Antibiotic immunosensing: Determination of sulfathiazole in water and honey

The development of two sensitive and selective immunosensors for sulfathiazole. using immunoreagents - haptens. polyclonal antibodies, enzyme conjugates - previously obtained and characterized, is presented One of them is based on the competitive immunocomplex capture format making use of an immobilized protein A/G sorbent, while the other employs a restricted access support in a novel homogeneous-heterogeneous (HH) assay mode Maximum sensitivity, achieved with a total assay time of 18 min for the capture sensor, is traduced in a dynamic range from 0 4 to 24 mu g L-1, with a lower limit of detection of 0.11 mu g L-1. increasing to 1 2 mu g L-1 when employing an accelerated capture assay protocol that yields a sampling rate of 7 cycles per hour The HH sensor shows the fastest response, performing each whole assay in only 2 min, with a limit of detection of 0 85 and a measurement interval of 3.9-181.0 mu g L-1. and with no need of support regeneration. Immunosensors are selective for sufathiazole. and only sulfamethoxypyridazine. sulfamethizole and sulfapyridine show non-negligible cross-reactivity, the same as in ELISA batch immunoassay. The application of the developed systems to the analysis of water, with no sample treatment, as well as honey samples after solid-phase extraction, demonstrate the reliability of the immunosensing for the monitoring of this type of pollutants. (C) 2010 Elsevier B V All rights reserved.