Table 3. Comparison of the presented method with other methods used in preconcentration and determination of the VPA .

Sample	RSD% a	Extraction time (min)	LR b (µg mL-1)	LOD c	Method	Ref.
Human serum	8.8	20	0.5-100	NR f)	HS-SPME-GC-MS d	39
Human serum	13.2	20	2-20	0.8	HS-LPME-GC-FID e	13
Human serum	7	10	2-100	1.7	HS-SPME-GC-FID f	14
Human serum	7	15	0.25-100	0.065	DLLME-VADLLME- GC-FID g	40
Human plasma	9	< 15	0.2-100	0.057	Presented method	-

^a Relative standard deviation

^b Linear range.

^cLimit of detection (mg L^-1).

^d Headspace -solid-phase microextraction-gas chromatography-mass spectrometry.

^e Headspace-liquid phase microextraction-gas chromatography-flame ionization detector.

^fHeadspace-solid phase microextraction- gas chromatography-flame ionization detector.

^g Dispersive liquid-liquid microextraction- vortex assisted dispersive liquid-liquid microextraction- gas chromatography-flame ionization detector.