Table 2.
Concentration (mg/L) of representative leachates generated by a citric acid (CA) solution produced by Aspergillus niger NRRL 334 (CA 334) and by a commercial CA (CA Com) (10.65 mM) at the beginning (T0) and after 7 days (T7) of mouse circuit boards soaking. Data represent average concentrations from three independent TXRF measures ± uncertainty.
| Elements | CA 334 | CA Com | ||
|---|---|---|---|---|
| T0 | T7 | T0 | T7 | |
| Br | 0.06 ± 0.01 | 0.62 ± 0.03 *** | <LOD | 0.65 ± 0.09 ** |
| Cr | <LOD | 0.04 ± 0.02 | <LOD | 0.08 ± 0.05 |
| Cu | 0.013 ± 0.004 | 0.04 ± 0.01 * | <LOD | 0.04 ± 0.03 * |
| Fe | 0.09 ± 0.01 | 67.99 ± 3.52 *** | 0.01 ± 0.00 | 123.46 ± 7.69 *** |
| Mn | 0.05 ± 0.01 | 0.25 ± 0.01 *** | <LOD | 0.49 ± 0.04 *** |
| Ni | <LOD | 4.55 ± 0.24 *** | <LOD | 1.54 ± 0.10 *** |
| Pb | <LOD | 0.12 ± 0.01 *** | <LOD | 0.16 ± 0.01 *** |
| Sn | <LOD | 404.09 ± 21.15 *** | <LOD | 495.10 ± 33.20 *** |
| Sr | 0.031 ± 0.022 | 0.04 ± 0.01 | <LOD | 0.05 ± 0.01 ** |
| Zn | 0.06 ± 0.01 | 1.92 ± 0.10 *** | 0.017 ± 0.006 | 1.75 ± 0.24 ** |
Note: * p < 0.05; ** p < 0.01; *** p < 0.001: statistically significant versus T0 values according to Student’s t-test. LOD: limit of detection.