The best and most widely used technique to measure trace elements (mainly metals) to parts per trillion levels is Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Typically, there are 2500 units purchased every year; sampling cones and skimmer cones are a consumable supply all ICP-MS equipment requires.
The sampling cone sees the brunt of the sample, which is why it requires frequent cleaning and replacement as it is being bombarded by samples with high dissolved solids (for example, soils and those with high salt levels) or by corrosive samples.
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