Table 1: Results obtained for the standard reference materials together with certified value.

SRMElementCertified value (μg g−1)Measured value

Pine needlesPb0.167 ± 0.0130.161 ± 0.102
NIST-SRM 1575aCd0.233 ± 0.0090.214 ± 0.013
Spinach leavesPb0.200 ± 0.0060.198 ± 0.012
NIST-SRM 1570Cd2.890 ± 0.0702.830 ± 0.095