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.
Amazon is testing a $7.99 per month pricing scheme for its Prime program -- the same exact cost as monthly streaming services from Netflix and Hulu. Amazon is testing a $7.99 per month pricing scheme for its Prime program, the same exact cost as the monthly streaming services from Netflix () and Hulu. That's a pricier option than Amazon Prime's traditional $79 annual fee. The blog Hacking Netflix first reported on the pricing trial after a reader spotted the offer.