Soy lecithin phospholipid determination by Fourier transform infrared spectroscopy and the acid digest arseno-molybdate method: A comparative study

A study was conducted to determine the accuracy and precision of phospholip id analysis by a simple Fourier transform infrared spectroscopy (FTIR) meth od relative to the conventional phospholipid phosphorus analysis by the aci d digest/arseno-molybdate method by Bartlett. Commercial soy lecithins of k nown concentrations of phospholipid were prepared and the phospholipid cont ent measured by the FTIR and Bartlett methods. The coefficients of determin ation and of variances using the two methods were determined. The coefficie nt of determination for the FTIR method was >0.976 while that for the Bartl ett method was similar to 0.821. The coefficients of variances (CV) for 1-2 0% phospholipid concentration range using 10 replicate samples were found t o lie between 3.59 and 9.45% for the FTIR method, while the Bartlett method had much higher CV for the same range and replicates (8.95 to 48.73%), sig nifying the higher accuracy and precision of the FTIR compared to the Bartl ett method in the determination of the actual percentage of phospholipid. T he Bartlett method gave no significant difference in the phospholipid level s at smaller concentrations, indicating its limitation in accurately determ ining percentage phospholipid of samples at low concentrations. The one-way analysis of variance at the 1-20% phospholipid concentration range showed that there were significant differences in the mean percentage phospholipid levels for the FTIR data, which was therefore able to distinguish samples with smalt differences in phospholipid levels. The FTIR method gave consist ently reliable results within the range chosen (1-20% phospholipid content) . FTIR is a fast, simple, and reliable analytical tool for quantitative pho spholipid analysis.