T. Frentiu, M. Ponta, E. Levei, M. Senila, M. Ursu, E. Cordos, Interlaboratory study on Cu, Pb and Znd determination in soil by inductively coupled plasma optical emission spectrometry using the Bland and Altman test, J. Optoelectronic. Adv. Mater., 9/11 (2007) 3505 – 3513

Title: Interlaboratory study on Cu, Pb and Znd determination in soil by inductively coupled plasma optical emission spectrometry using the Bland and Altman test

Abstract: The application of the Bland-Altman plot for an interlaboratory study on Cu, Pb and Zn determination over a large concentration range by Inductively Coupled Plasma Optical Emission Spectrometry is described. The method-performance study was selected to estimate the figures of merit within and between two laboratories following the same digestion procedure and analysis technique for 89 soil samples. The regression analysis, the confidence interval of differences mean between results and its 1.96 s limits of agreement revealed a good between-laboratory agreement for a 95 % confidence level. The confidence interval of bias (mg kg(-1)) was -6 +/- 10 Cu, 11 +/- 11 Pb and -8 +/- 10 Zn. The within-laboratory standard deviations (mg kg (-1)) were similar (29-32; 29-33), while the between-laboratory standard deviations were 47; 51 and 46 mg kg(-1) for Cu, Pb and Zn up to 1000 mg kg(-1). The within-laboratory accuracy and precision were assessed using 4 certified reference materials.

Key words: interlaboratory study; Bland and Altman test; regression analysis; soil analysis; optical spectrometry