Methodology and Quality Assurance/Quality Control of Environmental Analysis - Fundamentals of Environmental Sampling and Analysis - page 109

factors, such as the project objective, the ease of operation, the availability of
instruments, MDLs, and analytical cost.
Discussed below is a general guide for beginners in choosing standard
methods based on the major types of analytical parameters. There is no set rule as
to which method is preferred. In the meantime, the reader should note that a
current trend within the EPA is to break down the barriers using new monitoring
techniques with a program called performance based measurement system
(PBMS). The PBMS conveys ''what'' needs to be accomplished, but not
prescriptively ''how'' to do it. With this new approach, the EPA promotes flexibility
in method selection.
5.2.1 Methods for Sample Preparation
Sample preparation is always the required first step prior to any trace analysis. With
the exception of analyzing very clean matrices (such as groundwater or pristine
natural water), environmental samples should always be ''pretreated'' first and then
directly introduced into the instrument for quantitative analysis. We will briefly
introduce three major types of methodologies for metals, SVOCs, and VOCs in
liquid and solid waste samples. The technical details of sample preparation will be
the subject of Chapter 7.
EPA 3000 Series: Digestion Methods for Metal Analysis
Samples for metal analysis must have an acid digestion procedure using heated
HCl, HNO 3 ,H 2 SO 4 , HClO 4 , or the combined use of these acids to release
metals from sample matrix, so that the instrument will respond. Several EPA 3000
series methods in SW-846 will be the methods of choice. Detailed digestion
methods can also be found in APHA 3030. Although SW-846 is proposed for
solid waste, the methods are also applicable for other matrices, such as the examples
given below:
Method 3005A: Digestion of water for analysis by FLAA or ICP
Method 3010A: Digestion of water for analysis by FLAA or ICP
Method 3015: Microwave digestion for aqueous samples
Method 3020A: Digestion of water for analysis by GFAA
Method 3031: Digestion of soils for analysis by AA or ICP
Methods 3050B: Digestion of sediments, sludge, and soils.
Note, slight variations exist depending on the types of metals to be analyzed or
the instrument to be used. For example, Method 3005A is for total recoverable or
dissolved metals, while Method 3010A is used for preparation of aqueous samples
and wastes that contain suspended solids. Total recoverable metals refer to the
concentration of metals in an unfiltered sample treatment with hot dilute mineral
acid. Samples are acidified with HNO 3 at the time of collection. Total dissolved