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.
Users can now subscribe to Prime Video for $8.99 a month or all of Prime for $10.99 a month. Amazon Prime is going monthly and taking even more direct aim at Netflix. Users can now subscribe to Prime Video for $8.99 a month or all of Prime for $10.99 a month. Amazon Prime is going monthly and taking even more direct aim at Netflix. 1  On Sunday night the online retailer is turning on a monthly subscription option for its bundle of Prime services, like free shipping, a music library, and a growing collection of original TV shows and movies.