Precision of the proposed method (n = 6).

Conc. (ng per spot)	Repeatability (intraday precision)			Intermediate precision (interday)
	Area ± SD (n = 6)	Standard error	% RSD	Area ± SD (n = 6)	Standard error	% RSD
200	3891.20 ± 18.63	7.63	0.48	3895.20 ± 22.78	9.33	0.58
300	5273.60 ± 33.49	13.72	0.64	5291.60 ± 45.69	18.72	0.86
400	6546.40 ± 29.80	12.21	0.46	6544.40 ± 31.51	12.91	0.48