Determination of formaldehyde in cosmetic products using gas-diffusion microextraction coupled with a smartphone reader

Abstract

The use of digital image-based methods in analytical determinations has been reported in several areas of science such as clinical, food and pharmaceutical analysis. These determinations have the advantages of low cost, reduced reagent and sample consumption, fast analysis, automation, and portability. Formaldehyde has been suggested as a probable human carcinogen. Formaldehyde and formaldehyde-releasers are commonly used as preservatives in cosmetics and other pharmaceuticals. Thus, this study aims to determine formaldehyde in cosmetics and personal care products using digital images of gas-diffusion microextraction captured using a smartphone. Seven samples of various toiletries and cosmetics were analyzed by digital images using a Motorola Moto G5 smartphone. The captured images were converted to RGB values by ImageJ software. The blue channel signal intensity was selected as analytical response. Formaldehyde was extracted using gas-diffusion microextraction (GDME) and collected in acetylacetone solution. The product formed is a yellow colored dye. The method developed presented detection and quantification limits of 0.200 mg kg-1 and 0.500 mg kg-1, respectively. The formaldehyde concentration found in the different cosmetic products analyzed with the method ranged from 2.13 to 4.21 mg kg-1. The proposed method was compared with a reference method and the data obtained using a smartphone did not present significant differences compared to the reference method.