Giampaolo Cartoni

Determination of phenolic acids in wine by high-performance liquid chromatography with a microbore column

Abstract A method for the extraction and separation of the non-volatile phenolic acids of wine is described. The extracts are analysed by HPLC with a microbe column and UV detection. The free phenolic acids and depsides in different wine samples were identified and determined.

Separation and identification of free phenolic acids in wines by high-performance liquid chromatography

Abstract Free phenolic acids in Italian wines and a sherry were identified by high-performance liquid chromatography. The samples were concentrated and passed through a Sep-Pak C18 cartridge and the acids were recovered by elution with 2 ml of tetrahydrofuran. The separation was carried out by gradient elution on a reversed-phase column with methanol—water and phosphate buffer (pH 2.7). Detection was carried out 280 and 230 nm.

Capillary electrophoretic separation of phenolic acids

Phenolic acids such as syringic, p-coumaric, vanillic, caffeic, 3,4-dihydroxybenzoic and gallic acid, which are present in wines and other alcoholic drinks, were determined by capillary electrophoresis using an uncoated fused-silica capillary. The optimum conditions for their separation were investigated. Examples of electropherograms of phenolic acids contained in some Italian wines are reported.

Evaluation of small diameter capillary columns for gas chromatography

Abstract Glass and fused silica capillary columns of inner diameter 50–200 μm were compared for their chromatographic characteristics and their application to the analysis of complex mixtures. The results show that columns of small diameter can be usefully employed in gas chromatography despite some instrumental difficulties.

ANALYSIS BY HPLC-MS/MS OF BIOPHENOLIC COMPONENTS IN OLIVES AND OILS

The aim of this work was to analyze by HPLC-MS-MS natural biophenolic compounds in complex natural samples like olives and olive oils. Eleven benzoic and cinnamic acids, vanillin and other eight biophenolic compounds were studied by liquid chromatography-atmospheric pressure ionization mass spectrometry/mass spectrometry with a Turbo Ion source in the negative mode. To confirm the specific presence, with great sensitivity, of such compounds in olive samples, in brine samples and in extravirgin olive oil the fragmentation of precursor ions into the product species acquisition was used in Multiple Reaction Monitoring (MRM) mode.

Characterization of some styrene-divinylbenzene sorbents for reversed-phase chromatography

Abstract The preparation and characterization of laboratory made polymeric columns of Chromosorb 101 and Porapak Q are described, with reference to a PRP-1 column packed under the same conditions. Column parameters such as permeability, efficiency and peak asymmetry factor were calculated. The swelling propensity of the materials was measured and the dependence of peak shape on the type of organic solvent used was investigated. The efficiencies of Chromosorb 101 and Porapak Q columns were satisfactory but the spherical material PRP-1 gave better results. Porapak Q exhibited very good physical properties such as high rigidity and permeability. The swelding of polymers in acetonitrile is higher than in methanol, so a better column performance is obtained when acetonitrile is employed as the eluent.

Effects of ionic strength and electrolyte composition on the aggregation of fractionated humic substances studied by flow field-flow fractionation

A sample of humic substances (HS) from Aldrich Co. has been studied by flow field-flow fractionation. The effect of the injected mass on retention, comparable to that previously found for synthetic water-soluble polyelectrolytes, suggests that the components present in this sample as Na salts are highly charged in water. Charges are, however, screened when a simple electrolyte is added to the carrier liquid. The electrolyte also appears to induce molecular aggregation to an extent that depends on the type of the metal ion and on its concentration. Investigation of the effect of the solution ionic strength and composition on fractions separately collected from the flow FFF channel confirms the aggregating effect of the salt added to the solubilizing medium and reveals a stronger tendency to particle aggregation by the HS in the presence of divalent cations. This finding seems common to all the fractions except that containing particles of lower size that appear to respond only to the ionic strength. A comparative analysis of the ionic strength effect on some fractions and on the unfractionated sample seems to support the hypothesis that, in the latter, the aggregation process occurs through a non-size-specific pathway. Therefore, in a broadly-dispersed humic mixture in solution of simple electrolytes, the size distribution is likely to be determined by random interactions of species of different size.

Analysis of lemon and bergamot essential oils by HPLC with microbore columns

SummarySome citrus essential oils were analyzed by HPLC with both microbore and standard columns in reversed and normal phase. Volatile and non-volatile fraction were investigated. In the non-volatile fraction some coumarins have been identified. Fractions are detected spectrophotometrically at 220 nm and 320 nm before and after evaporation of samples. Some components were also identified by LC/MS.

Flow field-flow fractionation and characterization of ionic and neutral polysaccharides of vegetable and microbial origin

The flow field-flow fractionation (FlFFF) analysis of a variety of neutral as well as ionic polysaccharides from plants and micro-organisms shows the generally broad distribution in molecular size of these polymers. This result is also obtained on a commercial sample of pullulan whose size distribution appears much wider than that of any of five standard fractions of the same polymer. Clear evidence of some physico-chemical properties of the polysaccharides is given by the study of the effect of the carrier ionic strength on salep, oxidized salep and konjac, carboxymethylcellulose and hyaluronic acid. While neutral polysaccharides, regardless of their origin, only slightly change size distribution in the presence of a simple electrolyte in solution, charged polymers, either naturally charged or chemically ionized, consistently exhibit very low retention levels in water which dramatically increase even at low salt concentrations. Exclusion mechanisms, including steric effects, are shown to be responsible for the anticipated retention times in water of these species that assume the expected statistical coil behavior only when electric charges are screened by the added electrolyte. Under these conditions, higher retention levels are obtained because the volume adjacent to the accumulation wall becomes more accessible to the sample during relaxation. On the basis of these findings, the elution behavior of a number of polysaccharide samples in-laboratory obtained from the fungus Aureobasidium pullulans under different incubation conditions is attributed to the presence of species varying in physico-chemical properties and molecular size.

Comparison of the sequential simplex method and linear solvent strength theory in hplc gradient elution optimization of multicomponent flavonoid mixtures

SummaryUsing a camomile flavonoid extract as the sample and four different reversed-phase partition systems, the ability of the Simplex procedure to produce optimum gradient separation of unknown multicomponent mixtures was checked against the linear solvent strength (LSS) gradient elution theory. On the same partition systems the mean solvent strenghts were measured by experimentally determined logk′ vs. mobile phase composition plots. These mean solvent strengths are compared to those inferred from the optimum gradients and the usefulness of LSS theory in multicomponent mixture gradient elution optimization is discussed.