Establishment and Validation of an Accelerated Oxidation-Ion Chromatography Method for the Quantification of Phosphorus Content in Biodiesel

A new accelerated oxidation-ion chromatography method has been proposed to determine the phosphorus content in biodiesel. The feasibility of the method was verified based on its linear correlation, detection limit, accuracy, and comparison with other methods. Further, the effects of interfering ions and accelerated oxidation time on the phosphorus content determination have been discussed. The results revealed a good linear correlation coefficient (r = 0.99996) over a PO₄³⁻ concentration range of 0.1–4.0 mg·L⁻¹. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.005 and 0.016, mg·L⁻¹, respectively. The intra-day accuracy (relative standard deviation (RSD), n = 5) ranged between 1.08–3.96%, while the inter-day accuracy (RSD, n = 15) was 1.66–6.67%, and the recovery rate was between 80.88% and 89.71%. The matrix elements in the biodiesel samples had no significant effect on the determination of phosphorus content. Under an oxidation temperature of 110 ℃ and ventilation rate of 10 L·h⁻¹, the optimum accelerated oxidation time of biodiesel was found to be 18 h. Compared with other methods, the proposed method exhibited a better linear range and the lowest LOD. Furthermore, the efficacy of the method for quantifying the content of phosphorus in biodiesel has been validated through actual sample analysis.