The ninhydrin reaction, one of the most important method of detecting amino acids, both technically and historically, has been conventionally used to detect their microgram amounts. When amino acids with a free alpha amino groups are treated with an excess of ninhydrin, they yield a purple colored product.
Update January 19: Amazon has increased the monthly price of Amazon Prime from $10.99 to $12.99 for those who opt for the month-to-month plan. However, the annual price remains untouched at $99 per year, which makes it the better option for avid Amazon shoppers.
There is a large yellow button that says âstart your one month free trial,â and beneath that the text indicates that Amazon Prime is just $7.99/month afterwards. That works out to $95.88/year, so itâs more expensive than the annual subscription.