Biological reference materials with well-characterized s
table isotope compositions are lacking in the field of
‘isotope biochemistry’, which seeks to understand
bodily processes that rely on essential metals by determining
metal stable isotope ratios. Here, we present Zn stable isotope
data for six biological reference materials with certified trace metal concentrations, fish muscle, bovine muscle, pig kidney, human hair,
human blood serum and human urine. Replicate analyses
of multiple aliquots of each material achieved reproducibilities
(2sd) of 0.04-0.13 ‰ for δ66/64Zn 22 (which denotes the deviation of the
66 Zn/64Zn ratio of a sample from a pure Zn reference material
in parts per 1000). This implies only very minor isotopic heterogeneities within the samples, rendering them suitable
as quality control materials for Zn isotopeanalyses. This endorsement
is reinforced by (i) the close agreement of our Zn isotope data for
two of the samples (bovine 2 muscle and human blood serum) to previously published results for different batches of the same
material and (ii) the similarity of the isotopic data for the samples (δ66/64Zn≈ –0.8 to 0.0 ‰) to previously published Zn isotope
results for similar biological materials. Further tests revealed
that the applied Zn separation procedure is sufficiently effective to enable accurate data acquisition even at low mass resolving power (M/ΔM ≈ 400), as measurements and analyses conducted at much higher mass resolution (M/ΔM ≈ 8500) delivered essentially identical
results.