The Technicon RA-1000 evaluated for measuring sodium, potassium, chloride, and carbon dioxide

We evaluated the Technicon RA-1000 "random-access" analyzer for the measurements of sodium, potassium, and carbon dioxide by an indirect potentiometric method (ion-selective electrode) and for chloride by a colorimetric method (mercuric thiocyanate). For various concentrations of control materials the total precision (CV) ranged from 0.9 to 1.2% for sodium, 1.1 to 1.3% for potassium, 1.0 to 1.2% for chloride, and 2.8 to 3.8% for carbon dioxide. The system demonstrated acceptable performance in linearity and carryover. Patients' results from the RA-1000 correlated well with those from the Beckman ASTRA-8. In a study on potential interferences, we found that high concentrations of salicylate and bromide significantly affected measurements of carbon dioxide and chloride, respectively. The RA-1000 requires only 30 microL of sample for all four tests and it offers a high throughout (30 specimens analyzed for the four tests in 25 min). This precise, easy-to-use, random-access analyzer requires minimal maintenance.