Spectrophotometric determination of total phosphorus in rape seeds and oils at various stages of technological process: calculation of phospholipids and non-hydratable phospholipids contents in rapeseed oil

A new spectrophotometric method for determination of total phosphorus in rape seeds and rapeseed oils is described. The procedure is based on formation of the ionic—associate of molybdophosphate with Malachite Green (MG) in an acidic medium and compared with the standard vanadomolybdate and molybdenum blue methods. Satisfactory values of recovery ranged between 99.1–100.3% and RSD <1%, demonstrate the benefit of using MG method for the routine analysis of total phosphorus in oilseeds, crude and refined oils. The equivalent of phospholipids contents in the crude and hydrated oils were calculated from the phosphorus determinations. Obtained results are discussed in respect of accuracy and precision.