The term impurities applies to all components of a grain sample that differ from the normal basic cereal. It includes the following groups: broken grains, other cereals, grains damaged by pests, grains overheated during drying, sprouted grains, extraneous seeds, unsound grains, extraneous matter and impurities of animal origin.<\/p>\n
The principle of the determination of impurities content is to separate all the groups of impurities from the normal basic cereal grains of unimpaired quality by sieving and manual selection out of a subsample and to quantify them. There are various problems in the determination of impurities:<\/p>\n
Firstly, the identification of the different groups of impurities depends strongly on the experience and the knowledge of the investigator.<\/p>\n
Also experienced investigators can differ in their characterization of grains.<\/p>\n
Finally, one is faced with the fact that grain, even after mixing, is rarely homogenous. In other words, if a sample was divided by a sample divider into a number of portions, the amount of a specific group of impurities in each portion could be different, even if absolutely no human or machine error occurred in each determination.<\/p>\n
These problems will result in variation of the results of the determination.<\/p>\n
An international interlaboratory test for the determination of impurities, according to this standard and involving 14 laboratories in 4 countries, was carried out with 5 maize and 3 sorghum samples. It was asked to participants to make determination in duplicate.<\/p>\n
Ten laboratories reported results for the complete sample set and two only for corns. The test materials ranged between:<\/p>\n
0,0 % and 2,7 % for broken grains;<\/p>\n<\/li>\n
0,2 % and 3,5 % for grain impurities;<\/p>\n<\/li>\n
0,0 % and 0,1 % for sprouted grains;<\/p>\n<\/li>\n
0,5 % and 3,3 % for miscellaneous impurities;<\/p>\n<\/li>\n
1,8 % and 8,7 % for total impurities.<\/p>\n<\/li>\n<\/ul>\n
The aim of the study is to determine the precision, repeatability and reproducibility of the method of determination of impurities content in maize and sorghum samples.<\/p>\n
The analyses were realized in March – April 2011. It occurs according to ISO 5725:1994 .<\/p>\n
| PDF Pages<\/th>\n | PDF Title<\/th>\n<\/tr>\n | ||||||
|---|---|---|---|---|---|---|---|
| 4<\/td>\n | Contents Page <\/td>\n<\/tr>\n | ||||||
| 5<\/td>\n | European foreword <\/td>\n<\/tr>\n | ||||||
| 6<\/td>\n | Introduction <\/td>\n<\/tr>\n | ||||||
| 7<\/td>\n | 1 Scope 2 Normative references <\/td>\n<\/tr>\n | ||||||
| 8<\/td>\n | 3 Design of the study 3.1 Conception and organization 3.1.1 General 3.1.2 Method 3.1.3 Participants 3.1.4 Design and schedule of the study 3.2 Product 3.3 Fabrication 3.4 Homogeneity and stability 3.5 Form <\/td>\n<\/tr>\n | ||||||
| 9<\/td>\n | 4 Statistics 4.1 Methodology Figure 1 4.2 Statistical treatment 5 Results of the interlaboratory study 5.1 Validation of the raw results 5.2 Detection of stragglers and outliers <\/td>\n<\/tr>\n | ||||||
| 11<\/td>\n | 5.3 Stragglers and outliers detections Table 1 \u2014 Cochran\u2019s test: stragglers (in bold) and outliers for variances Table 2 \u2014 Grubb\u2019s test: stragglers (in bold) and outliers for means <\/td>\n<\/tr>\n | ||||||
| 12<\/td>\n | 5.4 Statistics 5.5 Results Table 3 \u2014 Statistical results of interlaboratory tests for broken grains <\/td>\n<\/tr>\n | ||||||
| 13<\/td>\n | Figure 2 \u2014 Precision standard deviations according to the mean for broken grains Table 4 \u2014 Statistical results of interlaboratory tests for grain impurities <\/td>\n<\/tr>\n | ||||||
| 14<\/td>\n | Figure 3 \u2014 Precision standard deviations according to the mean for grain impurities Table 5 \u2014 Statistical results of interlaboratory tests for sprouted grains <\/td>\n<\/tr>\n | ||||||
| 15<\/td>\n | Figure 4 \u2014 Precision standard deviations according to the mean for sprouted grains Table 6 \u2014 Statistical results of interlaboratory tests for miscellaneous impurities <\/td>\n<\/tr>\n | ||||||
| 16<\/td>\n | Figure 5 \u2014 Precision standard deviations according to the mean for miscellaneous impurities Table 7 \u2014 Statistical results of interlaboratory tests for total impurities <\/td>\n<\/tr>\n | ||||||
| 17<\/td>\n | Figure 6 \u2014 Precision standard deviations according to the mean for total impurities <\/td>\n<\/tr>\n | ||||||
| 18<\/td>\n | Annex A (informative) Raw results A.1 Broken grains Table A.1 \u2014 Broken grains for maize Table A.2 \u2014 Broken grains for sorghum <\/td>\n<\/tr>\n | ||||||
| 19<\/td>\n | A.2 Grains impurities Table A.3 \u2014 Grains impurities for maize Table A,4 \u2014 Grains impurities for sorghum <\/td>\n<\/tr>\n | ||||||
| 20<\/td>\n | A.3 Sprouted grains Table A.5 \u2014 Sprouted grains for maize Table A.6 \u2014 Sprouted grains for sorghum <\/td>\n<\/tr>\n | ||||||
| 21<\/td>\n | A.4 Miscellaneous impurities Table A.7 \u2014 Miscellaneous impurities for maize Table A.8 \u2014 Miscellaneous impurities for sorghum <\/td>\n<\/tr>\n | ||||||
| 22<\/td>\n | A.5 Total impurities Table A.9 \u2014Total impurities for maize Table A.10 \u2014 Total impurities for sorghum <\/td>\n<\/tr>\n<\/table>\n","protected":false},"excerpt":{"rendered":" Cereal and cereal products. Technical report of the interlaboratory study for the determination of impurities content in maize (Zea mays, L.) and sorghum (Sorghum bicolor, L.)<\/b><\/p>\n |