the environmental laboratories, data quality assurance (QA)
is now recognized as being of paramount importance for detection.
Locating and minimizing sources of data variability. Quality
is so important economically that it has been labeled as
the " business cornerstone of the 1990s"
control of environmental data quality has moved from an
often neglected activity in the 1970s and early 1980s to
a well developed science . The trend toward lower detection
limits put increasing demands on QA,
quality laboratories generate analytical data for different
agencies to establich the water quality for different purposes
as irrigation or drinking, These data can also be used as
a basis for regulatory policy decisions,
order to ensure data quality. It is very important that
the persons involved in generating these data are knowledgeable
and fully committed to the production of high quality data,
This is achieved by careful implementation of a comprehensive
quality assurance program.