Sodium Cromoglycate in Race Horses: Development of Enzyme-Linked Immunosorbent Assay (ELISA) Screening and Gas Chromatography/Mass Spectrometry Confirmation Techniques

ABSTRACTDevelopment of a rapid and sensitive ELISA for detection of sodium cromoglycate in equine urine is described. Detection limit of the assays was less than 1 ng/mL. Enzyme conjugate binding to immobilized sheep antibody was inhibited 50% by less than 10 ng/mL. Intraassay and interassay variabilities, as measured by percent coefficient of variation, were less than 9% and 15% respectively. The test was capable of reliably detecting cromoglycate in post administration urine samples for 6 hours following 80 mg nebulized or for 17 hours following an 80 mg intratracheal dose. Background and matrix effects were found to be minimal. The test was very specific—no compound has yet been found to significantly cross react.Investigations into extraction and analysis of cromoglycate using GC/MS are also reported.