Arsenic Table reference materials

Table II. XPS Binding Energies for Arsenic Reference Materials...

Schramel [103] discusses the conditions for multi-element analysis of over 50 trace elements, giving detection limits. Wolnik [104] described a sample introduction system that extends the analytical capability of the inductively coupled argon plasma/polychromator to include the simultaneous determination of six elemental hydrides along with a variety of other elements in plant materials. Detection limits for arsenic, bismuth, selenium and tellurium range from 0.5 to 3 ng/ml and are better by at least an order of magnitude than those obtained with conventional pneumatic nebulisers, whereas detection limits for the other elements investigated remain the same. Results from the analysis of freeze-dried crop samples and NBS standard reference materials demonstrated the applicability of the technique. Results obtained by the analysis of a variety of plant materials are presented in Table 7.10. 

The measurement of standard reference materials (SRMs) provides the best method for ensuring that an analytical procedure is producing accurate results in realistic matrices. Many SRMs are available (Govindaraju, 1994 Rasmussen and Andersen, 2002). The most widely used are those supplied by National Institute of Standards and Technology (NIST). Arsenic and selenium concentrations have been certified in a range of natural waters, sediments, and soils (Tables 4 and 5). The SLRS range of certified standards from the National Research Council of Canada also includes several river waters with much lower arsenic concentrations than the NIST standards ( 0.2-l pgL ). Certified standards for As(III)/As(V) and Se(lV)/Se(VI) speciation are available commercially (e.g., SPEX Certiprep speciation standards). 

From the given detection iimits it is obvious that in the past neutron activation anaiysis (NAA) was the most promising method for basic studies (e.g. Heydorn, 1984). This is aiso reflected in the literature particularly for the quite low normal arsenic levels in human materials (see data and references for Table 2). Despite the fact that this method is less used at present routinely it still is valuable as a reference method, and particularly useful for the certification of reference materials as a multielement approach (Van Renterghem et al., 1992). 

Loess refers to deposits of fine-grained wind-blown (eolian) sediments, which may accumulate up to 100 m thick. The material mostly consists of silt grains with perhaps 5-30% clay-sized particles and 5-10% sand (Benn and Evans, 1998), 291. Like other sediments, loess may contain considerable arsenic depending on the chemistry of its source rocks (Table 3.15). 

Because of differences in the solvents and chemical agents in CAIS materials and recovered chemical munitions, the RRS and MMD use different neutralization chemistries and produce different liquid waste streams—collectively referred to in this study as neutralent wastes or neutralents. A summary of nonstockpile CWM that will be treated by the RRS and MMD, as well as the major constituents of their neutralent waste streams, is given in Table ES-1. According to the Army, the maximum permissible concentration for blister agents in a neutralent stream is 50 parts per million (ppm) (although in practice the actual concentration is more likely to be about 1 ppm). The maximum for nerve agents is 20 to 30 parts per billion (ppb). RRS neutralents may contain arsenic, a toxic heavy metal that must be captured and immobilized. 

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