Identification and quantitation of vitamins K1 and K3 in cosmetic products for facial skin protection.

A simple and rapid analytical method was developed for the determination of vitamins K1 and K3 in facial anti-rash creams. The procedure is based on an ultrasonic extraction of the cosmetic sample with dimethylacetamide, in the presence of an internal standard, followed by HPLC separation. HPLC was performed using a C18 column and spectrophotometric detection at 333 nm.

Direct quantification of test bacteria in synthetic water-polluted samples by square wave voltammetry and chemometric methods.

A home-made microelectrode array, based on reticulated vitreous carbon, was used as working electrode in square wave voltammetry experiments to quantify the bacterial load of Escherichia coli ATCC 13706 and Pseudomonas aeruginosa ATCC 27853, chosen as test microorganisms, in synthetic samples similar to drinking water (phosphate buffer). Raw electrochemical signals were analysed with partial least squares regression coupled to variable selection in order to correlate these values with the bacterial load estimated by aerobic plate counting. The results demonstrated the ability of the method to detect even low loads of microorganisms in synthetic water samples.

Intercalation of iron(III) hexacyano complex in a Ni,Al hydrotalcite-like compound.

The product obtained by the intercalation of hexacyanoferrate(III) inside a Ni, Al hydrotalcite-like compound (Htlc) has been characterized using XRD, FT-IR, Raman, and XAS spectroscopy. The intercalation was carried out by anionic exchange of the originally existing chloride ions. The combined use of those techniques gave more insight on the insertion chemistry of Htlcs.

Development of an HPLC method for the identification and dosage of non-allowed substances in cosmetic products. Part I: local anaesthetics and antihistaminics.

An HPLC method with ultraviolet detection coupled with a solid-phase extraction sample clean up was developed for the analysis of five local anaesthetics and four antihistaminics in cosmetic products. The presence of these compounds in commercial cosmetic samples is fordbidden. Extracts from real samples were applied to a solid-phase extraction C18 cartridge, and the analytes were eluted with 8:2 (v/v) acetonitrile/water containing 1% trifluoroacetic acid.

Spectrophotometric determination of aluminium and nickel.

A simple spectrophotometric method, based on the complexes with xylenol orange (XO) and EDTA, is presented for the rapid determination of aluminium and nickel, respectively, in synthetic samples of hydrotalcite. The method only requires the solubilization in sulphuric acid of the inorganic material before the ligand addition. Under optimum conditions, the complexes Al-XO and Ni-EDTA showed maximum absorption at 554 nm and 380 nm, respectively.