Validation of a digestion procedure for ICP-AES and dynamic reaction cell ICP-MS for trace elemental analysis in environmental samples

Environ Chem Lett (2009) 7:381387 DOI 10.1007/s10311-008-0183-9

ORIGINAL PAPER

Validation of a digestion procedure for ICP-AESand dynamic reaction cell ICP-MS for trace elemental analysis in environmental samples

X. J. Yang G. K.-C. Low

Received: 3 June 2008 / Accepted: 1 October 2008 / Published online: 14 November 2008 Springer-Verlag 2008

Abstract Due to chloride polyatomic interferences, hydrochloric acid is not recommended for preparation of samples analysed by ICP-MS and separate digestion procedures are used for ICP-MS and ICP-AES. Here we demonstrate that a single digestion procedure using a mixture of HNO3 and HCl can be used for ICP-AES and dynamic reaction cell (DRC)-ICP-MS. Hotplate, block digester and microwave digestion were investigated. For a quantitative recovery of 26 elements including Ag, Sb and Ti from waters, soils and sediments, the nal concentration of 10% (v/v) HCl in the digest is required regardless of the digestion techniques. The method detection limits of 0.31.2 lg/L were obtained for chloride-interfering elements As, V, Cr and Se by DRC-ICP-MS using ammonia and oxygen as the DRC gas.

Keywords Sample digestion Chloride interferences

DRC-ICP-MS ICP-AES

Introduction

Inductively coupled plasma atomic emission spectrometry (ICP-AES) and inductively coupled plasma mass spec-trometry (ICP-MS) are powerful techniques for trace analysis of elements and the latter is preferred for ultra-trace levels due to its higher sensitivity. In general, an acid digestion, either using HNO3 alone or a combination of

HNO3 and HCl, rather than a total acid digestion, where

hydrouoric acid (HF) is used together with HNO3 ? HCl,

is sufcient for determining environmentally available

elements (USEPA 1996). The mixed acids (HNO3 ? HCl) digestion is commonly used for preparation of environmental samples of waters, wastewaters, sediments, sludges and soils for ICP-AES (USEPA 1994a; 1994b; American Public Health Association 2005), while the use of HCl is not recommended for sample preparation for ICP-MS (American Public Health Association 2005; USEPA 1996) due to chloride-based polyatomic ion interferences such as ClO, ClOH, ArCl and ClN (Tan and Horlick 1986). Consequently, separate digestion procedures using mixed acid (HNO3 ? HCl) and HNO3 only are recommended for ICP

AES and ICP-MS, respectively, and the extracts are not interchangeable between these two techniques (USEPA 1996). However, the reporting of a certain elements (e.g. Ag, Sb, V, Ni and Cu) is not...