Liquid-phase reactions started by rehydrating lyophilized reagents in a centrifugal analyzer

In the disposable rotor of the SAM microcentrifugal analyzer, various lyophilized reagents are predistributed in 24 33-microL cuvets, for determination of multiple analytes in one specimen (e.g., for patient profiles). We evaluated a prototype of this system, which can be used at 25, 30, or 37 degrees C; absorbance readings at 340, 405, and 500 nm varied linearly up to 2.0 A. Starting the reactions by rehydrating the reagents with diluted serum is adequate because absorbance readings do not begin until 180 s after initiating the rehydration. Analytical performances of kinetic determinations at 30 degrees C showed good accuracy and correlation with other methods for creatine kinase, amylase, aspartate aminotransferase, and gamma-glutamyltransferase. Kinetic determinations for urea, and equilibrium determinations with blank corrections for glucose, cholesterol, and triglycerides gave excellent results for glucose and correct results for the other analytes. This compact analyzer combines the analytical performances of a centrifugal analyzer with the practicability of instruments having predistributed reagents.