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L Lepri

Publications and source records attributed to L Lepri.

17 recordsLinked to original sources
PubMed2001

Reversed-phase planar chromatography of some enantiomeric amino acids and oxazolidinones.

The resolution of two enantiomeric amino acids and four structurally related oxazolidinones was evaluated by reversed-phase planar chromatography using both home-made microcrystalline cellulose triacetate (MCTA) layers and mobile phase additivies, such as beta-cyclodextrins (beta-Cy), modified alpha, beta, gamma cyclodextrins and bovine serum albumin (BSA), on commercially available RP-18W/F254 and SilC18-50/UV254 plates. All the enantiomers were partially or baseline resolved by at least one of the chiral phases tested. Densitograms of optical antipodes and their mixtures were measured on MCTA layers developed with hydroalcoholic solvents.

Amino Acids↗
PubMed1997

Effect of pasteurization and storage on some components of pooled human milk.

Pooled human milk was subjected to Holder pasteurization and storage at -20 degrees C up to 90 days and examined for its content of fat and L-lactate and for lipid composition. This treatment reduced fats by 6% and L-lactate by at least 7%. In addition, pasteurization and storage induced triglyceride hydrolysis. The absolute amount of free fatty acids (FFAs) which was 0.5% after collection, doubled after pasteurization and rose even more after storage. Different FFA compositions were found by several authors using the same analytical method even for milk samples subjected to the same treatment. More detailed information on procedures must be given to explain the different results.

Adult↗
PubMed1991

Simultaneous separation and determination of hydrocarbons and organochlorine compounds by using a two-step microcolumn.

The simultaneous separation and determination of a mixture of hydrocarbons and organochlorine compounds was successfully carried out by using sorption chromatography on a two-step microcolumn of silica and aluminium oxide for their fractionation, and a dual detector system. In addition to the separation and identification of hydrocarbons and heterocompounds containing nitrogen, oxygen and sulphur atoms, separation and identification of chlorinated hydrocarbons (dichlorobenzenes, p-chlorotoluene, hexachlorobutadiene, 1,2,4-trichlorobenzene and 2-chloronaphthalene), pesticides (chlorpicrin, aldrin, lindane, alpha- and beta-benzene hexachloride (BHC), endrin, dieldrin, endosulphan, methoxychlor) and herbicides (propanil, dichlobenil, trifluralin, difolatan) were achieved in mixtures containing polychlorinated biphenyl, strobane and chlordane.

Chromatography↗
PubMed1980

Reversed-phase and soap thin-layer chromatography of amino acids.

The chromatographic characteristics of 33 amino acids have been studied using soap thin-layer chromatography (TLC). The influence of the type of detergent, the organic solvent and the acid concentration in the eluent on the chromatographic behaviour of the amino acids was investigated. Many interesting separations that cannot be effected by ion-exchange TLC have been performed.

Amino Acids↗
PubMed1978

Separation and identification of water-soluble food dyes by ion-exchange and soap thin-layer chromatography.

Eighteen water-soluble food dyes have been studied by chromatography on thin layers of anion-exchange (AG 1-X4, DEAE-cellulose, PAB-cellulose and chitosan) and cation-exchange (Dowex 50-X4, Rexyn 102 and humic acid) materials; layers of silanised silica gel impregnated with cationic or anionic detergent were also used. Fourteen of the dyes were separated, but the two orange and the two black dyes were not. Some applications of the techniques to commercial products are reported.

Cacao↗
PubMed1977

Chromatographic behaviour of nucleic acid constituents and of phenols on chitosan thin layers.

The chromatographic characteristics of several nucleic acid constituents and of 36 phenols have been investigated on mixed layers of powdered chitosan and microcrystalline cellulose, with water, water-methanol mixtures and aqueous salt solutions at different pH values at mobile phases. The behaviour of the phenols was strongly correlated with the form in which these compounds were present in solution and therefore with the pH of the eluent. Chitosan was more effective than PEI- and DEAE-cellulose as adsorbent in separating phenols. Analytical applications of chitosan layers are reported.

Chemical Phenomena↗
PubMed1976

Chromatographic behaviour of alkaloids on thin layers of cation exchangers. II. Alginic acid, Rexyn 102, Dowex 50-X4 and CMCNa.

The chromatographic behaviour of 48 alkaloids on cation exchangers with cellulose, paraffin and polystyrene matrices in both the acid and sodium salt forms has been investigated. Water-organic solvent mixtures, aqueous buffer solutions and organic and mineral acid solutions in both water and in aqueous-organic solvents have been used as eluents. The retention mechanisms of these compounds on alginic acid, Rexyn 102 (Hplus) and Dowex 50-X4 (Hplus) thin layers are discussed. Interesting separations of the alkaloids were carried out on alginic acid and Rexyn 102 (Hplus).

Alginates↗
PubMed1976

Chromatographic behaviour of alkaloids on thin layers of anion and cation exhangers. I. AG 1-X4 and cellex D.

The chromatographic behaviour of 48 alkaloids has been studied on Bio-Rad AG 1-X4, Cellex D and microcrystalline cellulose, eluting with solutions of different pH but constant ionic strength (0.5). Many interesting separations were effected on both AG 1-X4 and Cellex D layers. The influence of pH on the chromatographic behaviour of alkaloids has been quantitatively studied and an equation was used that expresses the behaviour of the alkaloids on both AG 1-X4 (AcO-) and microcrystalling cellulose layers. The nonapplicability of this equation to Cellex D layers is discussed.

Alkaloids↗
PubMed1975

Chromatographic behaviour of phenols on thin layers of cation and anion exchangers. II. Dowex 50-X4 and Rexyn 102.

The chromatographic characteristics of 58 phenols on Rexyn 102 and Dowex 50-X4 thin layers in both the acidic and sodium salt forms have been studied, using elution with water, water-alcohol mixtures and aqueous salt solutions at different pH values. The influence of the percentage of alcohol, the pH and the ionic strength on the chromatographic behaviour of these phenols was investigated. The validity of the relationships among the RF values, the pH of the eluent and the pKa of the phenol has been verified on Dowex 50-X4 (Na+) thin layers. It has been shown that from the RFac, RFalk and pKa values of the different phenols, it is possible to predict their behaviour over the whole pH range and therefore to select the best conditions for their chromatographic separation.

Acetates↗
PubMedDate not supplied

Performance of horizontal subsurface-flow treatment wetlands in fecal bacteria removal.

This work evaluated sub-surface flow (SSF) constructed wetlands and activated sludge plant efficiency in pathogen removal. The two were also compared. The removal of fecal bacteria (total coliforms, fecal coliforms, fecal streptococci) was evaluated. Analysis was carried out during one year by determining the amount of bacteria in the inflow and the outflow of four systems: three SSF systems (two were pilot plants and one a fully operating plant) and an activated sludge plant. MPN techniques were used to determine the quantity-value of the microorganisms. Percentages of fecal bacteria removal in wetlands systems were as good as (and sometimes better than) those recorded in the activated sludge plant. Optimal values of these bacteria were obtained in the outflow of the post-treatment pilot plant: very high bacterial removal percentages (>99%) were recorded. SFS constructed wetlands are a valid solution for the final treatment of the outflow of existing plants.

Bacteria↗