title: Tendency for interlaboratory precision in the GMO analysis method based on real-time PCR.
abstract: The Horwitz curve estimates interlaboratory precision as a function only of concentration, and is frequently used as a method performance criterion in food analysis with chemical methods. The quantitative biochemical methods based on real-time PCR require an analogous criterion to progressively promote method validation. We analyzed the tendency of precision using a simplex real-time PCR technique in 53 collaborative studies of seven genetically modified (GM) crops. Reproducibility standard deviation (SR) and repeatability standard deviation (Sr) of the genetically modified organism (GMO) amount (%) was more or less independent of GM crops (i.e., maize, soybean, cotton, oilseed rape, potato, sugar beet, and rice) and evaluation procedure steps. Some studies evaluated whole steps consisting of DNA extraction and PCR quantitation, whereas others focused only on the PCR quantitation step by using DNA extraction solutions. Therefore, SR and Sr for GMO amount (%) are functions only of concentration similar to the Horwitz curve. We proposed S(R) = 0.1971C 0.8685 and S(r) = 0.1478C 0.8424, where C is the GMO amount (%). We also proposed a method performance index in GMO quantitative methods that is analogous to the Horwitz Ratio.
authors.affiliation: Food and Agricultural Materials Inspection Center, 2-1, Shintoshin, Chuo-ku, Saitama-shi, Saitama 330-9731, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kodama
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Kurosawa
authors.forename: Kazumi
authors.initials: K
authors.lastname: Kitta
authors.forename: Shigehiro
authors.initials: S
authors.lastname: Naito
mesh_terms: D002623:Chemistry Techniques, Analytical; D018556:Crops, Agricultural / Q000235:genetics*; D004247:DNA / Q000235:genetics; D005504:Food Analysis / Q000379:methods; D030821:Plants, Genetically Modified / Q000235:genetics*; D016133:Polymerase Chain Reaction; D012015:Reference Standards; D012044:Regression Analysis; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013025:Glycine max / Q000235:genetics*; D003313:Zea mays / Q000235:genetics*
chemical_list: D004247:DNA