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The chemical characterization of the bark from eight broad-leaved trees ( Betula pendula, Quercus suber, Quercus ilex, Castanea sativa, Quercus robur, Carpinus betulus, Fagus sylvatica and Populus nigra ) was carried out using evolved gas analysis-mass spectrometry (EGA-MS) and gas chromatography/mass spectrometry (GC/MS) following alkaline hydrolysis, solvent extraction and derivatisation with a sylilating agent. Not only does bark account for a high percentage of residues from forestry and the wood industry, but it is also rich in suberin, a biopolyester, whose sub-monomeric units can be converted into value added chemicals, as well as being used as starting blocks for the production of new materials. EGA-MS along with principal component analysis (PCA) of the mass spectral data were used to obtain information on the thermal complexity of the barks and on the thermal degradation areas of all their main chemical constituents: suberin, polysaccharides, lignin, tannins and extractives. GC/MS analysis was used for the depolymerisation of suberin, and to examine its monomeric composition. This enabled us to determine aliphatic and mid-chain substituted long-chain α,ω-diacids and ω-hydroxyacids (all with mainly 16, 18, and 22 carbon atoms) along with aliphatic long-chain alkanoic acids and alkanols. Our results may be useful for the exploiting the investigated barks – but not just for energy recovery. In fact, as their suberin shows a high abundance of mid-chain substituted monomers, alternative uses are possible such as the synthesis of polymeric materials by condensation and cross-linking reactions.

This paper discusses the partitioning of metals (K, Na, Ca, Mg, Al, Cu, Fe, Pb and Zn) between the aqueous phase and the suspended insoluble material in fog samples collected in the Po Valley during two extensive fields campaigns. Metals represent on average 11% of the mass of suspended insoluble matter, while the main component is carbon (both organic carbon, OC = 35%, and black carbon, BC = 8%). The unaccounted suspended matter mass is very high, on average 46%, and is attributable to non metallic species, such as O and N and of Si. The principal metals in the insoluble suspended fraction are Fe and Al (2-5%), while the contributions of other metals (Na, Mg, Cu, Pb and Zn) are lower than 1%. Ca and K exhibited high blank values and could not be detected above blank detection limit threshold. The main components in the aqueous phase are NO,- (34%), WSOC (23%), SO 4 2 - (18%) and NH 4 + (19%), while trace metals and remaining cations and anions accounted for less than 1% of solute mass. The main dissolved trace metals in fog droplets are Zn, Al and Fe, while the main metallic cations are Na and Ca. Fe and Al are the only metals preferentially distributed in the suspended insoluble matter of fog droplets (partitioning ratio respectively 37% and 33%). All other metals are mostly dissolved in the aqueous phase (mean partitioning ratios of Mg, Pb, Zn, Cu and Na are 69%, 70%, 77%, 81% and 87%). These findings are in agreement with literature data on metal speciation in cloud and rain samples. The dependence of partitioning ratios on pH is investigated for the different metals, with only Al showing a clear partitioning ratio decrease with increasing pH. Conversely, the other metals show no dependence or a complex and highly variable behaviour. The partitioning ratio of iron (mean 37%) observed in the Po Valley fog samples is much higher than the water extractable iron in aerosol particles (typically 1-2 %): this fact can be explained by differences in the aerosol sources and composition among sites and by chemical processes in the aqueous phase, such as complexation and redox reactions involving organic ligands (oxalate, or other organic acids as humic-like organic matter) which may promote Fe solubility.

A conspicuous fraction of the water soluble organic compounds (WSOC) in fog and fine aerosol samples is composed by monosaccharide anhydrides, such as levoglucosan and its stereoisomers, galactosan and mannosan. Levoglucosan is produced exclusively during wood combustion processes, making it a very useful tracer for plant combustion emissions in the atmosphere. This paper describes a new experimental approach, based on electrospray-tandem mass spectrometry (ESI-MS/MS), for the identification of levoglucosan in fog water samples. The analytical method proposed allows to identify the specific sugar anhydrides directly in the liquid phase without the need of any derivatization process.

We describe a method, based on a new nano-HPLC gradient generator coupled to a modified direct electron ionization (EI) LC–MS interface, for the analysis of several compounds of environmental interest. The gradient generator was installed on a conventional HPLC system and the nano-flow rate was achieved using a double splitter. Reproducible gradients of different shapes (i.e. linear, convex, concave) can be generated at micro- and nano-flow rates. This attribute makes this device particularly appropriate for coupling with direct-EI LC–MS interface. The combination of the gradient generator with the direct-EI interface optimizes the analytical conditions for the generation of good quality EI spectra for trace level analytes. The performance of this new system was tested at a flow rate of 250 nl min−1, evaluating linearity, intra-day reproducibility and limits of detection of several compounds of environmental interest belonging to three different classes: nitro-polycyclic aromatic hydrocarbons, pesticides and human hormones. Excellent signal stability and low detection limits were obtained in most cases. Enhanced performance was observed for critical separations due to the possibility to run gradients of different shapes.

Carbograph 6, a new graphitized carbon black with a specific surface area of 203 m2 g−1, as measured by BET, both uncoated and coated with up to 12% (w/w) of squalane, a non-polar stationary phase, has been studied by gas chromatographic determination of the enthalpy, entropy, and free energy of adsorption of a series of alkanes (C2−C6) and benzene. The data obtained are discussed and compared with those available in the literature for other graphitized carbon blacks. An example of a separation obtaned with Carbograph 6 is reported.

The volatile fraction of heavy fuel oils used in thermal power plants is characterized by the presence of trace amounts of potentially carcinogenic compounds, i.e. benzene and toluene, ethylbenzene and the xylenes (BTEX). In this paper, an original methodology for the determination of these compounds in such a complex matrix is presented. It consists of a capillary gas chromatographic-quadrupole mass spectrometric method preceded by the extraction and enrichment of the substituted benzenes by using a “purge and trap” technique. Results obtained analyzing heavy fuel oil actual samples are reported as well.

Chlorofluorocarbons are man-made long lasting atmospheric pollutants of great environmental concern, responsible for important global change phenomena. Recently, they were replaced by hydrogenated halocarbons that, even if less persistent, do not lack in environmental impact. Atmospheric concentrations of these compounds were measured in Antarctica by gas chromatography. The extremely low atmospheric mixing ratios of these compounds require a pre-concentration step of the air sample on suitable adsorbent in order to meet the sensitivity of the analytical method Results obtained analyzing air samples collected in Antarctica since 1988 for the determination of CFC-12 and CFC-11 are reported, together with data concerning the less abundant species.

Permission to reproduce this table online was not granted by the copyright holder. Readers are kindly asked to refer to the printed version. Two recent approaches for coupling capillary scale liquid chromatography and electron ionization mass spectrometry are reviewed and discussed. The first one, Cap-EI, is the latest evolution of the micro-scale particle beam interface, in which the nebulizer has been optimized to overcome the limitations of the former approach, in terms of sensitivity and linearity. It can be easily hosted in pre-existing instruments without major modifications and can use helium and the less-expensive nitrogen to generate library-matchable electron ionization spectra. The second one is a miniaturized interface for nano- and micro-HPLC, in which the interfacing process takes place into a suitably modified ion source. Because the eluate from the column is completely transferred into the ion source for ionization, superior sensitivity, linearity, and reproducibility are obtained. No signs of chemical ionization are observed at flow rates up to 1.5 μL/min. These two interfaces demonstrate that electron ionization can be successfully used for the analysis of small—medium molecules of various polarities, and also at the trace level. The possibility to record library-matchable electron ionization spectra offers the analyst a powerful tool that can be particularly useful in real-world applications.© 2001 John Wiley & Sons, Inc., Mass Spec Rev 20: 88–104, 2001

A new solid-phase extraction on-line device for micro-HPLC is presented. This device optimizes the injection of very dilute samples into a packed capillary column. It consists of two capillary, reversed-phase, HPLC columns of different length that can be linked together as a single chromatographic column. The first segment, only 2 cm long is connected to the HPLC injector. When disconnected from the longer column, several milliliters of an aqueous sample can be passed through at a high flow rate for fast trapping. On the basis of the retention mechanism, all suitable compounds are focused on the short column head in a sharp band. As soon as the chromatographic column is recomposed, the trapped analytes are eluted and separated at the optimal flow rate and gradient conditions. Due to the high preconcentration factor, trace-level analysis can be performed successfully. Different classes of analytes of various polarities and molecular weights can be determined, depending on the stationary phase and on the detector used. Some pesticides belonging to different classes were chosen to evaluate the performance of the device using an electron ionization mass spectrometer as HPLC detector. A fungicide in an irrigation canal water was determined at a concentration level of 4.5 microg x L(-1).

A new ion-interaction micro-HPLC method, for the simultaneous separation of acidic and base-neutral pesticides, was coupled to a capillary-scale particle beam LC/MS interface for EI mass spectrometric detection of the analytes. The method was employed for analysis of tap water in which a large number of functionally different pesticides can be determined in a single run. Capillary-scale technology of the LC/MS apparatus yields full compatibility with hexylammonium phosphate, a nonvolatile salt used as ion-interaction reagent in the HPLC mobile phase, and provides an excellent sensitivity with instrument detection limits (IDLs) ranging between 0.07 and 0.7 ng in SIM mode. Method sensitivity lower than 0.1 ppb in water was achieved using a large-volume injection technique specifically developed for capillary columns typical flow rates.

A fast, simple, and reliable method is presented for the determination of atmospheric semi-volatile organic pollutants at μg m−3 levels. The method has been used to monitor potentially carcinogenic toxic compounds to which workers are exposed in workplaces, and to measure the same compounds in outdoor air.

A method for the characterization of coal thermal behaviour, based on gas chromatographic-mass spectrometric analysis of the pyrolysate, is presented. Twelve different coal samples, representative of the entire coal rank, were selected for this study. The pyrolysis products, obtained at 800°C, were first collected and then analysed in two GC-MS systems. The sampling apparatus consisted of three different traps in order to separate the products into three fractions on the basis of their volatility. The GC-MS analysis was also arranged according to this criterion. A packed column, coupled to a double-focusing magnetic mass spectrometer, was used for the volatile fractions of the pyrolysate and a capillary column, coupled to a quadrupole analyser, was employed for the analysis of the condensed fraction. Sampling and analysis procedures were carried out separately, thus allowing careful optimization of the strategy for the characterization of the pyrolysate. The condensate was analysed in the selected-ion monitoring mode for the determination of different classes of compounds. Some evaluations and comparisons, extrapolated from the results obtained, are presented.

Data concerning tropospheric levels of some chlcrofluorocarbons and other halogenated hydrocarbons are reported. These are referred to atmospheric samples collected during the 1993/94 Austral Summer Antarctic Campaign in Terra Nova Bay. Samples collected in Stainless Steel canisters were analyzed in our laboratory by gas chromatography-electron capture detection (GC-ECD). A comparison with data obtained in previous campaigns is reported as well.

Data concerning chlorofluorocarbons and other halogenated hydrocarbons concentrations in ground-level atmosphere at Antarctica are reported. Measurements were carried out during two campaigns: Austral summer 1989/90 and 1990/91. Samples collected were analyzed in the laboratory by gas chromatography-mass spectrometry and “in situ” by gas chromatography-electron capture detection. Substantial improvements in the instrumentation are also reported where for what trapping and injection of both air samples and calibration mixtures are concerned.

The preparation of graphite layer open tubular (GLOT) columns is described together with their application to the analysis of priority pollutants and polar compounds such as alcohols, free carboxylic acids, aliphatic amines and phenols at the sub-nanogram level.

Volcanic gas emissions are strictly related to a specific stage of volcanic activity. Complete knowledge of their chemical composition can be extremely useful for efficient geochemical surveillance of active volcanism sites. A new, effective and simple method for the evaluation of light hydrocarbons in volcanic gases is described. A rapid sampling procedure and GC-FID analysis are employed. Data from different volcanic areas are shown and a their possible correlation is also discussed.

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.

Very low concentrations (down to 0.2 ng/mL) of an antispasmodic drug (Eperison) can be extracted from human plasma and analyzed by GC/MS. For sample preparation and preconcentration, solid phase extraction (SPE) has been employed. A double focussing mass spectrometer was interfaced with a capillary GC column for the GC/MS analysis. The gas chromatograph was equipped with an on-column injector to avoid thermal decomposition.

The outstanding properties of fused-silica capillary columns coated with graphitized carbon black impregnated with liquid phases are described together with the details of their preparation, HETP vs. u curves are reported, together with some separations of industrial and environmental interest. Fast and more effective analyses may be achieved with such columns.

Phenyl acetic acid, a metabolite of 2-phenyl ethylamine, acts as a neuromodulator in the nigrostriatal dopaminergic pathway stimulating the release of dopamine. The evaluation of phenyl acetic acid concentration in the biological fluid reflects phenyl ethylamine levels thus allowing the assessment of the modulatory role of this endogenous substance. Changes in biological fluids levels of 2-phenylethylamine and/or in its metabolite have been reported in affective disorders, such as depression and schizophrenia. Recently, the occurrence of the "attention deficit hyperactivity syndrome" has been frequently reported in childhood population and involvement of dopaminergic dysfunction in this disease has been suspected. A fast, reliable and reproducible method for the determination of phenyl acetic acid in human blood, is therefore needed in order to have a screening tool for monitoring both healthy childhood population and suspected "attention deficit hyperactivity syndrome" patients. The gas chromatographic-mass spectrometric method here described makes use of a deuterated internal standard in order to overcome problems related to the lack of reproducibility often encountered when a derivatization step is performed.

A new, simple device generates accurate nano- and microflow rate gradients from any conventional HPLC system. The core of the new device is represented by an electric-actuated, computer-controlled, multiposition HPLC valve. The valve hosts six reservoirs for as many different mobile-phase compositions of increasing strength. A low flow rate stream pushes the weakest solvent through the column as long as required and at the desired flow rate, until the chromatographic run is started. From this time on, the electric actuation allows one to select which reservoir will be on-line with the column and for how long, thus generating a specific solvent gradient, through a sequence of controlled segments of precise mobile-phase composition. This permits one not only to exactly reproduce the programmed slope but also to achieve different gradient shapes (i.e., linear, convex, concave) for different separation needs. The new device has proven to be reliable and reproducible even at the lowest flow rate tested (250 nL x min(-1)) and in different chromatographic conditions.

Our recent on-line solid-phase extraction (SPE) device for micro-liquid chromatography, known as micro-solid-phase extraction (μSPE), was compared with traditional SPE for the analysis, from aqueous samples, of 4 pesticides belonging to different classes. Two different kinds of adsorbents, C18 and graphitized carbon black, were tested. A 2-stage ion trap mass spectrometer, equipped with homemade microflow electrospray ion (ESI) source, was used. Detection limits with a signal-to-noise ratio of 3:1 for both extraction methods were in the range of 0.1 μg/L for all compounds. However, better recoveries were obtained when μSPE traps were used.

Electron paramagnetic resonance (EPR) has been used to investigate the adsorption capability and the surface interacting ability towards Cu(II) solutions (CuCl2, Cu(NO3)2, CuSO4 in water or ethanol) of various carbon blacks, both graphitized and ungraphitized, selected on the basis of the surface area, namely, Carbograph1 (area=100 m2/g), Carbograph4 (area=210 m2/g), and Carbograph5 (area=560 m2/g), which were indicated as C1g, C4g, C5g (g=graphitized), and C1ng, C4ng, C5ng (ng=ungraphitized). The EPR analysis was supported by surface analysis, for evaluating the surface area, the pore volume and the porosity, and by atomic absorption to obtain the adsorbed Cu(II) amounts. Graphitization provokes a decrease in surface area, but C1g, at low surface area, showed a unexpected increase of the adsorption ability ascribed to the formation of new surface porosity closed by graphite layers. The carbon samples showed a broad unresolved EPR signal due to mobile unpaired electrons in the carbon matrix. Graphitized samples presented a narrower signal than ungraphitized samples, which increases in width with the increase in surface area (with the exception of C5ng due to the high exposition of the wide surface to oxydizing external agents) and upon prolonged thermal treatment. The signal intensity of the carbon paramagnetic centers decreases upon Cu(II) adsorption. Computer aided analysis of the EPR spectra of the solids after Cu(II) adsorption allowed to extract structural information on the Cu-surface site complexes. The Cu2+ ions coordinated with surface polar sites, mainly oxygenated. Adsorption depends on the different Cu(II) salts, caused by the salt solubility and the interacting ability of the counter-ion. In several cases the solutions concentrated in the carbon porosity leading to precipitation of the salt. Ethanol solutions are more adsorbed at the carbon surface than water solutions; Cu(II) partially retains its solvation shell and partially presents electron transfer to the carbon surface. Adsorption is favored to ungraphitized carbons with respect to the graphitized ones due to both the higher surface area, and the higher hydrophilicity of the surface. In summary, these carbon powders, widely used for chromatographic applications, show an adsorption capability towards Cu(II) solutions higher than expected due to both a definite porosity, and the presence of polar groups which are not eliminated with chemical surface treatments.

A new LC/MS method for the determination of organophosphorus pesticides in water, based on the use of direct-electron ionization (EI) interface, is presented. Direct-EI is a new device that, in a very simple fashion, couples a nano-HPLC system with a mass spectrometer equipped with electron ionization capability. The nanoscale liquid flow allows for a direct introduction of eluate into the ion source and, after nebulization, for its ionization under typical EI conditions. Library-matchable EI spectra are generated for a choice of full scan or SIM detection of the analytes. In our case, a selection of organophosphorus pesticides, commonly distributed in local sugar beet cultivation, were considered. The new interface permits a very sensitive detection of the analytes in a wide range of linear response (0.09-9 ng). When applied to a real sample, the method allowed detecting four different pesticides at a concentration level of approximately 3 ng x L(-1).

The use of a new LC-MS interface (cap-EI), part of a Waters Integrity system, capable of generating EI spectra at micro flow rates is presented. The cap-EI interface relies on the production of a fine aerosol by means of a nebulizer and supported by a nitrogen jet. Sensitivity, response linearity, reproducibility, and LC compatibility of the interface were thoroughly examined using testosterone, caffeine, a mixture of antiinflammatory drugs, and 3,4-dihydroxybenzoic acid as test compounds. The interface is fully compatible with LC requirements such as high-water- and/or -buffer-content mobile phases. Reproducibility, high sensitivity in scan mode, as well, to produce library-searchable EI spectra, 2 orders of magnitude linearity, together with an intrinsic simplicity of the entire system are the key features of cap-EI interface.

The simultaneous determination of chlorofluorocarbons and their replacement compounds in ambient air samples requires the preconcentration of appropriate air volumes on suitable adsorbents. The performance of a dual-layer adsorption tube to be used in this type of analysis was evaluated in terms of breakthrough volumes (BTV) for the compounds of interest at ambient temperature. To verify the effectiveness of such adsorption tubes, real air samples were enriched at ambient temperature and were subsequently analyzed by capillary gas chromatography coupled with quadrupole mass spectrometry, operating in SIM mode. The results obtained confirmed the efficacy of the proposed method, in terms both of sensitivity and chromatographic separation efficiency.

A capillary-scale particle beam interface was used to detect 18 phenolic compounds in red wine samples. This technique allows reproducible, library searchable electron ionization spectra at only 1 microliter/min mobile phase flow-rate for a sensitive detection of the analytes in complex matrices. The method makes use of a narrow bore, reversed-phase packed capillary column for sample separation. Detection limits were in the low picogram range for most compounds. Sensitivity and response linearity were evaluated for eight phenolic acids, which are often encountered in red wines. The phenolic compound composition was outlined in two red wines obtained using different aging processes.

This paper presents the results obtained using fused-silica fibers coated with graphitized carbon black (Carbograph-Alltech) for solid-phase microextraction (SPME). The extraction and calibration curves relative to organic micro-pollutants present in gaseous and aqueous samples are reported. Examples of applications of this extraction procedure to GC and GC-MS analysis of organic micro-pollutants in actual samples are also reported.

Coumarins are a large group of compounds that are naturally present in plant tissues and that exhibit a wide range of pharmacological properties. Analytical methods based on chromatographic techniques and conventional detectors are inadequate to accurately analyze coumarins in complex matrices such as plant extracts. In this article a new method based on a modified particle beam liquid chromatography-mass spectrometry interface is described. The method allows specific and accurate determination of several coumarins in biological matrices. An application regarding the analysis of 18 coumarins in the extract of Smyrnium perfoliatum L. is also reported.

Plastic tubing of polyetheretherketone (PEEK) is used for the preparation of HPLC packed capillary columns. The polymer is rigid but not fragile, has great resistance to chemical and physical agents and comes in standard 1/16″ O.D. These features can extend the column lifetime and facilitate the overall employment of HPLC capillary columns. Serial connection of short columns is also possible with no increase in dead volume. A new, rapid and effective packing method has been developed to be compatible with the characteristics of the material. Several C8 and C18 columns have been prepared and tested and some applications are shown.

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.

The exceptional properties of graphitized carbon blacks in gas chromatography are described and the explanation of their behaviour is explained in terms of the thermodynamic functions related to the chromatographic process and of the k inetics of adsorption. Analytical applications u sing both packed and capillary columns using the working mechani sm of gas 1 i qui d solid chromatography are r eported.

A coating procedure for preparing fused-silica capillary columns with graphitized carbon black, modified with a liquid stationary phase, is described. This yields reproducible results in terms of column efficiency, separation power and retention parameters. The factors that affect the final results are discussed and some analytical applications are reported.

A sample enrichment method for herbicides from water, based on chromatographic extraction of organic compounds using graphitized carbon black is presented and its advantages and limits described. GC-MS and ECD are employed for qualitative analysis and quantitative determination.

The properties of different kinds of graphitized carbon black as traps for the extraction and preconcentration of polynuclear aromatic hydrocarbons from water and mineral oil have been investigated. The best results are obtained with Carbopack F, eluted with toluene at 100°C. Graphitized carbon black is preferred because of its thermal and chemical stability and its high purity.

Retention data and heats of adsorption on a new low-surface-area graphitized carbon black have been determined and are compared with values for other adsorbents. The new adsorbent has been applied to gas chromatography of polar compounds such as alcohols, free fatty acids and phenols, and to environmental analyses.

The use of traps containing graphitized carbon black for the collection and pre-analysis of atmospheric pollutants in industrial areas is presented. The working conditions, in terms of trapping capability and effectiveness of release by thermal desorption are discussed. Some practical applications are also given.

The 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.

A miniaturized, aerosol based interface for directly coupling a liquid chromatograph with a mass spectrometer is presented. The interface is entirely within the electron ionization (EI) source of the mass spectrometer and no additional, external devices are needed. This simple and effective approach exploits micro-flow nebulization technology providing a new interface suitable for a variety of applications of environmental and biological interest. The new interface provides necessary linearity, ruggedness, sensitivity, and reproducibility of response for trace level analysis, and readily interpretable mass spectra for unambiguous identification of unknown compounds of small to medium molecular weight.

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.

A new procedure based on liquid-solid chromatography for the extraction of polynuclear aromatic hydrocarbons has been implemented. This yields results analogous to those of Soxhlet extraction for low molecular weight compounds. A very important reduction in the time required for sample preparation prior to gas chromatography/mass spectrometry analysis is obtained.

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.

Some of the most commonly employed carbon blacks (Carbograph 1,2,4,5 from Lara and Carbopack X form Supelco), were evaluated by the BET surface characterization method for pore size distribution, porosity and specific surface. This information is often incomplete as furnished by manufacturers and is needed for a deeper understanding of carbon adsorption properties in chromatography.

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.