Single-laboratory validation of a method for detection of Roundup Ready soy in soybeans: application of new strategies for qualitative validation

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C.S.W. Miaw
G.C.S. Amâncio
V.N. Rocha
J.E.G.C. Madeira
S.V.C. Souza


genetically modified organisms, screening method, single-laboratory validation, Roundup Ready soy, labelling regulations


Considering expansion of genetically modified organisms and the basic principle of consumers’ right to access information about products, legislations of several countries establish a limit for labelling transgenic food. Qualitative tests based on the polymerase chain reaction (PCR) have been recommended. However, validation of qualitative methods is still a critical point in the quality management of food analysis laboratories. A screening method for the detection of Roundup Ready (RR) soy in soybeans by nested PCR was validated by a novel qualitative approach, in a single-laboratory, considering all fundamental parameters for an adequate evaluation of fitness for purpose. Blank samples of soybeans and formulations containing 0.001 to 1% of RR soy were analysed. Agarose gel electrophoresis and fluorimetry techniques were compared in terms of the quantification of extracted DNA. False-positive rate obtained was 0%, with selectivity and reliability rates of 100.0% for both techniques. Sensitivity and reliability rates varied between 23.3 and 100.0% (agarose gel) and between 30.0 and 100.0% (fluorimetry), respectively. Levels above 0.030% presented 100.0% positive results. Unreliable regions were estimated by non-linear models, and the calculated detection limits were 0.0067 and 0.0047%, for agarose gel electrophoresis and fluorimetry, respectively. Accordance and concordance values of 1.0 were obtained for levels near the regulated limit. The method was considered fit for screening purposes. Analysis of commercial samples demonstrated the applicability of the method and the compliance with Brazilian legislation.

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