Lindemann S.,U.S. Food and Drug Administration |
Kmet M.,Illinois Institute of Technology |
Reddy R.,U.S. Food and Drug Administration |
Uhlig S.,QuoData GmbH
Journal of Food Protection | Year: 2016
The U.S. Food and Drug Administration (FDA) oversees a long-standing cooperative federal and state milk sanitation program that uses the grade "A" Pasteurized Milk Ordinance standards to maintain the safety of grade "A" milk sold in the United States. The Pasteurized Milk Ordinance requires that grade "A" milk samples be tested using validated total aerobic bacterial and coliform count methods. The objective of this project was to conduct an interlaboratory method validation study to compare performance of a film plate method with an automated most-probable-number method for total aerobic bacterial and coliform counts, using statistical approaches from international data standards. The matrix-specific validation study was administered concurrently with the FDA's annual milk proficiency test to compare method performance in five milk types. Eighteen analysts from nine laboratories analyzed test portions from 12 samples in triplicate. Statistics, including mean bias and matrix standard deviation, were calculated. Sample-specific bias of the alternative method for total aerobic count suggests that there are no large deviations within the population of samples considered. Based on analysis of 648 data points, mean bias of the alternative method across milk samples for total aerobic count was 0.013 log CFU/ml and the confidence interval for mean deviation was -0.066 to 0.009 log CFU/ml. These results indicate that the mean difference between the selected methods is small and not statistically significant. Matrix standard deviation was 0.077 log CFU/ml, showing that there is a low risk for large sample-specific bias based on milk matrix. Mean bias of the alternative method was -0.160 log CFU/ml for coliform count data. The 95% confidence interval was -0.210 to -0.100 log CFU/ml, indicating that mean deviation is significantly different from zero. The standard deviation of the sample-specific bias for coliform data was 0.033 log CFU/ml, indicating no significant effect of milk type. © 2016, International Association for Food Protection. All rights reserved.
Results of a European interlaboratory method validation study for the quantitative determination of lipophilic marine biotoxins in raw and cooked shellfish based on high-performance liquid chromatography-tandem mass spectrometry. Part I: Collaborative study
Klemm C.,Federal Office of Consumer Protection and Food Safety |
Nausch I.,Landeslabor Schleswig Holstein |
Uhlig S.,Quo Data GmbH
Analytical and Bioanalytical Chemistry | Year: 2011
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.
Lacorn M.,R Biopharm AG |
Scherf K.,Leibniz Institute |
Uhlig S.,QuoData GmbH |
Weiss T.,R Biopharm AG
Journal of AOAC International | Year: 2016
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.
PubMed | Leegionella Ltd, ALcontrol Laboratories, QuoData GmbH, SWM Consulting and 6 more.
Type: Evaluation Studies | Journal: Journal of water and health | Year: 2015
In this study, the performance of a new most probable number (MPN) test (Pseudalert()/Quanti-Tray()) for the enumeration of Pseudomonas aeruginosa from hospital waters was compared with both international and national membrane filtration-based culture methods for P. aeruginosa: ISO 16266:2006 and UK The Microbiology of Drinking Water - Part 8 (MoDW Part 8), which both use Pseudomonas CN agar. The comparison based on the calculation of mean relative differences between the two methods was conducted according to ISO 17994:2014. Using both routine hospital water samples (80 from six laboratories) and artificially contaminated samples (192 from five laboratories), paired counts from each sample and the enumeration method were analysed. For routine samples, there were insufficient data for a conclusive assessment, but the data do indicate at least equivalent performance of Pseudalert()/Quanti-Tray(). For the artificially contaminated samples, the data revealed higher counts of P. aeruginosa being recorded by Pseudalert()/Quanti-Tray(). The Pseudalert()/Quanti-Tray() method does not require confirmation testing for atypical strains of P. aeruginosa, saving up to 6 days of additional analysis, and has the added advantage of providing confirmed counts within 24-28 hours incubation compared to 40-48 hours or longer for the ISO 16266 and MoDW Part 8 methods.
Kaiser C.,Leibniz Institute of Plant Genetics and Crop Plant Research |
Uhlig S.,Quo data GmbH |
Gerlach T.,Leibniz Institute of Plant Genetics and Crop Plant Research |
Korner M.,Leibniz Institute of Plant Genetics and Crop Plant Research |
And 5 more authors.
Science of the Total Environment | Year: 2010
A novel Arxula adeninivorans yeast estrogen screen (nAES) assay has been developed for detection of estrogenic activity in various liquid samples such as wastewater, seawater, brackish water and swine urine. Two bio-components were engineered to co-express the human estrogen receptor α (hERα) and an inducible reporter gene; either the non-conventional phytase gene (phyK, derived from Klebsiella sp. ASR1) or the non-conventional tannase gene (ATAN1, derived from Arxula). Both reporters were put under the control of an Arxula derived glucoamylase (GAA) promoter, which was modified by the insertion of two estrogen-responsive elements (EREs). The Arxula transformation/expression platform Xplor® 2, which lacks resistance markers and E. coli elements, was used to select stable mitotic transformants. They were then analyzed for robustness and suitability as the bio-component for the nAES assay. Two types of the nAES assay based on the reporter proteins phytase and tannase (nAES-P, nAES-T) were used in this work. The nAES-P type is more suitable for the analysis of seawater, brackish water and urine whereas the nAES-T type exhibited higher robustness to NaCl. Both assay types have similar characteristics for the determination of estrogen in sewage and urine samples e.g. 6-25h assay period with detection and determination limits and EC50 values for 17β-estradiol of 2.8ngL-1, 5.9ngL-1, 33.2ngL-1 (nAES-P) and 3.1ngL-1, 6.7ngL-1 and 39.4ngL-1 (nAES-T). Substrate specificity and analytical measurement range (AMR) for both assay types are also similar. These characteristics show that the nAES assay based on non-conventional salt tolerant yeast is applicable for a high throughput estrogen analysis in the environmental and regulatory control sectors. © 2010 Elsevier B.V.
Pham H.T.M.,Leibniz Institute of Plant Genetics and Crop Plant Research |
Giersberg M.,Leibniz Institute of Plant Genetics and Crop Plant Research |
Uhlig S.,Quo Data GmbH |
Hanke G.,Prolatec Prozess und Labortechnik GmbH |
And 4 more authors.
Sensors and Actuators, B: Chemical | Year: 2012
The EstraMonitor has been developed to provide a device suitable for monitoring estrogens in sewage treatment plants, i.e. provide rapid detection in semi-online operation. This monitor is based on recombinant Arxula adeninivorans yeast cells as the biocomponent. The cells were engineered to co-express the human estrogen receptor α (hERα) gene and the inducible phytase (phyK, derived from Klebsiella sp. ASR1) reporter gene under the control of a promoter with estrogen response elements (EREs). The monitor comprises two measuring chambers containing immobilized transgenic yeast cells - a measuring strain with receptor and reporter gene cassettes and a control strain with only the reporter gene cassette. To measure the estrogenic activity, the measuring and control strains are incubated with the samples. In the presence of estrogenic substances, such as 17β estradiol (E2), the phyK gene is expressed and recombinant phytase is secreted into the sample. Any signal in the control strain is due to background activity and is used to correct the measuring strain signal. Phytase dephosphorylates p-aminophenyl phosphate (pAPP) and the level of phytase was quantified by electrochemically reducing the intermediate product, p-aminophenol (pAP). The electrons are detected as current and are proportional to the level of phytase activity. Since E2 concentration is correlated with phytase activity, the estrogenic activity can be calculated. The EstraMonitor can detect the total estrogenic activity in about 4 h with a measurement range between 5 and 100 ng L -1, and limit of detection of 5.3 ng L -1. © 2011 Elsevier B.V. All rights reserved.
Pham H.T.M.,Leibniz Institute of Plant Genetics and Crop Plant Research |
Pham H.T.M.,Vietnam Academy of Science and Technology |
Kunath K.,QuoData GmbH |
Gehrmann L.,Institute fur Energie und Umwelttechnik E.V. IUTA |
And 7 more authors.
Sensors and Actuators, B: Chemical | Year: 2013
The 'EstraMonitor' was developed to provide an automated system for the detection of estrogenic compounds. It can be used for semi-online and continuous monitoring without additional instrumentation. Previously it was used to detect pure estrogenic molecules. In this investigation, the 'EstraMonitor' is used to detect the estrogenic activity in five non-pretreated wastewater samples. The 'EstraMonitor' employs genetically modified Arxula adeninivorans G1212/YRC102-hERα-phyK yeast cells as the detection component. Both immobilized and non-immobilized A. adeninivorans G1212/YRC102-hERα-phyK cells remained fully functional in a wide range of samples, including samples that contained up to 5% NaCl. The results demonstrate that it is possible to determine the estrogenic effects in environmental samples without the need for sterilization, extraction or concentration. The 17β-estradiol equivalent quotient (bio-EEQ) values in these samples were measured by both biochemical and amperometric methods and were compared to GC-MS analyses (ana-EEQ). The three methods showed a good correlation over a similar detection range. © 2013 Elsevier B.V. All rights reserved.
PubMed | University of Canterbury, New diagnostics GmbH, QuoData GmbH and Leibniz Institute of Plant Genetics and Crop Plant Research
Type: Journal Article | Journal: Analytical and bioanalytical chemistry | Year: 2015
This study describes the development of a bioassay to detect the presence of progesterone and progesterone-like molecules in wastewater samples. The basis of the bioassay is the integration of the human progesterone receptor gene into the yeast Arxula adeninivorans for the constitutive synthesis of the receptor. After incubation, binding of the analyte to the receptor induces the production of a reporter protein. Two reporter proteins were compared for detection parameters such as half-maximal activity (EC50), limit of detection (LoD) and limit of quantification (LoQ). When the extracellular phytase K was used, an EC50 value of 155ngL(-1) and a LoD of 27ngL(-1) progesterone were obtained after 4h incubation, while use of the fluorescent dsRED as the reporter protein, resulted in an EC50 of 320ngL(-1) and a LoD of 65ngL(-1) after 20h incubation. Use of phytase K as the reporter protein offers decreased incubation time and increased sensitivity; however the dsRED reporter system is less labor-intensive. Additionally, the affinity of known agonists and antagonists of the human progesterone receptor was determined. The utility of this bioassay was confirmed by measuring total progesterone equivalent concentration of samples from a wastewater treatment plant. The A. adeninivorans-based transactivation assay was able to measure concentrations of about 311ngL(-1) in the influent stream but could not detect progesterone activity in effluent. One key feature of the assay is the robustness of A. adeninivorans, which allows sample measurement without any sample preparation.
PubMed | Quo Data GmbH, New Diagnostics GmbH, University of Canterbury and Leibniz Institute of Plant Genetics and Crop Plant Research
Type: | Journal: The Science of the total environment | Year: 2014
The novel A-YAS assay for the detection of androgenic activity in liquid samples such as urine has been developed and assessed. The assay is based on transgenic Arxula adeninivorans yeast cells as the bio-component. The cells were engineered to co-express the human androgen receptor (hAR) gene and the inducible phytase reporter gene (phyK, derived from Klebsiella sp. ASR1), under the control of an Arxula derived glucoamylase (GAA) promoter, which had been modified by the insertion of hormone-responsive elements (HREs). The Arxula transformation/expression platform Xplor2 was used to select stable mitotic resistance marker free transformants and the most suitable cells were characterized for performance as a sensor bio-component. The assay is easy-to-use, fast (6-25 h) and is currently the most sensitive yeast-based androgen screen with an EC50, limit of detection and of quantification values for 5-dihydrotestosterone (DHT) of 277.153.0, 56.54.1 and 76.56.7 ng L(-1), respectively. Furthermore, the assay allows the determination of androgenic and anti-androgenic activity of various compounds such as naturally occurring androgens and estrogens, pharmaceuticals and biocides. The robustness of the A-YAS assay enables it to be used for analysis of complex samples such as urine. The results of the analysis of a number of cattle urine samples achieved by the A-YAS assay correlate well with GC-MS analysis of the same samples.
Uhlig S.,Quo Data GmbH |
Gowik P.,Federal Office of Consumer Protection and Food Safety
Journal fur Verbraucherschutz und Lebensmittelsicherheit | Year: 2010
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.