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  • Author or Editor: Mohd Afzal x
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Abstract  

An ion chromatographic method has been developed for the determination of traces of Li+, Na+, K+, Ca2+, Mg2+, Sr2+, Fe3+, Cu2+, Ni2+, Co2+, Zn2+, Cd2+, Mn2+ in UO2, ThO2 powders and sintered (Th,U)O2 pellets. This new method utilizes poly-(butadiene-maleic acid) (PBDMA) coated silica cation exchange column and mixed functionality column of anion and cation exchange to achieve the separation of alkali, alkaline earths and transition metal ions, respectively. It involves matrix separation after sample dissolution by solvent extraction with TBP (tri butyl phosphate)-TOPO (tri octyl phosphine oxide)/CCl4. Interference of transition metal ions in the determination of alkali, alkaline earth metal ions are removed by using pyridine 2,6-dicarboxylic acid (PDCA) in the tartaric acid mobile phase. Mobile phase composition is optimized for the base line separation of alkali, alkaline earth and transition metal ions. Linear calibration graphs in the range 0.01–20 μg mL−1 were obtained with regression coefficients better than 0.999. The respective relative standard deviations were also determined. Recoveries of the spiked samples are within ±10% of the expected value. The developed method is authenticated by comparison with certified standards of UO2 and ThO2 powders.

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Abstract  

A single-column ion chromatography (SCIC) for the simultaneous determination of alkali, alkaline earth and transition metal elements in UO2, ThO2 powders and sintered (Th, U) O2 pellet is described in this paper. Metrosep cation 1-2 analytical column containing poly butadiene-maleic acid (PBDMA) coated silica has been applied to the ion chromatographic separation of 12 cations (copper, lithium, sodium, ammonium, nickel, potassium, zinc, cobalt, manganese, magnesium, calcium and strontium) using an isocratic elution with tartaric acid and oxalic acid as mobile phase with non-suppressed conductivity detection. Mobile phase composition was optimized to 1 mM tartaric acid and 0.75 mM oxalic acid for the baseline separation of 12 cations. The calibration plots were linear in the range of 0.05–40 mg L−1 with regression coefficients better than 0.998. The relative standard deviations (RSDs) of the retention time, peak area and peak height were less than 1, 2.8 and 3.0%, respectively. The recoveries of the spiked samples for the cations were 94–110%. The method developed was validated by comparison with certified standards of UO2 and ThO2 powders.

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Abstract  

Pyrohydrolysis is a fast, reliable and convenient method for the decomposition of solid refractory samples. Thoria based mixed oxide nuclear fuels requires more than 1,200 °C reaction temperature to lose its structural integrity so as to release the halides. In the present paper, we report WO3 accelerated pyrohydrolytic extraction technique for the separation of F and Cl from thoria based fuels along with the feasibility of using MoO3 and V2O5. The mechanism of extraction has been investigated in detail using X-ray diffraction and recovery studies. ThO2 along with its halides undergo high temperature solid state reaction with WO3 forming Th(WO4)2 and releasing the halides for their subsequent hydrolysis. The quantification was carried out by ion chromatography with suppressed ion conductivity detection. The average recoveries of the spiked samples for F and Cl were 93–99%. The method was successfully applied for simultaneous determination of F and Cl in thorium based nuclear fuel samples at 950 °C.

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Context

Bacoside A, a triterpenoid saponin, is a major constituent isolated from Bacopa monnieri (L.) Wettst. (Scrophulariaceae), used as a memory enhancer. Bacoside A and B are active ingredients in Bacopa herb and have antioxidant and hepatoprotective activities

Objective

A new rapid, simple, and economical high-performance thin-layer chromatographic (HPTLC) method was developed and validated for densitometric quantitative analysis of bacoside A in powdered leaves from different geographical regions of India.

Materials and methods

An amount of 10 mg mL−1 methanol extract of powdered leaves from different geographic regions was used for sample application on precoated silica gel 60 F254 aluminum sheets. Standard bacoside A (1 mg mL−1) was used for calibration curve. HPTLC separation was performed on percolated silica gel aluminum plate 60 F254 (20 cm × 10 cm with 0.2 mm thickness) as a stationary phase using ethyl acetate–methanol–water (4:1:1) as the mobile phase. Quantification was achieved by densitometric analysis at 598 nm over the concentration range of 500–4000 ng band−1.

Result

Compact and well-resolved bands for bacoside A from powdered leaves of different geographic regions were found at retardation factor (R f) 0.53 ± 0.02. The linear regression analysis data for calibration curve showed good linear relationship with regression coefficient r 2 = 0.9996 and r 2 = 0.99810 with respect to peak area and peak height. The method was validated for precision, recovery, and robustness as per the International Conference on Harmonization (ICH) guidelines. Variation in quantitative analysis of bacoside A in powdered leaves sample from different geographic regions was found by HPTLC method.

Discussion and conclusion

The highest and lowest content of bacoside A in powdered leaves sample from Jammu and Kerala regions, respectively. The variety of B. monnieri in Jammu is superior to other regions of India. The proposed developed HPTLC method can be applied for the quantitative determination of bacoside A in powdered leaves of plant and its formulation.

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