Abstract
A method has been developed for the rapid analysis of permanent waving lotions by high performance liquid chromatography (H. P. L. C.). Permanent waving lotions containing cysteine have been conventionally analysed by N-Ethylmaleimide Method (Official Method), but the method was time-consuming, tedious and complicated, as well as poorly reproducible, so not practicable.
Cysteine was separated from other components and oxidation products, using μ-Bondapak C18 (4mm i.d., 300mmL.) and methanol-water (40:60v/v) containing 0.4% phosphoric acid and 0.005M sodium lauryl sulfate as an eluent. The detection of cysteine was monitored at 220nm or 225nm with separations accomplished in approximately 15min. The relative standard deviation of cysteine was less than 1.5%. This method could be also applied at the quality-control and the stability testing, and when the simultaneous determination of cysteine and thioglycollic acid as a stabilizer was accomplished by using 0.1% phosphoric acid as an eluent, the relative standard deviations of them were less than 2%.
Thus, it is found the present H. P. L. C. method is accurate, precise, rapid and highly reproducible for the analysis of permanent waving lotions containing cysteine.
