Table 2.

Results of matrix effect (ME), extraction recovery (ER), and process efficacy (PE) for dTG, dTG-IS, and dC-IS determined at low and high concentrations, as mean values in six different hydrolysed DNA samples

n =6	Calibrator I			Calibrator VII
	0.04 nmol/L			2.5 nmol/L
Compound	ME%	ER%	PE%	ME%	ER%	PE%
dTG	91.9	106.7	98.0	90.2	105.2	94.8
	Internal standards
dTG-IS	1 nmol/L
	ME%	ER%	PE%	ME%	ER%	PE%
	91.2	106.0	96.7	86.7	102.2	88.6
dC-IS	2.5 µmol/L
	ME%	ER%	PE%	ME%	ER%	PE%
	93.8	107.2	100.5	89.1	105.2	93.7

Abbreviations: dTG, 2′-deoxythioguanosine; dTG-IS, 2′-deoxyguanosine-¹³C₁₀¹⁵N₅; dC-IS, 2′-deoxycytidine-¹³C₁₅N₂