Estimation of Hg(II) in Soil Samples by Bioluminescent Bacterial Bioreporter ARL1, and the Effect of Humic Acids and Metal Ions on the Biosensor Performance.

Mercury is a ubiquitous environmental pollutant of dominantly anthropogenic origin. A critical concern for human health is the introduction of mercury to the food chain; therefore, monitoring of mercury levels in agricultural soil is essential. Unfortunately, the total mercury content is not sufficiently informative as mercury can be present in different forms with variable bioavailability.

A single-parameter logistic equation for fitting concentration-response curves from standard acute ecotoxicity assays.

A set of 69 concentration-response curves from 5 acute ecotoxicity assays was fitted with a 2-parameter logistic equation. High correlation between values of regression parameters suggested similar slopes of the curves. This enabled derivation of the empirical single-parameter logistic equation with the sole median effective concentration (EC50) parameter.

Effect of insignificant bias and its uncertainty on the coverage probability of uncertainty intervals Part 1. Evaluation for a given value of the true bias.

This paper investigates the coverage probability of the uncertainty intervals determined in compliance with the GUM and EURACHEM Guide, which are defined by expanded uncertainty U about the results uncorrected with the insignificant biases and corrected with the significant biases. This coverage probability can significantly fall below the chosen level of confidence in some cases as Maroto et al. discovered by using the Monte Carlo method.

Differential pulse polarographic determination of europium in the presence of humic substances.

Humic substances (HS) and other substance of similar nature ("building blocks" of HS, such as salicylates or phthalates) influence strongly a polarographic behaviour of europium at a mercury drop electrode. An addition of these substances into the supporting electrolyte causes an enhancement of the differential pulse polarographic (DPP) peak of Eu and an anodic shift of the maximum peak potential. It was deduced from the dependence of the peak height on the pulse time and from other experimental dependencies that an adsorption of the Eu-HS (salicylate, phthalate) complexes on the working electrode is the main mechanism responsible for the peak enhancement.

Attempts to include uncorrected bias in the measurement uncertainty.

In ISO Guide it is strictly recommended to correct results for the recognised significant bias, but in special cases some analysts find out practical to omit the correction and to enlarge the expanded uncertainty for the uncorrected bias instead. In this paper, four alternatively used methods computing these modified expanded uncertainties are compared according to the levels of confidence, widths and layouts of the obtained uncertainty intervals. The method, which seems to be the best, because it provides the same uncertainty intervals as in the case of the bias correction, has not been applied very much, maybe since these modified uncertainty intervals are not symmetric about the results.

Extraction-spectrometric determination of lead in high-purity aluminium salts.

Trace amounts of lead were determined in high purity aluminium salts (especially in ammonium aluminium sulfate) using inductively coupled plasma-optical emission spectrometry (ICP-OES) after extractive pre-concentration and matrix separation. Metals were extracted from the aluminium matrix in the form of chelates with ammonium pyrolidine dithoocarbamate into methyl isobutyketone. The organic extract was digested with nitric acid and hydrogen peroxide.

Effect of insignificant bias and its uncertainty on the coverage probability of uncertainty intervals Part 2. Evaluation for a found insignificant experimental bias.

This paper continues in studying the coverage probability of uncertainty intervals. It particularly investigates the uncertainty intervals determined in compliance with the GUM and EURACHEM Guide in case of the results uncorrected for the systematic error, since the experimental bias has been found insignificant. The problem is solved for known values of the experimental bias, its standard uncertainty and the overall standard uncertainty.