Lead Stable Isotope Ratio Testing

Brooks Applied Labs currently offers lead isotope ratio testing for environmental forensic studies. Lead has four stable isotopes, one of which is primordial (204Pb) and three of which are radiogenic (206Pb, 207Pb, and 208Pb), being produced by the decay of parent isotopes of uranium or thorium. Each parent isotope decays at a different rate, resulting in varying proportions of lead isotopes in different geological sources. Once formed, lead isotopes do not fractionate significantly through natural physical or chemical processes in the environment. Consequently, analysis of lead stable isotopes can be used in environmental forensics to identify sources of lead based on their unique isotopic “fingerprints.”

Human activities, particularly the use of leaded gasoline and industrial processes like ore smelting, have released significant amounts of lead into the environment. This anthropogenic lead often carries a distinct isotopic signature, which may be used to trace its origin. For example, lead from different mines may have distinct isotopic compositions that can aid in identifying the source of lead contamination in nearby soil or water. Similarly, atmospheric transport of lead from an ore smelter may be traceable via the isotopic signatures of lead in dust, soil, or biota collected downwind from the source.

Lead isotope ratio analysis also has valuable applications in archaeology, where it may be used to study the provenance and trade of ancient materials like metals, ceramics, glass, and coins. By comparing the lead isotope ratios of these artifacts with those from known sources, the origin and distribution of raw materials and finished products across different cultures and periods may be studied. Additionally, insights into the diet and migration patterns of ancient humans or animals can be gained by measuring lead isotope ratios in their bones and teeth; these ratios typically reflect those of their diet (food and water), which in turn are influenced by the geology of the regions they inhabited.

Meaningful lead isotope ratio measurements require purification of lead from the samples followed by high accuracy and precision analyses. Separation of lead isotopes from the sample matrix and potential interferants may be accomplished by different methods, depending on the type and amount of sample available, but Brooks Applied Labs typically employs ion exchange chromatography. The purified lead is then analyzed via multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS), which offers the flexibility, speed, and precision necessary for commercial testing. All reports issued by Brooks Applied Labs include appropriate QA/QC (see tables below for an example), which are not usually provided from academic institutions. Brooks Applied Labs utilizes both a Nu 1700 Multi Collector ICPMS and a Nu HR Multi Collector ICPMS to achieve high accuracy and high precision isotopic measurements,

For project inquiries, applicability of methodologies, and pricing information feel free to contact us today.

Reference Materials

Sample ID	208Pb/204Pb Ratio	207Pb/204Pb Ratio	206Pb/204Pb Ratio
HIPB-1 (NRC) Certified Value	39.99 ± 0.04	15.873 ± 0.014	21.133 ± 0.014
HIPB-1 (NRC) CRM	39.9921 ± 0.0010	15.8713 ± 0.0008	21.1342 ± 0.0006
HIPB-1 (NRC) CRM Duplicate	39.9891 ± 0.0014	15.8697 ± 0.0005	21.1321 ± 0.0008
HIPB-1 (NRC) CRM Triplicate	39.9876 ± 0.0010	15.8695 ± 0.0005	21.1311 ± 0.0006
External Precision (% RSD)	0.006%	0.006%	0.007%

Triplicate Set

Sample ID	208Pb/204Pb Ratio	207Pb/204Pb Ratio	206Pb/204Pb Ratio
Sample 1	37.8560 ± 0.0010	15.5809 ± 0.0005	18.0079 ± 0.0010
Sample 1 Duplicate	37.8536 ± 0.0010	15.5807 ± 0.0005	18.0069 ± 0.0009
Sample 1 Triplicate	37.8560 ± 0.0008	15.5816 ± 0.0005	18.0071 ± 0.0008
External Precision (% RSD)	0.004%	0.003%	0.003%