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Biomedical subjects

M Gallignani

Publications and source records attributed to M Gallignani.

10 recordsLinked to original sources
PubMed2005

Determination of cocaine and benzoylecgonine by direct injection of human urine into a column-switching liquid chromatography system with diode-array detection.

A method for the determination of cocaine (COC) and benzoylecgonine (BZE) in human urine using a column-switching liquid chromatography system is reported. A homemade precolumn (20 mm x 4.6 mm i.d.) dry-packed with Alltech ODS-C18 (35-750 microm) was employed as an extraction precolumn in order to extract and concentrate the COC and BZE from the human urine sample. The analytes were continuously transferred to the analytical column (Spherisorb-C8, 250 mm x 4.6 mm i.d.; dp = 5 microm) by means of the switching arrangement in the backflush mode. Detection was carried out at 235 nm in a UV-diode array detector. The validation of the method revealed analytes quantitative recoveries (96-102%) at three concentrations in the range from 0.25 to 4.00 and from 0.5 to 12.0 microg/mL for COC and BZE, respectively. These values demonstrate the excellent extraction efficiency of the precolumn. The detection limits for COC and BZE at a signal-to-noise ratio of 3 were 0.08 and 0.15 microg/mL when a sample volume of 50 microL was injected. The overlap of sample preparation, analysis and recondition of the precolumn increases the sample throughput to four samples per hour. The proposed method has been applied to the determination of COC and BZE in human urine samples from 73 suspecting drug addicts. Urine concentrations of 1.0-118.10 microg of BZE/mL and 0.1-41.0 microg of COC/mL were found.

Chromatography, Liquid↗
PubMed1999

Serum trace elements and fat-soluble vitamins A and E in healthy pre-school children from a Venezuelan rural community.

Zn (SZn), Cu (SCu), Fe (SFe), vitamin A (SVA) and vitamin E (SVE) were measured in blood serum samples of 85 healthy pre-school children aged 2-6 yr. from the rural community of Canaguá, Mérida State, Venezuela. The relationship between these biochemical indexes was also investigated. The mean serum concentrations of zinc, copper, iron, vitamin A and vitamin E were 0.74 +/- 0.25, 1.18 +/- 0.30, 0.76 +/- 0.20, 0.30 +/- 0.15 and 5.87 +/- 0.43 mg/L, respectively. There was a tendency for SZn to increase with age, whereas SCu and SVA decreased. There was no significant difference in serum trace elements and fat-soluble vitamin concentration between males and females in the different age groups. SFe tended to be lower than that reported in the literature. However, the age groups studied showed no statistically significant sex- and age-related differences. The present study shows that there is a complex interaction between SZn, SCu, SFe, SVA, SVE and age of the children. Multiple regression analysis showed serum zinc was strongly related to serum copper, and serum iron. Serum vitamin A was strongly related to serum zinc and serum vitamin E, whereas serum vitamin E was strongly related to serum zinc, serum copper, and serum vitamin A. On the other hand, our observations also suggest that more detailed studies of these metals and fat-soluble vitamins should be carried out, and that the study should include nutritional surveys, metabolic balances and associations between SZn, SCu, SFe, SVA and SVE and anthropometric variables (height, weight, body mass index and skinfold thickness).

Aging↗
PubMed1999

Determination of methylmercury and inorganic mercury in whole blood by headspace, cryofocusing gas chromatography and atomic absorption spectrometry.

A method for the determination of different mercury species in whole blood is described. Inorganic mercury (InHg) was determined in 2 ml of standard solutions or blood samples using head space (HS) injection coupled to atomic absorption spectrometry (AAS) after treatment with concentrated sulfuric and tin(II) chloride as a reductant agent in a closed HS vial. After stirring, the InHg was converted to elementary mercury and carried with a nitrogen flow through a quartz cell heated at 200 degrees C and the absorbance signal was evaluated by AAS. For the determination of methylmercury (MeHg), 2 ml of a standard solution or a blood sample were treated with 10 mg of iodoacetic acid and 0.4 ml of concentrated H2SO4. Then, the MeHg species were HS-injected into a gas chromatograph (GC), separated on a semicapillary column (AT-1000) with a flow of helium, then carried to the quartz cell heated at 1000 degrees C and detected by AAS. The high content of salts in blood samples, where sodium chloride is the major component (0.14 mol l-1), affected the gas-liquid distribution coefficient of both mercury species in the HS vial. A linear calibration graph was obtained in the ranges 1-20 and 1-125 micrograms Hg l-1 added as InHg and MeHg, respectively. The detection limits for InHg and MeHg were 0.6 and 0.2 microgram Hg l-1, respectively. The relative standard deviations for eleven independent measurements were 5% for both mercury species. Recovery values ranging from 98 to 106% for InHg and from 95 to 105% for MeHg and from 93 to 95% for ethylmercury (EtHg) were obtained. The accuracy of the proposed method was also established by the analysis of certified whole blood samples for InHg and MeHg. No difference between the sum of these two species determined by our procedure and the recommended total mercury concentrations in the certified samples was observed. Results for the determination of MeHg and InHg in 30 controls and 30 dentists are presented to illustrate the practical utility of the proposed method.

Chromatography, Gas↗
PubMed1996

A factorial design to determine the effects of some variables in the long-term stability of methylmercury standard solutions in water.

A factorial composite design has been employed for a rapid exploration of the effect of some parameters on the stability of spiked methylmercury iodide solutions. The analysis has been performed by capillary gas chromatography with electron-capture detection. The results obtained by the factorial and the univariate methods are in a good agreement. Although, the factorial design does not allow a discrimination of the significance among the same kind of factors, it greatly reduces the number of experiments when the different variables are investigated.

Journal Article↗
PubMed1995

Selective determination of antimony(III) and antimony(V) in liver tissue by microwave-assisted mineralization and hydride generation atomic absorption spectrometry.

Antimony(III) and antimony(V) species have been selectively determined in liver tissues by optimizing the acidic conditions for the evolution of stibine using the reduction with sodium borohydride. The results show that a response for Sb(III) of 0.5 to 20 microg l(-1) was selectively obtained from samples in a 1 mol l(-1) acetic acid medium. The best response for total antimony from 1 to 20 microg l(-1) is obtained after sample treatment with a 0.5 mol l(-1) sulfuric acid and 10% w/v potassium iodide. Microwave digestion has been necessary to release quantitatively antimony species from sample slurries. The amount of Sb(V) was calculated from the difference between the value for total antimony and Sb(III) concentrations. A relative standard deviation from 2.9 to 3.1% and a detection limit of 0.15 and 0.10 microg l(-1) for Sb(III) and total Sb has been obtained. The average accuracy exceeded 95% in all cases comparing the results obtained from recovery studies, electrothermal atomic absorption spectrometry and the analysis of certified reference materials.

Journal Article↗
PubMed1995

Gastric tissue selenium levels in healthy persons, cancer and non-cancer patients with different kinds of mucosal damage.

The gastric tissue levels of selenium (Se) were examined in 15 healthy subjects aged 18-43 (mean 36 +/- 12) years, 17 patients with stomach cancer aged 23-79 (mean 60 +/- 17) years, 20 patients with mild gastritis aged 18-65 (mean 35 +/- 12) years, 13 patients with chronic gastritis aged 28-69 (mean 47 +/- 15) years, 33 patients with erosive gastritis aged 16-70 (mean 49 +/- 17) years and 23 patients with ulcers aged 22-76 (mean 49 +/- 17) years. The Se concentration was determined by electrothermal atomic absorption spectrometry (ETAAS) with palladium as a matrix modifier. The mean +/- the standard deviation (SD) of the gastric tissue Se levels were 473 +/- 80, 36 +/- 9.0, 355 +/- 243, 567 +/- 246, 571 +/- 241 and 813 +/- 427 micrograms/Kg in healthy subjects and in patients with cancer, ulcers, mild gastritis, chronic gastritis and erosive gastritis, respectively. The Se concentration in the biopsies of patients with gastric ulceration and cancer were significantly lower than that in patients with gastritis (p < 0.05) and the other conditions (p < 0.0001).

Adolescent↗
PubMed1990

A comparative study of methods for determining selenium in biological materials.

A comparative study of the analytical performance of fluorimetric spectrophotometric, atomic absorption spectrometric, flow injection analysis with atomic absorption spectrometric, flow injection analysis with atomic absorption spectrometric detection, hydride generation with atomic absorption spectrometric detection and hydride generation with molecular emission cavity analysis detection methods has been carried out for the determination of selenium in biological materials. Based on results concerning detection limit, linearity and sensitivity, only the fluorimetric and hydride generation with atomic absorption spectrometric detection methods were suitable for the determination of selenium in biological materials. Whereas, the spectrophotometric, flame absorption spectrometric flow injection-atomic absorption spectrometric and hydride generation with molecular emission cavity detection, due to its worse detection limits and poorer sensitivities, were found to be unsuitable for the determination of selenium in such matrices. The accuracy of the fluorimetric and hydride generation with atomic absorption spectrometric detection methods were tested by using NBS standard reference materials.

Biological Products↗
PubMed1990

Blood serum selenium in the province of Mérida, Venezuela, related to sex, cancer incidence and soil selenium content.

Blood serum selenium levels were measured in healthy subjects of six districts located throughout the province of Mérida, Venezuela. There were either high (87-115 micrograms/L) or low (58-72 micrograms/L) serum selenium-containing districts. Serum selenium in males from three districts were statistically significantly lower (p less than 0.001) than in females. There was a general tendency for serum selenium to increase with age. On the average, a reduction in cancer was observed in the districts with high serum selenium content. Further, serum selenium was lower in male patients from the Mérida district with cancer disease. Association between selenium in soil and in the blood serum of healthy subjects has been observed.

Adolescent↗
PubMed1983

Direct determination of sodium and potassium in blood serum by flow injection and atomic absorption spectrophotometry.

A simple and reliable method for the measurement of sodium and potassium in blood serum without any sample dilution by using flow injection and atomic absorption spectrophotometry is described. A sample throughout of 100 measurements per hour is possible. Matrix problems have not been encountered. The coefficient of variation for within-run determinations is about 1,14 and 2,36% for sodium and potassium, respectively, in serum samples (n = 10). The method is easily adaptable to pediatric research, because of the low required sample volume of 5 microliter.

Blood Specimen Collection↗