Estudio comparativo de la densidad del agua y su aplicación en el presupuesto de incertidumbre para calibraciones en volumen

In the quantity of volume, gravimetric method is considered the best accuracy method for the quantitative determination of an analyte based on its mass. The distilled water is selected as calibration liquid because it is well known how its density changes with temperature. For volume calculation at reference temperature, the water density value is obtained by known mathematic models, for example, Tanaka equation (Tanaka, et al., 2001). According to ISO 3696 (International Organization for Standardization, 1987), there are requirements for water (Grade 3), the lab needs to perform periodic studies of conductivity, but it is necessary to study the water density deviation and comparing this value with that obtained by Tanaka equation. If this deviation value (calculated by Tanaka Equation vs Oscillation – type density meter is significant, it must be considered in the uncertainty estimation for volume calibration using gravimetric method.