Laboratory for Metrology in Chemistry, Semiconductor Physics Institute, A. Gotauto 11, LT-01108 Vilnius, Lithuania
A sector field high-resolution inductively coupled plasma mass spectrometry (ICP-MS) was developed for the determination of total amount of trace metals (Cd, Cr, Cu, Ni and Pb) in textiles after microwave-assisted acidic digestion of samples at 300 C for 28 min. Spectral interferences arising from the plasma gases or the major components of the samples were identified and removed. Detection limits of the studied analytes were between 0.5 1011 g/g for 208Pb and 8.5 1011 g/g for 110Cd. The method was applied to determine Cd, Cr, Cu, Ni and Pb in four textile samples using standard addition calibration technique. The accuracy of the proposed technique was checked against certified comparative reference material. Good agreement between the certified values and the concentrations measured was obtained.
Key words: inductively coupled plasma mass spectrometry, heavy metals, textile products
The major chemical pollutants on textiles are dyes containing carcinogenic amines and toxic heavy metals [1, 2]. Heavy metals can exist in natural structures of textiles or they can penetrate into the textiles during the production, dying process or via the protection agents used for the storage of these textiles. Furthermore, cotton, flax and hemp sometimes adsorb very large amounts of metals from the environment .
The basic requirements deciding whether textile products may be successfully commercialised are health and safety for the user, and harmlessness for the environment. People are often exposed to different allergenic and toxic chemicals coming from textiles due to daily contact with clothes, bed linen and similar products. Toxic effects of heavy metals on human health are very well known: damages of organs, disorders in the respiratory tract and lung diseases, dysfunction of heart, blood and blood producing organs, skin diseases and some others. Due to the toxicity of some heavy metals, the guidelines for tolerable amounts of these metals in textile products have been provided and are being adopted by countries all over the world .
Determination of the metal content of different textile materials is very important not only for the safety of consumers, but also for the textile industry. It is known that some metals present in cotton may contribute to problems in yarn manufacturing, bleaching and dyeing, and processing quality . Problems reported from dyeing processes are related to metal contribution to the light-induced yellowing of whitewashed denim. Transition metals catalyze organic reactions and function as mordants that strongly bind many organic compounds to cotton. The use of chromium-based dyes is essential for fast black-dyeing of wool and nylon . For this reason the textiles treated in those processes should be monitored for the presence of different metals, and their presence has to be reduced by applying different production methods .
Hence, much attention should be devoted to the development of a fast, reliable and sensitive method for the determination of toxic metals in textile materials. Several analytical techniques, such as anodic stripping voltametry , spectrophotometry , atomic absorption spectrometry  and X-ray fluorescence spectrometry  have been proposed for the determination of total or extractable amounts of heavy metals in textiles. Each method has its own merits, but generally they are laborious, time-consuming, not selective enough and often lack sensitivity.
Inductively coupled plasma mass spectrometry (ICP-MS) is a powerful technique for the measurement of ultratrace metals in a wide range of sample types . Virtually, all the elements can be measured, high sensitivity and low background signals combine to give very low detection limits (ng/L in most cases), and the measurement of a full set of elements takes only about few minutes per sample. Recently, laser ablation ICP-MS technique has been proposed for the examination of the metal content in historical textiles , but this non-destructive method permits only a semi-quantitative and comparative (the comparison of the intensity of peaks) analysis.
This paper describes the application of sector field high-resolution ICP-MS technique for the determination of total amounts of cadmium, chromium, copper, lead and nickel in textile products.
A double-focusing sector field ICP mass spectrometer Element2 of high resolution (Thermo Finnigan AB, Germany) was used for the measurements. Typical routine operating conditions are given in Table 1. The instrument has the capability to use three different resolution settings, m/Δm (10% valley definition): 300 (low-resolution mode); 4000 (medium-resolution mode) and 10000 (high-resolution mode).