Table 2.

SRM transitions used in the bioanalysis of nucleoside reverse transcriptase inhibitor (NRTI) antiviral drugs in negative-ion mode. MP, DP, and TP are mono-, di-, and tri-phosphorylated anabolites.

Compound	m/z of [M−H]–	Formula	m/z of SRM product-ion	Formula	Literature
didanosine (ddI)	235.084	[C10H11N4O3]–	135.031	[C5H3N4O]–	[26,30]
dideoxyadenosine-TP (ddA-TP)	473.999	[C10H15N5O11P3]–	158.925	[HO6P2]–	[27,41]
			143.006	[C7H5ClF]+	[42]
emtricitabine-TP (FTC-TP)	485.934	[C8H12FN3O12P3S]–	158.925	[HO6P2]–	[35]
lamivudine-MP (3 TC-MP)	308.011	[C8H11N3O6PS]–	78.959	[O3P]–	[27]
lamivudine-TP (3 TC-TP)	467.944	[C8H13N3O12P3S]–	158.925	[HO6P2]–	[27,35,41]
stavudine (d4T)	223.072	[C10H11N2O4]–	125.036	[C5H5N2O2]–	[26]
			41.999	[CNO]–	[11]
d4T-MP	303.039	[C10H12N2O7P]–	176.996	[C5H6O5P]–	[27]
d4T-DP	383.005	[C10H13N2O10P2]–	256.962	[C5H7O8P2]–	[27]
d4T-TP	462.971	[C10H14N2O13P3]–	158.925	[HO6P2]–	[27,41]
tenofovir (TFV)	286.071	[C9H13N5O4P]–	134.047	[C5H4N5]–	[27]
TFV-MP	366.037	[C9H14N5O7P2]–	78.959	[O3P]–	[27]
TFV-DP	446.004	[C9H15N5O10P3]–	158.925	[HO6P2]–	[27,35]
zidovudine (AZT, ZDV)	266.089	[C10H12N5O4]–	223.072	[C10H11N2O4]–	[11,26,30]
			41.999	[CNO]–	[37]
			42.010	[N3]–
AZT-MP	346.056	[C10H13N5O7P]–	176.996	[C5H6O5P]–	[27]
AZT-DP	426.022	[C10H14N5O10P2]–	176.996	[C5H6O5P]–	[27]
AZT-TP	505.988	[C10H15N5O13P3]–	379.946	[C5H9N3O11P3]–	[32]
			158.925	[HO6P2]–	[27]