Aqua regia digestion

Fig. 3. Distribution of Cu and Au in B and C horizon soil west of the north zone, Shiko Lake. C horizon geochemical data are from BCGS studies by Lett Doyle (2009) and a Novagold Resources till survey by Petsel (2006). Gold abundance in the C horizon samples was determined by an aqua regia digestion and instrumental analysis.

Methods and Results At 15 sites along a 1000 m transect across the Talbot deposit, soil profiles were sampled in 10 cm depth intervals, up to 50 cm. The <250 pm (silt + clay) and <2pm (clay) fractions of the soil samples were analysed using an aqua regia digestion and ICP-MS measurement of 53 elements. 

Testing the variants of aqua regia digestion using certified reference... 

KEYWORDS aqua regia digestion, certified reference materials, analysis of variance, Trinational soil survey... 

The details, beyond the model, are not presented, however, the key conclusions are for some of the elements there is no statistical difference between the standard Aqua Regia digestions analytical protocols and a significant difference for some elements with the EPA 3050B digestion. These differences are shown in the interaction plots of Figure 4. 

Two samples from the soil profile were randomly separated into very small subsamples (a few millimetres across) and analysed after aqua regia digestion to assess the heterogeneous nature of the Au distribution. Replicate sub-samples were analysed to assess the likelihood of finding Au in other soil particles using LA-... 

Analytical Methods Whole rock and LA-ICPMS analyses were carried our at Universite du Quebec a Chicoutimi (UQAC). Sulfur was determined by combustion and IR analysis. Ni and Cu were determined by atomic absorption spectrophotometry after aqua regia digestion. Gold and PGE were determined by Ni-sulfide fire assay followed by Te co-precipitation followed by ICPMS. 

All soil samples were sieved into four size fractions and analyzed for 36 elements by aqua regia digestion/ICP-MS finish. The size fractions included a coarse size (-8+35 mesh), a medium size (-35+80 mesh), a fine size (-80+150 mesh), and a very fine size (-150 mesh). The coarse and medium size fractions were pulverized to 70% passing 150 mesh prior... 

In order to dissolve adequately all selenium species including selenium metal and selenium in steel samples, an aqua regia digestion procedure was used in lieu of the existing NIOSH extraction method. 

The sample treatment stage, focused microwave aqua regia digestion of beans, was studied to determine the metals simultaneously... 

For the sample digestion of sediments, Scancar et al. found that significantly lower results were obtained for chromium, nickel and cadmium when aqua regia digestion was employed, compared to total acid dissolution and acetic acid extraction methods [266]. 

For quality control, the residue from step 3 has to be digested in aqua regia ( step 4 ) and the cumulative amount of metal extracted [i.e. 2(step 1 + step 2 + step 3 + step 4 )] is compared with the pseudototal amount of metal obtained by aqua regia digestion of a separate 1-g soil sample. In the modified BCR procedure, a 0.5 M hydroxylamine hydrochloride solution at pH 1.5 is applied in step 2. 

The US EPA Method 3050B and its optional method (see Figures 5.2 and 5.3, respectively, above) were used, plus an aqua regia digest method (Figure 5.26). In each case, an accurately weighed 1.0000 g sample was used. 

Basically, three ways are used for carrying out the wet digestion procedure. The first one is a very conventional device such as conical flask and refluxing device. This is mainly used for aqua regia digestion of a large amount of soil (3 g dry matter) as detailed in the ISO standard 11466 this apparatus can be applied to one sample or a batch of samples. 

Sewage sludge poT Metrosep Anion Dual one l.OmMNazCOsM.OmM NaHC03 at 0.5 ml/min 20 Supp. Cond. Determination of phosphate at 1.314 g/1 after aqua-regia digestion 64... 

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