{"id":78,"date":"2020-03-08T13:28:27","date_gmt":"2020-03-08T13:28:27","guid":{"rendered":"http:\/\/gabonalabor.hu\/?p=78"},"modified":"2020-11-14T11:22:13","modified_gmt":"2020-11-14T11:22:13","slug":"experience-with-certified-reference-material-proficiency-testing-for-quality-control-of-wheat","status":"publish","type":"post","link":"https:\/\/gabonalabor.hu\/index.php\/2020\/03\/08\/experience-with-certified-reference-material-proficiency-testing-for-quality-control-of-wheat\/","title":{"rendered":"Experience with Certified Reference Material \u2013 Proficiency Testing for Quality Control of Wheat"},"content":{"rendered":"\n

Summary<\/strong>. The Chemical Section of OMH1-2 have\nembarked on the preparation of wheat sample series as CRMs in 1992. The\ncertification process are cerried out accordingly to the recommendations of\nISO. Since then we have developed a series of flour samples as well. The\ninvestigations of the long-term stability and the application of wheat and\nflour CRMs are continouos.<\/p>\n\n\n\n

Wheat is one of\nthe most widely grown crops in Hungary and it is one of the major determinative\nfactor in the economy. Its uniform and objective qualification is of great\nimportance. There are well equipped laboratories available with sufficient\nexperience, however, as the proficiency testing regularly showed, certified\nsamples need to be used to achieve exact and uniform measuring results.               <\/p>\n\n\n\n

Choosing the Sample<\/strong><\/p>\n\n\n\n

The certified\nreference wheat series consists of three, the flour serie of two samples, they\nare produced – in the required quantity – annually, from the new harvest. For\nthe wheat samples clean-bred, sound material is used from various habitats. <\/p>\n\n\n\n

The most important conditions of the selection are:<\/p>\n\n\n\n

– in case of wheat the difference of protein and wet gluten content
– in case of flour the difference in grindings, the difference of wet gluten content and that of the value of water absorption must be at least three times greater than the permissible error of measures between various laboratories.<\/p>\n\n\n\n

Sample Preparation <\/strong><\/p>\n\n\n\n

The wheat samples    
– are cleaned, the broken and the other grains and the dust are removed
– the homogenisation is carried out with TURBULA Shaker <\/p>\n\n\n\n

The prepared\nsamples are filled in the necessary quantity into moisture-proof triplex foil\nbags and vacuum-closed. The packed material is sterilised by 5 KGy radiation\ndose.<\/p>\n\n\n\n

Testing for Homogenity by protein content measurement\nresults<\/strong><\/p>\n\n\n\n

12 containers are\nselected at random after dividing the sample bulk into the containers that will\nbe distributed to the participants. The content of each of the 12 selected\ncontainers are homogenised separately and from each of them two test portions\nare taken.<\/p>\n\n\n\n

The sampling\nvariance (ss) are estimated from the results of randomly analysed each second test\nportions.<\/p>\n\n\n\n

The analytical variance (sa) are estimated from all results by one-way analysis of variance without exclusion of outliers. There are no significant differences between the samples on the basis of F-test. <\/p>\n\n\n\n

So the material is\nsufficiently homogenous for the purpose of preparation CRM. <\/p>\n\n\n\n

Certification Campaign<\/strong><\/p>\n\n\n\n

For testing  the samples are sent to 15 accredited\nlaboratories which are suitably experienced in testing cereals. They are to\ncarry out the tests with great care according to the currently standard\nprocedure. Some measurement method are specified:<\/p>\n\n\n\n

 – measurement of the moisture content by drying the samples at 130-133 \u2103 for 2 hours;
– determination of the protein content by measuring the Kjeldhal nitrogen after digestion; and
– determination of wet gluten by manual or mechanical gluten washing. <\/p>\n\n\n\n

The organisation of the interlaboratory test and the evaluation of the results are based on ISO GUIDE 353 (Certification of Reference Materials – General and Statistical Principles). Cohran’s Test is used for analysing the deviation in the laboratory’s replicate measurement results and for discard the outlier values: Grubb’s Test helps us to find the outlier results on inter- and intralaboratory basis, and to discard them from the evaluation. <\/p>\n\n\n\n

Based on the\nresults the consensus value is certified and its uncertainty is defined.<\/p>\n\n\n\n

The Long-term Stability of the Certified Values and\nthe Storability of the Samples<\/strong><\/p>\n\n\n\n

In 1995. the certified samples – prepared with the method above – were kept at room temperature. During their storage they were tested six monthly at 18 laboratories regarding their certified and other parameters.<\/p>\n\n\n\n

The evaluation of the results shows that during the storage the samples’ internal properties changed within the uncertainly of the certified values. These results prove that the packaging and storage we apply is suitable for wheat and flour CRMs.<\/p>\n\n\n\n

Using Wheat and Flour Samples<\/strong><\/p>\n\n\n\n

We have used a certificate compaign the same samples for proficiency testing. The material is sufficiently homogenous for the purpose of the proficiency testing.<\/p>\n\n\n\n

In the test thirteen laboratories took part, all of them differs and are independent of the above mentioned laboratories. The organisation of test and the evaluation of the data was based on the ISO REMCO N280 19934 (PROFICIENCY TESTING FOR CHEMICAL ANALYTICAL LABORATORIES). Based on the resulting “z-score” values the laboratories are classified. The results of several laboratories are significantly different from each other and from the average of the measurement, they exceed the alloved target value for standard deviation. The calculated z-score of laboratory measurement is clearly shows the direction and the extent of the deviation of laboratory result from the consensus value. If the z-score value is 3 of an measurement the laboratory has to carry out improving activity for which our samples are efficiently used.<\/p>\n\n\n\n

Conclusion<\/strong>.The test described above as well as the need of\nlaboratories, producers of instruments and services for our samples prove that\nour goal has been achieved and we have succeeded in developing a practically\nusable CRMs series. <\/p>\n\n\n\n

The proposed\napplication of the CRMs series are<\/p>\n\n\n\n

 – assesment of different measurements
– adjustment of the calibrate measuring instrument
– validation of different measurements. <\/p>\n\n\n\n

The results of our examinations demonstrate that our wheat and flour samples are suitable for checking and detection of mistakes and for the unifying of measuring results.<\/p>\n\n\n\n

dr. Judit BUDAI  and  Judit F\u00dcK\u0150<\/strong> National Office of Measures (OMH) Budapest, 1124 N\u00e9metv\u00f6lgyi u. 37-39, Hungary <\/p>\n","protected":false},"excerpt":{"rendered":"

Summary. The Chemical Section of OMH1-2 have embarked on the preparation of wheat sample series as CRMs in 1992. The certification process are cerried out accordingly to the recommendations of ISO. Since then we have developed a series of flour samples as well. The investigations of the long-term stability and the application of wheat and flour … Continue reading Experience with Certified Reference Material \u2013 Proficiency Testing for Quality Control of Wheat<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-78","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/posts\/78","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/comments?post=78"}],"version-history":[{"count":4,"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/posts\/78\/revisions"}],"predecessor-version":[{"id":128,"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/posts\/78\/revisions\/128"}],"wp:attachment":[{"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/media?parent=78"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/categories?post=78"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/gabonalabor.hu\/index.php\/wp-json\/wp\/v2\/tags?post=78"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}