Abstract
One of the most important tasks of water
microbiology laboratories is to provide accurate and reliable analysis results
when the customer undertakes. Laboratories receive accreditation certificates
by applying to various national and international accreditation bodies to demonstrate
that the results of the analysis are accurate and reliable on the international
platform. In Turkey, this certification is carried out by the Turkish
Accreditation Agency (TÜRKAK). One of the most important subjects examined
under the TÜRKAK inspection in the laboratories is the measurement uncertainty
of laboratories according to TS EN ISO / IEC 17025 standard. The
reproducibility results are used in the calculation of measurement
uncertainties in water microbiology laboratories. In Escherichia coli measurement uncertainty calculations, 60 cases of
analysis were devised for 30 studies, supposed to be performed by two analysts
(Analyst and Analyst B). As a result of our studies, RSDR was found
to be 0.075. RSDR was considered to be combined uncertainty. For our
95% confidence interval as a result of our studies, the measurement uncertainty
was calculated 15. Accurate implementation of method verifications of water
microbiology laboratories will contribute to improving customer satisfaction by
improving public health as it will increase quality assurance
Introduction
One of the most important tasks of water
microbiology laboratories is to provide accurate and reliable analysis results
when the customer undertakes. Laboratories receive accreditation certificates
by applying to various national and international accreditation bodies to
demonstrate that the results of the analysis are accurate and reliable on the
international platform. In Turkey, this certification is carried out by the
TÜRKAK. This organization is an independent organization which is a member of
the European Accreditation Association (EA), the International Accreditation
Forum (IAF) and the International Laboratory Accreditation Association (ILAC). TÜRKAK
conducts audits in accordance with ISO / IEC 17025 standard, which sets general
conditions for testing and calibration laboratories, one of the quality
management systems. One of the most important issues examined under the audit
under the ISO / IEC 17025 standard is the measurement uncertainty of
laboratories (1). Since standard methods are often used in water microbiology
laboratories, a complete validation study is not performed. As stated in ISO /
TR 13843, secondary validation, in other words, verification studies is
sufficient (2). Prior to TÜRKAK's application,
laboratories are responsible for proving the validity of the standard methods
used by the laboratories, ie the methods for their laboratories. Method
verification is the proof of the suitability of a measurement procedure for its
intended use by written tests with objective testing with various performance
studies The method verification
also provides information on both analytical requirements (incubation
temperature, food preparation and storage conditions) as well as results such
as recovery (3). One of the most important criteria prior to laboratory
work is the calculation of measurement uncertainty as well as starting work
with competent and sufficient personnel (4). Measurement uncertainty results,
which are part of the verification studies, show how accurate and reliable the
analysis can be. Measurement uncertainty indicates the range of values that may
be encountered with the measured value and the value supplied with the measured
value. The measurement uncertainty account in microbiology laboratories is a
category that prevents metrological and statistically valid computation, so it
is difficult to calculate each measurement uncertainty source (5). To
understand measurement uncertainty calculations in microbiology laboratories,
ISO / TS 19036 (Microbiology of food and animal feeding stuffs -- Guidelines
for the estimation of measurement uncertainty for quantitative determinations)
is a good standard. In this standard, measurement uncertainty calculation is
proposed based on experimental studies carried out in the laboratory with a
black box approach that measures total variation irrespective of source (6). However,
since ISO / TS 19036 is a food microbiology standard, it cannot be used in the
measurement uncertainty calculations of samples in water microbiology
laboratories. In water microbiology laboratories methods such as ISO / TR 13843
and ISO 17994 which provide statistical information can be used in method
verification (2,7). However,
laboratories may have difficulty reaching these documents because these
standards have to be paid. However, the Canadian laboratory accreditation
document P19 CALA provides free access (8). Another advantage of this method is
that it allows the calculation of measurement uncertainty using routine samples
in the laboratory. In this work, it is aimed to introduce the P19 method of the
Canadian Accreditation Laboratories Association (CALA), which can be
practically applied at low cost for measurement uncertainty calculations in
method verification studies to accredited water microbiology laboratories
according to the ISO / IEC 17025 (1).
References
- Şükriye Karadayı1, Beytullah Karadayı2, Bülent Turhan3
- 1 İstanbul Kemerburgaz University, Vocational School of Health Services 2 İstanbul University, Cerrahpaşa Medical Faculty, Department of Forensic Medicine 3 Istanbul Public Health Directorate, Istanbul 3 Number Public Health Laboratory
Abstract
References
- Şükriye Karadayı1, Beytullah Karadayı2, Bülent Turhan3
- 1 İstanbul Kemerburgaz University, Vocational School of Health Services 2 İstanbul University, Cerrahpaşa Medical Faculty, Department of Forensic Medicine 3 Istanbul Public Health Directorate, Istanbul 3 Number Public Health Laboratory
Details
| Journal Section | Articles |
|---|---|
| Authors | |
| Publication Date | June 1, 2017 |
| Published in Issue | Year 2017 Volume: 2 Issue: 1(3) - Volume 2, Issue 1(3) |
