I am currently studying the problem with the quality of distilled glycerin. When stored, it acquires a pink tint (see photo). We analyzed glycerol on a gas chromatography mass spectrometer. In the sample 1099/2, the following impurities were found:
1,2,3-Propanetriol, 1-acetate CAS No. 106-61-6;
3-Methoxy-1,2-propanediol CAS No. 623-39-2;
1,3-Dimethoxypropan-2-ol CAS No. 623-69-8;
2-tert-butylhydroquinone CAS No. 1948-33-0.
Which of these substances can give a pink color and why?