The use of ultrasonic treatment for improvement of metrological performance of sorption atomic absorption determination of lead(II) and cadmium(II) traces

The optimal parameters for ultrasonic treatment (frequency 200–300 kHz, intensity 2–4 W cm^?2) were obtained to intensify Pb(II) and Cd(II) sorption concentration by carbon sorbent from apricot pit. The combined action of ultrasonic frequency of 18 kHz and 1 MHz on concentrate slurry increases its sedimentation stability from 3 to 180 minutes and decreases S_r value up to 7% at Pb(II), Cd(II) hybrid sorption atomic absorption determination in natural waters, brines, common salt.      

Evaluation of the radon concentration in Ocna Dej salt mine,Romania

Measurement of radon is of interest both for the health risk assessment and development of radon therapy in enclosed spaces like as caves, mines and spas. In Romania, radon therapy is not in use, yet. The development of this treatment method in mines from our country involves primarily, the evaluation of radon levels in the salt mines. In this paper, the results of radon gas measurement that were performed at Ocna Dej salt mine (Romania) are presented. The radon measurements were performed using two systems: radon monitor Pylon AB-5 system and CIS-P5M system. The average radon concentration was found to be between 9.14 ± 5.10 Bq/m³ and 31.70 ± 2.76 Bq/m³. These radon levels are lower in comparison to those reported for mines, caves or spas in other countries where radon therapy and speleotherapy is frequently in use. Radon concentration and environmental conditions from Ocna Dej salt mine are suitable for therapeutic applications.     

Enantioseparation of Chiral Antimycotic Drugs by HPLC with Polysaccharide-Based Chiral Columns and Polar Organic Mobile Phases with Emphasis on Enantiomer Elution Order

The separation of enantiomers of 10 chiral antimycotic drugs was studied on polysaccharide-based chiral columns with polar organic mobile phases. The emphasis was placed on some interesting examples of enantiomer elution order reversal observed depending on the chemistry of the chiral selector, separation temperature, major component, as well as the minor additive in the mobile phase. In particular, it was found that the elution order of enantiomers of chiral drug terconazole was opposite on cellulose- and amylose-based columns with the same pendant group. The affinity pattern of enantiomers of another chiral drug bifonazole was opposite towards to two amylose-based chiral selectors with different pendant groups. The affinity pattern of terconazole enantiomers also changed on some columns when the alcohol-based mobile phase was replaced with acetonitrile. An interesting effect of the minor acidic (formic acid) additives to the mobile phase on the affinity pattern of terconazole enantiomers was observed on Cellulose-2 and Cellulose-4 columns. In addition, a reversal of elution order of bifonazole enantiomers was observed on Amylose-2 column by variation of a separation temperature.     

Enantioseparation of Chiral Antimycotic Drugs by HPLC with Polysaccharide-Based Chiral Columns and Polar Organic Mobile Phases with Emphasis on Enantiomer Elution Order

The separation of enantiomers of 10 chiral antimycotic drugs was studied on polysaccharide-based chiral columns with polar organic mobile phases. The emphasis was placed on some interesting examples of enantiomer elution order reversal observed depending on the chemistry of the chiral selector, separation temperature, major component, as well as the minor additive in the mobile phase. In particular, it was found that the elution order of enantiomers of chiral drug terconazole was opposite on cellulose- and amylose-based columns with the same pendant group. The affinity pattern of enantiomers of another chiral drug bifonazole was opposite towards to two amylose-based chiral selectors with different pendant groups. The affinity pattern of terconazole enantiomers also changed on some columns when the alcohol-based mobile phase was replaced with acetonitrile. An interesting effect of the minor acidic (formic acid) additives to the mobile phase on the affinity pattern of terconazole enantiomers was observed on Cellulose-2 and Cellulose-4 columns. In addition, a reversal of elution order of bifonazole enantiomers was observed on Amylose-2 column by variation of a separation temperature.

     

Solvatochromic Study of Two Carbanion Monosubstituted 4-Tolyl-1,2,4-triazol-1-ium Phenacylids in Binary Hydroxyl Solvent Mixtures

Two 4-tolyl-1,2,4-triazol-1-ium methylids, namely 4-tolyl-1,2,4-triazol-1-ium-phenacylid and 4-tolyl-1,2,4-triazol-1-ium-4′-nitro-phenacylid, are studied from solvatochromic point of view in binary solvent mixtures of water with ethanol and water with methanol. The contributions (expressed in percent) of the universal and specific interactions are separated from the spectral shifts recorded in the visible range for each composition of the binary solvent mixture. The essential role of the orientation and induction interactions in the studied solutions was demonstrated. Based on the statistic cell model of the binary solvent mixture solutions, the difference between the formation energies of ylid-water and ylid-alcohol complexes is estimated. The composition of the ylid’s first solvation shell was also established using the model of the binary solvent mixture solutions. The results obtained from the statistical cell model were compared with those obtained by using the Suppan’s model, resulting a good agreement.     

Assessment of calibration parameters for gamma-ray spectrometry systems

The Gamma-ray spectrometers are complex instruments and the quality of the data they provide depends strongly on their proper calibration. This paper describes the energy and efficacy calibration of two gamma-ray spectrometers in order to validate the method for measuring the activity of gamma-ray emitting radionuclides. The punctiform standard sources ⁶⁰Co, ¹³³Ba, ¹³⁷Cs and ²⁴¹Am were used in this study. Minimum Detectable Activity, Peak to Compton Ratio and the peak shape parameters were determinate. An inter-comparison of the results obtained with both systems was done. The results demonstrated that the activity values are comparable with low errors respecting with those for conventionally true activities.     

Kinetic study of atomization in atomic absorption analysis of solid samples using flame-furnace atomizer

Direct solid sampling analysis in atomic absorption spectrometry using flame-furnace atomizer allows to significantly decrease analysis duration, to avoid sample pollution and to exclude toxic reagents. The choice of chemical modifiers that decreases the detection limit and improves the repeatability of results is based on the mechanism of analyte-free atom formation. The kinetic approach developed here allows determination of pre-exponential factors k₀ and apparent activation energies E_a of the atomization processes for Pb(II) and Cd(II) compounds and enables use of CaCO₃ and KHF₂ as effective chemical modifiers for soil samples. A fast and precise technique for lead and cadmium determination in soils using the proposed chemical modifiers was developed.     

SUBSTITUENT EFFECTS OF PHOSPHORUS CONTAINING GROUPS Concerning the Meta-Nitration of the N- and O-Phosphorylated Aniline and Phenol

Abstract

Polar effects of the acylated amino and hydroxy groups NH?X, O?X (X ? COCH₃, PO₃Et₂) upon the adjacent benzene ring are compared. The specific mechanism for the meta nitration of the phosphoryl derivatives, involving the nucleophilic assistance of the PO group, is postulated.