Aqueous two-phase system (ATPS) is a liquid-liquid fractionation technique and has gained an interest because of great potential for the extraction, separation, purification and enrichment of proteins, membranes, viruses, enzymes, nucleic acids and other biomolecules both in industry and academia. Although, the partition behavior involved in the method is complex and difficult to predict. Current research shows that it has also been successfully used in the detection of veterinary drug residues in food, separation of precious metals, sewage treatment and a variety of other purposes. The ATPS is able to give high recovery yield and is easily to scale up. It is also very economic and environment friendly method. The aim of this review is to overview the basics of ATPS, optimization and its applications.

Food contamination with antibiotic residues has become a worldwide problem due to the heavy and improper use of antibiotics. The development of fast, high-throughput, easy, and economical screening methods for the detection of antibiotic residues is an important requirement as an alternative to the traditional assays. Immunoassays are widespread promising methods that can achieve the conditions of an analytical method in the evaluation of food and environmental protection. This review offers an overview of the preparation of antibodies and the currently established immune-assays for the antibiotic residues detection, including enzyme-linked immunosorbent assay, fluorescence immunoassay, radioimmunoassay, colloidal gold immunoassay, and chemiluminescence immunoassay. Furthermore, it will elaborate on the future perspective on the performance and improvement of these assays for the determination of antibiotic residues in food samples. These assays include a simple sample preparation and high-sensitive detection that offer a significant assurance for the screening of antibiotic residues. GRAPHICAL ABSTRACT