Fig. 4

Approach to eliminate cross-sensitivity peaks. a shows the false-high ‘sevoflurane exposure’ of a surgeon (purple line; [ppm] mean: 0.73 ± 0.70, maximum: 6.93; red triangle: use of disinfectant). After logarithmic presentation of the data (purple line in b), the 10th percentile baseline is drawn (green line; here 0.29 ppm), and the recovery time is marked (red dotted line in c; here 39 min). This line is moved to the peak’s maximum (black arrow in c). The intersection with the curve marks the end of the cross-sensitivity peak (blue cross in c). This time interval is replaced by the baseline concentration (dark blue line in c). If interfering agents are used before the decay curve has reached the baseline concentration (back star in c) the cross-sensitivity interval should not be replaced by the 10th percentile, but by the measured concentration at the beginning of the cross-sensitivity peak (orange in c). In this example the ‘corrected’ mean and maximum sevoflurane concentrations were 0.53 ± 0.33 ppm and 1.76 ppm, which is a reduction by 28% (d)