Dissecting the Test: Lead in Surface Coating Part 1
In this week’s edition of Dissecting the Test, we turn our focus to one of the leading tests in the consumer products industry.
Lead, a chemical element in the carbon group (also known as Pb) was once used for products such as, paints, bullets, and pipes. Once the realization of the dangers that lead has on adults and children’s became more publicly aware, lead limits were put into place to combat the medical issues.
The Danger
Lead is a highly poisonous metal if inhaled or swallowed, affecting almost every organ and system in the body, especially the nervous system.
Invisible to the naked eye and having no distinctive smell, adults and children may be exposed to it from consumer products even through normal handling of products.
If ingested, lead is poisonous to humans. Like the element mercury, another heavy metal, lead is a neurotoxin that accumulates both in soft tissues and in the bones.
The driving factor for lead still being found in consumer products is cost. Lead paints are cheaper than most alternatives, which gives way to the manufactures whom cut corners and use the cheaper leaded paint. Not helping matters is the "consumer products" market being intensely competitive as well as a poorly regulated market in most foreign countries.
If your product falls under the lead regulation requirement, you must insure that it does not contain levels of lead in excess of the 0.009 percent limit (90 parts per million).
Part One: Digestion of Samples
Step one in the process is removing the painted surface coating from the sample. This is typically performed by using a razor blade to carefully scrape the surface coating paint, while making sure to remove as little of the substrate (or base material) as possible from the sample.
Once 30-100mg of coating is removed, it is placed in a digestion tube, where nitric acid is added. After cooling, a second acid, hydrochloric is added along with distilled water. The tube is then lightly shaken and/or stirred (insert bad James Bond joke of your choosing).
Part Two: Total Lead in Metals Analysis
Step two in the process is taking the tube sample with it’s contents and placing them into a machine called an ICP spectrometer. With additional science that I won’t bore you with, the contents are calculated, accounting for all dilution and is reported as a percent by weight.
Tada……….Your lead test is complete!
Next Monday we will continue with Dissecting the Test: Lead in Surface Coating Part 2