Use of differential scanning potentiometry in pharmaceutical analysis.
The use of differential scanning potentiometry (DSP) to assay pure drugs and mixtures is illustrated through a set of model cases. The profiles obtained by scanning glycine (0.3 mmol), sulfanilamide (0.3 mmol), epinephrine (0.06 mmol), and norfloxacin (0.05 mmol) are reported, as well as the areas (A+, A-, and At) obtained in each scan. Such information is useful to assess identity and/or chemical purity and to get the pKa of the ionizing groups of the drugs. The degree of hydrolysis of a parenteral solution of procaine hydrochloride is also determined through DSP as an example of mixture assay. Comparison with conventional aqueous acid-based potentiometry shows that the new technique exhibits much better performance to assay small samples or samples carrying weak acidic and/or basic groups.
Manzo
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RH
Departamento de Farmacia, Facultad de Ciencias Quimicas, Universidad Nacional de Córdoba, Argentina.
Luna
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E
Allemandi
D A
DA
D002626:Chemistry, Pharmaceutical / Q000379:methods*; D004837:Epinephrine / Q000737:chemistry; D005998:Glycine / Q000737:chemistry; D015394:Molecular Structure; D009643:Norfloxacin / Q000737:chemistry; D011199:Potentiometry / Q000379:methods*; D011343:Procaine / Q000737:chemistry; D012996:Solutions; D000077145:Sulfanilamide; D013424:Sulfanilamides / Q000737:chemistry
D012996:Solutions; D013424:Sulfanilamides; D000077145:Sulfanilamide; D011343:Procaine; D009643:Norfloxacin; D005998:Glycine; D004837:Epinephrine