Statistical comparison of the results obtained by the proposed SPE sensors and the official method^a.

Taken (mol L−1)	Sensor 1		Sensor 2		Sensor 3		Official method
	Found (mol L−1)	% recovery	Found (mol L−1)	% recovery	Found (mol L−1)	% recovery	Taken (μg mL−1)	Found (μg L−1)	% recovery
1 × 10−5	0.9823 × 10−5	98.23	0.9913 × 10−5	99.13	1.0023 × 10−5	100.23	2	1.991	99.55
5 × 10−5	5.057 × 10−5	101.14	4.942 × 10−5	98.84	4.917 × 10−5	98.34	4	4.0032	100.08
1 × 10−4	0.986 × 10−4	98.60	0.9945 × 10−4	99.45	0.99 × 10−4	99.00	6	5.887	98.12
5 × 10−4	4.988 × 10−4	99.76	4.982 × 10−4	99.64	4.9325 × 10−4	98.65	8	7.9086	98.87
1 × 10−3	1.0022 × 10−3	100.22	1.0087 × 10−3	100.87	1.011 × 10−3	101.10	10	9.909	99.09
Mean ± S.D.	99.59 ± 1.189		99.58 ± 0.780		99.46 ± 1.162		99.14 ± 0.736
% RSD	1.194		0.783		1.168		0.742
Variance	1.414		0.609		1.350		0.541
Student’s t-test	0.716 (2.306)b		0.925 (2.306)b		0.523 (2.306)b
F-value	2.610 (6.338)b		1.123 (6.338)b		2.493 (6.338)b

^aOfficial method (HPLC method using an octadecylsilane column and a methanol–0.01 mol L⁻¹ ammonium phosphate buffer at pH 6.0 (60 : 40) as the mobile phase).

^bThe values in parentheses are the corresponding tabulated t and F values at P = 0.05.