D. Giacosa

Identification and determination of red dyes in confectionery by ion-interaction high-performance liquid chromatography

Abstract In this paper an ion-interaction HPLC method for the separation and determination of red dyes used to decorate home-made sweets is presented. In particular E122, E123 and E124 dyes are considered, with special interest for E123 (amaranth), prohibited by the US Food and Drug Administration in 1976 and by Italian legislation in 1977 and then again permitted (with restrictions) in the European Community in 1994, (94/36 EEC Directive). A RP-ODS stationary phase is used and an ion-interaction reagent (octylammonium phosphate) is added to the hydro-organic eluent [water-acetonitrile (30:70, v/v), pH = 6.4]. Spectrophotometric detection at 520 nm was employed and detection levels below 12 μg/l for the three dyes were achieved. The method is applied to two commercial products, respectively produced in France and in Italy, and the results are discussed in the light of the recent EEC Directive concerning food dyes.

Separation of phenylurea pesticides by ion-interaction reversed-phase high-performance liquid chromatography Diuron determination in lagoon water

An ion-interaction HPLC method is developed for the separation of the phenylurea herbicides asulam, diuron, isoproturon, linuron and monuron. C18 was used as stationary phase and octylammonium phosphate as ion-interaction reagent, in the presence of methanol or acetonitrile as organic modifier. Detection limits lower than 9 μg/l can be obtained without preconcentration steps. The method was applied to the analysis of diuron in a sample of lagoon water. Using liquid-liquid extraction, a diuron concentration of 42 μg/l was found.

The Role of pH of the Mobile-Phase in Ion-Interaction RP-HPLC

Abstract The dependence of retention on pH of the mobile phase is investigated in reversed-phase ion interaction chromatography, being the mobile phase an aqueous solution of 5.0 mM octylammonium and ortho-phosphoric acid at different pH values. The analytes considered were amines, diamines, amides, and species characterized by different functionalities. The behaviour of retention as a function of pH is discussed with comparison with literature data and correlation with pka values is shown. The optimization of separation and resolution in a mixture of acids and amines through pH variations is also presented.

Hallucinogenic Species in Amanita Muscaria. Determination of Muscimol and Ibotenic Acid by Ion-Interaction HPLC

Abstract Ibotenic acid and muscimol are considered the principal components responsible of the hallucinogenic properties of Amanita muscaria. In this paper a sensitive ion-interaction HPLC method is presented which permits the simultaneous determination of ibotenic acid and muscimol. A C18 reverse phase is the stationary phase and the mobile phase is an aqueous solution of 5.0 mM octylammonium o-phosphate. A spectrophotometric comparative detection performed at 230 and 254 nm is employed. Detection limits are of 18 μg/L for ibotenic acid and of 30 μg/L for muscimol.

Analysis of vegetable and fish oils by capillary supercritical fluid chromatography with flame ionization detection

SummaryCapillary SFC with supercritical CO2 as mobile phase and flame ionization detection was adopted to separate and determine triacylglycerols in vegetable and fish oils. The effect on separation of many experimental variables has been checked along with the selectivity of several stationary phases of different polarity. A standard mixture of 13 triacylglycerols was used to optimize the procedure and their retention times were used as reference to identify peaks in real samples. In spite of the fact that many peaks remained unidentified, the chromatograms obtained were useful as fingerprint analyses of the real samples examined.

Reversed-phase high-performance liquid chromatography and chemometrics, a combined investigation tool for complex phytochemical problems

Abstract The phenolic content in the bark of poplar trees was analysed by RP-HPLC with the aim of finding some evidence of a relationship between the presence of phenols (either the total amount or the amount of an individual specific compound) and the differential resistance to the fungus Dothichiza populea that is found in different clones of these trees. Direct comparison of chromatographic results did not allow any useful information to be gleaned on this subject. On the other hand, the application of principal component analysis and linear discriminant analysis methods to the quantitative chromatographic data gave very promising results, allowing discrimination between resistant and susceptible poplars and the identification of phenolic compounds that are important for such discrimination.

HPLC in the investigation of taxonomic problems. Classification of poplar genotypes

SummaryThe RP-HPLC technique has been applied to the analysis of the flavonoid content of leaf extracts from various genotypes ofPopulus nigra andPopulus deltoides and from several of their hybrids. Two elution procedures different either as regards gradient program or the type of organic modifier used were checked to optimize the reliability of the results obtained. Before making any identification, the chromatographic profiles proved so typical of each species as to allow of their use as fingerprints in this type of taxonomic problem. Individual identifications were carried out by spiking real samples with known amounts of standard substances. The presence of flavonoid compounds previously identified was confirmed and a few new identifications were proposed.

A chromatographic and chemometric study of the bark phenolic compounds of two poplar clones with different resistance toDiscosporium populeum

SummaryReversed-phase high performance liquid chromatography with diode array detection was used to analyze phenolic compounds contained in bark extracts of two different poplar clones known to have different resistance toDiscosporium populeum infection. Statistical treatments both monovariate and multivariate were applied to the results in order to identify regularities useful to discriminate the polar resistance and to check the importance of seasonal and cultivation site related factors. For the two clones examined phenolic compounds showed great discrimination ability not influenced by either sample collection period or cultivation site.

Determination of nitrite, nitrate, iodide, bromide, chloride, sulfate, in venice lagoon‐water by reversed‐phase ion‐interaction HPLC. The effect of the geographical position

Abstract The paper reports analytical data concerning water samples in Venice lagoon collected in different geographical sites, characterized by different salinity and kind of pollution. Chloride, iodide, bromide, sulfate, nitrite, nitrate were determined by means of ion‐interaction chromatography, while phosphate determination was performed spectrophotometrically. The results are discussed with reference to literature data.

Chromatographic and chemometric investigation of the chemical defence mechanism of poplar tree genotypes against a bark fungine parasite

Phenolic compounds in bark extracts of seven different clones of poplar trees were analysed by RP-HPLC with diode-array UV detection. The chromatographic results obtained were treated by means of chemometric methods to highlight any pattern in the data allowing one to discriminate poplars in terms of resistance to the fungus Discosporium populeum. The phenolic compounds turned out to be more related to the genetic origin of the clones than to their resistance.