Microwave digestion
Take 0.2-0.5g sample into a vessel of microwave digestion system, add 8ml Nitric acid, put into microwave digestion system to digest. After digestion well, put on the electronic heating plate 120C to remove acid.
Zn：Remove acid until about 0.5ml sample volume residual, add water to 10ml mark of volumetric flask, ready to test.
As : Remove acid until about 1.0 ml sample volume residual, add water to the mark of 10ml volumetric flask, take 5ml pretreatment solution to 10ml colorimetric tube, add 0.5ml HCL and 1ml 10% thiourea solution, then add water to the mark, mix well, wait for 30mins, ready to test.
Hg: Remove acid until about 1.0 ml sample volume residual, add water to 10ml mark of volumetric flask, ready to test.
Cd: Remove all acid, add 2% HCL to the mark of 10ml volumetric flask, take 6ml pretreatment solution to 10ml colorimetric tube, add 0.1ml 1000µg/mL Co2+ and 3mL10% thiourea solution, then add water to mark, mix well for testing.
Pb: Remove all acid, add 2% HCL to the mark of 10ml volumetric flask, ready to test.
Test Methods
Hg, As, Pb and Cd were determined by Heavy metal analyzer.
Table2 Heavy metal analyzer parameters
Zinc was determined by AAS-Flame method.
Test result
Hg
As
Pb
Cd
Zn (AAS-Flame method)
