Thermogravimetric analysis (TGA)
Since amino acid salts were prepared from an aqueous solution and two
commercial amino acid salts were reported to contain water, the water
content was determined by TGA, which was then used for an accurate
concentration of amino acid in oil. A Model Q50 TGA (TA instruments, New
Castle, DE, USA) was used for TGA experiments. The sample (8-10 mg) was
weighed onto a platinum sample pan and loaded with the autosampler. The
temperature was increased at a rate of 20 °C/min from 25 °C to 250 °C
and nitrogen was blown into the sample chamber at a flow rate of 60
ml/min during measurements. Universal Analysis software was used to
analyze data. The weight loss was recorded at the temperature where
dehydration was completed (typically at 120-180 °C). The experiments
were conducted in duplicate, and results are shown in Supplementary
Table 1.