For quality control of acid digestion, a CRM was analysed in every batch of samples
measurements (total As concentration). The comparison between
each obtained value of total As with its corresponding certified
value (Table 1) showed no significant difference at a 95% confidence
level when Student’s t-test was applied. The repeatability
(six times within a day, n = 6) was assessed for the results obtained
by analysis of different replicates of CRMs (Table 1). The RSD (%)
values were: 4.9% for TORT-2 and 1.2% for DOLT-4. The detection
(LOD) and quantification limits (LOQ) were calculated as three
times the standard deviation (3r) and ten times the standard
deviation signal (10r) of ten digestion blanks, respectively
(Llorente-Mirandes et al., 2014). The results obtained were as
follows: 0.006 mg As kg1 dry weight basis for method detection
limit and 0.021 mg As kg1 dry weight basis for method quantification
limit.