Systematic study on the variability in the gasoline sampling process at service stations and its contribution to the measurement variance

A full-factorial experimental design (2^4) was performed to study the impact of the sampling and handling processes on the analysis of gasoline samples. Four independent variables were selected based on the most critical parameters to control during sampling. Vapor pressure determination and distillation curve were chosen as response variables, and the data collected were assessed by analysis of variance as a statistical approach. There were statistically significant differences related to the sample container’s material and the sample’s storage time in the laboratory before the analysis. Also, the measurement variance was estimated at 0.11 from the contributions of the variance of the sampling process and the variance of the analysis process considering vapor pressure results (kPa), which allows the evaluation and control of the random error associated with the sampling process.