Analysis of children modelling clay (toy) using inductively coupled plasma-based methods

Dayara Virgínia Lino Ávila; Sidnei Oliveira Souza; Maria Graças A Korn; Amália G G Pessoa; Rennan G O Araujo

doi:10.1016/j.talanta.2018.05.083

Analysis of children modelling clay (toy) using inductively coupled plasma-based methods

Talanta. 2018 Oct 1:188:273-281. doi: 10.1016/j.talanta.2018.05.083. Epub 2018 May 25.

Authors

Dayara Virgínia Lino Ávila¹, Sidnei Oliveira Souza¹, Maria Graças A Korn², Amália G G Pessoa¹, Rennan G O Araujo³

Affiliations

¹ Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Salvador, Bahia 40170-115, Brazil.
² Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Salvador, Bahia 40170-115, Brazil; Instituto Nacional de Ciência e Tecnologia do CNPq - INCT de Energia e Meio Ambiente, Universidade Federal da Bahia, Salvador, BA, Brazil.
³ Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Salvador, Bahia 40170-115, Brazil; Instituto Nacional de Ciência e Tecnologia do CNPq - INCT de Energia e Meio Ambiente, Universidade Federal da Bahia, Salvador, BA, Brazil. Electronic address: rgoa01@terra.com.br.

PMID: 30029376
DOI: 10.1016/j.talanta.2018.05.083

Abstract

This work proposes the application of a Doehlert design to optimize dilute HNO₃ and H₂O₂ concentrations employed for the digestion of samples of modelling clay for children (used as toy). Inductively coupled plasma-based (ICP) methods were employed to determine 22 inorganic constituents (Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, S, Sb, Se, Sr, V and Zn) in children's modelling clay samples. The limits of quantification (LoQ) obtained were between 0.003 mg kg^-1 (Cd, Co and Sb) and 0.54 g kg^-1(Ca) employing ICP-based methods. The accuracy and precision of the methods were evaluated by analysing the certified reference materials (CRMs) oyster tissue (NIST 1566b), rice flour (NIST 1568b), peach leaves (NIST 1547) and tomato leaves (NIST 1573a), along with addition and recovery tests. The children's modelling clay samples presented concentrations of As, Ba, Cd, Cr, Pb, Sb and Se in agreement with the maximum values established by National Institute of Metrology, Quality and Technology (Instituto Nacional de Metrologia, Qualidade e Tecnologia - INMETRO). However, for other elements it were obtained concentrations within the following ranges: Al (0.83 ± 0.12-2.91 ± 0.04 g kg^-1), Ca (16.09 ± 0.20-24.56 ± 1.00 g kg^-1), Cu (< 0.30-30.01 ± 2.11 mg kg^-1), Fe (< 5.3 - 13.21 ± 3.94 mg kg^-1), K (1.31 ± 0.33-33.47 ± 0.75 g kg^-1), Mg (0.90 ± 0.04-1.36 ± 0.05 g kg^-1), Mn (3.32 ± 0.10-121.05 ± 1.88 mg kg^-1), Na (12.07 ± 0.88-36.77 ± 0.50 g kg^-1), Sr (4.23 ± 0.47-22.43 ± 6.95 mg kg^-1), P (1.00 ± 0.13-57.43 ± 0.88 g kg^-1), V (0.25 ± 0.07-1.15 ± 0.19 mg kg^-1), S (3.57 ± 0.77-48.49 ± 1.02 g kg^-1), Zn (< 4.4-11.82 ± 0.49 mg kg^-1), Co (0.020 ± 0.002-0.060 ± 0.020 mg kg^-1) and Ni (< 0.03-1.33 ± 0.46 mg kg^-1). These elements have no minimum and maximum limits established by legislation for children's modelling clay so, a comparison was not possible. The ICP-based methods presented an efficient routine application in the analysis of modelling clay.

Keywords: Children's modelling clay (toy); Experimental design; ICP OES; ICP-MS; Mineral composition.