AS 4479.2-1997

This Standard specifies a method for the extraction of heavy metals from soil using aqua regia. Analytical techniques appropriate to the analyte content in the soils are used for the subsequent determinations of heavy metals and metalloids in the resulting solution.Sediments, sludges (containing less than 20% organic carbon) and other silicate materials (e.g. fill material and brick) may be extracted using this method.NOTES:1 The method produces a solution for determination of aqua regia extractable metals. The solution is not suitable for speciation studies, nor do the values obtained necessarily represent the total or bio-available heavy metal content of the soils.2 No acid digestion procedure necessarily results in complete extraction of the analyte, therefore different acid digestion procedures may yield different results.Users of this Standard should carry out a programme of analysis using reference materials to assure themselves that the method given here is appropriate for their needs. This method is suitable for use in conjunction with ANZECC/NHMRC Guidelines*, provided the appropriate method validation details are given.Other methods use different acid combinations such as nitric/perchloric and reverse aqua regia.3 AS 4479.1 specifies requirements for pretreatment of soil samples for analysis.4 This procedure is to be performed only by an analyst familiar with the operational procedures associated with acid digestion.

First published as AS 4479.2-1997.