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 Prime costs Â£79 a year upfront or Â£7.99 a month. If you are a student you can get it for Â£39 a year. Occasionally Amazon offers discounted membership. In the past, weâve seen the retailer offer as much as Â£20 off in the run up to big shopping days like Black Friday, Cyber Monday and Prime Day.