The pharmaceutical industry mainly uses chromatographic techniques such as high performance liquid chromatography (HPLC) and gas chromatography (GC), to determine the quantity of the active ingredients and other materials in the drugs. Quantitative proton-nuclear magnetic resonance technique (q-NMR) provides an alternative method for quantification of these drugs and a wide variety of other organic compounds. In this study quantitative analysis of three representative drugs � two analgesic drugs, acetaminophen and acetylsalicylic acid and one antihistamine, cetirizine dihydrochloride � were accomplished by q-NMR technique using simple organic compounds as internal standards in 300 MHz NMR instrument. Those internal standards were chosen whose proton-NMR spectrum did not interfere with the spectrum of the analyte. Two sets of concentrations of acetaminophen in deuterated dimethyl sulfoxide � ranging from 6.12 mM to 102 mM and 0.84 mM to 6.75 mM � were analyzed using ethanol as an internal standard in quintuplicate to show the robustness of the method. The peak area of three sets of protons in acetaminophen � methyl group peak and two sets of aromatic ring peaks � were quantified with respect to the methyl group peak area of the internal standard, ethanol. The calibration curves of peak area vs. concentration for both sets of concentrations and three different sets of protons showed linear relationship with regression values ranging from 0.9979 to 0.9998. More than half of the data showed percent standard deviation values under 1%, indicating that the data had high precision. The percent standard deviation values over 4% were seen for aromatic peaks of the three lowest concentrations, suggesting that methyl peak areas of acetaminophen should be used for analysis of low concentration solutions. Two sets of similar concentration of cetirizine dihydrochloride, (ethyl alcohol as internal standard in deuterated water), acetaminophen and salicylic acid (ethyl ether in deuterated methanol) were also analyzed with similar results.

Quantitative analysis of acetaminophen, acetylsalicylic acid, and cetirizine dihydrochloride by q-NMR (quantitative nuclear magnetic resonance) technique

247th National Meeting (2014)

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