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Sunday 2025-10-19 19:51
Ethanol vs. Isopropyl Alcohol: Comparing Their Temperature-Dependent Effects on Hair Protein Loss
SeyedehAtefeh Kermani 1 ℗, Sara Sajjadi 1, Maryam Maghsoudi 2, Farnaz Monajjemzadeh 3 ©
Abstract
Introduction Topical hair products, including gels, creams, sprays, and hair serums, contain ingredients such as natural oils, vitamins, and plant extracts that are dissolved in solvents such as ethanol and isopropyl alcohol. This study aimed to investigate the impact of ethanol and isopropyl alcohol, two common solvents, on human hair at different temperatures, using the Lowry method. Methods and Materials Hair bundles were immersed in 10 mL of ethanol or isopropyl alcohol: propylene glycol: water (in the ratio of 7:2:1 v/v) and incubated for 10 minutes at either 25 °C or 40 °C. Following treatment, each bundle was then combed five times; after each set of ten strokes, both the hair and comb were rinsed in 30 mL of water. The protein released into all rinse water samples was quantified using the Lowry method, validated with bovine serum albumin (BSA). Absorbance was measured at 750 nm using a UV-visible spectrophotometer. Results The results demonstrated that the effect of temperature on protein loss was solvent-dependent. While ethanol induced no significant increase in protein loss at 40°C (110.4 µg/mL) compared to room temperature (100.6 µg/mL), isopropyl alcohol caused a statistically significant increase at the higher temperature (135.0 µg/mL vs. 100.6 µg/mL, p 0.05). Furthermore, no significant difference in protein loss was observed between the two solvents at either temperature. Conclusion and Discussion This study revealed a solvent-dependent effect of temperature on hair protein loss. Isopropyl alcohol caused significantly greater damage at 40°C than at room temperature, whereas ethanol did not. This key finding suggests that ethanol is a preferable solvent in products intended for use with heat, as it poses a lower risk of heat-aggravated hair damage.
Keywords: Protein loss, Human hair, Ethanol, Isopropyl alcohol
