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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