The Determination of Arsenic Compounds: A Critical Review

Table 1

Results for the arsenic speciation in NIST SRM 1568a (rice flour) in μg kg⁻¹. The material is not certified for species, only the total (290 ± 30 μg kg⁻¹, where the ± term is an expanded uncertainty and corresponds approximately to a 95% confidence interval).

Arsenite	Arsenate	DMA	MMA	Inorganic sum	Sum of species	Year of Publication	Reference
		174 ± 9	8 ± 2	92 ± 4	274	2001	[58]
		239	0	85	324	2001	[58]
75	12	180	9	97	276	2003	[59]
67 ± 4	39 ± 3	158 ± 5	13 ± 2	108	277	2003	[60]
55 ± 1	54 ± 3	165 ± 8	15 ± 2	109	288	2004	[61]
		171		70	241	2004	[62]
80 ± 14	0	160 ± 24	2	80 ± 14	242	2005	[63]
68 ± 4	20 ± 2	135 ± 4	8 ± 1	88	231	2005	[64, 65]
±2 s		168 ± 9	12.0 ± 0.2	87 ± 9	267	2005	[66]
		148 ± 7	11.0 ± 0.5	101 ± 7	260	2005	[66]
0	58	116	10	58	184	2006	[67]
68 ± 4	20 ± 2	135 ± 4	8 ± 1	88	231	2007	[68]
60 ± 10	28 ± 16	148 ± 22	12 ± 3	88	248	2007	[69]
69 ± 1	33 ± 1	155 ± 2	9.2 ± 0.2	102	266	2007	[70]
52 ± 1	44 ±2	173 ± 2	12 ± 0.8	96	281	2008	[71]
67 ± 5	36 ± 1	162 ± 1	5 ± 1	103	271	2008	[72]
				82 ± 9	268	2008	[73]
55 ± 6	41 ± 3	166 ± 6	10 ± 2	96	272	2009	[74]
		180 ± 3	sum of org	110 ± 10	290	2009	[75]
		185 ± 3	sum of org	99 ± 2	284	2009	[76]
		175 ± 5	0	87 ± 7	262	2009	[77]
52 ± 3	20 ± 3	128 ± 6	10.4 ± 0.2	72	210	2009	[78]
53 ± 1	45 ± 1	175 ± 2	13 ± 2	98	231	2010	[68]
71 ± 6	36 ± 4	188 ± 4	14 ± 2	107	309	2010	[79]
78	32	148	12	110	270	2010	[80]
69 ± 1	22 ± 1	171 ± 8	9 ± 2	91 ± 6	271	2010	[81]
63 ± 4	50 ± 3	142 ± 4	15 ± 4	113	273	2011	[82]
74.40 ± 0.09	35.1 ± 0.9	158 ± 2	10.50 ± 0.01	109.5	278	2011	[83]
		131 ± 6	72 ± 4	86 ± 6	289	2011	[84]
		134 ± 7	14 ± 5	101 ± 3	249	2011	[84]
		129	16	98	243	2011	[84]
51.9	39.6	188	12	91.2	291	2011	[85]
		160 ± 20	0	110 ± 5	270	2011	[86]
		168 ± 7	sum of org	76 ± 9	244	2011	[87]
		200 ± 12	11 ± 1	79 ± 7	290	2012	[88]
0	96 ± 1	166 ± 2	12 ± 1	96	274	2012	[88]
0	104 ± 4	168 ± 2	14 ± 2	104 ± 4	286	2012	[89]
0	105 ± 2	180 ± 5	13.2 ± 0.2	105 ± 2	298	2012	[89]
53 ± 1	46.1 ± 0.7	172 ± 2	13.2 ± 0.3	99	285	2012	[90]
74 ± 7	30 ± 3	165 ± 7	15.0 ± 0.7	104	284	2012	[91]

Notes. The ± terms are as provided by the researchers. They are predominantly standard deviations for some small number of replicates. Further details are provided in the text. Values have been rounded to the first uncertain digit. The numbers in the “sum” columns may differ from the sums of the numbers presented in the individual columns because of rounding effects. Not all researchers reported values for all four species. No ± terms have been calculated for the sums where this had not been done by the researchers, though clearly this would be possible for many entries. Many of the sample extraction methods did not preserve the redox state of the inorganic arsenic species.