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Aqua regia digestion

Aqua regia digestion

ALS offers the lowest detection levels available in the industry from our super-trace aqua regia and four-acid digestions. These methods are ideal for soil and sediment samples where well-characterised background values will improve anomaly identification. Super-trace detection levels can also be valuable with regional drilling samples where subtle changes in geochemistry can provide information used for large scale fluid flow models and other interpretations.

Digestão de água-régia

Aqua regia super trace

ALS achieves super trace detection levels using a combination of ICP-AES and ICP-MS determinations on the same sample. The two sets of data are combined to provide optimal detection and ranges for 50+ elements.

Aqua regia super trace analysis

ALS offers both a standard and variation of an aqua regia digestion from a 0.5g sample. Method ME-MS41L™ method utilises the typical aqua regia acid mixture of nitric and hydrochloric acids in a 1:3 ratio. A weaker digestion using a 1:1 ratio of nitric and hydrochloric acids is also an option with method ME-MS41W™. Both methods use relatively low temperatures for digestion to maintain volatiles such as Hg in the sample. Gold reported by these methods is usually considered as semi-quantitative as the sample weight is too low to be representative.

Super trace analysis (ME-MS41LTM)

Code Analytes & Ranges (ppm)
ME-MS41L™* 0.5g sample Ag 0.001-100 Co 0.001-10,000 La 0.002-10,000 Pt 0.002-25 Th 0.002-10,000
Al 0.01%-25% Cr 0.01-10,000 Li 0.1-10,000 Rb 0.005-10,000 Ti 0.001%-10%
As 0.01-10,000 Cs 0.005-500 Mg 0.01%-25% Re 0.0002-50 Tl 0.001-10,000
Au 0.0002-25 Cu 0.01-10,000 Mn 0.1-50,000 S 0.01%-10% U 0.005-10,000
B 10-10,000 Fe 0.001%-50% Mo 0.01-10,000 Sb 0.005-10,000 V 0.1-10,000
Ba 0.5-10,000 Ga 0.004-10,000 Na 0.001%-10% Sc 0.005-10,000 W 0.001-10,000
Be 0.01-1000 Ge 0.005-500 Nb 0.002-500 Se 0.003-1000 Y 0.003-500
Bi 0.0005-10,000 Hf 0.002-500 Ni 0.04-10,000 Sn 0.01-500 Zn 0.1-10,000
Ca 0.01%-25% Hg 0.004-10,000 P 0.001%-1% Sr 0.01-10,000 Zr 0.01-500
Cd 0.001-1000 In 0.005-500 Pb 0.005-10,000 Ta 0.005-500
Ce 0.003-500 K 0.01%-10% Pd 0.001-25 Te 0.003-500

*Gold determinations by this method are semi-quantitative due to the small sample weight used. A weak aqua regia (1:1 ratio HCl:HNO3) digestion is also available, use code ME-MS41W™. For Au with multi-element using a 25g or 50g charge please use AuME-ST43™ or AuME-ST44™.

Pb isotopes & rare earth element analysis

The rare earth elements (REEs) and lead isotope concentrations add new dimensions to super trace data. REEs may still be useful pathfinders despite reflecting only the labile (aqua regia extractable) component, while Pb isotopic signatures can be used in fingerprinting and hydrothermal fluid history.

Methods can be added onto the ME-MS41L™ or ME-MS41W™ analysis to provide Pb isotopes and/or rare earth element concentrations: MS41L-PbIS™ and MS14L-REE™ (or W variation). These analyses can add new dimensions to super trace data.

Super Trace REE and Pb Isotope add-ons

Code Analytes & Ranges (ppm)
MS41L-REE™ Dy 0.002-1000 Ho 0.001-1000 Sm 0.002-1000
Er 0.002-1000 Lu 0.001-1000 Tb 0.001-1000
Eu 0.002-1000 Nd 0.002-1000 Tm 0.001-1000
Gd 0.002-1000 Pr 0.002-1000 Yb 0.002-1000
MS41L-PbIS™ ²⁰⁴Pb 0.005-10000 ²⁰⁶Pb 0.005-10000 ²⁰⁷Pb 0.005-10000
²⁰⁸Pb 0.005-10000



ALS Super Trace Methods Tech Note (Rev1.0)


ALS Aqua Regia or Four Acid Technical Note

22 JUN 2022

Frequently asked questions

Related resources

Super trace-low level gold & multi-element

Gold & multi-element analysis

Aqua regia digestions using 25g or 50g sample aliquots allows gold to be reported quantitatively .

Base metal analysis

Higher detection level methods

For the analysis of more advanced projects, detection levels higher than the super trace methods may be applicable.