When measuring methamphetamine residues, the unit of measurement is µg (micrograms).  It can be hard to imagine just what this means, and some metaphors are useful to understand a little better.

A microgram is a millionth of a gram, and when measuring things in micrograms the term ‘parts per million’ is also sometimes used.  However, its also worth noting that laboratories are typically measuring methamphetamine residues at a level as low as 0.02 µg, which is actually 20 nanograms (or 20 parts per billion).

So what are some useful analogies to use for these low levels of measurement?

1 part per million or 1 microgram

• One second in 10 days or a minute in 2 years.
• A large cup of coffee emptied into an Olympic sized swimming pool (50 m long by 25 m wide and 2 m deep).
• 3 grains of rice in 100 kilograms of sugar.

1 part per billion or 1 nanogram

• 1 car in a line of cars that goes around the earth 100 times.
• 3 seconds in a century.
• A 10 cent coin compared with 100 million dollars.

In other words, the residues of methamphetamine that can safely be in a property are very low!! The equipment used for this testing by laboratories is very sensitive, and Analytica Laboratories has literally millions of dollars worth of sophisticated LC-MS/MS analysers for the task.