title: High Precision Zinc Stable Isotope Measurement of Certified Biological Reference Materials Using the Double Spike Technique and Multiple Collector-ICP-MS.
abstract: Biological reference materials with well-characterised stable 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 (which denotes the deviation of the66Zn/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 isotope analyses. This endorsement is reinforced by (i) the close agreement of our Zn isotope data for two of the samples (bovine 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.
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, Royal School of Mines, Prince Consort Rd, Kensington, London, SW7 2AZ, UK. r.moore13@imperial.ac.uk.
authors.forename: Rebekah E T
authors.initials: RE
authors.lastname: Moore
authors.affiliation: Department of Earth Sciences, University of Oxford, South Parks Road, Oxford, OX1 3AN, UK.
authors.forename: Fiona
authors.initials: F
authors.lastname: Larner
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, Royal School of Mines, Prince Consort Rd, Kensington, London, SW7 2AZ, UK.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Coles
authors.affiliation: Department of Earth Science and Engineering, Imperial College London, Royal School of Mines, Prince Consort Rd, Kensington, London, SW7 2AZ, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Rehkämper
mesh_terms: D000818:Animals; D002417:Cattle; D002568:Certification; D005399:Fishes; D006801:Humans; D038622:Internationality; D012016:Reference Values; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013054:Spectrophotometry, Atomic / Q000379:methods* / Q000592:standards*; D013552:Swine; D014131:Trace Elements / Q000032:analysis* / Q000592:standards*; D015033:Zinc Isotopes / Q000032:analysis* / Q000737:chemistry / Q000592:standards*
chemical_list: D014131:Trace Elements; D015033:Zinc Isotopes
keywords: Biological reference materials; Double spike; Ion exchange chromatography; Multiple collector inductively coupled plasma mass spectrometry; Stable isotopes; Zinc