Novel Non-parametric Assessment of Heavy Metals in Coated Card Wastes

Non-parametric tests were applied for the first time to coated mobile card waste in order to determine the correlation within risk assessment and instrumentation. The AAS concentrations of all the metals were higher than their XRF concentrations except in Al and Ag metals. Cr had the highest distribution pattern while Ag metal had the lowest respectively. The target hazard quotient (THQ) for all metals were below minor hazard level. On the contrary, only Fe and Zn were below the Oral reference dose (RfD) value and the daily metal intake (DMI) respectively. The Wilcoxon-Mann-Whitney test showed no significant difference between the concentration of the metals in XRF and AAS analysis results but identified the unusual behavior of Ag and Al metals; hence it depicted that both AAS and XRF analysis results were not sensitive to detect the different metal concentrations in the cards. Hence, similar coating specifications are utilized. The Kruskal Wallis test and Spearman correlation coefficient showed that the results from AAS and XRF were significantly different. Hence it showed that instrumentation showed sensitivity of metal concentrations from the recharge cards. This correlated with THQ, DMI, health risk index (HRI) risk assessment parameters that different coating specifications were used causing different values at same sampling points. Therefore, the results established that non-parametric tests are good analytical tools.