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Article written by
Jessica Raney,
Quality Control Group Leader, Analytical Products Group
Complete Article from Edition 3 APG eNewsletter
Jessica Raney, one of APG’s Technical Support Chemists contributed this
informative article about the importance of independently prepared
quality control materials. Jessica has been a chemist with APG for over
5 years and is able to assist you with any of your quality control
questions.
The goal of any analysis is to measure the components of
a sample as accurately and precisely as possible. In order to achieve
this goal, the analyst must be confident that they have control of the
measurement process.
A measurement process that is out of control produces data that is not
accurate or defensible. The key to maintaining control of the measurement
process and generating accurate, defensible data is the proper use of
quality control standards.
Many people think that the only requirement of a quality control standard
is that the value of the sample be known. While a known true value is
essential to a quality control standard, there are several other pieces of
information that should be available if it is to be considered a quality
control standard. For this reason, independently prepared quality control
samples purchased from an accredited provider are essential to producing
accurate, defensible data.
A properly prepared and utilized quality control standard verifies the
calibration and validates the unknown sample data. The quality control
sample should be independently prepared from the calibration standards and
should be treated in exactly the same manner as the unknown samples. In
addition, the quality control standard should meet the following guidelines:
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The quality control sample has a certified true value. This data allows
the analyst to evaluate the accuracy of the analysis.
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The quality control standard should be traceable to a NIST standard,
if possible.
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The quality control standard should have an EPA acceptance range.
This information provides assurance that the data generated in the
analysis would be accepted by a regulatory agency.
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The quality control standard should be accompanied by an
inter-laboratory acceptance range. This data provides assurance that
the results are comparable to the data generated by other laboratories
running the same method.
The confidence an analyst has in the quality control standard should be
directly related to the level of documentation they have about that sample.
If the quality control standard does not meet all of the guidelines listed
above, then the analyst loses confidence in the quality control standard
and therefore loses confidence in the accuracy and defensibility of the data
produced in the analysis. APG's quality control standards provide you with
the perfect level of documentation and confidence that cannot be achieved
when you prepare the standards yourself.
If you have any questions regarding quality control standards or how to
improve your quality system feel free to contact Jessica at
j.raney@apgqa.com.
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