Table 4.

The content of arsenic species in the dilute nitric acid solution (HNO₃: H₂O = 2: 98) extract

Sample ID	Total As (mg kg−1)	Inorganic arsenic (mg kg−1)a			Organic arsenic (µg kg−1)				Unknown (mg kg−1)
		As(III)	As(V)	Inorganic arsenic extraction efficiency (%)	MMA	DMA	AsC	AsB
W1	9.00 ± 0.21	0.41 ± 0.04	0.26 ± 0.01	7.45	N/A	ND	ND	ND	8.33
W2	9.93 ± 0.09	0.55 ± 0.02	0.35 ± 0.01	9.06	N/A	ND	ND	ND	9.03
W3	10.18 ± 0.15	0.73 ± 0.02	0.25 ± 0.01	9.56	N/A	ND	ND	ND	9.20
$\overline{w}$	9.70 ± 0.62	0.56 ± 0.16	0.29 ± 0.06	8.69	N/A	ND	ND	ND	8.85
S1	1.38 ± 0.14	0.08 ± 0.01	0.50 ± 0.01	41.80	N/A	ND	ND	ND	0.80
S2	1.41 ± 0.06	0.08 ± 0.00	0.39 ± 0.02	32.66	N/A	ND	ND	ND	0.95
S3	1.68 ± 0.08	0.07 ± 0.01	0.40 ± 0.02	28.14	N/A	ND	ND	ND	1.19
$\overline{\text{S}}$	1.49 ± 0.17	0.08 ± 0.01	0.43 ± 0.06	34.20	N/A	ND	ND	ND	0.98
C1	14.23 ± 0.10	0.59 ± 0.04	0.30 ± 0.01	6.30	N/A	ND	ND	ND	13.34
C2	13.62 ± 0.48	0.64 ± 0.07	0.28 ± 0.02	6.70	N/A	ND	ND	ND	12.71
C3	12.57 ± 0.03	0.48 ± 0.02	0.32 ± 0.00	6.35	N/A	ND	ND	ND	11.76
$\overline{\text{C}}$	13.47 ± 0.84	0.57 ± 0.08	0.30 ± 0.02	6.45	N/A	ND	ND	ND	12.60

Results are expressed as mean ± SD, (n = 3)

N/A: trace amounts (LOD < N/A < LOQ); ND: not detected

^a The concentration calculated based on the original samples. $\overline{\mathit{x}}$: the average value