Paolo Passamonti

Ion interaction chromatography of neutral molecules

SummaryThe chromatographic behavior of neutral molecules in ion-interaction chromatography (IIC) is investigated theoretically. The physical and chemical modification of the stationary phase in the presence of ion interaction Reagent (IIR) in the eluent, and adsorption competition between test analytes and IIR for inner layer sites are shown theoretically to change the partition coefficient of neutral molecules.The most reliable, literature experimental results, concerming retention behaviour of neutral molecules in IIC, were used to test the new theory. The wide variability among them was elucidated on the basis of the exhaustive retention model developed. Retention equations were compared to those which can be obtained, if the change of the analyte is zero, from the most important retention model in IIC.

Meat fatty acid composition of llama (Lama glama) reared in the Andean highlands

This study reports the results of the chemical analysis of the Longissimus thoracis and lumborum taken from 20 llama males, reared in the Andean highlands. The animals were slaughtered at 25 months and had a mean final body weight of 63kg. Llama meat shows a low fat (3.51%) and cholesterol content (56.29mg/100g). The fatty acid composition in llama meat contains 50.34% saturated fatty acids, 42.48% monounsaturated fatty acids and 7.18% polyunsaturated fatty acids. Llama meat appears to be a healthy alternative red meat choice.

Purification, characterization and analysis of sepia melanin from commercial sepia ink (Sepia Officinalis)

At the moment melanins are still enigmatic bio-pigments with structure and determination methods not clearly understood for the international scientific community. Among biopolymers, melanins are unique in many aspects. Some essential biopolymers (proteins, nucleic acids and carbohydrates) are chemically well characterized and can be determined using well established analytical methodologies. On the contrary, no available methods allow us to accurately determine melanin, mostly due to the intrinsic chemical properties of melanins. These pigments, in fact, are insoluble in a broad range of solvents and pH as well as difficult to purify as a result of the heterogeneity in their structural features. Mammalian melanins exist in two chemically distinct forms: the brown to black Eumelanin and the yellow to reddish-brown Pheomelanin. Sepia melanin obtained from Sepia Officinalis consists of more than 98% of Eumelanin and is therefore used as standard material in the analysis of melanic black. Commercial sepia melanin is purified according to an undescribed procedure. In this research, extraction and purification studies were carried out on sepia melanin using a hydrochloric acid (0.5 - 3.0 M) treatment under mechanical or ultrasonic agitation. A high degree purity sepia melanin was obtained and further characterized using Elemental Analysis (EA), UltravioletVisible (UV-VIS) and Infrared (IR) spectroscopy and Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for metal ion analysis. Finally, quantitative studies of the chemical degradation of Eu polymers to Pyrrole-2,3,5tricarboxylic acid (PTCA) and Pyrrole-2,3-dicarboxylic acid (PDCA) by High Performance Liquid Chromatography (HPLC) were performed. The procedure we developed can be used to obtain a considerably less expensive sepia melanin which could prove important as a standard in future determinations of eumelanin and pheomelanin as well as in a vast field of scientific and industrial applications in such fields as human and veterinary medicine, pharmacology and cosmetics.

Extraction of lycopene from tomato processing waste: kinetics and modelling.

Lycopene, a nutraceutical compound, was extracted from tomato processing waste, an abundantly available food industry by-product in Italy. The extraction kinetics was mathematically described using the first order kinetic model, the mass transfer model and Pelegs model to understand the physicochemical behaviour of the extraction. Samples were extracted using acetone/n-hexane mixtures at different ratios (1:3, 2:2 and 3:1, v/v) and at different temperatures (30, 40 and 50 °C) and simultaneously analysed using UV-VIS spectrophotometry. The lycopene yield was in the range 3.47-4.03 mg/100g, which corresponds to a percentage recovery of 65.22-75.75. All kinetic models gave a good fit to the experimental data, but the best one was Pelegs model, having the highest RAdj(2) and the lowest RMSE, MBE and χ(2) values. All the models confirmed that a temperature of 30 °C and solvent mixture of acetone/n-hexane 1:3 (v/v) provided optimal conditions for extraction of lycopene.

The dipole approach in ion-interaction chromatography of zwitterions

SummaryThe chromatographic behavior of zwitterions in Ion-interaction chromatography (IIC) is, investigated theoretically for the first time. The modification of the stationary phase in the presence of Ion-interaction reagent (IIR), and adsorption competition between test analytes and IIR for inner layer sites are shown theoretically to change the partition coefficient for zwitterions.Experimental results from the literature concerning retention behavior of zwitterions in IIC, were used to test the new thermodynamic theory. Very reasonable estimates of (i) ΔGo values for the IIR adsorption onto the stationary phase (II) total ligand concentration, and (iii) dipolar moments validate the present thermodynamic model for the IIC of zwitterionic analytes.Retention equations are compared to those which can be obtained, if the net charge of the analyte is zero, from the most important retention models in IIC. None of them is able to explain, even in a qualitative way, the retention behavior of zwitterions in IIC whereas, the present model is quantitatively able to do this.

Spectrophotometric study of coproporphyrin-I complexes of copper(II) and cobalt(II)

The reagent 3,8,13,18-tetramethyl-21H,23H-porphine-2,7,12,17-tetrapropionic acid or coproporphyrin-I (CPI) was used for the spectrophotometric determination of copper(II) and cobalt(II) in the presence of pyridine and imidazole catalysts. Optimum conditions were investigated and the methods were applied to the determination of parts per billion levels of copper(II) and cobalt(II). The Sandell sensitivities of the recommended procedures were 0.568 mum cm(-2) and 0.464 mug cm(-2) (for A = 0.001) for copper and cobalt, respectively. The relative standard deviations were 2.0% for copper and 1.0% for cobalt. The kinetics of the reaction of CPI with copper(II) and cobalt(II) in the presence of the catalysts and the influence of the temperature were studied, and their kinetic constants determined. The influence of light on the photodecomposition of CPI was also studied.

Optimization of extraction of high purity all-trans-lycopene from tomato pulp waste

The aim of this work was to optimize the extraction of pure all-trans-lycopene from the pulp fractions of tomato processing waste. A full factorial design (FFD) consisting of four independent variables including extraction temperature (30-50 °C), time (1-60 min), percentage of acetone in n-hexane (25-75%, v/v) and solvent volume (10-30 ml) was used to investigate the effects of process variables on the extraction. The absolute amount of lycopene present in the pulp waste was found to be 0.038 mg/g. The optimal conditions for extraction were as follows: extraction temperature 20 °C, time 40 min, a solvent composition of 25% acetone in n-hexane (v/v) and solvent volume 40 ml. Under these conditions, the maximal recovery of lycopene was 94.7%. The HPLC-DAD analysis demonstrated that, lycopene was obtained in the all-trans-configuration at a very high purity grade of 98.3% while the amount of cis-isomers and other carotenoids were limited.

Extended thermodynamic approach to ion interaction chromatography: effect of the electrical charge of the solute ion

Abstract The chromatographic behavior of multiply charged analytes in ion interaction chromatography (IIC) was theoretically investigated. Practical equations that describe the relationship between the retention factor and the concentration of the ion interaction reagent (IIR) were developed. They can be used to model analyte retention as a function of both the mobile and stationary phase concentrations of the IIR. A comparison between the retention behaviour of singly and doubly charged analytes is given.

Monovarietal Extra Virgin Olive Oils from the Marche Region, Italy: Analytical and Sensory Characterization

This study aims to contribute to the knowledge of the commercial, sensory, and analytical characteristics of extra virgin olive oil (EVOO) from the Marche region (Italy), renowned since ancient times. The chemical composition of all the most typical monovarietal oils collected in four crop seasons, was studied in relation to the year of harvesting (from 2004–2007) and the genotype. In order to obtain a complete description of oil samples, free acidity, peroxide value, fatty acid composition, ultraviolet indices, carotenoids, chlorophylls, and phenols were determined. The main characteristics of these oils are large total phenol content, low acidity and peroxide values, low oxidative susceptibilities. All the chemical parameters fell within the limits established for the maximum olive oil category. Sensory evaluation showed that the total score of all the monovarietal extra virgin olive oils was always much higher than the 6.5 limit established for the ‘extra-virgin’ category. The overall quality indices support claims of excellence for monovarietal EVOOs from this geographical area. Results from the present study are of key importance for the specific Production Standards a document that contains regulations for supervising the entire olive oil production cycle and a prerequisite for both the European Protected Denomination of Origin (PDO) and Quality granted by the Marche region (QM) labels.

Ion-interaction chromatography of zwitterions. The fractional charge approach to model the influence of the mobile phase concentration of the ion-interaction reagent

The chromatographic behavior of zwitterions in ion-interaction chromatography (IIC) was investigated theoretically, on the basis of the following picture of the retention mechanism. The zwitterionic analyte is considered to interact with the charged stationary phase via an effective fractional charge, opposite to the surface one. Adsorption competitions between analytes and the ion interaction reagent (H) concur to explain the retention factor of zwitterions. The present model is quantitatively able to explain the retention behavior of zwitterions in IIC and also to account for the influence of the zwitterion ionization degree, according to the mobile phase pH, on the course of retention as a function of the H concentration. The approach we used is simple and epistemologically interesting because the retention equation for zwitterions may also be obtained from the general retention equation of our extended thermodynamic approach to IIC. Estimated magnitudes of the effective charges are very reasonable and show the same trend as that of the molecular dipole moments, as expected; the total ligand concentration compares well with the bonded phase coverage of the two columns used. For the homologous series from 4-aminobutyric-, to 8-aminocaprylic acid, the estimated effective charge always increases with increasing chain length and this results in parallel growth of the analyte retention increase upon H addition, so that the retention increase for the highest member of the series compares with that of a positively charged analyte. The estimated dipole for this analyte compares excellently to the estimate obtained via a quantum mechanics calculation. The influence of the mobile phase pH on retention was taken into account for the very first time. The good predictive abilities of the retention equations, and the reliability of the estimated constants that make sense physically confirm that retention modeling is able, at the thermodynamic level, to disclose the complexity of the IIC system.