Internal standardization and plasma molecular species: signal correction approaches for determination of phosphorus from phospholipids in meat by MIP OES

Abstract

This study aims to establish strategies for phosphorus determination in the lipid fraction of meat by the microwave induced plasma optical emission spectrometry (MIP OES) technique. Phospholipids were extracted using a mixture of chloroform and methanol followed by simple dilution of the lipid extract in methanol. Due to the instrumental fluctuations caused by the introduction of organic solvents, the use of internal standards (Te and Co) and naturally occurring molecular species (OH and N₂⁺) was evaluated for signal correction. Moreover, an external gas control module (EGCM) was applied to allow carbon decomposition and to minimize the matrix effects. The accuracy of the method was evaluated by comparing the obtained values with the results obtained by ion chromatography. The use of Te as an internal standard proved to be adequate, presenting results with approximately 95% recovery. For the molecular species, two data treatments were employed, A × M and A/M, where A and M correspond to the analyte and the molecular species signals, respectively. The procedure using OH combined with the A × M treatment was shown to be more suitable for this analysis. In this circumstance, the recovery was equal to 94%. Hence, the results obtained with signal correction were more accurate compared to the external calibration results. Limits of detection when Te and OH were employed were found to be 25 mg kg⁻¹ and 27 mg kg⁻¹, respectively. The use of MIP OES along with signal correction and the employment of the EGCM presented satisfactory sensitivity and analytical performance. Besides, the application of these molecular species is more useful than the traditional methods because it is not necessary to prepare additional solutions.