Development and Validation of an Analytical Method for Determination of Al, Ca, Cd, Fe, Mg and P in Calcium-Rich Materials by ICP OES.

Anna Szymczycha-Madeja,Monika Zabłocka-Malicka,Maja Welna,Pawel Pohl,Włodzimierz Szczepaniak

doi:10.3390/molecules26206269

Anna Szymczycha-Madeja, Monika Zabłocka-Malicka + Show 3 more

Open Access

https://doi.org/10.3390/molecules26206269

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Abstract

Four procedures based on closed-vessel microwave-assisted wet digestion with different oxidative reagents, including HNO3 (P1), HNO3 + H2O2 (P2), aqua regia (P3) and Lefort aqua regia (P4), for preparation of calcium (Ca)-rich materials prior to determination of total concentrations of Al, Ca, Cd, Fe, Mg and P by inductively coupled optical emission spectrometry (ICP OES) were compared. It was found that digestion with Lefort aqua regia (P4) provided the best results for all examined elements, i.e., precision of 0.30–4.4%, trueness better than 2%, recoveries of added elements between 99.5–101.9%, and limits of detection within 0.08–1.8 ng g−1. Reliability of this procedure was verified by analysis of relevant certified reference materials (CRMs), i.e., Natural Moroccan Phosphate Rock—Phosphorite (BCR-O32). Additionally, selection of appropriate analytical lines for measurements of element concentrations, linear dynamic ranges of calibration curves and matrix effects on the analyte response were extensively investigated. Finally, the selected procedure was successfully applied for routine analysis of other Ca-rich materials, i.e., CRMs such as NIST 1400 (Bone Ash), CTA-AC-1 (Apatite Concentrate Kola Peninsula) and NCS DC70308 (Carbonate Rock), and six natural samples, such as a dolomite, a phosphate rock, an enriched superphosphate fertilizer, pork bones, pork bones after incineration, and after steam gasification.

Highlights

Calcium (Ca)-rich materials mainly include phosphorite, apatite, dolomite and bones
The validity of the tested wet digestion method with solutions of HNO3 (P1), HNO3 + H2O2 (P2), aqua regia (P3) and Lefort aqua regia (P4) applied to prepare the Natural Moroccan Phosphate Rock certified reference materials (CRMs) (BCR-032) before spectrometric measurement was evaluated by choice of appropriate analytical lines and assessing linear dynamic ranges (LDRs) of calibration curves, matrix effects, limits of detection (LODs), precision and trueness of results
The LDRs of calibration curves were assessed for these lines on the basis of a series of simple standard solutions that were used to calibrate the inductively coupled optical emission spectrometry (ICP OES) instrument

Summary

Introduction

Calcium (Ca)-rich materials mainly include phosphorite, apatite, dolomite (sedimentary carbonate rock) and bones. The most important are those that contain phosphorus (P) in addition to Ca. Phosphorites (sedimentary rocks) and apatite rocks (volcanic sediments) are the two main raw materials used for production of P fertilizers [1,2]. Due to a high P content, the phosphorite is the most important source of this element for the European industry of phosphoric acid. The dolomite is manly used for production of fertilizers, ceramic and refractory materials [3,4]. Utilization of bones as fertilizers represents a valuable recycling strategy [5,6]. Bones or other by-products obtained from their rendering industry may serve as an additional source of P

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