... positive ninhydrin reaction.Specifications ItemsRequirement (Common Grade)AppearancePale yellow liquid, no peculiar smellDifferentiationPositive ninhydrin reactionTotal nitrogenMin 2.8% ... 500 and 2,000, is better at making membrane, the membrane has nice luster, feels well and spring. The ... -COOH, -NH2, >NH, on the surface of the solid construct of its molecule. This structure shows that the silk ...