MicroVal: A European Approach to the Certification of New Microbiological Methods

1998 ◽  
Vol 61 (11) ◽  
pp. 1579-1582 ◽  
Author(s):  
ROY P. BETTS ◽  
IRENE M. F. RENTENAAR
Keyword(s):  
Method Validation ◽  
Limit Of Detection ◽  
Collaborative Study ◽  
Reference Method ◽  
Test Methods ◽  
International Standards ◽  
Test Method ◽  
Eu Member States ◽  
New Methods ◽  
Microbiological Methods

In recent years, food microbiologists have seen the development of a range of nonstandard methods designed to enumerate or determine the presence of various microorganisms in food products. Generally the new methods are designed to give the microbiologist advantages, such as greater automation or faster results, over standard conventional methods. The new methods, however, have often not been thoroughly tested to give the end user confidence in the results. In order to generate data to show that new methods give results that are comparable with standard methods, they must be validated. A number of validation schemes have been developed in various countries throughout the world. There has not, however, been an acceptable scheme recognized throughout Europe. The MicroVal project has been involved in the development of a European microbiological method validation and certification scheme; it involves 21 partners from 7 EU member States. New methods that are tested by the MicroVal system will undergo initial testing in a single expert laboratory, to establish the test's specificity, limit of detection, relative accuracy, sensitivity, and linearity. This testing will be followed by a collaborative study in a minimum of eight laboratories, which will be used to determine the test precision, repeatability, and reproducibility. All results will be assessed by two expert reviewers who will recommend or reject the test. Tests that are recommended will be finally accepted by a MicroVal committee. The committee will pass its comments to one of several certification bodies (working together through a memorandum of understanding) who will certify that the new method gives results that are equivalent to the reference method used throughout the validation work. The technical rules that describe the work required to certify a method are currently being considered by the European Committee for Standardization (CEN), with the objective that the rules will become a CEN standard for the certification of new test methods. When this objective has been achieved the rules will become an International Standards Organization (ISO) standard for new test method validation.

scholarly journals Direct 24-Hour Presumptive Enumeration of Escherichia coli 0157:H7 in Foods Using Hydrophobic Grid Membrane Filter Followed by Serological Confirmation: Collaborative Study

1998 ◽  
Vol 81 (2) ◽  
pp. 403-418 ◽  
Author(s):  
Phyllis Entis ◽  
◽  
D Bryant ◽  
J Bryant ◽  
R G Bryant ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Membrane Filter ◽  
Collaborative Study ◽  
Reference Method ◽  
Test Method ◽  
Cottage Cheese ◽  
Apple Cider ◽  
Dairy Foods ◽  
E Coli ◽  
Repeatability And Reproducibility

abstract Fifteen laboratories took part in a collaborative study to validate a method for enumerating Escherichia coli 0157:H7. The method is based on use of a hydrophobic grid membrane filter and consists of 24 h presumptive enumeration on SD-39 Agar and serological confirmation to yield a confirmed E. coli 0157:H7 count. Six food products were analyzed: pasteurized apple cider, pasteurized 2% milk, cottage cheese, cooked ground pork, raw ground beef, and frozen whole egg. The test method produced significantly higher confirmed count results than did the reference method for milk, pork, and beef. Test method results were numerically higher than but statistically equivalent to reference method results for cheese, cider, and egg. The test method produced lower repeatability and reproducibility values than did the reference method for most food/inoculation level combinations and values very similar to those of the reference method for the remaining combinations. Overall, 94% of presumptive positive isolates from the test method were confirmed serologically as E. coli 0157:H7, and 98% of these were also biochemically typical of E. coli 0157:H7 (completed test). Corresponding rates for the reference method were 69 and 98%, respectively. On the basis of the results of this collaborative study and the precollaborative study that preceded it, it is recommended that this method be adopted official first action for enumeration of E. coli 0157:H7 in meats, poultry, dairy foods, infant formula, liquid eggs, mayonnaise, and apple cider

scholarly journals A Collaborative Study for the Determination of Tobacco Specific Nitrosamines in Tobacco

2004 ◽  
Vol 21 (3) ◽  
pp. 192-203 ◽  
Author(s):  
WT Morgan ◽  
JB Reece ◽  
CH Risner ◽  
CB Bennett ◽  
CH Midgett ◽  
...  
Keyword(s):  
Methylene Chloride ◽  
Limit Of Detection ◽  
Collaborative Study ◽  
Internal Standard ◽  
Reference Method ◽  
Science Research ◽  
Average Accuracy ◽  
Limit Of Quantitation ◽  
Tobacco Sample ◽  
Tobacco Specific Nitrosamines

AbstractThe manuscript presents results from a collaborative study by 15 different laboratories using two different methods to determine tobacco specific nitrosamines (TSNAs) in tobacco and was performed under the auspices of the Tobacco Science Research Conference Analytical Methods Committee (TSRC-AMC). Although it is apparent that some of the laboratories failed to follow the provided protocols, both methods proved robust for determining TSNAs in a variety of different tobacco types. Twelve laboratories extracted the tobacco sample using an alkaline-methylene chloride extraction (Method 1) and nine used a buffer to extract the tobacco sample (Method 2). Six laboratories performed both methods. All participants used gas chromatography (GC) to separate the TSNAs and chemiluminescence detection. Method 1 used N-hexyl-N-nitroso-1-hexanamine (NDHA) as a surrogate (added prior to extraction) internal standard for quantitation. Method 2 used N-nitrosoguvacoline (NG) as the surrogate internal standard, NDHA as a chromatographic (added after extraction, prior to analysis) internal standard and external standard quantitation. After demonstrating that the average accuracy of both methods was at least about 92% through recovery studies, eight different tobacco types were analyzed in triplicate by each method. Means, reproducibility (precision between laboratories) and repeatability (precision within a laboratory) of results were determined for each method. After statistical analyses, it was established that both methods were capable of analyzing a variety of tobacco types and repeatability between methods was not significantly different. The limit of detection (LOD) and limit of quantitation (LOQ) were lower for Method 2 as compared to Method 1 when using the surrogate internal standard. Reproducibility variation, analyzed as the coefficient of variation, was 6% lower for Method 2 vs. Method 1 for N-nitrosonornicotine (NNN) and directionally 12% lower for 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Method 2 using NDHA as the chromatographic internal standard has been recommended by the TSRC-AMC for use as a reference method. However, Method 1 using NDHA as surrogate internal standard is favored by four of the study participants because of lower chemical and material costs and higher sample throughput.

Evaluation of a Polymerase Chain Reaction–Based Test for Detecting Salmonella spp. in Food Samples: Probelia Salmonella spp.

1999 ◽  
Vol 62 (12) ◽  
pp. 1387-1393 ◽  
Author(s):  
PATRICK FACH ◽  
FRANÇOISE DILASSER ◽  
JOËL GROUT ◽  
JOCELYNE TACHE
Keyword(s):  
Polymerase Chain Reaction ◽  
Limit Of Detection ◽  
Collaborative Study ◽  
Reference Method ◽  
Food Samples ◽  
Complete Agreement ◽  
Chain Reaction ◽  
Salmonella Spp ◽  
Sandwich Hybridization ◽  
Polymerase Chain

A commercially available polymerase chain reaction (PCR) kit was evaluated for the detection of Salmonella spp. in food samples. The test combines PCR amplification and sandwich hybridization of the amplified DNA in microtiter plates. The sensitivity and specificity was evaluated with 52 Salmonella strains and 51 non-Salmonella strains and showed that the test was entirely reliable. The threshold sensitivity was 102 CFU/ml. The limit of detection of dead cells that determines the minimum detection level of dead cells in food samples was superior to 106 CFU/25 g, a level rarely achieved in naturally contaminated samples. After an 18-h pre-enrichment step, the test could detect viable Salmonella in artificially contaminated food samples, even for the lower contamination level (3 CFU/25 g). There was complete agreement between the PCR test and the ISO 6579 bacteriological reference method with artificially contaminated samples. Regarding the accuracy of the results obtained from 253 naturally or noncontaminated foods and from 32 artificially contaminated foods, the agreement percentage was 99.6%. The fidelity of the technique was evaluated in a collaborative study with eight European laboratories and showed a correlation of 98.4%.

A Collaborative Study to Establish the 3rd International Standard for Tissue Plasminogen Activator

2002 ◽  
Vol 88 (08) ◽  
pp. 294-297 ◽  
Author(s):  
Dawn Sands ◽  
Colin Whitton ◽  
R. Merton ◽  
Colin Longstaff
Keyword(s):  
Plasminogen Activator ◽  
Tissue Plasminogen Activator ◽  
Collaborative Study ◽  
Reference Method ◽  
Mean Value ◽  
International Standards ◽  
International Standard ◽  
Tissue Plasminogen ◽  
The Mean ◽  
Study Participants

SummaryAn international collaborative study was organised to replace the 2nd International Standard (IS) for tissue plasminogen activator (tPA). The 2nd IS for tPA (86/670) was used to calibrate the replacement Standard, which was selected from two candidate materials included in the collaborative study. Participants were provided with five sets of four samples (A, B, C, D) and asked to use sample A (2nd IS, 86/670, 850 IU/ml) to determine the activity of B (86/624, approximately 850 IU/ml), C and D (coded duplicates of the same material, 98/714 approximately 11000 IU/ml). A total of 14 laboratories returned results from Europe, USA, Japan and Australia, providing data from 60 independent assays. Four laboratories used a reference method based on a published monograph from the European Pharmacopoeia for Alteplase for Injection, 1998, and the remaining 10 used their own method. Fibrin was used as promoter of tPA activity by 12 out of the 14 laboratories, the remaining two used kits where fibrinogen fragments were the promoter. Data from this collaborative study and the previous study to establish the 2nd IS for tPA show that tPA from melanoma cells and recombinant tPA from CHO cells are both suitable materials as International Standards. It was agreed that sample C, D, recombinant tPA, 98/714, be established as the 3rd International Standard for tPA with a potency of 10000 IU per ampoule, calculated as the mean value from laboratories using fibrin as a promoter of tPA activity. The standard was established by WHO in November 2000.

Detection of Salmonella species in a Variety of Foods by the DuPont™ BAX® System Real-Time PCR Assay for Salmonella: First Action 2013.02

2014 ◽  
Vol 97 (3) ◽  
pp. 868-875 ◽  
Author(s):  
F Morgan Wallace ◽  
Bridget Andaloro ◽  
Dawn Fallon ◽  
Nisha Corrigan ◽  
Stephen Varkey ◽  
...  
Keyword(s):  
Real Time ◽  
Real Time Pcr ◽  
Orange Juice ◽  
Collaborative Study ◽  
Reference Method ◽  
Probability Of Detection ◽  
Test Method ◽  
Pcr Assay ◽  
Test Portion ◽  
Significant Difference

Abstract A multilaboratory study was conducted to evaluate the ability of the DuPont™ BAX® System Real-Time PCR Assay for Salmonella to detect the target species in a variety of foods and environmental surfaces. Internal validation studies were performed by DuPont Nutrition & Health on 24 different sample types to demonstrate the reliability of the test method among a wide variety of sample types. Two of these matrixes—pork and turkey frankfurters and pasteurized, not-from-concentrate orange juice without pulp—were each evaluated in 14 independent laboratories as part of the collaborative study to demonstrate repeatability and reproducibility of the internal laboratory results independent of the end user. Frankfurter samples were evaluated against the U. S. Department of Agriculture, Food Safety and Inspection Service reference method as a paired study, while orange juice samples were evaluated against the U. S. Food and Drug Administration reference method as an unpaired study, using a proprietary media for the test method. Samples tested in this study were artificially inoculated with a Salmonella strain at levels expected to produce low (0.2–2.0 CFU/test portion) or high (5 CFU/test portion) spike levels on the day of analysis. For each matrix, the collaborative study failed to show a statistically significant difference between the candidate method and the reference method using the probability of detection statistical model.

Validation of Methods Used in the Florida Department of Agriculture and Consumer Services' Chemical Residue Laboratory

1991 ◽  
Vol 74 (5) ◽  
pp. 868-871 ◽  
Author(s):  
Gail Abbott Parker
Keyword(s):  
Method Validation ◽  
Method Development ◽  
Limit Of Detection ◽  
Collaborative Study ◽  
Raw Milk ◽  
Development Project ◽  
Limit Of Quantitation ◽  
Chemical Residue ◽  
Consumer Services ◽  
Validation Scheme

Abstract Very few methods for detecting residues of pesticides in food or agricultural samples have undergone rigorous collaborative study and possess official AOAC status. The Chemical Residue Laboratory has formalized a method validation scheme to use when incorporating or developing new, unofficial methods. These methods are validated by assessing certain performance parameters: scope, specificity, linear range, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). For accuracy and precision assessment, 12 replicate fortifications must yield recoveries within the range of 70-120% with a coefficient of variation (CV) that compares favorably to the Horwitz CV. LOD and LOQ are equivalent to 3 and 10 times, respectively, the background signal contributed by a sample matrix blank. This criterion that we use for LOD/LOQ is not universal. In fact, because of differing definitions, we have encountered difficulties in enforcing a tolerance by using a registrant's method. This paper also presents an example of our method validation scheme, using a recent method development project for detecting sulfamethazine in raw milk. The sulfamethazine project also revealed unanticipated personnel problems, underscoring the importance of the human factor in quality assurance.

scholarly journals Two-Day Hydrophobic Grid Membrane Filter Method for Yeast and Mold Enumeration in Foods Using YM-11 Agar: Collaborative Study

1996 ◽  
Vol 79 (5) ◽  
pp. 1069-1082 ◽  
Author(s):  
Phyllis Entis ◽  
A Athar ◽  
M Ballenger ◽  
M S Bendeck ◽  
W Birbari ◽  
...  
Keyword(s):  
Orange Juice ◽  
Membrane Filter ◽  
Collaborative Study ◽  
Ground Beef ◽  
Reference Method ◽  
Test Method ◽  
Filter Method ◽  
Garlic Powder ◽  
Reference Methods ◽  
Membrane Filter Method

Abstract Twenty laboratories participated in a collaborative study to validate a 2-day hydrophobic grid membrane filter method using YM-11 agar for enumeration of yeast and mold in foods. Six naturally contaminated food products were included in the study: garlic powder, raw ground beef, walnuts, flour/meal, orange juice, and yogurt. The test method produced significantly higher results than the 5-day pour plate reference method for orange juice and significantly lower, though numerically similar, results for walnuts and yogurt. Differences between the test and reference methods were not significant for garlic powder, raw ground beef, or flour/meal. Repeatability and reproducibility were similar for both the test and reference methods in all cases. The hydrophobic grid membrane filter method for enumeration of yeast and mold in foods has been adopted by AOAC INTERNATIONAL.

scholarly journals Multilaboratory Comparison of Proficiencies in Susceptibility Testing of Helicobacter pylori and Correlation between Agar Dilution and E Test Methods

2003 ◽  
Vol 47 (10) ◽  
pp. 3138-3144 ◽  
Author(s):  
L. M. Best ◽  
D. J. M. Haldane ◽  
M. Keelan ◽  
D. E. Taylor ◽  
A. B. R. Thomson ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Reference Method ◽  
Test Methods ◽  
Culture Collection ◽  
Test Method ◽  
National Committee ◽  
Reference Laboratory ◽  
Agar Dilution

ABSTRACT Susceptibility testing was performed at seven Canadian microbiology laboratories and the Helicobacter Reference Laboratory, Halifax, Nova Scotia, Canada, to assess susceptibility testing proficiency and the reproducibility of the results for clarithromycin and metronidazole and to compare the Epsilometer test (E test) method to the agar dilution reference method. Control strain Helicobacter pylori ATCC 43504 (American Type Culture Collection) and 13 clinical isolates (plus duplicates of four of these strains including ATCC 43504) were tested blindly. The National Committee for Clinical Laboratory Standards (NCCLS) guidelines for agar dilution testing were followed, and the same suspension of organisms was used for agar dilution and E test. Antimicrobials and E test strips were provided to the investigators. Methods were provided on a website (www.Helicobactercanada.org ). Each center reported MICs within the stated range for strain ATCC 43504. Compared to the average MICs, interlaboratory agreements within 2 log2 dilutions were 90% (range, 69 to 100%) for clarithromycin by agar dilution, with seven very major errors [VMEs], and 85% (range, 65 to 100%) by E test, with three VMEs. Interlaboratory agreements within 2 log2 dilutions were 83% (range, 50 to 100%) for metronidazole by agar dilution, with six VMEs and eight major errors (MEs), and 75% (range, 50 to 94%) by E test, with four VMEs and four MEs. At lower and higher concentrations of antibiotic, E test MICs were slightly different from agar dilution MICs, but these differences did not result in errors. When a standardized protocol based on NCCLS guidelines was used, most participants in this study correctly identified clarithromycin- and metronidazole-susceptible and -resistant strains of H. pylori 93% of the time by either the agar dilution or E test method, and the numbers of errors were relatively equivalent by both methods.

scholarly journals USGv6 Test Methods:

2020 ◽  
Author(s):  
Doug Montgomery ◽  
Erica Johnson ◽  
Michayla Newcombe ◽  
Timothy Winters
Keyword(s):  
Method Validation ◽  
Test Methods ◽  
Accreditation Process ◽  
Laboratory Accreditation ◽  
Test Method ◽  
Test Program

This document defines the scope of accreditation for the USGv6 Test Program, including test method validation procedures, laboratory accreditation process and roles of the accreditor.

scholarly journals Feasibility of using of accelerated test methods for determination of frost-resistance for concrete

2020 ◽  
Vol 157 ◽  
pp. 06035 ◽  
Author(s):  
Anna Pavlenko ◽  
Anastasia Mishakova ◽  
Olga Pertseva ◽  
Victoriia Ivanova ◽  
Yanis Olekhnovich ◽  
...  
Keyword(s):  
Frost Resistance ◽  
Test Methods ◽  
Test Method ◽  
Accelerated Test ◽  
Mechanical Fracture ◽  
Accelerated Methods ◽  
New Methods ◽  
Innovative Materials ◽  
Sufficient Precision

The article presents the results of studies of innovative materials in the field of testing frost resistance. In fact, present accelerated methods for the determination of concrete frost resistance have high labour consuming and low effectiveness. Moreover there is no such accelerated methods which can be sufficiently applicable fro different innovative concretes, for example, concretes with SAP or self-compacting concrete and so on. Therefore, it is highly important to investigate new accelerated test method with high operability, efficiency and sufficient precision. Previously, two new methods were developed. The main purpose of the research is to compare these methods by evaluation of their technology and accuracy and, consequently, to identify the more sustain and efficient one. First method is based on estimation of energy release due to mechanical fracture and thermo cycling. Second method consists of the calculation value z (relation between relative decreasing of strength and relative strain in the direction perpendicular to compression) and replacement of thermo cycles by mechanical cycles. Both methods have high operability and do not take a lot of time, in was tested on the 10 specimens made of concrete and results were compared with values derived by standard method.

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