The unavailability of certified reference materials for trace organic
contaminants in different types of water has placed a serious restrict
ion on the ability to validate analytical methodology and provide the
necessary quality assessment of environmental data generated from aque
ous samples. Lyophilised waters, concentrates and in situ spiking are
proposed as methods for the preparation of aqueous reference materials
to overcome the problems associated with the instability of the deter
minands in water, the bulk of the samples and the inherent heterogenei
ty of multi-phased samples with suspended solids, colloids and dissolv
ed material.