Ewa Niewiara

Determination of trace arsenic on hanging copper amalgam drop electrode

Hanging copper amalgam drop electrode has been applied for trace determination of arsenic by cathodic stripping analysis. Detection limit for As(III) as low as 0.33nM (0.02mug/L) at deposition time (240s) could be obtained. For seven successive determinations of As(III) at concentration of 5nM relative standard deviation was 2.5% (n=7). Interferences from selected metals and surfactant substances were examined. Absence of copper ions in sample solution causes easier optimization and makes method less vulnerable on contamination. The developed method was validated by analysis of certified reference materials (CRMs) and applied to arsenic determinations in natural water samples.

Influence of the Electrolyte on Triton X-100 Adsorption on Fumed Silica

Fumed silica was used for adsorption of Triton X-100 from electrolyte solutions. Influence of such parameters as the kind of fumed silica and its pretreatment, pH, ionic strength and ionic composition of solution on the process of surfactant adsorption has been studied using differential capacity measurements at a controlled growth mercury drop electrode. The kinetics of Triton adsorption on silica have also been studied. It was found that under optimal conditions 0.1% of fumed silica removes completely 5 ppm of Triton X-100 in time shorter than 1 minute.

The determination of molybdenum in selected mushrooms by stripping voltammetry

The highly sensitive method of adsorptive stripping voltammetry (AdSV), with differential pulse steps, was performed at a mercury film electrode and has been applied here for the determination of trace molybdenum content in selected wild mushrooms. Fruiting body caps of 12 selected macrofungi species from Basidiomycetes have been investigated. Molybdenum content of investigated samples was determined in the range of 0.006 to 0.38 mg kg−1 of dry matter. The highest value of molybdenum content was found in Leccinum rufum and the lowest in Lactarius deliciosus.

Potentiometric Titration of Industrial Samples—End‐point Detection by Means of Wavelets

A continuous wavelet transform with a specially defined dedicated mother wavelet is applied for data treatment as a signal‐processing tool in a potentiometric titration. The inflection points of the titration curve are localized in one step of the calculations. The imperfection of signal, random noise, or spikes has no influence on the operation of the procedure. The proposed algorithm does not require any prior information about the nature or the type of analyte and/or the shape of the titration curve. Although the optimization of transformation parameters should be done, they may be chosen from a wide interval.The accuracy and precision of the proposed end‐point estimation is examined on several simulated curves and instrumental potentiometric titrations. Under normal working conditions, analyte concentrations with variation coefficients between 1% and 5% have been determined. The procedure based on the wavelets provides an objective criterion for the determination of the end point. It can be reproduced...

Signal Processing in DP and NP Voltammetry by Means of a Dedicated Mother Wavelet

In the paper the new signal processing method which utilizes the continuous wavelet transform and especially defined a dedicated mother wavelet is proposed. In the definition knowledge of the ideal signal shape in the considered problem is used. The application of this algorithm in transformation of curves recorded by means of differential pulse voltammetry (DPV) and normal pulse voltammetry (NPV) is described. Transformation of the signals, elimination of noise, baseline correction and separation of overlapping data can be achieved in one step by means of the proposed procedure. Due to linearity of wavelet transform (WT) the whole process of quantitative determination of analyte may be realized in the wavelet coefficients space.

Chemometric Tools in Environmental Data Analysis

Chemometric analysis of the Dobczyce Reservoir sediments is presented herein. The sediments have been sampled at 17 points, dried, digested and quantitatively analyzed for 12 elements, covering a three‐year period (2004–2006). Substantial variations in composition due to the hydrological and environmental reasons were found. The use of mathematical and statistical tools enables objective and effective analysis of obtained data.