PAH analysis in biomass combustion wastes: an approach to evaluate bias and precision of analytical results using routine samples

The aim of this work was to optimize and evaluate an analytical procedure to determine selected polycyclic aromatic hydrocarbons (PAHs) using real samples. Samples of ash were collected during biomass combustion tests under different operating conditions during one week. PAHs were quantified using liquid chromatography with fluorescence detection. Samples were extracted by a simple sonication/agitation method using small amounts of solvent and samples. This paper includes how the performance (bias and precision) of the proposed method was estimated from the analyses of samples. In order to obtain reliable data, we estimated the possible presence of two types of analytical bias: bias proportional bias to the level of analyte, expressed as recovery, and constant bias, comparing results from analyses of different ash masses. Apart from bias studies, the analytical variability was also evaluated as intermediate precision from the overall analyses of different routine samples, with different mass fraction levels and test dates. Intermediate precision values were reduced among 5 % to 10 % when measures on the optimized sample sizes and similar mass fraction levels were taken. The use of samples is rarely applied to assess trueness of analytical methods. Therefore, the presented findings can be considered as an interesting contribution to the analytical chemistry research field.