Methodology and Quality Assurance/Quality Control of Environmental Analysis - Fundamentals of Environmental Sampling and Analysis - page 115

instrument. (c) EPA 625 would be the first choice as the chemicals are SVOCs and the matrix
is wastewater. (d) For the bodily fluids samples such as blood and urine, an OSHA method
would be the first option, which can be searched from OSHA's online Sampling and Analytical
Methods database for the particular method.
EXAMPLE 5.2. The use of National Environmental Method Index (NEMI) (http://
www. nemi.gov/). (a) Find a list of COD in water methods by the U.S. EPA and other
agencies; (b) What is the EPA method 508? Locate this method for a printable hardcopy.
SOLUTION: Use quick/advanced search on the NEMI Web site, type ''COD'' as the analyte
name and ''water'' as the media name. Eight methods are found—EPA 410.1, 410.2, 410.3,
410.4, standard method (APHA Method) 5220D, 5220C, USGS I-3561, and ASTM D1252B.
(b) Use general search, type ''508'' as the method number. This method is entitled
''chlorinated pesticide in water using GC-ECD.'' A printable method file in PDF format can
be located by clicking the method number on the search result. Only the governmental
methods by the EPA and USGS are downloadable free of charge.
5.3 FIELD QUALITY ASSURANCE/QUALITY
CONTROL (QA/QC)
In Chapter 1, we defined the concept of QA/QC. Recall that QA is an integrated
management system to ensure that QC system is in place and working as intended.
This management system may include viewing QC data, evaluating parameters,
taking corrective actions, planning for process, and personnel involved (data
generator, data reviewer, QA manager, and data user). QC is a set of routine
technical activities performed whose purpose is essentially error control with the use
of QC samples such as blanks and spikes. Together, QA and QC help us to produce
data of a known quality (e.g., precision, accuracy) and enhance the credibility of
reported results.
A formal QA/QC program is written in a document called Quality Assurance
Project Plan (QAPP). QAPP should be prepared and approved before sample
collection begins. It should address the following essential components: project
description, project organization and responsibility, QA objectives for measure-
ment data in terms of precision and accuracy, sampling procedures, sampling
custody, calibration procedures and frequency, analytical procedures, data
reduction/validation and reporting, internal quality control checks and frequency,
performance and system audit and frequency, specific routine procedures used to
assess data precision/accuracy and completeness, corrective actions, and QA
report and management.
In the following discussions on QA/QC, we first describe field QA/QC,
particularly the types and number of field QC samples that are required in various
instances. The laboratory counterpart of QA/QC, further divided into stages of
sample preparation and sample analysis, will be introduced in the next section. Note
that QA/QC samples (QC sample in short) are the extra samples collected during the
sampling and analytical processes. These QC samples are fundamentally different
from the true environmental samples used to represent the nature of the sampling