Miguel Angel Bello

Determination of paracetamol in dosage forms by non-suppressed ion chromatography.

An ion-chromatography procedure for the simultaneous determination of paracetamol and salicylic acid without suppression using UV detection is proposed. The method is applied to the determination of paracetamol in pharmaceuticals and also permits the quantitation of the total acetylsalicylic acid as salicylic acid.

Electrochemical reduction of cefminox at the mercury electrode and its voltammetric determination in urine

The electrochemical behaviour of cefminox in phosphate buffers solutions over pH range 2.0-9.0 using differential-pulse polarography, DC-tast polarography, cyclic voltammetry and linear sweep voltammetry (staircase) has been studied. In acidic media, a non reversible diffusion-controlled reduction involving two electrons occurs and the mechanism for the reduction was suggested. A differential-pulse polarographic method for the determination of cefminox in the concentration range 5.8x10(-6)-6.0x10(-5) M with a detection limit of 1.76x10(-6) M was proposed. Also, a method based on controlled adsorptive pre-concentration of cefminox on the hanging mercury drop electrode followed by linear sweep voltammetry, allows its determination in the concentration range 8.3x10(-8)-1.5x10(-6) M with a detection limit of 2.47x10(-8) M. These methods have been used for the direct determination of cefminox in human urine with recoveries between 98 and 103%, and precision around +/-2%.

Determination of beta-blocker drugs in pharmaceutical preparations by non-suppressed ion chromatography

A rapid and feasible chromatographic method for determining atenolol, metoprolol, alprenolol, oxprenolol, acebutolol and propranolol by non-suppressed ion chromatography is proposed. The mobile phase consisted of 50 mM nitric acid in an aqueous solution of 4% (v/v) acetonitrile. Detection limits are in the range 0.1-2.7 mg l-1. The method was successfully applied to the determination of beta-blockers in several pharmaceutical formulations.

Kaolin fractal dimension. Comparison with other properties

Abstract The fractal dimension values of several kaolins with different structural order and properties have been calculated from N2-adsorption isotherm data according to the Neimark method. All kaolins show a fractal regime in the same nitrogen relative pressure range, with fractal dimension values ranging between 2.38 and 2.57. The correlation between fractal dimension and other kaolin characteristics (structural order of kaolinite, BET surface area, brightness and particle-size distribution) was determined. The correlation matrix shows that the fractal dimension (Ds) is highly correlated with the degree of structural order-disorder and is also moderately correlated with the particle-size distribution and brightness. No correlation was observed between BET and Ds, probably because the first is a measurement of the accessible surface while Ds represents the scaling properties of the area. As Ds is a parameter easily calculated and related to the degree of surface heterogeneity, and well correlated with other kaolinite parameters, it can be used to estimate a set of kaolin technical properties for suitability of the kaolin in the paper industry.

Electrochemical oxidation at carbon paste electrode of tacrine and 1-hydroxytacrine and differential pulse voltammetric determination of tacrine in pharmaceuticals and human urine

The electrochemical oxidation of tacrine and its 1-OH-metabolite, has been studied by cyclic voltammetry and differential pulse voltammetry by using carbon paste electrodes. The peak current-concentration relationship was found to be linear up to 20 micrograms ml-1 with detection limits of 0.06 microgram ml-1 for tacrine and 0.18 microgram ml-1 for 1-OH-tacrine and quantitation limits of 0.20 microgram ml-1 for tacrine and 0.37 microgram ml-1 for 1-OH-tacrine. A method for determining tacrine by differential pulse voltammetry in pharmaceuticals and human urine, in the presence of 1-OH-tacrine, has been developed.

Spectrofluorimetric determination of cisatracurium and mivacurium in spiked human serum and pharmaceuticals

Spectrofluorimetric methods to determine cisatracurium and mivacurium are proposed and applied to the determination of both substances in human serum and to the determination of mivacurium in pharmaceuticals. The fluorimetric methods allow the determination of 5-500 ng ml(-1) of mivacurium in aqueous solutions and 5-500 ng ml(-1) of cisatracurium in water-acetonitrile solutions, both containing acetic acid-sodium acetate buffer (pH 5.5) with lambda(exc)=230 nm and lambda(em)=324 nm.

Spectrofluorimetric determination of tacrine in pharmaceuticals and spiked human serum

A spectrofluorimetric method to determine tacrine is proposed and applied to the determination of tacrine in human serum and pharmaceuticals. The fluorimetric method allows the determination of 1-70 ng ml-1 of tacrine in aqueous solutions containing acetic acid-sodium acetate buffer (pH 5.6) with lambda exc = 242 nm and lambda em = 362 nm.

Spectrofluorimetric determination of acrivastine in spiked human urine and pharmaceuticals

A spectrofluorimetric method to determine acrivastine is proposed and applied to its determination in human urine and pharmaceuticals. The fluorimetric method allows the determination of 58-2000 ng ml(-1) of acrivastine in aqueous solutions containing acetic acid-sodium acetate buffer (pH 6.5) with lambda(exc)=230 nm and lambda(em)=380 nm.

Determination of heavy metals in estuarine sediments by acid digestion and atomic absorption spectrometry

A method for the determination of environmentally significant elements in estilarme sediments is presented. Samples were digested with a mixture of nitric, perchloric and hydrofluoric acids in closed PTFE vessels without metallic mantle. Cadmium, chromium, copper, manganese, nickel, lead and zinc were determined by atomic absorption spectrometry. Good recoveries were obtained by analyzing those elements in reference sediments. Samples of estuarine sediments from Odiel river (southwest of Spain) were analyzed.