Silane with nitrogen ions

Double barrel capillaries are silanized by introducing the silanizing vapor into one channel, while continuously flushing the other channel with nitrogen. The channel not silanized is later used for the outer reference electrode. The silanized channel is filled with the ion-selective cocktail as described previously. 

The drugs are held on the ion exchanger whereas the sample matrix materials pass through. The packing is then washed with 0.5 ml of 1.0M aqueous ammonium hydroxide and then two, 1 ml aliquots of 5% methanol in water. The sample is then desorbed by two separate aliquots of 1 ml of 0.22M ammonium hydroxide in pure methanol. Finally, the sample is collected in a silanized glass tube and the solvent removed by evaporation under stream of dry nitrogen. The volume of the sample is then made up to 250 pi and 100 pi placed on the column. The separation obtained is shown in figure 3. 

Low levels of ammonia in ethylene, hydrogen, and other light hydrocarbons in industrial processes can canse downstream catalytic poisoning, and an IMS system with a limit of detection of 1 ppb was used to monitor NHj in hydrocarbons. A wide variety of process streams was tested without any evident interference from coexisting compounds. In another report, NH3 in ethylene was measured by an IMS with a silane polymer membrane, Ni ion source, H+fHjOln reactant ion, and nitrogen as the drift and source gas. Because ethylene has no noticeable effect on the analytical results, preconcentration or preseparation were unnecessary. Ethylene s flammability was made inconsequential by the nitrogen atmosphere inside the spectrometer. Response to NH3 concentrations between 200 and 1,500 ppb was nearly Unear, and a calculated minimum detection limit was 25 ppb. 

---