STABILITY ANALYSIS OF 3 UV-FILTERS USING HPLC

UV-absorbing substances are widely used in sunscreens to filter out ul traviolet radiation in sunlight. These substances need to be stable in sunscreens in order to obtain the expected protection during the shel f-life of the products. A conveniant HPLC method for the separation an d quantification of three common UV-filters in a sunscreen emulsion is presented. Using this method the stability of benzophenone-3, butylme thoxy dibenzoylmethane and octyl methoxycinnamate was determined. Cali bration curves for the three UV-filters showed linear response in the interval 0.03 to 30 mu g. The absolute recovery of the spiked sample w as close to 100%. The shelf Life data indicate good stability of the f ilters.