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Absorption of Salicylic Acid in Skin After Repeated Usage of Facial Cleansers. Ashley Covelli Chem 4101 December 8 th , 2010. What is Salicylic Acid?. Compound found naturally in willow tree, “Salix alba,” then prepared using Kolbe-Schmidt process

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Absorption of salicylic acid in skin after repeated usage of facial cleansers l.jpg

Absorption of Salicylic Acid in Skin After Repeated Usage ofFacial Cleansers

Ashley Covelli

Chem 4101

December 8th, 2010

What is salicylic acid l.jpg
What is Salicylic Acid?

Compound found naturally in willow tree, “Salix alba,” then prepared using Kolbe-Schmidt process

Purpose in cosmetic products: anti-acne agent, skin-conditioning agent, reported to enhance percutaneous penetration of other chemical agents in solution1

Problem: Salicylic acid is believed to be harmful to humans/animals (if found above toxic threshold of 30 mg/100mL), causing problems such as: skin irritation, increased sun sensitivity, and reproductive and developmental toxicity at concentrations ≤3% in personal care products1

Hypothesis l.jpg


Salicylic acid is hazardous to human health upon repeated exposure. Most facial cleansers contain roughly 2% of salicylic acid. The concentration levels of this compound found below the skin in humans will be analyzed, the analyte concentration in serum should be below the toxic threshold of 30 mg/100mL using a proper analytical method.

Importance of solving the analytical problem:

By analyzing the amount of salicylic acid in products and comparing these concentrations to concentrations of salicylic acid present below the dermis, would help the FDA regulate hazardous cosmetic products. As a result of this study, cosmetic companies may wish to reformulate their products in order to provide a less hazardous product for consumers.

Analytical method of choice hplc with uv vis detector l.jpg
Analytical Method of Choice: HPLC with UV-Vis detector

Sensitive method which is needed when analyzing low concentrations

Small sample volumes needed

Quantitative determination of analyte concentration in solution

Relatively low limit of detection (around 0.1 μg/mL for analyte)1

System is reasonably priced ($1,425 for C8 column and UV detector)

After analyzing, sample is not destroyed.

Relatively good reproducibility

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HPLC column (Ascentis® C8 column – 581444-U Supelco)4 and UV detector (Agilent 325 Dual Wavelength UV-Vis HPLC Detector)5

Reverse phase HPLC column (size=25 cm × 10.0 mm)4: (approximately $425.00)

Main advantage is the control of elution selectivity

Particle size of salicylic acid is <7.4 μm6

Mobile phase: combinations of methanol and water

Stationary phase: C8 packing (octyl) on silica gel with added buffer (i.e. sodium phosphate)

Flow rate: approximately 1 mL/min6

UV Detector 5 (approximately $10,000):

Excellent quantitative technique

Internal Standard to obtain calibration curve

Absorbances obtained at wavelength range: 305-310 nm due to salicylic acid6

From Beer’s law plot, concentration of salicylic acid can be determined

Rapid analysis

Relatively high sensitivity (around 0.1 μg/mL for analyte)1

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Experimental Design

Prepare Internal Standard and standard solutions

1.SubcutaneousMicrodialysisobtain blood samples

2. Centrifuge the blood samples to obtain plasma

3. Inject samples into HPLC-UV vis instrument

4. Obtain an absorbance spectrum of solution, the wavelength absorbed in the range 305-310 nm is due to salicylic acid.

Flow rate: 1 mL/min

Mobile Phase: methanol/water

Stationary Phase: C8

Figures of merit for analytical method of choice 1 l.jpg
Figures of Merit for Analytical Method of Choice1:

Analytic Characteristics Using Similar Methods:

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Proposed Analysis

Retention time for Salicylic acid=5.5 minutes

Quantify concentration of Salicylic acid in serum based on absorbance values obtained from UV detector and calibration plot

Confirm concentrations of SA obtained from UV with areas of peaks obtained from HPLC

Compare the levels of SA in serum to the concentration of the cosmetic product the consumer has been consecutively using

Be sure to run controls using animal serum and various concentrations of analyte

Conclusion l.jpg

Importance of usage of safe cosmetic products, detection of SA in consumers is important to monitor

Practical analytical method as all compounds are able to be detected, thus multiple analyte concentrations may be compared

Fast detection and moderate cost

High levels of SA may cause serious long term health effects

Salicylic acid is also an ingredient in asprin, how does consumption of this drug compare affect serum levels, is this also hazardous?

References l.jpg

1. Francis; Taylor. Safety Assessment of Salicylic Acid, ButyloctylSalicylate, Calcium Salicylate, C12–15 Alkyl Salicylate,

Capryloyl Salicylic Acid, HexyldodecylSalicylate, IsocetylSalicylate, IsodecylSalicylate, Magnesium Salicylate, MEA

Salicylate, EthylhexylSalicylate, Potassium Salicylate, Methyl Salicylate, MyristylSalicylate, Sodium Salicylate, TEA

Salicylate, andTridecylSalicylate. Int. J. of Tox. 2003, 22, 1-108.

2. Makino, K.; Itoh, Y. Determination of nonsteroidal anti-inflammatory drugs in human specimens by capillary zone

electrophoresis and micellarelectrokinetic chromatography. Electrophoresis. 2004, 25, 1488–1495

3. Kasprzyk-Horden, B.; Dinsdale, R.; Guwy, A. Multiresidue methods for the analysis of pharmaceuticals,

personal care products and illicit drugs in surface water and wastewater by solid-phase extraction and ultra performance

liquid chromatography–electrospray tandem mass spectrometry. A. Bioanal Chem. 2008, 391,1293–1308.

4. http://www.sigmaaldrich.com/analytical-chromatography/analytical-products.html?TablePage=16706624

5. http://www.chem.agilent.com/en-US/Products/Instruments/lc/analytical/systems/120 0seriesbinarylc/Pages/default.aspx

6. Sarveiya, Vikram. Liquid chromatographic assay for common sunscreen agents: application to in vivo assessment of skin

penetration and systemic absorption in human volunteers. J. of Chrom. 2004, 803, 225-231.

7. Uges, D. An HPLC method for the determination of salicylic acid, phenacetinand paracetamolin serum, with indications; two case-reports of intoxication. Int. Jour. Of Clin. Pharm. 2001. 3, 1309-1315.