Column quantitative

Residues of isoxaflutole, RPA 202248 and RPA 203328 are extracted from surface water or groundwater on to an RP-102 resin solid-phase extraction (SPE) cartridge, then eluted with an acetonitrile-methanol solvent mixture. Residues are determined by liquid chromatography/tandem mass spectrometry (LC/MS/MS) on a Cg column. Quantitation of results is based on a comparison of the ratio of analyte response to isotopically labeled internal standard response versus analyte response to internal standard response for calibration standards. 

Fig. 7 presents partial results of dynamic regime experiments for chromate adsorption and desorption by ODA-clinoptilolite. As shown by breakthrough curves, ODA-clinoptilolite column quantitatively removes chromate species from simulated waste water , apparently more efficiently by lower flow rate. Consequently to similar configuration of chromate and sulfate molecules, such loaded column was more efficient to regenerate with Na2S04 than NaCl solution, as elution curves at the Fig. 7 illustrate. 

TLC is the more popular of the two planar techniques. It is used for fast screening of mixtures and for surveying methods for use in columns. Quantitative analysis is better accomplished by column LC, but quantitative TLC is increasing in popularity as the instrumentation improves. Table 4 contains a summary of the advantages and disadvantages of the planar methods. 

Recovery from sequential extraction 93% LMW Se species eluted from preparative SEC were then separated on AE column, quantitative data for Se-Met, Se-Cys and inorganic Se HMW fraction from SEC (10D100 kDa) analyzed by GE Feasibility of ET-ICP-MS for specihc Se detection in protein spots demonstrated [62]... 

GC and CG-MS analysis of 1 single or 2-3 combined fractions on a strongly polar column. Quantitative results of individual components were based on tobacco stalk samples that were harvested from a single plot and steam distilled in one distillation run. 

In case of materials labelled with carbon-14 and/or tritium (Fig.l), after the additicn of a small amount of tungstic oxide to retain phosphoms and promote combustion, the sanple is burnt in a stream of oxygen. Halogens and sulfur are retained by silver wool, vhile the combustion products including HTO and carbon dioxide are led with the oj en stream caito a column of partially dehydrated alumina kept at 20CAi . The water is retained cn the column quantitatively, meamhile the carbon dioxide is transferred into an absorbent suitable for counting. The tritium (HTO) stored ten 5)orarily... 

A further development is the Dionex HPLC AS5A-SU analytical anion exchange column. Quantitation of all the anions in Figure 2.1(b) would require at least three sample injections under different eluent conditions. 

The low volatility of nonionic surfactants makes them challenging subjects for GC analysis. Even with the best of derivatization and high-temperature techniques, oligomers containing more than about 20 EO units will not elute from the GC column. Quantitative GC analysis of nonionics of higher degree of ethoxylation requires chemical reaction to put the sample into a more volatile form. 

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