Capillary Chromatography - The Analysis of Neutral and Acidic Drugs by Capillary Column GC

The Analysis of Neutral and Acidic Drugs by Capillary Column GC

1. Ethosuximide 6. Pentabarbital 11. Phenobarbital
2. Barbital 7. Secobarbital 12. Methaqualone
3. Aprobarbital 8. Meprobamate 13. Primidone
4. Butobarbital 9. Carisoprodal  
5. Amobarbital 10. Glutethimide  

Courtesy of SGE Ltd.


Figure 33. The GC Analysis of Some Acidic and Neutral Drugs



The same stationary phase was used for the neutral and acidic drugs as (BPX35), as that used for the basic drugs, but with a different set of operating conditions.. Its strong capability to be polarized by strong polar groups on the solute lead to strong polar-induced polar interactions that provided good relative retention ratios between the different components of the mixture and thus more than adequate resolution. The column was 25 m long, 0.22 mm I.D. and carried a film of stationary phase 0.25 mm thick. The initial temperature was 100ûC which was raised to 300ûC at a rate of 10ûC/min.. A split injector was used (split ratio 20:1) to place the sample on the column. Helium was used as the carrier gas at an inlet pressure of 150 kpa. The detector employed was, again, an FID maintained at a temperature of 380ûC. The results obtained for the neutral-acidic drug mixture is shown in figure 33. It is seen that again an excellent separation of the drugs is realized, with baseline separation obtained between all the components. In this case the separation is achieved in less than 25 min. a more than satisfactory analysis time. In fact, however, it is likely with some method development to reduce this analysis time still further.