Table 4.

Comparison of the proposed method with other methods for the detection of nicotine metabolites.

Sample (Amount)	Analyte	Sample Preparation	Extraction Step a	LOD b (pg/mg)	Ref.
Hair (10 mg)	COT	LLE	Extraction with DCM (0.5 mL)	6.6	[7]
Hair (1 mg)	COT	LLE	Extraction with diethyl ether (2 mL)	70	[24]
Hair (20 mg)	COT	LLE	Three step extraction: - Extraction with DCM (5 mL) and DCM/iPrOH (5 mL, 75/25, v/v) - Back-extraction with HCl (1 mL, 0.5 M) - Re-extraction with DCM (4 mL) and DCM/iPrOH (4 mL, 75/25, v/v)	2.5	[9]
Toenail (20–30 mg)	COT	LLE	Extraction with DCM (1 mL)	12	[25]
Toenail (20–30 mg)	COT	LLE	Repeated extraction (thrice) with DCM (0.5 mL)	35	[4]
Hair and nail (10 mg)	COT, 3-HCOT	QuEChERS	One-step extraction with acetonitrile (5 mL)	10 c	This work

^a Dichloromethane (DCM) and isopropanol (iPrOH). ^b Limit of detection (LOD). ^c Represented as LLOQ.