Monica Culea

Comparative analysis of some active principles of herb plants by GC/MS

A rapid extraction procedure for fingerprint chromatogram of different types of Mentha piperita L. (Labiatae family) is presented. The extracts were analysed by gas chromatography and gas chromatography-mass spectrometry (GC/MS). The main volatile compounds identified by the gas chromatography-mass spectrometric analysis of M. piperita L. were menthol, menthone, isomenthone, 1,8-cineole, menthyl acetate, limonene, beta-myrcene, carvone. M. piperita L. oil had the active principles: menthol, menthone, isomenthone, menthyl acetate, alpha-pinene, beta-pinene, champhor, limonene, linalool, piperitone. M. crispa L. showed carvone as major component.

Toward modeling phosphate tellurate glasses: the devitrification and addition of gadolinium ions behavior.

Glasses in the xGd2O3 x (100 - x)[7TeO2 x 3P2O5] system with 0 < or = x < or = 20 mol % have been prepared using the melt quenching method. The influence of gadolinium ions on structural behavior of the phosphate tellurate glass has been investigated using infrared spectroscopy and density functional theory (DFT) calculations. The addition of gadolinium ions into the host glass matrix leads to an increase of the glass network polymerization due to the replacement of P-O-P bonds by the more resistant P-O-Te bonds having as result the improvement of the chemical durability of the glass. The structural evolution of the studied glasses with the gradual increase of the gadolinium oxide content up to 20 mol % could be explained by considering that the excess of oxygen may be accommodated by the conversion of some orthophosphate structural units into metaphosphate or/and pyrophosphate units. X-ray diffraction and IR spectra revealed that heat treatment of the samples also causes an increase of the glass network polymerization for heat treatment times, t, up to 36 h, while for 36 h > t > or = 48 h showed a drastic structural modification which lead to the apparition of the Te4P2O13 crystalline phase. DFT calculations show that tellurium atoms occupy two different sites in the proposed model. In the first case the tellurium atom is coordinated with four oxygen atoms giving a trigonal bipyramide arrangement, while in the second case the tellurium atom is coordinated with three O atoms. The calculated IR absorption spectrum of the proposed model for phosphotellurite glasses is in good agreement with the experimental absorption data.

Separation, identification and quantitative determination of free amino acids from plant extracts

This research presents the results obtained from the separation, identification and quantitative determination of free amino acids from Gingko biloba and Hedera helix leaf extracts, using three modern techniques: thin layer chromatography (TLC), high performance liquid chromatography (HPLC), and gas chromatography-mass spectrometry. The presence of the determined amino acids explains the utilisation of G. biloba and H. helix leaf extracts in cosmetic and pharmaceutical products.

Dual role of the six-coordinated molybdenum and lead ions in novel of photochromic properties of the molybdenum-lead-borate glasses

Transparent glasses were prepared by conventional melting-quenching method in the xMoO(3).(100-x)[3B(2)O(3).PbO] system where 0<or=x<or=15 mol%. By increasing the MoO(3) content up to 20 mol% the PbMoO(4) crystalline phase appears. These systems exhibit a photochromic effect which can be induced through laser exposures (lambda=633 nm) directly on the bulk sample. Structural investigations by FTIR spectroscopy show that the photosensitive effect is due to a reduction of Mo(6+) to Mo(4+) and/or Mo(5+) promoted by the oxidation of Pb(2+) and some structural changes of the borate network.

Gas chromatographic study of some local anesthetics

SummaryA sensitive capillary gas chromatographic method is described for the simultaneous determination of lidocaine, tetracaine, procaine and dibucaine. The method was applied to the determination of anesthetics in tissue homogenates incubated at 38°C at doses between 10 and 400 mg/kg. In the liver tissue thein vitro metabolization of the studied anesthetics is most rapid for tetracaine, also fast for procaine, while for lidocaine and dibucaine the metabolization is very slow. In brain tissue thein vitro metabolization of anesthetics is very slow.The method shows good analytical parameters: linearity between 5 and 40 μg/ml; day-to-day reproducibility ca. 8% for a concentration of 20 μg/ml, precision ca. 7% for a concentration of 20μg/ml. Accuracy is also very good.

PAHs in Cigarette Smoke by Gas Chromatography-Mass Spectrometry:

Tobacco smoke is a major source of human exposure to carcinogenic pollutants, especially polycyclic aromatic hydrocarbons (PAHs). Our capacity to metabolise and so biologically activate PAHs from both tobacco smoke and occupational exposure puts us at even greater risk for PAH-related cancers, especially certain respiratory cancers. The techniques most used for determining pollutants in environmental or biological samples are GC-MS and HPLC methods. In the present work a GC-MS has been used in both the scan and SIM mode to characterise the organic compounds adsorbed on a charcoal cartridge comparable with the conventional cigarette filter or other types of cigarette. Charcoal cigarette filters and normal filters were compared. A method for quantitative determination of naphthalene, phenanthrene and anthracene in urine or in cigarette smoke was validated and tested. A Thermo Finnigan Trace gas chromatograph coupled with a Trace DSQ mass spectrometer was used. The chromatograms were obtained on a fused silica capillary column Rtx-5MS, (15m 0.25mm id) 0.25 m using 2 temperature programmes.

Volatile Organic Chemical Pollutants in Laboratory Indoor Air

A quantitative method for measuring volatile organic compounds by pre-con centration on Tenax GC followed by gas chromatography analysis is de scribed. The method showed good linearity, precision and reproducibility for the organic compounds investigated. The limit of detection permits the deter mination of 0.1-1 μg, depending on the compound. Measurements were used to determine the airborne chemical pollutants in a mass spectrometry labora tory at our institute.

Reliability of salivary theophylline in monitoring the treatment for apnoea of prematurity

Objective:To evaluate the reliability of salivary levels of theophylline in monitoring therapy of apnoea of prematurity.Study Design:Aminophylline was administered intravenously in 13 infants with apnoea, in a loading dose of 5 mg/kg and maintenance dose of 3 mg/kg, every 8 h. The patients were divided into two groups according to their postconceptional age (PCA): group A, of infants with small PCA (32.8±2.0 weeks; n=6 cases), and group B, infants with higher PCA (37.1±0.8 weeks; n=7 cases).Results:A total of 57 paired samples of serum and saliva were obtained in all 13 infants. The mean serum level of theophylline was 7.8±5.8 μg/ml and the ratio between serum and salivary concentration of theophylline was 1.53±0.28. A strong correlation between the serum and salivary concentration of theophylline (r=0.973) was found. Infants with small PCA had significant higher serum concentration of theophylline than those with higher PCA (10.6 vs 5.3 μg/ml; P=0.0002). The difference between the mean ratios of serum/salivary theophylline levels in the two groups was low (1.44 vs 1.62; P=0.0155).Conclusion:The strong correlation of theophylline in serum and in saliva recommends the salivary levels as a reliable method for monitoring the treatment of apnoea of prematurity.

Comparison of isotopic dilution methods for determination of theophylline in the plasma and saliva of infants and children

SummaryIsotope-dilution mass spectrometry (IDMS) using the direct inlet probe and an isotope dilution gas chromatographic-mass spectrometric (GC-IDMS) technique are presented for determination of theophylline in paired specimens of plasma and saliva from infants and children treated with theophylline for idiopathic apnea of prematurity, or for asthma.15N-theophylline was used as internal standard. A non-invasive means of individualization of the dosage was achieved by analysis of levels of the drug in saliva secreted in response to stimulation with citric acid.There was good correlation (r=0.99) between results from the two different methods of analysis, which employed two different mass spectrometers, the MAT 311 and HP 5989B, both in SIM mode. Good correlation was also observed between plasma and saliva determinations (r=0.97) and between two methods of calculation, one using the regression curve and the other the least squares approach (r=0.998). Applications to infants and children are described.

Exposure Assessment of Nicotine and Cotinine by GC-MS

Environmental tobacco smoke exposure of human subjects in different public houses was evaluated. The levels of airborne nicotine from environmental tobacco smoke and changes in urinary cotinine and nicotine levels between smoking and non-smoking subjects were compared. A gas chromatography-mass spectrometric (GC-MS) quantitative method for nicotine and cotinine levels in the indoor air and in urine was developed. A Thermo Quest Trace DSQ GC-MS equipped with a Rtx-5MS capillary column, 15m 0.25mm, 0.25 m film thickness, was used in a temperature programme starting from 50°C, for 2min, then increased at 8°C·min-1 to 250°C and held for 10min. The method was validated and gave good linearity, precision, accuracy and limit of detection. A significant correlation between urinary cotinine increase and airborne nicotine is presented.