[Dry chemistry of reagent strips]

Quantitative analysis with dry reagent strips for the determination of clinical chemistry parameters and drug monitoring in serum, plasma and whole blood is expanding in small laboratories and in office laboratories. The systems predominantly used are Ektachem DT 60, the Seralyzer and the Reflotron. - The methods offered comprise substrates, enzymes, electrolytes, CO2 and drugs. The spectrum of feasible tests varies with the manufacturer. On the whole all the tests commonly used in small laboratories are covered. The instruments used for quantitative dry reagent strip chemistry are calibrated by the manufacturer. Calibration data are either inputted to the instrument with each method or already programmed in the apparatus. Thus calibration is outside the control of the user, a change of philosophy which does not correspond to present concepts of quality control in clinical chemistry. The analytical precision is satisfactory for all three instruments for the common parameters measured. A comparison between "dry-chemistry" determinations and the classical aqueous analyses show good accuracy as long as patient samples are used. This is, however, not true for all reference materials, presumably due to matrix effects. Our own evaluation of the Seralyzer showed a good correlation of potassium analysis compared with flame photometry; this was also true of gamma-glutamyltransferase using the Reflotron with patient samples. Internal quality control can only be performed with materials assessed by the instrument manufacturers, and the results will often differ for these materials when assayed with conventional methods or with other "dry-chemistry" methods. External quality control also has its limitations due to the fact that no sera are available which could be used universally.(ABSTRACT TRUNCATED AT 250 WORDS)