Sample Requirements for Lead Isotopes

The lead isotopic ratios (e.g. 206Pb/204Pb, 207Pb/204Pb, 208Pb/204Pb) can be measured in various sample types such as igneous and metamorphic rocks, mineral dust, marine and lacustrine sediments, bones, tooth enamel, soil, etc. The following recommendations are general guidelines which help us to provide better service to our customers. Individual sample size requirements largely vary based on the sample type. We always recommend that you choose the best samples for your research objectives. Please feel free to contact us for advice if you are concerned that your samples are too small.

Mineral Dust (ashed) – 30 to 50 mg: Aerosol samples collected on filter paper must be ashed entirely prior to submittal. All organics must be removed from the sample either by ashing or with hydrogen peroxide. All carbonate fractions must be removed if you wish to measure Pb isotopes only on siliciclastic fraction. A larger sample size is required if we need to remove the carbonates and organics or ash the samples. For effective sample dissolution, high-temperature flux fusion is the method of choice. Aerosol samples will be fused at 1075°C with high-purity lithium metaborate (LiBO2, Puratronic) and ultra-pure grade lithium bromide to ensure complete recovery of the melt. The melt is directly digested in 6 M nitric acid.

Marine and lacustrine sediments – 50 mg: All organics must be removed from the sample either by ashing or with hydrogen peroxide. All carbonate fractions must be removed if you wish to measure Pb isotopes only on siliciclastic fraction. A larger sample size is required if we need to remove the carbonates and organics from the samples. For effective sample dissolution, high-temperature flux fusion is the method of choice. Sediment samples will be fused at 1075°C with high-purity lithium metaborate (LiBO2, Puratronic) and ultra-pure grade lithium bromide to ensure complete recovery of the melt. The melt is directly digested in 6 M nitric acid.

Igneous Rocks – 50 mg: Rock samples need to be homogenized prior to submittal. For effective sample dissolution, high-temperature flux fusion is the method of choice. Homogenized samples will be fused at 1075°C with high-purity lithium metaborate (LiBO2, Puratronic) and ultra-pure grade lithium bromide to ensure complete recovery of the melt. The melt is directly digested in 6 M nitric acid.

Soil – 50 mg: All organics must be removed from the sample either by ashing or with hydrogen peroxide. Soil samples need to be homogenized prior to submittal. For effective sample dissolution, high-temperature flux fusion is the method of choice. Homogenized samples will be fused at 1075°C with high-purity lithium metaborate (LiBO2, Puratronic) and ultra-pure grade lithium bromide to ensure complete recovery of the melt. The melt is directly digested in 6 M nitric acid.

Bone (ashed) – 200 mg: All bone samples (cremated, intact) must be homogenized and ashed prior to submittal. For the best results, make sure your samples are clean and free from soil, clay particles, calcite and other detritus. Ash samples in a quartz crucible at 850°C for 3 hours and transfer the residues into clean small glass or plastic vials. Samples will be digested in 8 M nitric acid (lower concentrations may be used if the sample contains clay and detritus). A larger sample size is required if we need to ash the samples.

Metal Artifacts and coins – 20 mg: For the best results, make sure your samples are clean and free from soil, clay particles, calcite and other detritus. Samples will be digested in 8 M nitric acid (higher concentrations may be used if need be).

Water – 125 ml: Use any type of small-neck plastic bottle (HDPE, LDPE, PP) to collect your sample. Rinse the bottle with the running sample water prior to collection. Do not add any chemicals to the water, do not acidify the water. Fill the bottle all the way to the top, you may leave a small space at the top (keep the neck of the bottle empty) to allow for any necessary expansion during shipment. Please put the bottles inside a plastic bag and seal the bag with a zip-tie or duct tape. Clearly label both bottle and the plastic bag.

Note: Sample size is dependent on the lead concentration in the sample. If you have measured the lead concentration in your samples, providing that information prior to sample submission will help us better estimate the required sample size for Pb isotope analysis.