Table 2.

Comparisons of the various analytical methods of assaying cotinine

Reference	Methoda	Antigen	Cross-reactivityb (%)	Detection limit	Comparison with chromatographic methodsc
Heinrich-Ramm et al. [7]	RIA				2.4- to 2.9-fold higher than GC–MS
Kuo et al. [6]	ELISA			0.39–0.46 ng/mL	0.6- to 0.9-fold higher than GC-nitrogen-phosphorus
Ohta et al. [9]	ELISA	Cotinine-3-thyroglobulin	Nicotine (16)	0.03 ng/mL	1.4-fold higher than GC–MS
Wielkoszynski et al. [8]	ELISA	4-Carboxy-γ-cotinine	3HC (18.6), Nicotine N-oxide (5.1)	3–3.5 ng/mL	6-fold higher than TLC
Matsumoto et al. (present study)	ELISA	Cotinine-4 -γ-globulin	N (0.2), N-g (0.0), C-g (0.3), 3HC (101.3), 3HC-g (221.8)	1.3 ng/mL	3.2- to 5.9-fold higher than GC–MS

^aRIA Radioimmunoassay; ELISA enzyme-linked immunosorbent assay

^bRatio to cotinine reactivity (100%). N Nicotine, N-g nicotine-glucuronide, C-g cotinine, 3HC 3′-hydroxycotinine, 3HC-g 3′-hydroxycotinineglucuronide

^cComparison with cotinine values from urine specimens. GC–MS Gas chromatography–mass spectrometry, TLC thin-layer chromatography