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.
What is Amazon Prime Day? Amazon Prime Day is an all-day online deals event that's essentially Black Friday in the summer. This year's Prime Day takes place on July 12, and, as the name suggests, you'll need an Amazon Prime membership ($99 per year, or $10.99 per month) to participate. If you don't have a Prime account, you can sign up for one or get a free trial here. Amazon Prime.