Spectral methods speciation analysis

An important improvement in the calculation procedure for species-specific multiple spiking was obtained by introducing isotope pattern deconvolution (IPD). The difference from the conventional multiple-spiking technique is the use of isotopic abundances instead of isotope ratios for calculation. The measurement of additional isotopes not used for calculation of interconversion reactions provides internal correction for mass bias effects without the application of an external isotopic standard, but also correction for spectral interferences. The basic equations applied in IPD can be found in the literature [78], This new method is predominantly applied in speciation analysis, but also in metabolism studies using stable isotopes [97, 98]. For quantification of elemental species, including... 

HPLC-QFAAS is also problematical. Most development of atomic plasma emission in HPLC detection has been with the ICP and to some extent the DCP, in contrast with the dominance of the microwave-induced plasmas as element-selective GC detectors. An integrated GC-MIP system has been introduced commercially. Significant polymer/additive analysis applications are not abundant for GC and SFC hyphenations. Wider adoption of plasma spectral chromatographic detection for trace analysis and elemental speciation will depend on the introduction of standardised commercial instrumentation to permit interlaboratory comparison of data and the development of standard methods of analysis which can be widely used. 

Advantages High analysis rate 3-4 elements per hour Applicable to many more metals than voltammetric methods Superior to voltammetry for mercury and arsenic particularly in ultratrace range Disadvantages Nonspecific absorption Spectral interferences Element losses by molecular distillation before atomisation Limited dynamic range Contamination sensitivity Element specific (or one element per run) Not suitable for speciation studies in seawater Prior separation of sea salts from metals required Suspended particulates need prior digestion About three times as expensive as voltammetric equipment Inferior to voltammetry for cobalt and nickel... 

Another technology for speciation of ammonium salts is based on differentiating their infrared spectral signatures (Johnson et al., 1983). This method offers fast response and non-destructive analysis but thus far its application has been limited to the laboratory which developed it. 

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