Studies on Monoglycerides by the Differential Scanning Calorimetry. II.

Quantitative Determination of 1-Monopalmitin

Abstract

A procedure was developed to adapt a differential scanning calorimeter to rapid quantitative determination of 1-monopalmitin in the mixtures of 1- and 2-monopalmitin. The DSC analyses were carried out as follows; 510mg of the sample (pure 1-monopalmitin or mixture) is placed in an aluminium pan which is placed in a sample holder. An empty pan is put in the reference holder. Heating and cooling rate is 10°C/min. and sensitivity range is 16.
Fig.-1 shows the cooling curves which had two exothermic peaks (b, c) corresponding to the crystallization of α-form (65°C) and sub-α form (36.5°C). The areas above and below the base line are proportional to the amount of heat absorbed or evolved by 1-monopalmitin. In this case the ratio of larger peak area to smaller was 1.87 : 1.
Fig.-4 is the plot of the smaller peak area versus the amount of 1-monopalmitin. As shown in Fig.-5 the smaller peak area (shaded part) increases with the amount of 1-monopalmitin.
Therefore, the quantitative determination of 1-monopalmitin in the monopalmitin mixture, was made by measuring smaller peak area. The error of determination was within 2% (Table-1).