ENVIRONMENTAL-ANALYSIS IN THE WORKPLACE - DEVELOPMENT OF A RAPID, SENSITIVE ELISA FOR MONITORING AIRBORNE ALCALASE

Alcalase, in common with other proteases is a respiratory sensitiser a nd long term and short term occupational exposure limits of 60 ng m(-3 ) for periods of 8 h and 15 min respectively have been set for workers who may inhale these proteases in the work-place. Polyclonal antibodi es have been raised in rabbits that specifically recognise alcalase. T hese have been purified using immunoaffinity chromatography and the re sulting anti-alcalase antibodies used with alkaline-phosphatase labell ed anti-rabbit antibodies to generate a single reagent for use in a co mpetitive ELISA for alcalase that can be used in a rapid semi-quantita tive mode to screen samples from conventional filters following monito ring of worker exposure. Presence of alcalase in excess of the occupat ional exposure standard (OES) results in a lack of colour at the endpo int of the assay while samples with levels less than the OES produce a yellow colour. The ELISA can process 45 samples in duplicate in 60 mi n. The limit of detection of the assay is 1 pg ml(-1) in a 50 mu l sam ple volume. The assay has good precision with coefficients of variatio n less than 10%. and is better suited than current colorimetric enzyme assays for use on site by semi-skilled operatives immediately followi ng the monitoring period when exposure of workers above the OES can be rapidly ascertained and action taken.