LEACH DATA VS TOTAL - WHICH IS RELEVANT FOR SRMS

This paper presents an overview of the available leach data for NIST SRMs(1) currently in distribution or to be released in the near future. These include coal fly ash, soil, sediment and sludge matrices, each leached with only one of several potential acid mixtures as specified in the Toxicity Characteristics Leaching Protocol, Method 3050, or Method 3051. These leach values are method-specific and that specificity applies individually to each of several potential leach media which may be used. Therefore leach values cannot be confirmed by the agreement of results obtained by two or more independent methods or techniques, as is NIST practice for certified values. Additionally, the certified values, which have historically been total concentration values, do not provide the necessary quality assurance for environmental studies based on leach data. The information leach values provide this level of quality control for environmental studies.