Rare Earth Elements: A Review of Production, Processing ...

Rare Earth Elements Review Appendix A – Selected Chemical Properties
Although each method has their advantages and disadvantages, the predominant method utilized today is
ICP-MS. Listed in Table A-1 are three established ICP-MS methods that can be utilized for the analysis
of REEs. It is important to note that the EPA methods do not list REE as being successfully demonstrated
by these methods. However, if REEs are to be measured they need to meet the provisions outlined in the
method. Chapter K of the USGS document presented in Table A-1 was written specifically for the
analysis of REEs and addresses the common matrix interference issues associated with this group of
metals. Although not specifically mentioned in the EPA methods, REEs can be measured with these
methods as long as the elements of interest are validated by the procedures outlined in the perspective
method.
Table A-1. Analytical Methods and Sample Preservation and Holding Times
for the Analysis of Rare Earth Elements
Demonstrated
Reference Method Holding Preservation and Acceptable
Method Description Time Container Storage Elements
EPA 6020A Metals in
environmental
samples by ICP­
MS
EPA 200.8 Metals in
environmental
samples by ICP­
MS
6 months � Solid - (1) 4
oz. glass jar
� Liquid - (1)
500 mL plastic
bottle
6 months � Solid - (1) 4
oz. glass jar
� Liquid - (1)
500 mL plastic
bottle
� Solid –
Refrigerate at
4�C
� Liquid –
Refrigerate at
4�C; HNO3 to pH