M.I. Albero

Simultaneous determination of propacetamol and paracetamol by derivative spectrophotometry

A first-derivative spectrophotometric method for the simultaneous determination of propacetamol hydrochloride (PRO) and paracetamol (PA) is described. Measurements are made at the zero-crossing wavelengths at 242.0 for PRO and 239.0 nm for PA. The calibration graphs were linear up to 20.0 and 15.0 mg l(-1) of PRO and PA, respectively, the limits of quantification were 0.75 and 0.46 mg l(-1). The possible interfering effects of other substances were studied. The method was applied to determining the stability of PRO in ethanolic solutions and in glucose and saline parenteral solutions.

Flow-injection spectrophotometric determination of frusemide or sulphathiazole in pharmaceuticals

Two sensitive and fast flow-injection spectrophotometric methods are proposed for the determination of frusemide or sulphathiazole based on the formation of coloured complexes between these compounds and Pd(II) at pH 5.0 and 55 degrees C. Using the peak height as a quantitative parameter, frusemide or sulphathiazole was determined at 410 nm over the range 2.0 x 10(-5)-4.0 x 10(-4) M or 5.0 x 10(-5)-3 x 10(-4) M, respectively. The methods were applied to the determination of these sulphonamides in pharmaceuticals.

Flow-injection spectrofluorimetric determination of flufenamic and mefenamic acid in pharmaceuticals

Two sensitive and rapid flow-injection (FI) spectrofluorimetric methods are proposed for the determination of flufenamic acid (FF) and mefenamic acid (MF), based on the formation of complexes of these compounds with A1(III) in an ethanolic medium. The calibration graphs resulting from the measurements of the fluorescence at lambda exc = 351 nm and lambda em = 440 nm, and lambdaexc = 355 nm and lambda em = 454 nm for the complexes with FF and MF, respectively, are linear over the range 0.030-1.20 micrograms ml-1 for FF and 0.30-16.1 micrograms ml-1 for MF. The methods have been applied to the determination of these drugs in pharmaceutical preparations.

Flow-injection spectrophotometric determination of carbimazole and methimazole

Abstract A flow-injection method using spectrophotometric detection at 325 nm, is proposed for the determination of carbimazole or methimazole. The procedures are based on the formation of yellow complexes between these antithyroid drugs and Pd(II) in 0.5 M HC1. Methimazole or carbimazole are determined over the range 1 × 10 −5 −5 × 10 −4 M. The sampling frequency is 90 h −1 . The proposed methods are applied to the determination of methimazole or carbimazole in pharmaceuticals and methimazole added to human urine.

Determination of penicillamine or tiopronin in pharmaceutical preparations by flow injection analysis

Two flow injection analysis (FIA) methods, using spectrophotometric detection, are proposed for the determination of penicillamine or tiopronin [N-(2-mercaptopropionylglycine)]. The procedures are based on the formation of yellow complexes between these thiol-containing drugs and Pd(II), in a 1 M or 0.25 M HCl medium, respectively. With peak height as a quantitative parameter, penicillamine is determined over the range 1.0 x 10(-5)-7.0 x 10(-4) M; for tiopronin the range is 1.0 x 10(-5)-6.0 x 10(-4) M. The methods have been applied to the routine determination of the drugs in pharmaceutical preparations.

Determination of zinc (II) in pharmaceuticals based on a flow-through bulk optode.

A method based on flow injection (FI), was applied for the determination of Zn (II) using a flow-through bulk optode membrane that incorporates 1-(2-pyridylazo)-2-naphthol in a plasticized poly (vinyl chloride) membrane entrapped in a cellulose support. The calibration graph plotting the reflectance at 562 nm versus [Zn (II)] was linear in the range 0.16-3.27 mgl(-1) (2.5 x 10(-6)-5 x 10(-5) M) with a detection limit of 0.10 mgl(-1). The variation coefficients of the sensor response for 0.33 mgl(-1) of Zn (II) were +/-0.11% for consecutive measurements (n=10), +/-0.19% between days (n=5) and +/-0.22% between different membranes (n=6). The sensor can be readily regenerated with the same acetic/acetate carrier of pH 3.9. The FI method proposed was applied to the determination of zinc (II) in pharmaceuticals.

Spectrophotometric methods for the determination of cephradine or ceftazidine in human urine using batch and flow-injection procedures.

Sensitive and fast spectrophotometric methods for the determination of cephradine or ceftazidine in human urine, based on the formation of compounds between these drugs and Pd(II), are described. In the batch procedures the calibration graphs resulting from the measurement of the absorbance at 330 nm is linear over the range 5.0-60.0 micrograms. ml-1 for cephradine and 3.0-60.0 micrograms ml-1 for ceftazidine. The methods were successfully adapted to FI-systems, the peak heights being proportional to cephalosporin concentration over the range 5.0-60.0 micrograms ml-1 for cephradine and 3.0-60.0 micrograms ml-1 for ceftazidine. The sampling frequency was 60 h-1 with a sample injection of 72 microliters.

Kinetic methods for the determination of cadmium(II) based on a flow-through bulk optode.

Three kinetic methods based on flow injection, flow, and stopped-flow injection were applied for the determination of Cd(II) using a flow-through bulk optode membrane that incorporates 1-(2-pyridylazo)-2-naphtol (PAN) in a plasticized poly(vinyl) chloride membrane entrapped in a cellulose support. The calibration graphs plotting the reflectance at 560 nm versus [Cd(II)](1/2) for the first two methods and versus [Cd(II)] for the third were linear up to 56.2 mg l(-1). The detection limits of the methods were 0.01, 0.06 and 0.8 mg l(-1), respectively. The FI method was selected for application purposes. The variation coefficient of the sensor response for 11.2 mg l(-1) of Cd(II) was +/-0.31 and +/-0.65% between different membranes. The sensor can be readily regenerated with a carrier (acetic-acetate) buffer of pH 4. The FI method was applied to the determination of cadmium in an alloy and in water.

Flow-injection spectrophotometric determination of piroxicam

Two flow-injection analysis (FIA) methods are proposed for the determination of piroxicam. The first involves measurement of the UV absorbance of a solution containing the drug, methanol and hydrochloric acid at 332 nm; in the second method a Fe(III)-piroxicam complex is formed in a methanolic medium and the absorbance is measured at 520 nm. In both methods, the peak height is used as a quantitative parameter and piroxicam is determined over the ranges 0.5-15 and 30-500 microgram ml-1, respectively. The methods have been applied to the routine determination of the drug in dosage forms.

Flow-through bulk optode for the fluorimetric determination of perchlorate

A flow-through fluorescence bulk optode for the flow-injection determination of perchlorate is described. As the active constituents the optode incorporates the lipophilized pH indicator fluorescein octadecyl ester and methyl tridodecyl ammonium chloride, dissolved in a plasticized poly (vinyl) chloride membrane entrapped in a cellulose support. The optode is applied in conjunction with the flow injection technique for perchlorate determination at pH 4.5 (acetic-acetate). The sensor is readily regenerated with the pH 10.4 (TRIS) carrier solution. The analytical characteristics of this optode with respect to perchlorate response time, dynamic measurement range, reproducibility and selectivity are discussed. The proposed FI method is applied to the determination of perchlorate in waters from different sources.