Determinação incorreta do limite inferior de quantificação (LIDQ) dos métodos analíticos

Generally, a new analytical method for publication in a scientific journal should report some parameters to claim that the technique has acceptable validity and has acceptable sensitivity in contrast to other methods. The most commonly reported parameters are limit of detection (LOD), limit of quantification (LOQ), and lower limit of quantification (LLOQ). Recently, LLOQ was selected by researchers to show the lowest concentration level that can be determined. Based on the FDA’s guidelines, some criteria should be considered in reporting LLOQ. In this study, previously reported analytical methods were investigated to check if they considered FDA’s criteria (relative standard deviation of LLOQ, signal-to-noise, and back-calculated error for LLOQ). Besides the FDA guideline’s criteria, the established criteria based on the calibration curve equation and the linear range were calculated to confirm the validity of the reported LLOQ. Analysis of data indicates that the most LLOQ values are not defined based on FDA guidelines, and they do not show the correct sensitivity value of the reported analytical method.