Element specific chromatograms

Studied, these methods also require simultaneous UV detection of the HPLC eluents, followed by collection of those fractions of Interest for manual or automated Introduction into the ICP. These approaches are reminiscent of the HPLC-GFAA methods, and though producing semi-continuous HPLC-ICP element specific chromatograms, they are far from ideal or routine in operations. If the HPLC eluent can he continuously Introduced into a heated graphite rod or tube, with continuous pre-concentration and removal of solvent followed by continuous introduction of the analyte alone, this might he a practical approach. 

Element-specific chromatograms using an atomic emission detector (AED) have provided information on the types of additives in a variety of polymer extracts. The high resolution of capillary GC and the selectivity and sensitivity of the AED complemented mass... 

The availability of accurate mass measurements on all the peaks in each mass spectrum provides a very accurate and highly specific method for locating compounds of interest in such mixtures. This simply involves searching the data set for particular accurate masses (specific elemental compositions) versus scan number (chromatographic retention time) ie elemental composition chromatograms. 

After intravenous or oral administration of the drug, it undergoes several biotransformations that activate its toxicity (tumor cells as well as nephro- and neurotoxicity). A number of speciation studies that focused on characterization and quantification of parent drug and its possible metabohtes in vitro and in vivo have been reported. Element-specific ICP-MS detection has been applied after LC separation of platinum compounds. In Figure 6, the LC-ICP-MS chromatogram is presented, and this was obtained for the mixture of cancerostatic platinum compounds. ... 

Figure 1 Anion- and cation-exchange chromatograms of nitric acid digests of NRCC DORM 2 heated to different temperatures. An HP4500 inductively coupled plasma mass spectrometer was used as element-specific detector.

The identification of arsenic compounds using element-specific detectors in general is based on matching the retention time with known standards. This works perfectly as long as known standards are available. When unknown signals are obtained in a chromatogram, ICP-MS cannot provide any structural information and other detectors must be applied. 

Figure 6 Element specific detection by GC AED assisting in the interpretation of a complex GC-MS chromatogram from the analysis of a wastewater sample. Peaks 1, tribu-tylphosphoric acid 2, tris(2-chloroethyl)phosphate 3, hexachlorocycloh exane 4, tris(2-chloro-1-methyl-ethyl) phosphate 5, bis(2-chloro-l-methyl-ethyl)(2-chloropropyl)phos-phate 5, bromophos-ethyl and 7, tris(2-butoxyethyl) phosphate. (From Ref. 26.)...

One application involves the separation and measurement of rare earth species with IC-ICP-MS. A sihca-gel-based sulfonated cation-exchange column is used with a mixture of citric-hydroxyisobutyric acid as the mobile phase. Ion currents for each of the rare earth analytes are measured as a function of elution time to record a family of ion-specific chromatograms. This technique provides a means to eliminate several spectral isobaric interferences from rare earth oxides, hydroxides, and molecular hydrides on the analyte rare earth elements. For example, the isobaric interferences fiom the isotopes of Gd oxide and hydroxide on the primary isotopes ofYb and Lu were completely ehminated. In addition, the interference fiom the molecule, which directly interferes with the... 

Fig. 2.4. Chromatogram of a solution containing arsenite, arsenate, methylarsonic acid, dimethylarsinic acid, phenylarsonic acid, selenite, and phosphate recorded with an ARL 34000 simultaneous inductively coupled argon plasma emission spectrometer as the multi-element-specific detector [Hamilton PRP-1 resin-based reverse-phase column, Waters Associates Inc. Model 6000A high pressure liquid chromatograph, 0.1 ml injected flow rate 1.5 ml min", mobile phases 0.002 M aqueous HTAB at pH 9.6 to 250 sec, 99/1 (v/v) H2O/CH3COOH 250-1100 sec, 90/10 (v/v) H20/dimethylformamide 1100-1700 sec. ICP As 189.0 nm, P 241.9 nm, Se 203.9 nm, integration time 5 sec]. Redrawn from Spectrochimica Acta [11] by permission of Pergamon Press and the authors.

Temperatures reached are such that all elements can be detected by their emission lines. By choosing a line specific for one element, a selective chromatogram can be obtained for all compounds that contain this element. It is thus possible to search for classes of compounds corresponding to the association of many elements. This approach eliminates interferences due to sample matrices. 

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