Development of an aqueous temperature-indicating technique and its application to clinical laboratory instrumentation.

We describe a new technique for monitoring intra-cuvette temperatures in temperature-controlled spectrophotometric cells by use of two solutions, one for which absorbance is highly sensitive to temperature and one for which absorbance is insensitive to temperature. The first solution, cresol red in tris(hydroxymethyl)aminomethane buffer, is used to construct an absorbance-vs.-temperature calibration curvae. The second solution, cresol red in sodium hydroxide, is used for optical calibration of the spectrophotometric system to be tested. The combination of these two procedures allows accurate estimation of temperature. We show how this technique is applied to temperature measurement in several types of laboratory instrumentation.