Determination of nafcillin by room temperature phosphorescence Original Research Article

Room-temperature phosphorescence, as a very high selective and sensitive method, was applied to the determination of nafcillin in pharmaceutical preparations. The use of phosphorescence enhancer such as sodium dodecyl sulfate (micellar agent), thallium (I) nitrate (external heavy atom), and sodium sulfite (deoxygenation agent) was studied and optimized to obtain maximum sensitivity and adequate selectivity. The determination was performed in 0.092 M sodium dodecyl sulfate, 0.023 M thallium nitrate and 0.01 M sodium sulfite. A pH value of 7.2 was selected as adequate for phosphorescence development. The phosphorescence was totally developed in 15 min, after that the intensity was measured at λex=284 nm and λem=540 nm. The response obtained was linear for the concentration range from 0.2 to 1.5 mg l−1. The detection limit, according to the error propagation theory was 0.18 mg l−1. The repeatability and relative standard deviation were also determined according to this theory. The specificity of the method was studied by adding excipients and other penicillins to a solution of nafcillin with the result that only two penicillins, methicillin and penicillin G procaine, cause interference in the nafcillin quantification. The method has been validated with a fluorimetric method and HPLC method. A commercial pharmaceutical preparation was successfully analyzed using this method. In order to determine the ability of the phosphorimetric method proposed, nafcillin in a pharmaceutical preparation was analyzed and the results were compared with the certificated values by turbidimetry and by high pressure liquid chromatography (HPLC); there was an excellent agreement between values obtained by all techniques.