The use of emulsions in the preparation of samples and standards for analysis by atomic-absorption spectroscopy determination of Cu and Fe in mibk extracts of their apdc complexes

The use of aqueous/organic emulsions is shown to give advantages in the AAS determination of Cu and Fe extracted as their pyrrolidinedithiocarbamate complexes into methyl isobutyl ketone. The emulsions are more stable than the extracts, and the standards can be prepared from aqueous solutions by emulsification, but without extraction.

Sequential injection analysis for benzophenone-4 and phenylbenzimidazole sulphonic acid in sunscreen sprays by solid-phase extraction coupled with ultraviolet spectrometry

Abstract A sequential injection UV method was developed to determine benzophenone-4 (BZ4) and phenylbenzimidazole sulphonic acid (PBS) simultaneously, these being the most commonly used UV-filters in aqueous formulations used as sunscreen sprays. The selective elution of both was performed by on-line solid-phase extraction, by retention on a SAX microcolumn and separation by varying the pH of elution. The sensitivity obtained was 0.042±0.001 ml μg −1 for PBS and 0.0159±0.0003 ml μg −1 for BZ4. The limit of detection was 1.6 μg ml −1 for PBS and 0.6 μg ml −1 for BZ4. The R.S.D. of the results was 1–6% for PBS and 1–12% for BZ4. The method was validated using commercial sunscreen formulations…

Sensitive sequential-injection system for the determination of 2-phenylbenzimidazole-5-sulphonic acid in human urine samples using on-line solid-phase extraction coupled with fluorimetric detection

Abstract 2-Phenylbenzimidazole-5-sulphonic acid (PBS) is an UV-filter contained in many cosmetics as a sunscreen. A direct, selective and sensitive method to determine traces of PBS is presented. The on-line separation of this compound from urine matrix was directly coupled with fluorimetric detection in a sequential-injection system. The separation was performed using a SAX microcolumn in which the analyte was retained and eluted selectively. The determination is carried out without any derivatization reaction, by directly measuring the intrinsic fluorescence of the analyte. The wavelengths of excitation and emission were 301 and 681 nm, respectively. On-line standard addition calibration …

General Review of Published Analytical Methods for Cosmetics