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Stuttgart, Germany

Uhlig S.,Quo Data GmbH | Gowik P.,Federal Office of Consumer Protection and Food Safety
Journal fur Verbraucherschutz und Lebensmittelsicherheit

This paper presents a validation approach for microbiological methods based on a combination of interlaboratory tests and factorial experiments. It requires not more than 4 participants but is achieving comparable statistical confidence as in method validation studies with 8-12 participants, if properly designed. The approach is illustrated by a comprehensive validation of the Arxula adeninivorans yeast estrogen screen (A-YES) assay for the detection of estrogenic activity in mineral water. © Birkhäuser Verlag, Basel/Switzerland 2009. Source

Chamas A.,Leibniz Institute of Plant Genetics and Crop Plant Research | Giersberg M.,Leibniz Institute of Plant Genetics and Crop Plant Research | Friedrich K.,Carl Gustav Carus Institute | Sonntag F.,Fraunhofer Institute for Material and Beam Technology | And 5 more authors.
Protein Expression and Purification

For the first time, the full length recombinant HER-2[neu] receptor has been produced in a yeast (Arxula adeninivorans). It is one of the most studied membrane receptors in oncology and is involved in aggressive tumor formation. A yeast integration rDNA cassette containing the human gene coding for the HER-2[neu] protein was constructed and a screening procedure was performed to select the most productive transformant. Different detergents were tested for efficient solubilization of the membrane bound protein, with CHAPS giving the best results. To increase the yield of the recombinant protein from HER-2[neu] producing A. adeninivorans, optimal culture parameters were established for cultivation in bioreactor. The recombinant protein was subsequently assayed using ELISA and SPR immunoassays systems with antibodies raised against two different epitopes of the human receptor. In both cases, elution fractions containing the recombinant HER-2[neu] receptor successfully reacted with the immunoassays with limits of quantification below 100 ng ml-1. These results demonstrate that the full length recombinant HER-2[neu] reported here has the potential to be a new standard for the detection of HER-2 type cancer. © 2014 Elsevier Inc. Source

Lacorn M.,R Biopharm AG | Scherf K.,Leibniz Institute | Uhlig S.,Quo Data GmbH | Weiss T.,R Biopharm AG
Journal of AOAC International

In September 2013, the AACC International (AACI) Protein Technical Committee (now Protein and Enzymes Technical Committee) initiated a collaborative study of a method for the qualitative analysis of intact gluten in processed and nonprocessed corn products, using an R5 immunochromatographic dipstick system. It was validated to demonstrate that potential gluten-free products contain gluten lower than the Codex threshold of 20 mg/kg gluten. The results of the collaborative test with 18 participants confirmed that the method is suitable to detect gluten contaminations that are clearly lower than the threshold. It is recommended that the method be accepted by AOAC as Official First Action. Source

Klemm C.,Federal Office of Consumer Protection and Food Safety | Nausch I.,Landeslabor Schleswig Holstein | Uhlig S.,Quo Data GmbH
Analytical and Bioanalytical Chemistry

A European interlaboratory collaborative study was conducted to validate a method for the quantitative determination of lipophilic marine biotoxins based on high-performance liquid chromatography-tandem mass spectrometry. During this study, the diarrhetic shellfish poisoning toxins okadaic acid, dinophysis toxin1 and 2 including their esters, the azaspiracids 1-3, pectenotoxin2, and the yessotoxins were investigated at concentration levels near the limit of quantification and near the legal limit. Naturally contaminated blue mussels, both raw and cooked and spiked extracts of clams and oysters were studied and results were obtained for 16 test samples from 16 laboratories representing eight different countries. This article summarizes the study outcome concerning validation key parameters like specificity, linearity, limit of detection, accuracy/recovery, and precision. Further, influences of cooking of mussels before homogenization or hydrolysis on method robustness have been evaluated. © 2010 Springer-Verlag. Source

Uhlig S.,Quo Data GmbH | Eichler S.,Quo Data GmbH | Gowik P.,Federal Office of Consumer Protection and Food Safety
Journal of AOAC International

Precision data, such as laboratory-to-laboratory SD (sL) and repeatability SD, obtained from interlaboratory tests are needed to assess analytical test methods. These precision data describing random error are subject to random variation. In order to avoid distorted assessments of test methods, interlaboratory tests must fulfill minimal requirements for achieving, e.g., a desired reliability in sL. In 2009, McClure and Lee considered reliability of sL as a characteristic of an interlaboratory study. They developed an approach to approximate that reliability to make it possible to adapt the study design of an interlaboratory study to a desired reliability in sL. The McClure and Lee approach introduces the "margin of relative error" to arrive at the magnitude of the uncertainty in s L. This article discusses their approach and presents a generalized approach. The limitations of McClure and Lee's approximation are shown to result in underestimation of the actual variability of sL due to the disregard of the inherent negative bias of sL. This bias corresponds to the fact that the expected value of the obtained sL lies below the true value sL one would obtain in an interlaboratory study with an infinite number of laboratories and replicates. In order to achieve the reported level of reliability in sL, the actual number of laboratories required is typically approximately 25% higher than that calculated by McClure and Lee. We present a generalized approach using "margins of relative random error," which takes the impact of the bias of the sL into account, resulting in a more realistic estimation of the variability of the precision parameter sL. © 2013 Publishing Technology. Source

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