Preparation of Geochemical Samples
Good sample preparation underpins the whole analysis procedure – appropriate sampling and size reduction are critical to meaningful results.
Being a clean laboratory dedicated to geochem-level work, we go to extra lengths to ensure samples are not compromised in the preparation stages. For example, pulveriser bowls are routinely washed with barren material after every sample.
LabWest’s sample preparation regime has been devised to ensure conformity with accepted statistical sampling approaches. After reception and sorting, samples are dried at 110°C. Samples greater than ~700g are fine-crushed to less than 2mm, before being rotary-split to ~500g. A coarse duplicate is taken from every 40th sample for analysis. Samples are then pulverised to minus 75µm.
At LabWest pulveriser bowls are routinely cleaned with a barren charge between samples.
LabWest Code PREP-01a
Stream sediments, soil, samples <500g.
Sort, dry, pulverise to -75µm
LabWest Code PREP-01
Soil, aircore, RAB, samples <3kg.
Sort, dry, split, pulverise to -75µm
LabWest Code PREP-02
RC, Core, Rock samples <3kg
Sort, dry, crush, split, pulverise to -75µm
LabWest Code PREP-03
Vegetation samples <50g
Sort, dry, pulverise
LabWest Code PREP-04
Non-ferrous (Cr-free) prep, tungsten bowls
stream sediment, soil, samples <200g.
LabWest Code PREP-S80
Stream sediment, soil, samples <500g.
Screen to -80 mesh
LabWest has a dedicated dry/wet-sieving section, with state-of-the-art electromagnetically-driven sieving equipment. Screen fractions from 45µm to 4mm can be determined.