Blood ammonia measurement using a simple reflectometer.

We have assessed a compact Blood Ammonia Checker System (Ammonia Checker) consisting of a reflectometer which measures the intensity of colour formed by blood ammonia on a bromocresol green indicator reagent plate. The results show good correlation (r = 0.95) with our routine chemical method and a regression line y = 0.835X - 1.468. The Ammonia Checker has good precision (CV less than 10%) at the critical blood ammonia concentration and accurately measures predetermined ammonia concentrations. Blood sampling is improved with a precision pipette. The Ammonia Checker is simple, convenient and reliable and is ideally suited for a laboratory required to perform an urgent blood ammonia measurement.