A high-performance liquid chromatographic method for riboflavin determination in cheese samples w... more A high-performance liquid chromatographic method for riboflavin determination in cheese samples was developed. Reverse phase conditions were used, i.e., a C-18 column isocratically eluted with an acetonitrile water mixture (20:80). A shift of the detection wavelength from 267 to 446 nm was proposed as a simple and very effective means for circumventing the problem of incomplete resolution of riboflavin from interfacing peaks. The detection limit of riboflavin was 2.5 ng, a value well above the level required for determining the riboflavin content in cheese samples. From both high- and low-fat cheese, the riboflavin recovery was the same (90.2%). The riboflavin content of several different Italian cheeses was determined.
Analyse des carotenoides extraits de l'insaponifiable de l'huile d'olive par une meth... more Analyse des carotenoides extraits de l'insaponifiable de l'huile d'olive par une methode simple et rapide de chromatographie HPLC en phase inverse non aqueuse. La luteine et le β-carotene sont caracteristiques des huiles d'olive, leurs concentrations variant suivant la qualite de l'huile
Abstract A high-performance liquid chromatographic method developed for the determination of both... more Abstract A high-performance liquid chromatographic method developed for the determination of both okadaic acid (OA) and free fatty acids (FFA) was used for analysing mussel samples collected in the Gulf of Trieste. OA and FFA extracted from mussel ...
Abstract A high-performance liquid chromatographic method developed for the determination of both... more Abstract A high-performance liquid chromatographic method developed for the determination of both okadaic acid (OA) and free fatty acids (FFA) was used for analysing mussel samples collected in the Gulf of Trieste. OA and FFA extracted from mussel ...
Retinol (vitamin A1) and dehydroretinol (vitamin A2) geometric isomers, obtained in photosyntheti... more Retinol (vitamin A1) and dehydroretinol (vitamin A2) geometric isomers, obtained in photosynthetic mixtures or from natural samples, were simultaneously fractionated by means of isocratic normal phase high-performance liquid chromatography. The use of low percentages of isopropanol (0.4-1.1%) as a modifier in hexane was studied, and the resolution of both pairs of retinols (9-cis/all-trans and 13-cis/11-cis) whose baseline separation had not previously been achieved was obtained. The proposed chromatographic method therefore allows the complete separation of all six of the most commonly occurring retinols in natural samples, including the above four mono cis- retinols plus the two 9,13- and 11,13-di-cis- retinols . Photoisomerization of retinal and of retinol in different solvent systems and during the extraction process was also studied, before analyzing the unsaponifiable from fresh and marine water fish, which constitute rich natural sources of both vitamins A1 and A2. Vitamin A2 was found to be present in different relative percentages depending on the analytical matrix. Four cis isomers (9-cis-, 11-cis-, 13-cis- and 9,13-di-cis-retinol or corresponding dehydroretinols ) were found to occur naturally together with the main all-trans form, confirming the need to separate geometric isomers in every dosage of vitamin A-containing compounds.
A high-performance liquid chromatographic method for riboflavin determination in cheese samples w... more A high-performance liquid chromatographic method for riboflavin determination in cheese samples was developed. Reverse phase conditions were used, i.e., a C-18 column isocratically eluted with an acetonitrile water mixture (20:80). A shift of the detection wavelength from 267 to 446 nm was proposed as a simple and very effective means for circumventing the problem of incomplete resolution of riboflavin from interfacing peaks. The detection limit of riboflavin was 2.5 ng, a value well above the level required for determining the riboflavin content in cheese samples. From both high- and low-fat cheese, the riboflavin recovery was the same (90.2%). The riboflavin content of several different Italian cheeses was determined.
Analyse des carotenoides extraits de l'insaponifiable de l'huile d'olive par une meth... more Analyse des carotenoides extraits de l'insaponifiable de l'huile d'olive par une methode simple et rapide de chromatographie HPLC en phase inverse non aqueuse. La luteine et le β-carotene sont caracteristiques des huiles d'olive, leurs concentrations variant suivant la qualite de l'huile
Abstract A high-performance liquid chromatographic method developed for the determination of both... more Abstract A high-performance liquid chromatographic method developed for the determination of both okadaic acid (OA) and free fatty acids (FFA) was used for analysing mussel samples collected in the Gulf of Trieste. OA and FFA extracted from mussel ...
Abstract A high-performance liquid chromatographic method developed for the determination of both... more Abstract A high-performance liquid chromatographic method developed for the determination of both okadaic acid (OA) and free fatty acids (FFA) was used for analysing mussel samples collected in the Gulf of Trieste. OA and FFA extracted from mussel ...
Retinol (vitamin A1) and dehydroretinol (vitamin A2) geometric isomers, obtained in photosyntheti... more Retinol (vitamin A1) and dehydroretinol (vitamin A2) geometric isomers, obtained in photosynthetic mixtures or from natural samples, were simultaneously fractionated by means of isocratic normal phase high-performance liquid chromatography. The use of low percentages of isopropanol (0.4-1.1%) as a modifier in hexane was studied, and the resolution of both pairs of retinols (9-cis/all-trans and 13-cis/11-cis) whose baseline separation had not previously been achieved was obtained. The proposed chromatographic method therefore allows the complete separation of all six of the most commonly occurring retinols in natural samples, including the above four mono cis- retinols plus the two 9,13- and 11,13-di-cis- retinols . Photoisomerization of retinal and of retinol in different solvent systems and during the extraction process was also studied, before analyzing the unsaponifiable from fresh and marine water fish, which constitute rich natural sources of both vitamins A1 and A2. Vitamin A2 was found to be present in different relative percentages depending on the analytical matrix. Four cis isomers (9-cis-, 11-cis-, 13-cis- and 9,13-di-cis-retinol or corresponding dehydroretinols ) were found to occur naturally together with the main all-trans form, confirming the need to separate geometric isomers in every dosage of vitamin A-containing compounds.
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