Biomedical subjects

M Careri

Publications and source records attributed to M Careri.

23 records · Page 2Linked to original sources

PubMed1999

Liquid chromatography-electrospray mass spectrometry of beta-carotene and xanthophylls. Validation of the analytical method.

The investigation of beta-carotene and the xanthophylls beta-cryptoxanthin, lutein, zeaxanthin, canthaxanthin and astaxanthin using reversed-phase liquid chromatography-electrospray mass spectrometry interfaced with TurboIonspray (LC-TurboISP-MS) is described. Two narrow-bore C18 columns connected in series and an isocratic solvent system containing acetonitrile-methanol (0.1 M ammonium acetate)-dichloromethane at a flow-rate of 300 microl/min (without splitting) were used. Operating in the positive-ion mode over m/z 500-650, the effects on the formation of the molecular ion species or adduct ions and the MS detector response were investigated for carotenoids, varying the orifice plate voltage, the ring voltage and the ISP voltage. Both conventional ISP and TurboISP were performed; using the TurboISP-MS system, ionization efficiency increased with respect to ISP-MS, particularly at the highest temperature (500 degrees C). Good results were particularly obtained for beta-carotene, which was detectable at the low ng level, without the use of solution-phase oxidants. Using LC columns and acquiring in single-ion monitoring mode, detection limits were estimated to be in the 0.1-1 ng range; dynamic range was established between one- and two-orders of magnitude. Better sensitivity under positive-ion than negative-ion conditions was demonstrated.

Chromatography, High Pressure Liquid↗

PubMed1996

Applications of liquid chromatography-mass spectrometry interfacing systems in food analysis: pesticide, drug and toxic substance residues.

This paper reviews applications of different LC-MS techniques for the determination of xenobiotic substances in foods. Specific examples of contaminants discussed are pesticides, herbicides, insecticides and drugs; concerning toxic substances, mycotoxins, phycotoxins, cyanobacterial toxins, mutagenic and heterocyclic amines and beta-carbolines, arsenic, tin and inorganic halogen compounds, packaging materials and various epoxy resins are considered. Advantages and limitations are outlined for the different LC-MS interfacing systems (particle beam, thermospray, atmospheric pressure ionization with electrospray, ionspray and heated pneumatic nebulizer). The impact of developments in instrumental analysis on methodology and the limitations of the various LC-MS methods are discussed. Further, the coupling of LC with element-selective detection systems such as inductively coupled plasma mass spectrometry is discussed, with emphasis on speciation of trace toxic elements in foods.

Chromatography, Liquid↗

PubMed1996

Determination of phylloquinone (vitamin K(1)) by high performance liquid chromatography with UV detection and with particle beam-mass spectrometry.

A reversed-phase PB LC-MS method was used for the determination and unequivocal identification of vitamin K(1) in some vegetable samples. The method was also applied to the identification of other constituents in the food analyzed. LC-MS experiments were carried out in both EI and negative-ion CI modes. Preliminary sensitivity studies on vitamin K(1) showed a detection limit of 2 ng (signal-to-noise ratio=3) in negative-ion operation and in single-ion monitoring at m/z 450. Quantitative results obtained with LC-MS for the extracts of four vegetables were compared with those of LC-UV analyses performed at 247 nm.

Journal Article↗

PubMedDate not supplied

Development and validation of a method using on-line solid-phase extraction and liquid chromatography with ultraviolet detection for the determination of bisphenol A, octylphenol, and nonylphenol in groundwater.

Alkylphenols are nonbiodegradable metabolites arising from various pathways of aerobic and anaerobic degradation of the nonionic surfactants alkylphenol ethoxylates. A method based on the use of on-line solid-phase extraction (SPE) and liquid chromatography (LC) with UV detection was developed to determine bisphenol A, octylphenol, and nonylphenol at trace levels in water. The on-line coupled SPE procedure automatically enables an approximately 300-fold preconcentration of analytes, which can be further enhanced by an increase in applied sample volume. By using C18 cartridges, recoveries of >90% were obtained for all the analytes. A validation procedure was carried out with a groundwater sample to ensure the quality of the results; performance criteria such as detection limits (LODs), quantitation limits (LOQs), linearity, and precision were evaluated. LODs and LOQs in the range of 0.17-0.36 and 0.35-1.88 microg/L, respectively, were found; for all the analytes, linearity was established over 2 orders of magnitude (r2 >0.997, n = 54). The intraday repeatability values expressed as relative standard deviations were <5.3%; a nested analysis of variance was performed to verify the influence of 3 different factors, i.e., different days, extraction procedure, and LC replicate injection, on data precision.

Benzhydryl Compounds↗

PubMedDate not supplied

On-line purge-and-trap-gas chromatography with flame ionization detection as an alternative analytical method for dimethyl sulphide trace release from marine algae.

The release of dimethyl sulphide (DMS) by the seaweed Ulva spp at trace level was studied in aqueous solutions at different salinities, temperature and light intensities. For this purpose, the purge-and-trap technique combined with gas chromatography-flame ionization detection was used. The analytical method was evaluated in terms of linearity range, limit of detection, precision and accuracy by considering 10@1000 (w/v) and 30@1000 (w/v) synthetic seawater as aqueous matrices. Calculation of the recovery function evidenced a matrix influence. The method of standard addition was then used for an accurate determination of DMS in synthetic seawater reproducing the matrix effect. DMS fluxes were analysed in batch cultures of Ulva spp reproducing the conditions which usually occur in the Sacca di Goro lagoon (Northern Adriatic Sea, Italy).

Chlorophyta↗