The Purity of Atropine

 A very common use of analytical isotachophoresis is in the analysis of drugs for purity and an interesting example of this type of application is the examination of the effect of sterilization on atropine impurities. Isotachopherograms of atropine samples poorly sterilized and correctly sterilized are shown in figures 24 and 25 respectively.

In the left hand side isotachopherogram the leading electrolyte contained the cation potassium⁺ and the counter ion acetate^- at a concentration of 0.01M. The pH was maintained at a value of 5.0 and an additive of hydroxyethylcellulose 0.25% was included. The terminating electrolyte contained the cation hydrogen⁺ and again the counter ion was acetate^- at a concentration of 0.01M. The pH was maintained at a value of 4.0 and there was no additive included. The eluted components of the sample (2.98 mmol of the drug) are labelled in the isotachopherogram. The isotachopherogram on the left shows the degradation products tropane and methylamine. The period of the analysis was 12 minutes. The production of tropane would indicate that the hydrolysis product tropanic acid should also be present and so a separate isotachophoresis experiment was carried out to identify this degradation product and the results of which are shown as the isotachopherogram depicted in the interpherogram on the right hand side of figure 25.

Figure 24. Isotachopherograms of Poorly Sterilized Atropine

Figure 25. Isotachopherograms of Correctly Sterilized Atropine

The leading electrolyte contained the anion chlorine⁺ and the counter ion hidtidine⁺ at a concentration of 0.01M. The pH was maintained at a value of 6.0 and an additive of hydroxyethylcellulose 0.25%. The terminating electrolyte contained the anion morpnine-ethane sulphonic^- acid ad the counter ion tris-hydroxyethylaminoimethane⁺ at a concentration of 0.05M. The pH was maintained at a value of 6.0 and there was no additive included. It was shown that as a result of poor sterilization the atropine content of the drug was reduced to 60%. Comparable isotachopherograms of correctly sterilized atropine are shown in figure 25. It is seen that there are no degradation products to be observed.

The leading electrolyte contained the anion chlorine⁺ and the counter ion hidtidine⁺ at a concentration of 0.01M. The pH was maintained at a value of 6.0 and an additive of hydroxyethylcellulose 0.25%. The terminating electrolyte contained the anion morphine-ethane sulphonic^- acid ad the counter ion tris-hydroxyethylaminoimethane⁺ at a concentration of 0.05M. The pH was maintained at a value of 6.0 and there was no additive included. It was shown that as a result of poor sterilization the atropine content of the drug was reduced  to 60%.