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Biomedical subjects

Giorgio Famiglini

Publications and source records attributed to Giorgio Famiglini.

10 recordsLinked to original sources
PubMed2006

Adsorption of pure and mixed solvent solutions of spin probes onto stationary phases.

Water, methanol (MeOH), acetonitrile (ACN), and binary MeOH-water and ACN-water solutions of different spin probes (nitroxides), selected to mimic the behavior of different pollutants, were adsorbed onto stationary phases usually used in reversed-phase high-performance liquid chromatography (RP-HPLC). These stationary phases are constituted by porous silica and differ from each other regarding the surface area, the pore size, the particle size, the surface functions (NH2, C8, and C18), and the percentage of functionalization. The electron paramagnetic resonance (EPR) spectra of the probe solutions adsorbed into the pores were analyzed by computer-aided computation of the spectral line shape, which provided structural and dynamical parameters of the probes and their environments. These parameters provided information on the surface properties of the stationary phases, such as alkyl chain density, solvent penetration, stationary-phase ordering, and residual silanol effects, which modify the retention times in HPLC. A different availability of polar surface groups in the pure and mixed solvents was found for the different stationary phases depending on (1) the different functionalization degree, (2) the surface-chain length, (3) the particle size, and (4) the polarity of both the probe and the solvent. The C8 functionalization rendered the surface more hydrophobic with respect to C18. The endcapping process of the residual silanols strongly enhanced the surface hydrophobicity tested by the probes. At the highest water content, the adsorption of the polar or charged probes onto the hydrophobic surface is the lowest and self-aggregation occurs. When the probes bear both hydrophilic and hydrophobic moieties, the adsorption is enhanced by a synergy between hydrophilic and hydrophobic bonds with the surface. A balance between the hydrophilic and hydrophobic forces leads to high adsorption and partial insertion of the surfactant probes in an ordered C18 chain layer at the solid surface which forms in the binary mixtures; this layer is ascertained between 40% and 70% of the less hydrophilic solvent, depending on the type of both the solid and the probe. This insertion and the response on the formation of the ordered layer were favored in ACN-water with respect to MeOH-water.

Journal Article↗
PubMed2005

Determination of endocrine disrupting compounds in marine water by nanoliquid chromatography/direct-electron ionization mass spectrometry.

We present a new method for the determination of 29 endocrine-disrupting compounds in marine water. This method is based on a solid-phase extraction preconcentration technique, followed by a nanoscale liquid chromatography/direct-electron ionization (EI) mass spectrometric analysis. Direct-EI is a novel technique for the rapid conversion of a GC/MS into an efficient and reliable LC/MS for EI detection. The capability to acquire EI mass spectra of the analytes, and to operate in selected ion monitoring mode during real sample analyses, allows certain identification and precise quantification. In addition, this method is not influenced by the polarity of the analytes and does not require different detection modes (positive and negative) for identification with API techniques. Limits of detection of the method span from 0.4 to 118.7 ng.L(-1), corresponding to an instrumental detection limit of 0.005-1.260 ng. Linear regression and recovery experiment data, together with their standard deviations, are also presented. Marine water samples were collected along the middle-western Adriatic Coast (Italy), near the shore and at the mouth of rivers and canals.

Chromatography, Liquid↗
PubMed2004

Fate of enrofloxacin in swine sewage.

The fate of enrofloxacin present in raw sewage at a swine-breeding facility was investigated by liquid-liquid extraction and reversed-phase liquid chromatography with photodiode array detection. Samples were collected in the storage pits of each pigsty and in a nonaerated lagoon used to stock the sewage. In the pigsties, the sewage was mixed with 10% olive oil groundwater, following a certified procedure (cod. Cer 020301) which reduces the bad odors and produces a better manure. This sewage treatment for 8 months in the lagoon dramatically reduced the amount of enrofloxacin to levels under the detection limit of 0.6 microg.L(-)(1). The results stress the importance of correct sludge management in limiting the impact of enrofloxacin in the environment.

Animals↗
PubMed2003

Variable-gradient generator for micro- and nano-HPLC.

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.

Journal Article↗
PubMed2002

Trace level determination of organophosphorus pesticides in water with the new direct-electron ionization LC/MS interface.

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).

Chromatography, High Pressure Liquid↗
PubMed2002

A simple approach for coupling liquid chromatography and electron ionization mass spectrometry.

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.

Journal Article↗
PubMedDate not supplied

Liquid chromatography-electron ionization mass spectrometry: fields of application and evaluation of the performance of a Direct-EI interface.

A comprehensive evaluation and a thorough discussion of the fields of possible applications of the Direct-EI interface are described in this review. Direct-EI allows the direct introduction of the effluent from a capillary HPLC column into the electron ionization (EI) ion source of a mass spectrometer. Thanks to the reduced liquid intake and an in-source nebulizer, the interfacing process occurs smoothly and entirely into the ion source. No intermediate interfacing mechanisms of any sort are interposed between the column and the mass spectrometer, thus circumventing any undesired sample loss and minimizing the effort for instrument modification. Theoretically, any GC-MS system can be converted into an LC-MS for EI amenable compounds. Several parameters, crucial for a successful integration of liquid chromatography and mass spectrometry, have been considered in the evaluation of the functioning of such an interface: limit of detection, linearity of response, reproducibility, and chromatographic compatibility. Different mobile phases, also containing non-volatile buffers, were taken into account, demonstrating an outstanding separation flexibility. The entire set of experiments was carried out at different flow rates and temperatures of the ion source. The interface behavior was also tested in real world applications, with mixtures of pesticides, hormones, nitro-PAH, and endocrine-disrupting compounds, allowing picogram level detection and the possibility to record library-matchable, readily interpretable electron ionization mass spectra, for prompt compound characterization and confirmation.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

New liquid chromatography/electron ionization mass spectrometry methods in water analysis.

A method to extract and analyze organic compounds from water is presented. A solid phase micro-trap (micro-SPE) directly connected to the micro-analytical column is used. Sensibility and specificity needed for trace analysis are guaranteed by mass spectrometric electron ionization (EI) detection. A new micro-HPLC/EI-MS interface called Capillary-EI (Cap-EI) is described. The ultimate evolution of this interface is also presented: in this extremely simplified interface the analytes are nebulized, vaporized and ionized in the small volume of the ion source. This interface, called Direct-EI, exploits nano- and micro-HPLC columns with a mobile phase flow rates ranging from 0.3 to 1.5 microL/min. Contemporary use of micro SPE, Cap-EI or Direct-EI gives us a powerful technique to identify and quantify organic pollutants at part per billion level (ppb).

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Comparison of solid-phase extraction and micro-solid-phase extraction for liquid chromatography/mass spectrometry analysis of pesticides in water samples.

Our recent on-line solid-phase extraction (SPE) device for micro-liquid chromatography, known as micro-solid-phase extraction (microSPE), 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 microg/L for all compounds. However, better recoveries were obtained when microSPE traps were used.

Adsorption↗