Methodology and Quality Assurance/Quality Control of Environmental Analysis - Fundamentals of Environmental Sampling and Analysis - page 110

metals refer to the concentration of metals determined in a sample after filtration
through a 0.45- m filter. As HCl can cause interference during GFAA (graphite

furnace atomic absorption) analysis, the digestate can be analyzed by only FLAA or
ICP.

m

EPA 3500 Series: Extraction of Liquid and Solid Samples
for Nonvolatile/Semivolatile Compounds

Several common extraction methods for nonvolatile or semivolatile compounds
are listed in Table 5.3. The classical liquid-liquid (L-L) extraction is usually
carried out with a 1-L aqueous sample using methylene chloride (CH 2 Cl 2 ) as the
extraction solvent. The volume of extract is reduced to 1 mL by evaporation, so
that a factor of about 1000 in analyte concentration is achieved. For solid
samples, the benchmark method is the Soxhlet extraction, which is tedious and
consumes a great deal of solvent. As shown in Table 5.3, new methods have evolved
from the classical L-L extraction (aqueous samples) and Soxhlet extraction (solid
sample), including continuous L-L, automated Soxhlet, sonication, solid phase
extraction (SPE), and supercritical fluid extraction (SFE). These new methods are
commonly used because the amount of solvent needed and the extraction time are
both reduced.

Table 5.3 Sample extraction methods for semivolatiles and nonvolatiles

Method
Series Matrix Extraction type Analytes

3510 Aqueous Separatory funnel liquid- Semivolatile and

liquid extraction nonvolatile organics

3520 Aqueous Continuous liquid-liquid Semivolatile and

extraction nonvolatile organics

3535 Aqueous Solid phase extraction (SPE) Semivolatile and

nonvolatile organics

3540 Solids Soxhlet extraction Semivolatile and

nonvolatile organics

3541 Solids Automated Soxhlet Semivolatile and

extraction nonvolatile organics

3542 Air sampling Separatory funnel and Semivolatile

train Soxhlet extraction

3545 Solids Pressurized fluid extraction Semivolatile and

(ASE) nonvolatile organics

3550 Solids Ultrasonic extraction Semivolatile and

nonvolatile organics

3560/3561 Solids Supercritical fluid extraction Semivolatile petroleum

(SFE) hydrocarbons and

PAHs