N-(2-acetamido) iminodiacetic acid (ADA) belongs to Good’s buffer family. And pH range is from 6.0 to 7.2. ADA is practically insoluble in water. It will dissolve in the solution with a strong base, and forms complexes with various metal ions such as manganese ions and nickel ions. ADA buffer can be applied to protein crystallization, electrophoresis buffer and so on. Below we describe the use of ADA buffer for capillary electrophoresis separation and determination of amiodarone and desethylamiodarone [1].

Amiodarone is an anti-arrhythmic drug used to treat supraventricular and ventricular arrhythmias. It is widely considered to be the drug of choice for the treatment of tachycardia associated with Wolff-Parkinson-White syndrome. Amiodarone is metabolized via N-desethylation, and desethylated metabolite is detectable in the plasma of patients during long-term treatment. Since the therapeutic plasma concentration of amiodarone in plasma is in the range of 0.5-2.0 ug/ml, the determination of amiodarone and amiodarone for each individual must prevent toxic accumulation and discover maximum therapeutic effects. Pérez-Ruiz et al. [1] used MEKC capillary electrophoresis to separate and determine amiodarone and its metabolite.

The pH of the electrophoretic solution has an important effect on selectivity in capillary electrophoresis. It affects the electroosmotic flow in the capillary and the degree of dissociation of the analytes, and thus affects the electrophoresis mobility. At pH < 5, amiodarone and desethylamiodarone are completely protonated and could not be separated; at pH > 5, the above two compounds are hydrophobic and organic solvents are needed.

In the selection of electrophoresis buffers, Pérez-Ruiz et al. studied five different buffers, namely phosphate, borate, ADA, MES and HEPES, comparing each resoluiton at 15 mM, pH=6 and 7 in separation amiodarone and its metabolite. The results show that the ADA buffer exhibits the best resolution. Further study of the ADA buffer showed that the best resolution is that pH value is 7.5.

For the separation and determination of amiodarone and its metabolite, the above studies showed that the electrophoretic buffer with best resolution was ADA buffer which pH value is 7.5 and the concentration is 15 mM.

Reference:

[1] Pérez-Ruiz et al. Chromatographia, 2002, 56, 63-67.