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Among cereals, rice is the second most cultivated staple crop in the world. It may be contaminated by toxic heavy metals present in water or soil. Therefore, monitoring the presence of heavy metals in rice and its products is a matter of a great importance from the nutritional and toxicological view. In this paper, a simple and effective analytical procedure based on dispersive micro solid-phase extraction with the use of oxidized multiwalled carbon nanotubes and batophenanthroline was developed for the determination of lead, cadmium, zinc, manganese and iron in white and wild rice samples. Due to the high preconcentration factor of 200, the optimized procedure allows obtaining detection limits between 0.13 and 0.35 ng mL −1 using flame atomic absorption spectrometry (FAAS). Novel preconcentration method can successfully be applied in food analysis with accuracy better than 7% rel. and repeatability lower than 3%. [ABSTRACT FROM AUTHOR]

Highlights: [•] Application of graphene (G) and graphene oxide (GO) in analytical chemistry. [•] Adsorption capacity of G and GO towards organic compounds and metal ions. [•] Application of G and GO in SPE, magnetic-SPE and SPME. [ABSTRACT FROM AUTHOR]

A method to determine zinc, yttrium and europium in luminophore type materials: ZnS:Cu+, ZnS:Ag+, Y2O2S:Eu3+ in solution is presented in this paper. Scattered radiation was used to correct for the influence of the acid matrix. The results obtained using the W Lα1 Compton scatter peak were compared with these obtained using the coherent scattered Lα1 and Lβ1 as well as the continuum measured near the lines of the analyte. To correct the matrix influence, equations with total mass attenuation coefficients were also applied. The best results were achieved with Compton scattered radiation and the continuum measured near the lines of the analyte. Preparation of the luminophore samples for X-ray fluorescence analysis involves digesting of 25 mg of sample in acid mixtures depending on the analyzed material. The analysis is conducted by the standard addition method. The results achieved are comparable to the results obtained by inductively coupled plasma atomic emission spectrometry. Relative standard deviations (R.S.D.) for zinc, yttrium and europium with contents of 65% Zn, 68% Y and 5% Eu amount to approximately 1%. [Copyright &y& Elsevier]

[Display omitted] • Ultrasensitive and selective determination/speciation of Se. • Reliable and highly precise analysis of the samples with complex matrix. • Wide range of applicability for various samples, i.e., water, beverages or foods. • Low detection limits of pg/mL using TXRF spectrometry. • Reduction of wastes and toxic reagents with the exclusion of organic solvent usage. The paper presents a new analytical procedure for the determination and speciation of trace and ultratrace selenium in water, beverages, seafood, milk, and vegetables. The developed method is based on the dispersive micro-solid phase extraction with the use of new thiosemicarbazide-incorporated graphene as a solid sorbent, in combination of the total-reflection X-ray fluorescence spectrometry (TXRF). As a result, we have created an auspicious analytical tool for fast and sensitive analysis of samples with a complex matrix. Regardless of the specimen type, the method is characterized by a very low detection limit of 1.7 pg mL−1 and high precision. The developed strategy allowed us to solve common problems associated with selenium loss during the sample preparation for the TXRF measurement and also improve its performance toward the analysis of beverages and high saline/solid samples, which may even be impossible to perform using standard sample preparation procedures for a TXRF measurement. [ABSTRACT FROM AUTHOR]

[Display omitted] • Highly selective and ultrasensitive determination of mercury ions. • Very low detection limits using benchtop EDXRF and TXRF instruments. • Simple and robust analysis of waters, beverages, seafood, plants, etc. • Green approach based on reducing the reagent usage and sample preparation time. The paper presents novel analytical methods for sensitive mercury determination in various samples, i.e., waters, beverages, seafood, plants, and biological samples. The procedure is based on selective preconcentration/separation of Hg(II) ions using graphene oxide/thiosemicarbazide in dispersive micro-solid phase extraction (DMSPE) and detection by energy-dispersive (EDXRF) and total-reflection X-ray fluorescence spectrometry (TXRF). The DMSPE/EDXRF and DMSPE/TXRF procedures are characterized by very high enrichment factors and low detection limits (LODs). DMSPE/TXRF allows obtaining LODs of 2.1 pg mL−1 for liquids and 1.8 ng g−1 for solid samples. In the case of DMSPE/EDXRF, the LODs are higher, 60 pg mL−1 for liquid and 73 ng g−1 for solid samples, due to the worse sensitivity of EDXRF measurement. The method was validated using spiked samples (water, apple juice, beer, wine) and certified reference materials (seawater, groundwater, wastewater, herring, cormorant and cod tissues, pig kidney, lobster, tobacco, scallion, celery, and spinach). [ABSTRACT FROM AUTHOR]

Controlling carbon and nitrogen chemistry is essential for human life and civilization. In particular, high-temperature combustion of carbon fuels in the air results in the formation of ecotoxic carbon and nitrogen oxides (NOx). Specifically, NOx needs to be removed from the flue gases of electric power stations. The selective catalyst reduction (SCR) systems support the deNOx (NOx removal) process; however, surface deposits deactivate the SCR system while operating. Moreover, the surface texture is damaged during the exploitation. We show here how this damage reveals itself in the pore landscape of the commercial SCR catalysts. In particular, for the first time, we showed how this could be assessed by a combination of thermoporometry (TPM) and gas physisorption. Accordingly, a correlation between the assessed quality of the pore landscape and the catalyst activity was determined and discussed. We designed a broad collection of new innovative regeneration procedures, which appear to be robust and selective methods for removing surface poisons. The optimal regeneration scheme fully restored the catalyst activity. [Display omitted] • New regeneration procedures for commercial SCR catalysts were designed and tested. • Selective method for removing catalyst poisons was developed. • Thermoporometry (TPM) is a new method for assessment of catalyst pore landscape. • Catalyst activity correlates with and TPM pore landscape. • A method for reconstruction of catalyst pore landscape was developed. [ABSTRACT FROM AUTHOR]

Microextraction techniques, both liquid-liquid and solid-phase microextraction, are becoming increasingly popular as a sample pre-treatment step mainly due to their simplicity and environmental-friendliness. Nevertheless, the small amount of the sample obtained after preconcentration step requires application of special measurement techniques and/or development of different strategies used for introduction of micro-samples into spectroscopic instruments and chromatographs. In this review the most recent approaches that have been applied for introduction of micro-amounts of samples into different measurement systems are presented. Advantages and disadvantages of developed sample introduction systems as well as new achievements in these approaches are discussed in detail. [ABSTRACT FROM AUTHOR]