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Biomedical subjects

A Bettero

Publications and source records attributed to A Bettero.

17 recordsLinked to original sources
PubMed1997

Stability of vitamin C derivatives in solution and topical formulations.

The stability of ascorbic acid, ascorbyl palmitate and magnesium ascorbyl phosphate (VC-PMG) in both standard solutions and topical formulations was investigated by direct RP-HPLC analysis after sample dilution with a suitable aqueous-organic solvent mixture. The results showed that, whereas the two vitamin C derivatives were more stable than ascorbic acid, the ascorbyl esters showed significant differences. Esterification with palmitic acid in 6 position did not prevent hydrolysis of the molecule, either in solution or in emulsion; only the special preparation of products with high viscoelastic properties was able to reduce the typical behaviour of this compound. Conversely, the introduction of the phosphoric group in 2 position protected the molecule from break-up of the enediol system, confirming VC-PMG as a very stable derivative of vitamin C that may be easily used in various types of cosmetic products.

Ascorbic Acid↗
PubMed1991

Silicon membrane interface for the direct analysis of Kathon CG in aqueous solutions and cosmetic emulsions.

An easy determination of Kathon CG, an antimicrobial agent widely used in cosmetic and toiletry products, has been achieved by means of silicone membrane interfaced mass spectrometry. Low levels of the above preservative (up to p.p.b.) could be easily detected in both aqueous solutions and cosmetic emulsions. Valuable information has been obtained on the stabilization and decomposition processes to which the organic components of Kathon CG are subject. The role of magnesium ions, which are present as a stabilizing agent in Kathon CG formulation, in these processes has been investigated, leading to the identification of some degradation products.

Cosmetics↗
PubMed1989

High-performance liquid chromatographic determination of free formaldehyde in cosmetics.

An improved, sensitive method for the determination of formaldehyde in cosmetics and other commercial products is reported. The procedure is based on dilution of the sample with tetrahydrofuran-water (9:1), followed by precolumn derivatization with 2,4-dinitrophenylhydrazine and direct reversed-phase high-performance liquid chromatography. The formaldehyde derivative is stabilized in the reaction medium by addition of phosphate buffer and neutralization and detected in less than 10 min by the standard additions methods. The method also appears to be suitable for the direct evaluation of the formaldehyde donors used in cosmetics as preservatives.

Chromatography, High Pressure Liquid↗
PubMed1985

A rapid HPLC technique for determining levels of histamine in tears from normal and inflamed human eyes.

Because of the important role of histamine in the inflammatory process, the measurement of histamine levels in tears has been considered as a possible index of eye irritancy. Histamine levels have been measured using an HPLC procedure involving fluorimetric detection after fluorescamine derivatization. Analyses, at picomole levels, were carried out in less than 5 minutes using 10 microliter of tear samples collected from either normal or inflamed human eyes.

Chromatography, High Pressure Liquid↗
PubMed1982

[Determination of the coumarinic constituents of Ficus carica leaves by HPLC].

The coumarinic compounds of fig leaves (Ficus carica) here examined closely. The furocoumarins psoralen, bergapten and the coumarins umbelliferone, 4',5'-dihydropsoralen and marmesin are present. These substances were determined in a "coumarinic extract" by high pressure liquid chromatography (HPLC). The seasonal variations of the above mentioned compounds were also studied in a series of samples of leaves picked from the same plant, at regular fortnightly intervals during the period 1/VI-2/XI/1979. From the data obtained it is noticeable that the total coumarinic content is maximun--0.5% as compared with the dry weight--in the extract of leaves picked on the first August, while it is lowest in the extract of leaves picked on the 15th June. The quantity of psoralen is always greater than that of bergapten, umbelliferone, 4',5'-dihydropsoralen and of marmesin. The ratio psoralen: bergapten is not constant, but fluctuates extensively with the seasonal variations from 2.8 to 7.7.

5-Methoxypsoralen↗
PubMedDate not supplied

Rapid pentachlorophenol evaluation in solid matrixes by second derivative UV spectroscopy for application to wood and leather samples.

A method for the quail-quantitative evaluation of pentachlorophenol (PCP) in solid matrixes has been developed. The procedure is based on solid-liquid extraction of solid samples (leather or wood), followed by purification on a cyanopropyl column and determination of the preservative by second derivative UV spectroscopy considering the PCP A peak-through value (304-297 nm). The method allows rapid PCP determination in the concentration range 1-40 micrograms/mL; any matrix interference is avoided by the purification step and recoveries of the preservative were 99.12% (RSD% 0.13) for the leather matrix and 98.03 (RSD% 0.17) for the wood matrix.

Microchemistry↗