There are a lot of questions here looking for simple methods to measure caffeine content (or extract it), including one of mine here and on the Coffee site:
- Home science optical absorption test for approximate caffeine quantity in coffee?
- Are there any ways that coffee consumers can measure the caffeine content of what they are drinking by themselves?
But here I'd like to ask something different:
Question: Is there a standard industrial method for measuring caffeine content in food and drinks?
For example, if there were government requirements to post the amount of caffeine in a product there may be some standard way that government advised that it be done (i.e., "this is the way we're going to do it to verify what you report."). While I don't know of any such requirements, that doesn't mean there aren't any.