Heavy metals are associated with serious adverse health effects in humans ranging from kidney disease to birth defects to cancer. Cannabis plants are more susceptible to heavy metal contamination because they are in a unique class of hyperaccumulating plants that can tolerate uptake of significant levels of heavy metals from soil before their growth cycles are negatively affected. Thus heavy metal testing is vital to ensure consumer safety.
We use a state-of-the-art technique called Inductively-Coupled Plasma-Mass Spectrometry (ICP-MS) to quantify for arsenic, cadmium, mercury, and lead. ICP-MS is a highly sensitive technique that allows for detection of analytes at very low levels (e.g. ppt, sub-ppb). Typically a sample is first fully digested in a microwave apparatus, diluted, and then injected into the ICP-MS instrument. The sample is then ionized in an inductively-coupled plasma flame that reaches temperatures between 6,000K and 10,000K (comparable to temperatures on the Sun!). The resulting ions are separated and quantified by their mass-to-charge ratios in a mass spectrometer.