Good Day, Sunshine — High Speed Analysis of UV Absorbers

July 2, 2010
Dr Björn-Thoralf Erxleben

Shimadzu Europa GmbH

The Application Notebook

The Application Notebook, The Application Notebook-07-02-2010, Volume 0, Issue 0
Page Number: 34–35

Use of UV filters in cosmetic formulations is regulated by international authorities. The concentration of these compounds in cosmetic products is controlled constantly. The following methods describe a simple, fast and ultra fast LC method for determination of UV absorbers. HALO C18* was used as column.

Introduction

Sun protection cosmetics contain UVA/UVB wide filters. They absorb significant parts of the UV radiation and protect the skin from a high dose. UVA filter protects from long-term skin damage, whereas UVB filters protect against sunburn. The UV absorbers are dissolved in the sun protection cosmetics. After applying, they form an invisible layer on the skin and in the upper parts of the skin. Although UV filters have a protective function, their levels in cosmetic products are regulated by the European Union and are controlled by scientific consultants of the EU and by international authorities.

Figure 1: Chromatogram of the separation of 11 UV absorbers.

For determination of 11 ultraviolet absorbing compounds a fast and an ultra fast method were developed using HALO C18 columns. For detection a UV detector in dual channel mode was used. Peak identification was performed in either one or the other channel.

Figure 2

Standard preparation

Standards were prepared in a concentration of 100 mg/L dissolved in methanol.

Method description

For the fast method (runtime 7 minutes) a binary gradient elution was used.

Analytical conditions (fast method)

Column: HALO C18 (150 mm × 2.1 mm i.d.)

Mobile phase:

A) 0.085% phosphoric acid in water

B) Acetonitrile

Time programme: B conc. 30% (0 min) → 70% (3.5 min) → 75% (7 min)

Flow rate: 0.8 mL/min

Temperature: 60 °C

Detection: Absorbance at 310 nm and 355 nm with semi-micro flow cell

Sample volume: 2 µL

For ultra fast analysis a isocratic method was used (runtime < 1.5 minutes).

Analytical conditions (ultra fast method)

Column: HALO C18 (150 mm × 2.1 mm i.d.)

Mobile phase:

A) 0.085% phosphoric acid in water

B) acetonitrile

A/B 15/85 (vol./vol.)

Flow rate: 0.8 mL/min

Temperature: 60 °C

Detection: Absorbance at 310 nm and 355 nm with semi-micro flow cell

Sample volume: 2 µL

The method presented is sufficient to detect typical UV absorbing compounds in cosmetic products.

*HALO is a registered trademark of Advanced Materials Technology Inc.

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