Element analytical protocols

Free-radical scavenger n-Butylamine nickel-2,2 -thio-bis-(4-t-octylphenolate) P, Ni, S 

Heat stabiliser Organotin mercaptides/sulfides/carboxylates antimony mercaptides metal carboxylates lead stearate/phosphite/phthalate/sulfate S, Sb, Sn, Ba, Ca, Cd, Mg, Sr, Zn P, Pb, S 

Flame resistance A1203, antimony oxides, boron compounds, halogen compounds, phosphate esters, metal hydrates, magnesium compounds, tin compounds, molybdenum compounds, silicones Al, B, Br, Cl, Mo, P, Sb, Si, Sn, Zn 

Filler/reinforcementi c Active fillerc Carbonates, glass fibres, Al(OH)3, kaolin, talc, silica, wollastonite, glass spheres, mica Al, Ca, Fe, Mg, K, Na, S, Si, Zr 

Magnetic properties Barium ferrite, iron oxide Ba, Fe 

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Of the 53 elements determined, 48 had useful values above the method detection limits. The data for As and Cr are shown as dotplots (Figs. 1 and 2) as examples of metals and metalloids that occur in both soluble and acid-resistant mineral phases. Dotplots highlight the varying analytical precision for each material and each analytical protocol. 

Figures 3 and 4 display what are known as, interaction plots , where the mean of triplicate analyses is plotted with respect to CRM and analytical protocol. Where all methods extract a similar amount of the element, the lines representing CRMs will be parallel. In cases where the lines cross, there is an interaction between the mineralogy of the CRM and the analytical protocols. For Cr, this latter effect is clearly demonstrated, whereas for As, the methods consistently extract proportionally similar amounts.

The details, beyond the model, are not presented, however, the key conclusions are for some of the elements there is no statistical difference between the standard Aqua Regia digestions analytical protocols and a significant difference for some elements with the EPA 3050B digestion. These differences are shown in the interaction plots of Figure 4. 

The major anions and cations in seawater have a significant influence on most analytical protocols used to determine trace metals at low concentrations, so production of reference materials in seawater is absolutely essential. The major ions interfere strongly with metal analysis using graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma mass spectroscopy (ICP-MS) and must be eliminated. Consequently, preconcentration techniques used to lower detection limits must also exclude these elements. Techniques based on solvent extraction of hydrophobic chelates and column preconcentration using Chelex 100 achieve these objectives and have been widely used with GFAAS. 

Hydride/vapour generation techniques provide extremely good sensitivity. When coupled to continuous flow methodologies for use in routine analysis, simple and reliable analytical techniques are provided. TTie extension of chemistries and sample transfer systems to provide analytical protocols to cope with a wider range of elemental analyses should be pursued in the search for lower detection levels. While multi-element techniques offer very low levels of detection, the use of specific single element analytical instruments with detection capabihties similar to those described above may be the best route for routine laboratories with high sample throughput. 

LA-ICP-MS was used for in situ determination of ultratrace elements in quartz. The analytical protocol included the following elements Al, Ba, Be, Cr, Ee, Ge, K, Li, Mg, Mn, Pb, Rb, Sr, Th, Ti and U . Apphcation of the LA technique to heterogeneous samples usually requires preparing a homogeneous glass by fusing with lithium borate . A difficulty encountered with multi-element LA-ICP-MS analysis is the absence of standards... 

It is not possible to prescribe specific pretreatment procedures here because these can only be decided upon when the system and the purpose of the experiments has been properly defined. However, a wealth of information exist in various biochemical reference books on how to isolate various biological compounds. The recommended techniques and methods could be used as part of the trace element speciation protocol often after slight modification, taking into consideration the following points First, the trace element blank levels have to be low, less than 10% of the total concentration in the sample. Second, the regents used should not interfere with subsequent analytical determinations. Third, the experimental conditions should not deviate markedly from those found in vivo, especially the pH and ionic strength of the medium. 

Analysis of major elements (except Si) and total phosphorus on bomb-digested samples was accomplished by inductively coupled plasma emission spectrometry (ICP, ARL model 34,000). Silicon was analyzed colorimetrically (14). Phosphorus in total digests was also determined colorimetrically by the method of Murphy and Riley (15), as modified by Erickson (16). To avoid interference from fluoride ion used in the digestion technique, sample volumes were restricted to <1.5 mL in the standard P analytical protocol. 

Quality assurance (QA) is an essential part of analytical protocols. Each laboratory is required to detect and correct problems in analytical processes and to reduce errors to agreed-upon limits. To produce data that have acceptable quality, all laboratory members must follow established guidelines and protocols. Some of the essential elements that must be included in a QA program are as follows ... 

Even a cursory perusal of any analytical journal will demonstrate the increasing importance of trace and ultra-trace analysis. And as instrumentation continues to develop, the definition of the term "trace element" will undoubtedly continue to change. Covering the composition and underlying properties of freshwater and marine systems, Analytical Measurements in Aquatic Environments provides the basis for understanding both. It discusses all aspects of analytical protocols from the handling of representative samples to the metrological evaluation of specific steps and whole procedures.The book covers ... 

Currently, the methods based on immunoassays are improved by introducing new analytical solutions (Dequaire et al., 2000 Dequaire et al., 2002 Blais et al., 2003 Hildebrandt et al., 2005 Dill et al., 2006 Nichkova et al., 2007) and miniaturizing analytical elements (Bannon et al., 2008 Wolbers et al., 2006a,b). The underlying objectives are to increase the sensitivity of the assays, to broaden the range of applications, and to simplify the analytical protocols. An attempt to replace radioactive... 

ICP-MS-coupled techniques are expected to increase in popularity, possibly leading to the commercial availability of ready-to-use speciation systems. Among the several approaches so far developed for species identification and quantification with ICP-MS detection in foods, some led to the establishment of sufficiently practicable and reliable analytical protocols for selected analytes/matrices. In a few cases, therefore, there is already the potential for validating routine control methods and this should facilitate the laying-down of species-specific regulations in the international legislation on trace elements in food. 

Agency (EPA) analytical protocols corresponding, for example, to Methods 200.8 (ICP-MS), 200.7 (ICP-AES) and 200 Series (FAAS) are well established standard methodologies for the elemental analysis of waters. Although at present super- ... 

For operationally defined parameters (e.g. extractable forms of elements using a specific extraction method), results are obviously linked to the methods used, which hence requires that these methods are standardized if comparability of data has to be ensured. This justifies standard methods for these parameters to be made mandatory. In this context, given that analytical results are directly linked to the analytical protocol, standard methods will represent a key element in the traceability chain. In other words, the traceability chain is broken if the protocol is not strictly followed (Quevauviller, 2004b). 

Bulk geochemical analysis Any analytical protocol used for ESR or luminescent dating that involves determining the concentrations for the important radioactive elements using geochemical techniques, such as NAA, XRF, etc. 

Development of simpler analytical methodology and commercial instrumentation. Elemental speciation analysis is not yet routine, due to lengthy and cumbersome analytical protocols. Moreover, many methods have been developed for expensive MS detectors, only available in a limited number of laboratories. Simple and low-cost... 

The performance of any analytical procedure must be assessed through analysis of certified reference materials. As geological materials are varied, often with complex heterogeneous matrices, artificially produced standards are seldom sufficient. Homogenized, certified standard reference materials are available for a wide range of rock, soil, mineral, and biomaterial types and must be used to validate analytical protocols. Interlaboratory comparisons of measurements of the elemental and isotopic composition of reference materials are frequently published in dedicated journals such as the Geostandards Newsletter. 

Operationally defined RMs in which the assigned or certified values are directly linked to the applied method. These materials involve parameters that are associated with a certain properties, e.g., leachable or mobilizable fractions of elements from soils and/or bioavailable fractions, or an activity (e.g., enzymatic activity). The values are defined by the applied method following a very strict analytical protocol (e.g., a standardized method). 

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