3.3. Analytical performance
Several factors were evaluated to characterize this PAH determination method and demonstrate its suitability, including the linear range, limits of detection (LOD), repeatability and enrichment factor. The results are summarized in Table1. Over the range of 0.1-200 mg/L for PHE, the analytes all exhibited good linearity, with a correlation coefficient (r^2) ranging from 0.9987 to 0.9998. The sensitivity of the method was established by determining the limits of detection (LOD) according to the IUPAC method. The LOD was defined as the lowest detectable concentration with a signal-to-noise ratio of at least 3. In this study, the LODs were in the range of 0.1-10 ng/L. The LOQ values defined by signal-to-noise ratio of 10 (S/N = 10) were in the range of 0.5-34 ng/L. The repeatability,described as the relative standard deviations (RSDs) of a series of replicate experiments, was 1.9-3.4% for intraday precision and 2.3-3.8% for interday precision. The enrichment factor, defined as the ratio of the analyte concentrations obtained after the extraction/desorption process to the concentration in the initial sample solution, ranged from 106.3 to 123.8. Taken together, these results confirm that the present method has high sensitivity, a wide linear range, good precision and strong potential for the analysis of trace PAH levels in coffee and tea samples.