Determination of nafcillin by room temperature phosphorescence

Room-temperature phosphorescence, as a very high selective and sensitive me thod, was applied to the determination of nafcillin in pharmaceutical prepa rations. The use of phosphorescence enhancer such as sodium dodecyl sulfate (micellar agent), thallium (I) nitrate (external heavy atom), and sodium s ulfite (deoxygenation agent) was studied and optimized to obtain maximum se nsitivity and adequate selectivity. The determination was performed in 0.09 2 M sodium dodecyl sulfate, 0.023 M thallium nitrate and 0.01 M sodium sulf ite. A pH value of 7.2 was selected as adequate for phosphorescence develop ment. The phosphorescence was totally developed in 15 min, after that the i ntensity was measured at lambda(ex) = 284 nm and lambda(em) = 540 nm. The r esponse 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 d etermined according to this theory. The specificity of the method was studi ed by adding excipients and other penicillins to a solution of nafcillin wi th the result that only two penicillins, methicillin and penicillin G proca ine, cause interference in the nafcillin quantification. The method has bee n validated with a fluorimetric method and HPLC method. A commercial pharma ceutical 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 ch romatography (HPLC); there was an excellent agreement between values obtain ed by all techniques. (C) 2000 Elsevier Science B.V. All rights reserved.