Agriculture Reference
In-Depth Information
complicating factor in the application of this parameter to the zero tolerance
requirements for nitrofuran residues in edible tissue [15].
In order to ensure quality and comparability of the analytical results
generated by laboratories, a set of common performance criteria for residual
analysis was incorporated into the European legislation. Commission Decision
2002/657/EC [87], sets guidelines for the validation of both screening and
confirmatory analytical methods of analysis. This decision implements the
Council Directive 96/23/EC [18] concerning the method performance and
interpretation of results, for the fulfillment of key requirements set by the EU.
According to Commission Decision 2002/657/EC [87], performance
characteristics such as detection capability (CCβ), precision, selectivity and
applicability/stability need to be assessed in order to classify a screening
method as quantitative. For analytes which do not have a declared maximum
residual limit (MRL), such as nitrofuran metabolites, CCβ is defined as the
lowest concentration of a substance that can be measured by a method with an
error probability β = 5%. For quantitative screening, precision is acquired by
the determination of variation coefficients. Inter-assay variation testing gives
an indication of the precision of the assay over a longer period of time.
Selectivity or specificity is the ability of a method to distinguish between the
analyte being measured and other substances. Stability of the standard analyte
in solution and in the matrix should be included in the validation process. For
qualitative screening methods, only CCβ, selectivity and applicability need to
be assessed. Any positive findings assessed using screening methods should
always be re-analysed by a validated confirmatory method [15].
European Union residue legislation aims at a high level of human health
protection, but has also to strike a balance between different other legitimate
interests such as animal health and animal welfare, protection of the honest
user of medicinal products and lawful pharmaceutical manufacturers as well as
compliance with trade agreements. In the implementation of the current legal
framework a number of difficulties have been recognized. These have been
highlighted in a Reflection Paper. Adjustment of the framework can only
become effective after a full legislative codecision procedure [85].
With the MRPL approach the European Commission has proposed a
temporary measure to address urgent problems related to prohibited substances
particularly when it comes to third country trade.
