Disposable screen printed sensor for the electrochemical detection of delta-9-tetrahydrocannabinol in undiluted saliva

Table 2 Sensor performance at different time points on the CA3-CA1 response

Time/s	0.000–0.025	0.025–0.050	0.050–0.075	0.075–0.100	0.100–0.125	0.125–0.150	0.150–0.175	0.175–0.200	0.200–0.225	0.225–0.250
False positives	1	2	2	1	1	1	1	1	1	0
True negatives	172	168	169	168	166	165	165	167	165	165
True positives	14	95	95	68	39	30	22	20	15	14
False negatives	328	248	242	264	299	300	312	313	313	309
% Sensitivity	4	28	28	20	12	9	7	6	5	4
% Specificity	99	99	99	99	99	99	99	99	99	100
% Accuracy	36	51	52	47	41	39	37	37	36	37

Note that outlier responses were removed from the analysis. Outliers were defined as (1) did not trigger; (2) excessively noisy response resulting in atypical transient shape and (3) statistical outlier for each set of 12 sensors tested per sample, defined as outside 1.5x the interquartile range from the median current response