Spectrophotometric and atomic absorption determination of ramipril, enalapril maleate and fosinopril through ternary complex formation with molybdenum (V)-thiocyanate (Mo(V)-SCN).
Three different sensitive and accurate spectroscopic procedures were developed for the determination of three angiotensin-converting enzyme inhibitors, namely, ramipril, enalapril maleate and fosinopril. The first two spectrophotometric (extractive and non-extractive) procedures were based on ternary complex formation with molybdenum(V) thiocyanate. The formed complex can be determined by extraction with chloroform measured at lambdamax 517 nm Beer's law was obeyed in the concentration range from (10--90 microg ml(-1)) for ramipril and fosinopril and (4--36 microg ml(-1)) for enalapril maleate with molar absorptivity 1.2x10(4), 2x10(4) and 3.4x10(4) l mol(-1) cm(-1), respectively, or by direct measurement after addition of benzalkonium chloride as surfactant and measuring the formed ternary complex at lambdamax 545 nm with a linear relationship in the concentration range from (8-7-2 microg ml(-1)), (3--27 microg ml(-1)) and (8--72 microg ml(-1)) for ramipril, enalapril maleate and fosinopril with molar absorptivity 1.5x10(4), 5x10(4) and 2.1x10(4) l mol(-1) cm(-1), respectively. The third procedure is atomic absorption measurement through the quantitative determination of molybdenum content of the complex. These methods hold their accuracy and precision well when applied to the determination of ramipril, enalapril maleate and fosinopril in their dosage forms.
Baraka
Mohamed Mohamed
MM
Medicinal Chemistry Department, Faculty of Pharmacy, Zagazig University, Zagazig, Egypt. m3baraka@yahoo.com
El-Sadek
Mohamed
M
Moussa
Ewais Moussa Mohamed
EM
Abd-Alaty
Nashat Mohamed Alanowar
NM
D000806:Angiotensin-Converting Enzyme Inhibitors / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid; D004656:Enalapril / Q000032:analysis*; D005079:Excipients; D017328:Fosinopril / Q000032:analysis*; D007202:Indicators and Reagents; D008982:Molybdenum / Q000737:chemistry*; D017257:Ramipril / Q000032:analysis*; D013054:Spectrophotometry, Atomic; D013056:Spectrophotometry, Ultraviolet; D013607:Tablets; D013861:Thiocyanates / Q000737:chemistry*
D000806:Angiotensin-Converting Enzyme Inhibitors; D005079:Excipients; D007202:Indicators and Reagents; D013607:Tablets; D013861:Thiocyanates; D004656:Enalapril; D008982:Molybdenum; D017257:Ramipril; D017328:Fosinopril