# Effect of Particle Size on Composet Analysis by Portable X-ray Fluorescence
## 3 Results and Discussion
### Effect of the Sample Grinding on the Elemental Concentration Determined by pXRF
\begin{table}
\begin{tabular}{l l c c c c c c c} \hline \hline
**Compost** & **Element** & & & & **Element** & **Compost** & & \\ \hline  & & **Unground** & **Sig. 1** & **Ground** & & & **Unground** & **Sig. 1** & **Ground** \\ \hline Rb & Sewage & 26.0 & ns & 28.1 & & & Sewage & 16.8 & ns & 17.4 \\ MSW & 19.1 & ns & 18.0 & \(\mathrm{S}\times 10^{-3}\) & MSW & 8.14 & ns & 7.70 \\ Alperujo & 13.8 & ns & 14.4 & & Alperujo & 3.42 & ns & 3.21 \\ \hline Zr & Sewage & 82.7 & ns & 95.1 & & & Sewage & 7.84 & ** & 10.63 \\ MSW & 68.7 & ns & 75.4 & \(\mathrm{K}\times 10^{-3}\) & MSW & 15.7 & ns & 16.2 \\ Alperujo & 34.3 & ns & 35.6 & & Alperujo & 40.2 & ** & 46.2 \\ \hline Sr & Sewage & 159 & ns & 138 & & & Sewage & 12.5 & ns & 13.4 \\ MSW & 157 & ns & 184 & \({}^{2}\) P \(\times 10^{-3}\) & MSW & 4.72 & * & 6.17 \\ Alperujo & 66.2 & ns & 67.4 & & Alperujo & 1.97 & ns & 1.80 \\ \hline Zn & Sewage & 475 & ** & 405 & & & Sewage & 81.9 & ** & 112 \\ MSW & 677 & ** & 480 & \({}^{2}\) Si \(\times 10^{-3}\) & MSW & 36.2 & ** & 67.9 \\ Alperujo & 26.3 & ns & 24.8 & & & Alperujo & 21.6 & ** & 29.5 \\ \hline Cu & Sewage & 190 & ** & 164 & & & Sewage & ND & & ND \\ MSW & 256 & ** & 156 & \({}^{2}\) Cl \(\times 10^{-3}\) & MSW & ND & & ND \\ Alperujo & 72.9 & ns & 71.0 & & & Alperujo & 1.32 & * & 1.55 \\ \hline Pb & Sewage & 35.3 & ns & 32.1 & & & Sewage & 12.4 & ** & 17.0 \\ MSW & 52.9 & * & 63.0 & \({}^{2}\) Al \(\times 10^{-3}\) & MSW & 6.77 & ns & 7.84 \\ Alperujo & ND & & ND & & Alperujo & 3.33 & ** & 4.73 \\ \hline Mn & Sewage & 408 & ns & 391 & & & Sewage & 51.0 & * & 44.7 \\ MSW & 132 & ns & 232 & \({}^{2}\) Fe \(\times 10^{-3}\) & MSW & 24.5 & ns & 24.6 \\ Alperujo & ND & & ND & & Alperujo & 4.43 & ns & 4.81 \\ \hline As & Sewage & 13.3 & ns & 12.5 & & & Sewage & 54.2 & ns & 50.3 \\ MSW & 9.82 & * & 8.21 & \({}^{2}\) Ca \(\times 10^{-3}\) & MSW & 102 & ns & 109 \\ Alperujo & ND & & ND & & Alperujo & 47.9 & ns & 52.3 \\ \hline V & Sewage & 55.9 & * & 67.8 & & & Sewage & 745 & ** & 715 \\ MSW & ND & & ND & \({}^{2}\) Bal \(\times 10^{-3}\) & MSW & 776 & * & 747 \\ Alperujo & ND & & ND & & Alperujo & 895 & ns & 880 \\ \hline Ti & Sewage & 1733 & ** & 2404 & & & & & \\ MSW & 957 & ns & 1148 & & & & & \\ Alperujo & 537 & ** & 765 & & & & & \\ \hline \hline \end{tabular}  
* ns: non-significant difference.
* \(p<\) 0.05; *
* \(p<\) 0.01; \({}^{2}\) For these elements, the measurements were conducted in the precalibrated mining mode; for the rest of the elements, the measurements were performed with the precalibrated soil method.  
\end{table} 
Table 5: Effect of grinding the coarser than 0.5 mm particle size fractions on the pXRF elemental readings (comparison by \(t\)-test in the paired replicates per each fraction). the reading when grinding were due to the superposition of both effects: the particle size effect and the lack of the homogeneity of the sample. Contrary to the previous elements, the measured concentrations of Zn and, especially, Cu were lower in the milled fractions of the sewage and MSW compots, the As concentration decreased with grinding in the MSW compost, and the Fe concentration decreased in the sewage compost. Lower readings for Fe concentration were found in [28] when grinding soils to less than 0.15 mm. In summary, higher readings were obtained for the concentrations of the elements Rb, Zr, Sr, Pb, V, Ti, K, P, Si, and Al and lower for Zn and Cu in the ground samples, although the type of compost determined in which elements in particular differences appeared and the magnitude of the difference. These results are consistent with those of [PERSON] et al. [10], who indicated that the influence of the particle size on the detectability is different for each element. However, these researchers found that Zn, K, Ca, and Cu showed little change between particle size classes but As and Ni detection was clearly influenced (the comparison here was between types of compost with particle sizes <5 and >5 mm).