Analysis of tetracycline antibiotics in soil: Advances in extraction, clean-up, and quantification

Abstract

Residues of tetracyclines end up in the environment due to the common practice of land application of manure from treated animals. The environmental behavior and the fate of tetracyclines in manure and soil after cropland application remain largely unknown. The lack of information on the nature of the biodegradation products of tetracyclines formed at environmentally-relevant concentrations is mostly due to analytical difficulties encountered when trying to analyze trace levels of these compounds in the presence of complex matrices. Liquid chromatography coupled to mass spectrometry (LC-MS) has become widely used in detecting polar pollutants such as antibiotics. In applying LC-MS for environmental investigations, the analyst is faced with two major challenges: poor detectability of analytes; and, highly variable matrix interferences that compromise quantification. To improve our understanding of the fate and effects of tetracycline antibiotics in the environment, improved methods for detection, quantification, and unknown identification are needed. In this review, we discuss strategies for sample preparation, extraction, clean-up using solid-phase extraction (SPE) and molecularly-imprinted polymers (MIPs), and analysis of tetracyclines and their transformation products in soil, in order to facilitate future environmental fate studies, and to challenge analytical chemists to develop the necessary tools to allow a complete risk assessment of other pharmaceutical contaminants in the environment.