Enantioselective separation of the sunscreen agent 3-(4-methylbenzylidene)-camphor by electrokinetic chromatography: Quantitative analysis in cosmetic formulations

Abstract

Enantioselective separation of the sunscreen agent 3-(4-methylbenzylidene)-camphor by electrokinetic chromatography: Quantitative analysis in cosmetic formulations3-(4-Methylbenzylidene)-camphor (MBC) is a chiral sunscreen agent used in cosmetic products. In this work, the enantioseparation of MBC has been performed by EKC and applied to the analysis of the MBC enantiomers in cosmetic creams. Different experimental conditions (type and concentration of the chiral selector, temperature, and sample solvent) have been optimized. Due to the neutral nature of this compound, anionic CD derivatives were investigated as chiral selectors. Carboxymethylated-b-CD (CM-b-CD) showed the highest chiral separation power, observing that a 15 mM concentration of this CD at a working temperature of 157C enabled to obtain the highest enantioresolution. However, under these conditions, tailing of peaks obtained for the enantiomers was observed. The addition of increasing concentrations of the neutral a-CD to CM-b-CD at a 15 mM concentration in a 100 mM borate buffer at pH 9.0 improved the enantiomeric separation and decreased peak tailing. The use of DMF for the total dissolution of the cosmetic creams, and methanol:water (1:1 v/v) for appropriate dilution enabled to observe good shape and size for the peaks of the MBC enantiomers. After optimizing a method for the preconditioning of the capillary, the analytical characteristics of the chiral separation method for the analysis of MBC were investigated. Linearity, LODs and LOQs, precision (instrumental repeatability, method repeatability, intermediate precision), accuracy, and selectivity were evaluated.The method was applied to analyze MBC enantiomers contained in two commercial cosmetic creams containing racemic MBC and to study the skin absorption of this compound with time.

Determination of UV filters in river water samples by in‐line SPE‐CE‐MS

“…It should be highlighted that repeatability and reproducibility values were relatively higher than those obtained by CE‐ESI‐MS. As far as we know, the LODs obtained in the present study are the lowest obtained by CE for the determination of UV filters .…”

“…CE represents a very interesting alternative to chromatographic techniques due to the range of advantages it offers including simplicity, high separation efficiency, speed and low solvent consumption. This technique has been used to determine UV‐filter compounds in PCPs , since they are found in concentration levels that could be achieved by CE without any previous preconcentration step. However, determination of UV filters by CE in environmental waters samples has not been studied so far.…”

Review of aqueous chiral electrokinetic chromatography (EKC) with an emphasis on chiral microemulsion EKC

“…A combination of anionic and neutral CDs (CM-b-CD and a-CD) was able to differentiate the enantiomers of 3-(4-methylbenzylidene)-camphor, a sunscreen agent [85]. Enantioresolution was improved when a low temperature (157C) was used along with a high concentration of a-CD (120 mM).…”

Chiral Separations

“…A study on the reproducibility of CE enantioresolution with randomly substituted cyclodextrins was reported (29), using 1,1′-binaphthyl-2,2′-diyl hydrogen phosphate as a test solute. The antidepressant mirtazapine and its active demethylated metabolite were enantioseparated by CE using carboxymethyl-β-CD as chiral selector (30), and carboxylmethyl-β-CD showed the highest chiral separation power as chiral selector for the enantiomeric separation of the sunscreen agent 3-(4-methylbenzylidene)camphor by EKC (31). The addition of methanol was found to enhance the enantioseparation of dimetindene using carboxymethyl-β-CD as chiral selector in CE (32), and the influence of methanol was studied on the enantioresolution of antihistamines again employing carboxymethyl-β-CD as chiral selector (33).…”