P.G. Desideri

Concentration, separation and determination of hydrocarbons in sea water

Abstract A method for determining the hydrocarbons dissolved in sea water, including their concentration and separation into homogeneous classes, is described. Extraction with organic solvents, determination of the optimum volumes for n-hexane and carbon tetrachloride and concentration procedures for the extracts were investigated. Separation of hydrocarbons from polar compounds and their fractionation into five classes (aliphatic, monoaromatic and polynuclear with 2, 3–4 and 5–6 rings) were achieved using adsorption chromatography on a two-step microcolumn of silica gel and aluminium oxide. The overall recovery efficiency of the procedures and the detection limits of several hydrocarbons in 11 of sea water are reported.

Organic Compounds in Surface and Deep Antarctic Snow

Abstract Eight surface snow samples taken during the 1987/88, 1988/89 and 1990/91 Italian Antarctic Expeditions and six samples collected at different depths from two dissimilar sites during the 1990/91 Expedition, were analyzed for the non-chlorinated organic content using the GC capillary columns technique and GC-MS. Several biogenic and anthropogenic classes of organic compounds were identified and quantitatively determined. The data obtained give a more complete picture of the pollution level in Antarctica.

Reversed phase planar chromatography of dansyl DL amino acids with bovine serum albumin in the mobile phase

SummaryThe chromatographic behavior of twelve dansyl DL amino acids, one D isomer and eleven L isomers on RP18W/UV254, RP18W/F254s, and Sil C18−50 UV254 plates developed with aqueous—organic solutions containing bovine serum albumin (BSA) as chiral complexing agent has been extensively investigated. Enantiomeric resolution is highly dependent on mobile phase pH and ionic strength, and on the concentration of both BSA and organic modifier. All the racemates have been resolved within a development time of 1 h 30 min. The selectivity factors (α) for the dansyl amino acids have been compared with those from planar chromatography for the corresponding DNP, DNPy, and Fmoc amino acids, and with those of the same dansyl derivatives on a column prepared from BSA bound to silica gel.

Transport of organic compounds across the air/sea interface of artificial and natural marine aerosols

A modified Gershey apparatus for artificial aerosol formation from salt solutions and sea-water samples was used to study the transfer of selected organic compounds from water to air and the parameters that influence this transfer. These parameters include the surface properties, the vapour pressure and the structure of the organic compounds and the presence of surfactants and suspended particles in the solution. In particular, alkylbenzenes and lower molecular weight n-alkanes were transported into the atmosphere while the remaining organic compunds studied were distributed between the liquid aerosol and the depleted sea water. Phthalates were present in the aerosol at high percentages (60–80%) and this behaviour is due to their surface properties towards the air/water interface. The addition of surfactants to the salt solutions generally led to a greater transfer of organic compounds into the aerosol. The results allowed the prediction of the organic composition of natural aerosol collected near Livorno (Italy) during storms in the Tyrrhenian sea.

Transport of organochlorine pesticides across the air/sea interface during the aerosol process

Abstract A modified Gershey apparatus was used to study the transfer to the atmosphere of selected organochlorine; pesticides from salt solutions with and without the addition of ionic and non-ionic surfactants at different concentrations and from untreated and filtered Tyrrhenian sea water. Pesticides were transported into the atmosphere both in the gas phase land in the liquid aerosol depending on their chemical structure and their physical characteristics (surface properties, volatility, water solubility, hydrophobicity). The results obtained gave useful information about the behaviour of the tested organocthlorinated compounds in long-range transport from temperate environments to frigid polar regions.

Organic Compounds in Antarctic Sea-Water and Pack-Ice

Abstract Pack-ice and sea-water samples collected at different depths from Terra Nova Bay and Ross Sea, during 1990/1991 Italian Antarctic Expedition, were analyzed using HRGC and GC-MS. Several classes of biogenic and anthropogenic organic compounds were identified and measured in both matrices. The results showed the changes in the organic composition at varying depths of pack-ice and sea-water and the enrichment of organic compounds in the pack.

Recovery, Identification and Determination of Organic Compounds in Marine Sediments

Abstract A simple, rapid and reliable micro-method for the analysis of organic compounds in marine sediments is proposed. A quantitative extraction method for the recovery of analytes from the natural matrix was realized by cold magnetic stirring; the best conditions as to amounts of sediments and of extractive solvent were also studied. The extracts were reduced to small volume by cold evaportion under a stream of nitrogen and then fractionated on a mixed microcolumn of RP-18 and silica using organic solvents of increasing polarity. The homogeneous fractions obtained were analysed by HRGC with specific detectors and by GC-MS. The identification of almost one hundred organic compounds, such as PAHs and chlorinated compounds, was realized by this method. The application to sediments coming from the Ligurian Sea confirmed the reliability and applicability of the method to samples with a great compositional variation.

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.

Determination of polycyclic aromatic hydrocarbons with more than four rings in crude oils on a RP-18 column

Abstract The hydrocarbon fraction in crude oils has been separated from Asphaltenes on a RP-18 column. The hydrocarbons were subsequently fractionated on an aluminium oxide micro-column, yielding an homogeneous fraction of polycyclic aromatic hydrocarbons with more than four rings. The method was applied to crude oils from different geographical areas. The limits of application of the method, related to the percentage of Asphaltenes in crude oils, are discussed.

Fingerprinting of crude oil spills

Abstract The use of a two-step microlumn of silica gel and aluminium oxide for the fractionation of crude oil spills is described. The 3–4 and 5–6-ring polynuclear aroamtic hydrocarbon fractions were used to identify eleven crude oils according to their areas of origin and individually. Fractionation by thin-layer chromatography was also studied and the results are compared with those obtained on the microcolumn.