Skin whitening cosmetics are lately in great demand by women who want to look more attractive. Skin whitening cosmetics contain several active chemicals that act as whitening agents, both safe and harmful to health. Harmful skin whitening agents include mercury and hydroquinone. Hydroquinone is a whitening agent that is very effective compared to other bleaches. Hydroquinone can whiten the skin in a relatively short time with low concentrations and has been used for decades.
The mechanism of hydroquinone as a whitening agent in whitening cosmetics is by inhibiting the activity of the tyrosinase enzyme in melanogenesis. In this process, melanin formation is inhibited by destroying melanocyte cells, increasing damage to melanosomes and damaging organelle membranes, so there is less melanin formed. Melanin is a pigment that plays a role in determining the color of the skin, the more the amount of melanin in the skin the darker the skin color.
Based on the regulation of Food and Drug Monitoring Agency (BPOM) No. HK.03.1.23.08.11.07517 and the Food and Drug Administration (FDA) use of hydroquinone in whitening cosmetics has been banned with zero tolerance because it has a negative impact on health. Side effects of hydroquinone use in whitening cosmetics include skin irritation, redness of skin, burning sensation, causing black spots while long-term side effects can be skin cancer, kidney and liver function disorders due to hydroquinone accumulating in the body. For medical purpose such as treatment of hyperpigmentation, the use of hydroquinone is still permitted but must be under a doctor’s supervision.
By the end of 2019 BPOM had found 113 various kinds of dangerous cosmetics, from domestic and foreign markets, 33 of them were skin whitening cosmetics that contained hydroquinone (Tribunnews.com/2019/12/27). Based on this fact it has been proven that the use of hydroquinone in skin whitening cosmetics is still widely practiced and widely circulated in the community despite the existing regulations prohibiting the use of hydroquinone. Therefore, a fast, inexpensive and accurate method is needed to detect the use of hydroquinone in cosmetics. So it is expected to be the first step to prevent and control the negative effects from the use of these compounds for health.
Various methods have been developed for hydroquinone analysis, including spectrophotometry, HPLC, and GC-MS. Some of these methods have good sensitivity but have some disadvantages such as requiring experts to operate the equipment, complicated sample preparation stages and expensive analysis and equipment costs. This is what drives the need for the development of hydroquinone analysis method that are easy to operate, inexpensive, fast, efficient and sensitive.
UNAIR Faculty of Science and Technology Analytical Chemistry Laboratory Research Group has developed several studies related to hydroquinone analysis and manufacture of electrometric-based sensors. This hydroquinone test kit has been created by involving students in PKM research activities (2014) and entrepreneurship PKM (2015). This product has been granted a patent (IDP000049706), and has been sold in an exhibition or online in the name of nonikit. This test kit product can be used directly by the users to detect hydroquinone in skin whitening cosmetics they normally use. However, the hydroquinone analysis method in the laboratory is still needed as a reference analysis if needed if there are consumers / cosmetic manufacturers who are complaining about dissatisfaction of the test results.
An alternative method that can be developed for hydroquinone analysis is the voltammetry method with a modified working electrode. The voltammetry method is an electrolysis method that measures current as a potential function. Voltammetry is based on the measurement of current in an electrochemical cell where the rate of reduction of analyte oxydation is based on the rate of mass transfer of the analyte to the surface of electrode. This method can be used to analyze organic and inorganic compounds. Measurement of organic compounds by voltammetry is based on the presence of functional groups that can undergo oxidation or reduction on the electrode surface. Hydroquinone can be detected using the voltammetry method because it is an electroactive compound that can undergo oxidation and reduction reactions.
In this study the modified nanopore carbon paste electrode with the addition of ferocene was used as a hydroquinone sensor. The use of carbon as an electrode is based on the inert carbon properties, a good conductor of electricity and has a wide potential range. In addition, carbon is also cheap and easy to obtain. Modification of the working electrode is done by adding ferocytes, which function as a mediator to increase the electrocatalytic activity of the redox hydroquinone reaction.
This research aims to develop new methods as an alternative to hydroquinone analysis in cosmetics that are easy, inexpensive, selective, and accurate. The working electrode as a hydroquinone sensor is made by mixing carbon nanopore powder with paraffin. The paraffin added to the working electrode works as an organic binder that is inert and stable in the mixture. Furthermore, the electrodes are used for voltammetric analysis of hydroquinone.
The parameters studied were optimization of the ferocene composition, the effect of pH, and the effect of scan rate. Also studied the validity of methods which include linearity, sensitivity, limit of detection, accuracy, precision and selectivity in the mixture with arbutin. The optimum results of each parameter are then applied to determine the hydroquinone content in artificial whitening cosmetic samples that are loaded with hydroquinone with certain levels to determine its accuracy.
The results showed the composition of the electrode membrane that gave the best results was carbon nanopore: paraffin: ferocene = 6: 3: 1. Based on the voltammogram, the effect of the scan rate shows that, on the electrode surface, an electrochemical reaction occurs followed by a chemical reaction. The pH of the solution has an effect on the cyclic hydroquinone voltammogran, pH 7 giving a voltammogram that is closer to a reversible reaction. The validity of the hydroquinone analysis method using carbon paste / ferocene as an electrode showed good results from the working range.
The validity of the hydroquinone analysis method using carbon paste / ferocene as an electrode showed very good results with a working range of 0.20-10 mM, sensitivity of 10.436mA / mM, and a detection limit of 0.06 mM. This method is selective in the analysis of a mixture of hydroquinone and arbutin without disturbing each other. Please note that lately arbutin is also used as a skin whitening agent, but its use is still allowed at certain levels.
These electrodes have excellent accuracy in the recovery of hydroquinone analysis in cosmetic samples with an average accuracy value of 99%. These electrodes can also be used for arbutin analysis in cosmetics with an accuracy of 99%. This method is suitable for skin whitening analysis, both hydroquinone and arbutin. It is also suitable for use in skin whitening cream analysis, both hydroquinone and arbutin for routine BPOM analysis purposes.
Author / researcher: Muji Harsini
Details of this article can be seen at:
https://rasayanjournal.co.in/admin/php/upload/831_pdf.pdf
Muji Harsini, Untari, Erna Fitriany, Ainy Nur Farida, M. Zakki Fahmi, Satya Candra Wibawa Sakti, dan Gustan Pari. 2019. Voltammetric Analysis of Hydroquinone in Skin Whitening Cosmetic Using Ferrocene Modified Carbon Paste Electrode. Rasayan J.Chem Vol. 12 No. 4 2296 – 2305 October – December.
