Total Fluorescence and Zero-Crossing First-Derivative Synchronous Fluorescence Determination Of Acetylsalicylic Acid Metabolites in Biological Fluids

Principal component analysis-adaptive neuro-fuzzy inference systems (ANFISs) for the simultaneous spectrophotometric determination of three metals in water samples

A spectrophotometric method for the simultaneous determination of Al(III), Co(II) and Ni(II) using Alizarin Red S as a chelating agent was developed. The parameters controlling the behavior of the system were investigated and optimum conditions were selected. The presence of non-linearities was checked using Mallows augmented partial residual plots. To take into account these non-linearities, a principal component analysis-adaptive neuro-fuzzy inference systems (PC-ANFISs) method was used for the analysis of ternary mixtures of Al(III), Co(II) and Ni(II) over the range of 0.05-0.90, 0.05-4.05 and 0.05-0.95 microg mL(-1), respectively. Absorbance data were collected between 370 and 700 nm. The method was applied to accurately and simultaneously determines the content of metal ions in several synthetic mixtures.

Combined liquid and solid-surface room temperature fluorimetric determination of naproxen and salicylate in serum

A rapid and sensitive method for the determination of naproxen and salicylate in serum is presented. The employed strategy combines solid-phase extraction on a reverse-phase membrane with spectrofluorimetry. Solid-phase extraction under optimum pH conditions makes NX to be retained over the solid surface (where it is directly determined by a fluorimetric technique). Salicylate passes through the disk and is also fluorimetrically determined, but in solution. The linear calibration ranges for NX in the membrane and salicylate in solution were 0.014-0.250 and 0.010-0.250 microg ml(-1), respectively. The lowest value, in each case, is the corresponding limit of quantitation. The performance of the method is demonstrated with the successful determination of both drugs in spiked and real human serum samples.

Potentiometric determination of acetylsalicylic acid by sequential injection analysis (SIA) using a tubular salicylate-selective electrode

This paper deals with the development of an automated procedure for formulation assays and dissolution tests based on a sequential injection analysis (SIA) system involving an ion-selective electrode as sensing device. Construction of a tubular salicylate (Sal) selective electrode suitable for potentiometric determination of acetylsalicylic acid (Asa) in pharmaceutical formulations is described. The flow-through electrode is formed by a PVC membrane containing 29.2% (w/w) PVC, 5.8% (w/w) tetraoctylammonium salicylate (ionic sensor), 58.5% o-nitrophenyloctylether (plasticizer) and 6.5% (w/w) p-tert-octylphenol (stabilising additive which increases electrode selectivity). The calibration range is 0.05--10 mM Sal, the limit of detection (LOD) is 0.05 mM Sal, the slope is 56.0 mV per decade at 22 degrees C. The R.S.D. is 0.20% (15 readings) when determining 2.5 mM Sal in standard solution. The electrode is used for sensing Asa after its on-line chemical hydrolysis to Sal in a SIA system. The sampling rate is 6 h(-1) but for the dissolution tests the frequency is increased to 20 h(-1). The SIA set-up is employed for the assay of Asa in plain tablets, composed tablets and effervescent tablets and for performing dissolution tests of normal and sustained release tablets. Results obtained by this technique compare well with those required by the US Pharmacopoeia XXIV.