Occurrence of para-aminobenzoic acid and benzocaine as contaminants in sunscreen agents of para-aminobenzoic acid type

Para-aminobenzoic acid (PABA) and some of its esters, such as amyl para-dimethylaminobenzoate, ethyl 4-bis(hydroxypropyl)aminobenzoate, 2-ethylhexyl para-dimethylaminobenzoate and glyceryl para-aminobenzoate are used as Sunscreen agents. Methods for separating PABA and the 5 mentioned PABA esters by thin layer chromatography and high pressure liquid chromatography (HPLC) are presented. Contamination with PABA and benzocaine were measured quantitatively by the HPLC technique in samples of the 4 PABA esters, using different brands and different batches of the same brand. PABA was detected in all 12 samples examined and benzocaine in 11. The degree of contamination was batch-dependent. Minimal amounts of PABA and benzocaine were found in most batches but in glyceryl para-aminobenzoate both substances were present at a level above 0.1% (w/w). High levels of benzocaine were also detected in batches of ethyl 4-bis(hydroxypropyl)-aminobenzoate.