On the use of certified reference materials for assuring the quality of results for the determination of mercury in environmental samples

Ewa Bulska,Agnieszka Krata,Mateusz Kałabun,Marcin Wojciechowski

doi:10.1007/s11356-016-7262-4

Abstract

This work focused on the development and validation of methodologies for the accurate determination of mercury in environmental samples and its further application for the preparation and certification of new reference materials (RMs). Two certified RMs ERM-CC580 (inorganic matrix) and ERM-CE464 (organic matrix) were used for the evaluation of digestion conditions assuring the quantitative recovery of mercury. These conditions were then used for the digestion of new candidates for the environmental RMs: bottom sediment (M_2 BotSed), herring tissue (M_3 HerTis), cormorant tissue (M_4 CormTis), and codfish muscle (M_5 CodTis). Cold vapor atomic absorption spectrometry (CV AAS) and inductively coupled plasma mass spectrometry (ICP MS) were used for the measurement of mercury concentration in all RMs. In order to validate and assure the accuracy of results, isotope dilution mass spectrometry (IDMS) was applied as a primary method of measurement, assuring the traceability of obtained values to the SI units: the mole, the kilogram, and the second. Results obtained by IDMS using n(200Hg)/n(202Hg) ratio, with estimated combined uncertainty, were as follows: (916 ± 41)/[4.5 %] ng g−1 (M_2 BotSed), (236 ± 14)/[5.9 %] ng g−1 (M_3 HerTis), (2252 ± 54)/[2.4 %] ng g−1 (M_4 CormTis), and (303 ± 15)/[4.9 %] ng g−1 (M_CodTis), respectively. Different types of detection techniques and quantification (external calibration, standard addition, isotope dilution) were applied in order to improve the quality of the analytical results. The good agreement (within less than 2.5 %) between obtained results and those derived from the Inter-laboratory Comparison, executed by the Institute of Nuclear Chemistry and Technology (Warsaw, Poland) on the same sample matrices, further validated the analytical procedures developed in this study, as well as the concentration of mercury in all four new RMs. Although the developed protocol enabling the metrological certification of the reference value was exemplified by the determination of mercury in environmental samples, it could be considered as valid for any certification procedure required whenever new certified RMs are introduced.

Highlights

The quality of results is an important issue in a whole range of scientific disciplines, in which chemical measurements are necessary
The same digestion conditions were used for new reference materials called BMODAS^ CRMs
The determination of mercury was performed with the use of Cold vapor atomic absorption spectrometry (CV AAS), inductively coupled plasma mass spectrometry (ICP MS), and validated by isotope dilution mass spectrometry (IDMS) as a primary method of measurement

Summary

Introduction

The quality of results is an important issue in a whole range of scientific disciplines, in which chemical measurements are necessary. It has been recognized by those interested in environmentally related investigations that the quality of analytical results should be transparent and confident. It is important to deliver accurate results and to be able to show their traceability (Bulska 2009). Mercury was found to be one of the most toxic elements (Leermakers et al 2005; Lubick 2009), causing several symptoms related to polyneuropathy mercurialis, neuroasthemia, tremor mercurialis, and other (Harada et al 1999). Mercury pollution is an important issue that demands an ongoing development of analytical procedures to ensure its reliable determination.

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