Clinical Chemistry, Vol 21, 151-154, Copyright © 1975 by the American Association for Clinical Chemistry

Electronic Correction of Values That Are "Off-Scale" in the "SMA-6" System for Continuous-flow Analysis

¹ Department of Pathology, Clinical Chemistry Laboratory, New York University Medical Center, New York, N. Y. 10016.

Data are presented for an electronic device that automatically halves "off-scale" signal voltages on the "SMA Flex-6" System (Technicon). This extends the usefulness of the system by obviating the need for most repeat analyses on dilutions of specimens containing constituents in concentrations that exceed the limits of the pre-calibrated chart paper. Accurate results are obtained because the chemical reactions are shown to be linear up to nearly twice the maximum calibration on the recorder paper for the following analytes: bilirubin, total and direct (20.0 mg/dl); alkaline phosphatase (700 U/ liter); lactate dehydrogenase (1200 U/liter); creatine kinase (2400 U/liter); and aspartate aminotransferase (600 U/liter). In contrast, dilution of sera 2-, 5-, and 10-fold with sodium chloride solution (8.5 g/liter) produces positive errors ranging from 6 to 38% for these enzymes, but has no significant effect on bilirubin.

Submitted on July 10, 1974
Accepted on October 12, 1974