A Comparison of Paired Calibration Check Results of Alco-Sensor IV- RBT IV and Intoxilyzer® 5000 C in Real Cases

Abstract

More than 1600 paired-control tests data obtained on Alco-Sensor IV—RBTIV and Intoxilyzer® 5000 C have been reviewed. A quasi-normal distribution around the target value of 100 mg/100 mL was observed. Moreover, not only are instruments accurate, but they are also stable. In sequences of tests in real cases, paired data comparison of first (CTRL1) and second (CTRL2) control results showed a difference (CTRL1—CTRL2) of zero in about one-third (⅓) of assays. The majority of cases (98.5%) were found to have a cumulative absolute difference of 3 mg/100 mL. In just one case, the difference between CTRL1 and CTRL2 was 10 mg/100 mL, the maximum acceptable in Quebec. Thus, although calibration checks of 95 to 105 mg/100 mL are acceptable, measurement uncertainty of these instruments should be considered well below 10 mg/100 mL in the great majority of cases.