Fig. 3.

Validation of the CBM-29-1-2 probe in detecting hydroxyethylcellulose (HEC) in placebo vaginal gel. a Positive detection of various amounts of pure, dissolved HEC powder by the probe confirming the feasibility of the detection protocol (left). Positive detection of HEC in various dilutions of placebo vaginal gel (right). b Positive detection of HEC in vaginal swab extracts containing HEC gel ± semen. Extracts from vaginal swabs only or vaginal swabs containing semen are negative confirming specificity