G. Crescentini

Simultaneous extraction and reverse-phase high-performance liquid chromatographic determination of adenine and pyridine nucleotides in human red blood cells☆

A simple and rapid method for the determination of ATP, ADP, AMP, NADP+, NAD+, NADPH, and NADH in human erythrocytes is described. A single-step extraction procedure employing alkaline medium and CF 50A Amicon ultrafiltration membranes allows a simultaneous and total recovery of the compounds of interest. Analysis is performed by reverse-phase high-performance liquid chromatography on a 5-micron Supelcosil LC-18 column and uv detection. Extraction and analysis require about 30 min. Levels of adenine and pyridine nucleotides in normal adults are also presented.

Fast reversed-phase high-performance liquid chromatographic determination of nucleotides in red blood cells

A method for the accurate determination of ATP, ADP, AMP, NADP and NAD in 20 min in red blood cell extracts by reversed-phase high-performance liquid chromatography is described. Experimental parameters affecting the separation are discussed.

Critical evaluation of sampling and gas chromatographic analysis of halocarbons and other organic air pollutants

Problems connected with the analysis of ultra-trace amounts of halocarbons in air are discussed in terms of trapping procedures, interferences and chromatographic columns. A suitable column for the qualitative and quantitative analysis of C1-C2 halocarbons is described, and examples of applications are given. High-efficiency micropacked columns have been used for the analysis of hydrocarbons in the open atmosphere.

Graphitized carbon black: A unique adsorbent for gas chromatography and related techniques

SummaryThe properties of graphitized carbon blacks which have been exploited in gas chromatography and related techniques, are reviewed together with some of the many applications accomplished in the last twenty years. Graphitized carbon blacks are non-specific, non-porous adsorbents, characterized by a high surface homogeneity. These adsorbents can therefore be used in gas-solid chromatography even for the elution of polar compounds, though gas-liquid-solid chromatography is the main field of application. In fact, by changing the type and amount of liquid modifier, highly selective and efficient (packed or capillary) columns, tailored for the separation of very complex mixtures, can be prepared. Graphitized carbon blacks also possess hydrophobic properties so that they can be efficiently used for the trapping and the preconcentration of organic compounds contained in air and water samples.

Performance of graphitized carbon black cartridges in the extraction of some organic priority pollutants from water

Abstract The use of graphitized carbon black (GCB) cartridges for the extraction of organic pollutants (pesticides, phthalates, herbicides and polynuclear aromatic hydrocarbons) from water is discussed. Recovery tests carried out by spiking either the adsorbent or the water showed that nearly 100% recoveries can be obtained in most instances with 1 ml of a suitable eluent using 50 mg of GCB (Carbopack B). Examples of analyses of actual samples by gas chromatography—mass spectrometry are also shown. Levesl as low as 10 ppt can be determined.

Discussion of thermodynamic data obtained by adsorption gas chromatography of hydrocarbons on graphitized carbon blacks

Abstract Thermodynamic data, such as the enthapy, entropy and free energy of sorption, were determined by adsorption gas chromatography on graphitized carbon blacks for C 3 C 6 n -alkanes and benzene. The data are compared with those available in the literature obtained by either gas chromatography or static methods. The adsorptive properties of graphitized carbon blacks were also evaluted by considering the changes in the isosteric heat of adsorption when a non-polar stationary phase (squalene) was added to the adsorbent.

Performance and use of wall-coated open tubular fused-silica columns with liquid-modified graphitized carbon black

Abstract The kinetic and thermodynamic changes induced in capillary columns with the internal area modified by a thin layer of graphitized carbon blacks are discussed and were tested experimentally. The selectivity due to the mechanism of gas—liquid—solid chromatography is greatly increased and the efficiency in terms of HETP is much improved at high linear gas velocities. This results in the possibility of obtaining faster analyses without the usual increase in operating temperature with respect to the gas—liquid technique. Examples of applications in practical analysis are given.

PAHs, PCBs and Chlorinated Pesticides in Mediterraneal Coastal Sediments

Abstract Polynuclear aromatic hydrocarbons, chlorinated pesticides and polychlorobiphenyls have been identified and determined in coastal sediments by capillary gas chromatography-mass spectrometry after Soxhlet extraction with a petroleum ether-acetone mixture. Samples collected in three different areas along the Italian coast were analyzed and consistently different concentrations were found for the three locations. Possible sources of pollution have been investigated and identified.

Advances in the determination of volatile organic solvents and other organic pollutants by gas chromatography with thermal desorption sampling and injection

SummaryThe problem of the separation of 34 volatile organic chlorinated compounds is solved by using three different GC columns selected according to the needs of the particular separation required. The effect of water vapor contained as moisture in the trapped air on the retention of some characteristic compounds is studied. The influence of dead volumes on trap injection is also studied.

Calibration method for the gas chromatographic analysis of halocarbons in atmospheric samples using permeation tubes and an electron-capture detector

Abstract A method for calibrating the electron-capture detector for the analysis of halocarbons in atmospheric samples is presented. Permeation tubes are used as primary standards. The precision is evaluated under different operating conditions, and a standard deviation of 5% was the optimal. The difficulty of determining halocarbons present at very different concentrations is discussed.