Appendix 2.
Concentrations (μg/g) of copper, lead, and zinc measured by ICP-AES in the blanks and standards included with analysis of historical and new herbarium specimens. All measurements were above the detectable limit of 1 μg/kg.
| Sample IDa | Cu | Pb | Zn |
| Blanks | |||
| Mean | 0.00 | 0.00 | 0.01 |
| SD | 0.00 | 0.00 | 0.01 |
| EPA Quality Control Standard 28 | |||
| Reference | 0.10 | 0.10 | 0.10 |
| Mean | 0.08 | 0.08 | 0.09 |
| SD | 0.00 | 0.00 | 0.00 |
| Apple Standard | |||
| Reference | 5.64 ± 0.24 | 0.47 ± 0.2 | 12.50 ± 0.30 |
| Mean | 4.82 | 0.73 | 10.76 |
| SD | 0.20 | 0.13 | 0.16 |
| Pine Standard | |||
| Reference | 3.00 ± 0.30 | 10.80 ± 0.50 | n/a |
| Mean | 2.67 | 9.32 | 56.20 |
| SD | 0.23 | 0.37 | 3.48 |
a
“Reference” refers to mean and expected variation for the apple and pine standards.