Capillary Chromatography - The Analysis of Pharmaceutical Products

The Analysis of Pharmaceutical Products

 

Probably one of the most important applications of capillary columns is in the GC analysis of pharmaceutical products. Stringent specifications are placed on the purity and strength of pharmaceutical products and these are largely maintained with product monitoring by GC analysis. There are two basic classes of drugs for which analytical conditions have been developed and they are Basic Drugs and Neutral and Acidic Drugs. The two analytical methods will be discussed separately. The stationary phase used was BPX35 which is also a proprietary product of SGE Ltd. and consists of a dimethyl silicone polymer containing 35% of a phenyl derivative. This relatively high concentration of phenyl groups in the stationary phase, confers a strong interactive capacity for solute polar groups by induced dipoles. 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 325ûC at a rate of 5ûC/min.

The Analysis of Basic Drugs by Capillary Column GC

 

 

1. Benzocaine 6. Tripelennamine 11. Diazepam
2. Unknown 7. Amitriptylamine 12. Flurazepam
3. Meperidine 8. Tetracaine 13. Papaverine
4. Diphenylhydramine 9. Pyrilamine 14. Triazolam
5. Lidocaine 10. Unknown  

 

Courtesy of SGE Ltd.

 

Figure 32. The GC Analysis of Some Basic Drugs

 

 

The stationary phase used was BPX35 (also a proprietary product of SGE Ltd.) and consists of a dimethyl silicone polymer containing 35% of a phenyl derivative. The relatively high concentration of phenyl groups in this stationary phase, confers a strong interactive capacity for solute polar groups. 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 325ûC at a rate of 5ûC/min. A split injector was used (split ratio 20:1) and 0.5 ml of sample was placed on the column. Helium was used as the carrier gas at an inlet pressure of 150 kpa. The detector employed was an FID maintained at a temperature of 380ûC. The separation obtained is shown in figure 32

 

It is seen that more than adequate resolution of each drug was obtained and, thus, could be very useful for forensic purposes. The analysis time is a little long (cf 50 min.) but is, nevertheless acceptable considering the wide range of molecular types that are being separated. Some further method development might well reduce the analysis time significantly