Hair shaft damage from heat and drying time of hair dryer

BACKGROUND

Hair dryers are commonly used and can cause hair damage such as roughness, dryness and loss of hair color. It is important to understand the best way to dry hair without causing damage.

OBJECTIVE

The study assessed changes in the ultra-structure, morphology, moisture content, and color of hair after repeated shampooing and drying with a hair dryer at a range of temperatures.

METHODS

A standardized drying time was used to completely dry each hair tress, and each tress was treated a total of 30 times. Air flow was set on the hair dryer. The tresses were divided into the following five test groups: (a) no treatment, (b) drying without using a hair dryer (room temperature, 20℃), (c) drying with a hair dryer for 60 seconds at a distance of 15 cm (47℃), (d) drying with a hair dryer for 30 seconds at a distance of 10 cm (61℃), (e) drying with a hair dryer for 15 seconds at a distance of 5 cm (95℃). Scanning and transmission electron microscopy (TEM) and lipid TEM were performed. Water content was analyzed by a halogen moisture analyzer and hair color was measured with a spectrophotometer.

RESULTS

Hair surfaces tended to become more damaged as the temperature increased. No cortex damage was ever noted, suggesting that the surface of hair might play a role as a barrier to prevent cortex damage. Cell membrane complex was damaged only in the naturally dried group without hair dryer. Moisture content decreased in all treated groups compared to the untreated control group. However, the differences in moisture content among the groups were not statistically significant. Drying under the ambient and 95℃ conditions appeared to change hair color, especially into lightness, after just 10 treatments.

CONCLUSION

Although using a hair dryer causes more surface damage than natural drying, using a hair dryer at a distance of 15 cm with continuous motion causes less damage than drying hair naturally.

Simultaneous HPLC analysis of ceramide and dihydroceramide in human hairs

Ceramide, a major class of hair lipid, can help determine the physicochemical properties of human hairs such as the chemical diffusion barrier and water retention. In this study, we developed a quantitation method for ceramide and dihydroceramide, a saturated form of ceramide, in human hairs. Lipids were extracted with ethanol from human hairs spiked with N-oleoyl-D-erythro-C(17) sphingosine, an internal standard. Ceramide and dihydroceramide were resolved by TLC and deacylated by sphingolipid-ceramide deacylase to release sphingosine and dihydrosphingosine, respectively. The hair content of ceramide was measured by HPLC following derivatization with o-phthalaldehyde. The limits of detection and quantification for ceramide extracted from hair fibers were 0.1 and 1 pmol, respectively. The linear range of hair weight for determining ceramide and dihydroceramide contents was 1 to 50 mg, with R(2) values of 0.9695 and 0.9898, respectively. The recoveries of ceramide and dihydroceramide from intra-day and interday assays were 99.55% to 98.53%, respectively. Concentrations of dihydroceramide from the hair roots to distal tip ends ranged from 10.42 +/- 2.19 to 1.20 +/- 0.11 nmol/g hair, while those of ceramide ranged from 2.27 +/- 0.22 to 1.47 +/- 0.15 nmol/g hair. The present analytical method provides a simultaneous and reproducible quantification of ceramide and dihydroceramide, and may be used as a potential biomarker for lipid abnormality-related diseases.

Quantitative determination of cationic modified polysaccharides on hair using LC–MS and LC–MS–MS

Cationic polysaccharides containing N-hydroxypropyl-N,N,N-trimethylammonium substituents are widely used as conditioning agents for hair-care products. A sensitive method has been developed for the quantitation of these polymers. After acidic extraction from hair the polysaccharides are hydrolyzed using trifluoroacetic acid. The cationic monoglycosides are determined using liquid chromatography-tandem mass spectrometry (LC-MS-MS). The developed method is independent of hair treatment. Even hair cut from test persons after customary hair wash can be analyzed. After treatment of natural and bleached hair tresses using a real-life treatment procedure 180 microg and 300 microg of polymer per gram hair were quantified, respectively. Additionally the fragmentation mechanism of the cationic N-hydroxypropyl-N,N,N-trimethylammonium group during electrospray ionization was investigated. A mass loss of 60 Da in combination with loss of a single charge is observed and associated with cleavage of trimethylamine and a proton. It is assumed that this process is promoted by the anionic counter-ion which might be hydroxide in an aqueous environment.