Fig. 8

Disposable breathalysers can successfully indicate if glycerol or PG raw materials have been substituted with DEG or EG. Zoomed-in images of the crystals seen through the viewing window of the breathalyser are shown. All alcohols were diluted to 1% v/v except for DEG which was additionally tested at 5% v/v. In only 10 s, glycerol and PG used in raw materials changed the crystals in the breathalyser from white to dark brown whereas DEG showed no change in colour and EG showed a very faint pink colour. There was also no change in the colour of the crystals after 10 s when DEG was tested at the 5× higher concentration. At 2 min, there was still no colour change for DEG. The crystals changed to dark brown for EG suggesting that the white crystals do oxidise EG but at a slower rate compared to glycerol and PG, both of which remained dark brown at 2 min. For DEG, there was a slight change in the colour of the crystals to pink after 2 min when tested at the 5× higher concentration although was still a lot less intense than glycerol and PG when tested after 10 s.