Evaluation of the "Auto-Stat 6010" automatic osmometer and its comparison with the "digimatic-advanced 3DII" manual osmometer.

The results are presented of a comparative study between two osmometers, a manual one, Digimatic-Advanced 3DII (Advanced Instruments, Medical Europa, Barcelona), and an automatic one, Auto-Stat 6010 (Kyoto, Daiichi, Kagaku, Menarini, Firenze). Both osmometers have the same operation principle, but they employ different systems for determination of the freezing point depression. Both instruments showed good precision (CV < 1%), accuracy, and a wide range of linearity. In the assay of 133 sera and 101 24-h urines, the methods showed a good correlation (r = 0.945 and r = 0.999) and the Anova test showed no statistical difference between the means (p > 0.05). The carry over effect in the Auto-Stat was statistically significant (p < 0.001) but within the range of imprecision of the osmometers. Variation due to evaporation is lower than 0.8%. In conclusion, we are sure that both osmometers are useful in the laboratory, although the Auto-Stat 6010 osmometer has the advantage over the Digimatic-Advanced 3DII of automatic sample processing.