Hair dyes and determination of the active dye ingredients
Active dye ingredients in hair dyes have acute, allergic, sub-chronic, chronic, genetic and reproductive toxicities or carcinogenicity. They are amongst the most extensively studied and regulated cosmetic ingredients. The monitoring of levels of active ingredients in commercial hair dyes or biological samples is important to ensure product quality and protect human health. Many techniques have been used for determination of dye ingredients. Among those, HPLC, GC and CE methods are the mostly commonly used. In this article we overview the analytical methods in recent 10 years.
Hair dyes are cosmetics used to change hair color. Since ancient times people have the desire to change their hair color. In earlier times especially natural hair dyes, e.g. henna or indigo were used, whereas since the 1950s synthetic hair dyes have become more and more important. More than 50% of women in the industrialized world use hair dyes for short or long period in their life. Recently, hair coloring is regarded as fashionable and has become popular even among men (1). In this review, many abbreviations will be used. We list them in appendix A.
CATEGORY, SAFETY AND REGULATION
Generally, there are three major types of hair dyes: temporary, semi-permanent and permanent hair dyes (2, 3). Temporary hair dyes do not penetrate into the cortex, deposited on the surface of the hair and can be shampooed out of the hair with a single shampooing. The dye ingredients have a high molecular weight including azo-, triphenylmethane-, anthraquinone- or indamine dyes. Semi-permanent hair dyes have high affinity to the keratin and can diffuse into hair. The color persists after four to six shampooing. Compounds belonging ...