Table 3.

Retention time (RT), percent retention time difference (%RTD, as defined by Equation 1), retention time difference (RTD, defined as the difference between a compound and the one listed below), and retention index (RI) for a subset of the frequently seen compounds analyzed by the targeted method. Retention times and indices are the average of three replicates of an approximately 100 μg mL⁻¹ solution. Uncertainties represent the standard deviation of three replicates.

Compound	RT (min)	%RTD	RTD (min)	RI (a.u.)
Tramadol	2.085 (±0.006)	12.3	0.257	2265
Xylazine	2.342 (±0.011)	2.5	0.058	2363
o-Desmethyl-cis-Tramadol	2.400 (±0.010)	12.4	0.298	2386
Norfentanyl	2.698 (±0.005)	0.4	0.011	2473
Acetyl norfentanyl	2.709 (±0.003)	70.6	1.912	2483
4-ANPP	4.621 (±0.004)	17.3	0.799	2834
AP-238	5.420 (±0.006)	8.5	0.462	2929
2-Methyl AP-237	5.882 (±0.012)	11.5	0.677	2980
6-Monoacetylmorphine	6.559 (±0.007)	3.8	0.247	3047
U-47700	6.806 (±0.004)	3.0	0.205	3071
U-48800	7.011 (±0.000)	1.4	0.099	3091
Benzyl Fentanyl	7.110 (±0.002)	11.9	0.845	3103
Remifentanil	7.955 (±0.000)	3.2	0.251	3174
m-Fluoroisobutyryl Fentanyl	8.206 (±0.003)	0.4	0.035	3192
U-49900	8.241 (±0.003)	0.4	0.033	3198
Oxycodone	8.274 (±0.008)	3.7	0.306	3198
FIBF	8.580 (±0.004)	1.1	0.098	3222
trans-3-methyl Fentanyl	8.678 (±0.002)	1.9	0.169	3231
Fentanyl	8.847 (±0.009)	1.1	0.094	3243
Acetyl fentanyl	8.941 (±0.006)	0.1	0.005	3249
Acrylfentanyl	8.946 (±0.003)	1.7	0.151	3250
cis-3-methyl Fentanyl	9.097 (±0.002)	1.3	0.117	3266
Heroin	9.214 (±0.014)	0.1	0.012	3269
p-Fluorofentanyl	9.226 (±0.003)	1.3	0.117	3274
Metodesnitazene	9.343 (±0.008)	1.4	0.131	3279
Butyryl Fentanyl	9.474 (±0.002)	3.1	0.293	3289
Cyclopropyl Fentanyl	9.767 (±0.002)	2.2	0.213	3308
Etodesnitazene	9.980 (±0.007)	1.3	0.132	3333
p-Fluorobutyryl Fentanyl	10.112 (±0.000)	0.1	0.014	3324
Isodesnitazene	10.126 (±0.007)	0.8	0.082	3340
Quinine	10.208 (±0.011)	0.1	0.008	3334
4’-methyl Acetyl Fentanyl	10.216 (±0.006)	5.1	0.519	3340
Crotonyl Fentanyl	10.735 (±0.003)	0.5	0.049	3377
Carfentanil	10.784 (±0.000)	0.1	0.016	3385
Valeryl Fentanyl	10.800 (±0.002)	10.7	1.159	3379
Methoxyacetyl Fentanyl	11.959 (±0.004)	8.3	0.997	3461
Cyclopentyl Fentanyl	12.956 (±0.004)	3.9	0.507	3320
p-Methoxyfentanyl	13.463 (±0.005)	7.1	0.961	3551
Tetrahydrofuran Fentanyl	14.424 (±0.005)	2.8	0.403	3607
Furanyl fentanyl 3-furancarboxamide isomer	14.827 (±0.004)	2.8	0.408	3632
Furanyl fentanyl	15.235 (±0.005)	39.3	5.989	3652
Noscapine	21.224 (±0.011)	2.7	0.575	3977
Flunitazene	21.799 (±0.015)	10.5	2.298	4009
Etizolam	24.097 (±0.010)	3.4	0.819	4130
Brorphine	24.916 (±0.023)	8.2	2.035	4173
Bendioxole Fentanyl	26.951 (±0.002)	0.2	0.045	4281
Metonitazene	26.996 (±0.010)	4.0	1.079	4283
Isotonitazene	28.075 (±0.015)	N/A	N/A	4341