DIGITALNA ARHIVA ŠUMARSKOG LISTA

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ŠUMARSKI LIST 7-8/2010 str. 44 <-- 44 --> PDF |

T. Jakovljević, G. Pánczél, M. Manninger, N. Potočić, I. Seletković, T. Dubravac, M. Gradečki-Poštenjak: LIŠĆE ... Šumarski list br. 7–8, CXXXIV (2010), 361-370 bon in the reference sample of common beech leaveves on elemental analyser CNS 2000 (Method A) in the laboratory of Croatina forset reserach institute and on the elemental analyser EA 300 (Method B) in the labratory of Hungarian forest institute involved ICP Forests programme.Statistical analysis included comparative description of results for determination of total nitrogen and carbon, descriptive statistics for 2 methods, Boxplot analysis, F test, T test, Regression analyses and Control charts for method B. The comparation of the results showed big oscilations of the results of Method B for nitrogen and some of them were out of specification limits. For carbon, the values were higer then in Method A (Figure 2). Furthermore, F values were over critical but variance of Method A was smaller than of Method B.Therefore, metod A was more accura- ted.For carbon, F was over critical values.Variance of method A was more significant than of method B with probability of 95 % (Table 5). Coefficient of corelation, r in regression analysis for methods (Table 6) gave positive correla- tion.With t-test (Table 7) was proved that results of these methods for determination of total nitrogen and carbon with probability of 95 % were significanty different. Control chart for nitrogen showed difference in repetability, also more than 30 % of results were out of specification limits. Repetability of reuslts forcarbon was good (Figure 4). Chemical analysis of leaves are reduced for choise of instruments and methods for determination of elements because of specificity of samples from forest. Therefore this kind of testing confirmed better applicability of element analyser such as CNS 2000 than EA 300 for determination of total nitrogen and carbon. Key words:common beech leaves, CNS 2000, EA 300, elemental analyser, ICP Forests, interlaboratory testing, reference sample, total nitrogen and carbon |