Gas chromatographic determination of incurred chloramphenicol residues in eggs following optimal extraction

Extraction and determination of chloramphenicol in feed water, milk, and honey samples using an ionic liquid/sodium citrate aqueous two-phase system coupled with high-performance liquid chromatography

A green, simple, non-toxic, and sensitive sample pretreatment procedure coupled with high-performance liquid chromatography (HPLC) was developed for the analysis of chloramphenicol (CAP) that exploits an aqueous two-phase system based on imidazolium ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, [Bmim]BF(4)) and organic salt (Na(3)C(6)H(5)O(7)) using a liquid-liquid extraction technique. The influence factors on partition behaviors of CAP were studied, including the type and amount of salts, the pH value, the volume of [Bmim]BF(4), and the extraction temperature. Extraction efficiency of the CAP was found to increase with increasing temperature and the volume of [Bmim]BF(4). Thermodynamic studies indicated that hydrophobic interactions were the main driving force, although electrostatic interactions and salting-out effects were also important for the transfer of the CAP. Under the optimal conditions, 90.1% of the CAP could be extracted into the ionic liquid-rich phase in a single-step extraction. This method was practical when applied to the analysis of CAP in feed water, milk, and honey samples with a linear range of 2~1,000 ng mL(-1). The method yielded a limit of detection of 0.3 ng mL(-1) and a limit of quantification of 1.0 ng mL(-1). The recovery of CAP was 90.4-102.7% from aqueous samples of real feed water, milk, and honey samples by the proposed method. This novel process is much simpler and more environmentally friendly and is suggested to have important applications for the separation of antibiotics.

Concentrations of salinomycin in eggs and tissues of laying chickens fed medicated feed for 14 days followed by withdrawal for 3 days

Laying chickens were fed medicated feed containing various concentrations of sodium salinomycin (SAL) for 14 days followed by a 3 day withdrawal period. Eggs, collected during treatment and withdrawal, tissues and ovarian yolk of birds slaughtered after 0, 1, and 3 days' withdrawal were extracted and analysed by high performance liquid chromatography (HPLC). Tissues, ovarian yolk and freeze-dried egg albumen and yolk were extracted with acetone, followed by partitioning with petroleum ether and HPLC analysis. Albumen was extracted with methanol and analysed without further clean-up. Salinomycin was detected at 520 nm after post-column reaction with vanillin at 95 degrees C. Recoveries of fortified salinomycin from freeze-dried eggs (albumen and yolk) and tissue, premix and feed were nearly quantitative (> 90%), except liver which was < 85%. The detection limit was estimated to be 5 ng g-1, with the practical quantifiable limit being about 10 ng g-1. Highest SAL concentrations were in the more fatty components such as egg yolk, ovarian yolk and subcutaneous fat. SAL residues in other tissues were generally low and followed the order liver, kidney, thigh and breast muscles. SAL residues were dependent on the SAL concentration in feed and declined rapidly during withdrawal.