. The proposed method is the first attempt of a diazo-coupling reaction between diazotized chloramphenicol and imipramine hydrochloride yielding an intense purple-coloured product at room temperature, with λmax = 575 nm. The concentration of reagents, temperature, and acid medium were optimised. Enhancement of molar absorptivity coefficient of the dye by a range of different salts and nanoparticles, and their effect on reaction kinetics were also studied in details for the first time. Iron (III) was seen to show highest catalytic efficiency. The increase in molar absorptivity coefficient for the dye product was calculated to be from 0.14 to 0.2 μM−1 cm−1. The catalysed reaction was employed for determination of chloramphenicol. The linear range was from 0.2135 to 20 ppb and detection limit for CAP was 2.321 ppb. This method is simple, sensitive, and economical without the need of specific reaction conditions or dedicated sophisticated instrumentation.