Patent ID: 9435785
Filing Date: 2016-09-06
CPC Classification: B01D,G01N,Y10T

Claim Text:
1. A method of analyzing purity of a composition comprising cysteamine comprising: (i) injecting a sample solution comprising cysteamine onto a reverse-phase HPLC column; (ii) eluting the sample from the column using a mobile phase comprising an alkyl sulfonic acid, a buffer, acetonitrile, and methanol; and (iii) measuring the eluted sample using a UV detector at a wavelength of about 170 nm to about 250 nm; wherein the sample is eluted using a gradient elution, the elution comprising gradient eluting the sample using first and second mobile phases, wherein the first mobile phase comprises: about 75% to about 95% by volume of an aqueous solution having a pH of about 2.0 to 3.0, the aqueous solution comprising an alkyl sulfonic acid and a phosphate buffer, about 1% to about 8% by volume of acetonitrile, and about 5% to about 20% by volume of methanol; and the second mobile phase comprises: about 5% to about 30% by volume of an aqueous solution having a pH of about 2.0 to 3.0, the aqueous solution comprising an alkyl sulfonic acid and a phosphate buffer, about 8% to about 30% by volume of acetonitrile, and about 50% to about 85% by volume of methanol.