Adolfo Cid | Basque Government (original) (raw)

Papers by Adolfo Cid

Journal of Thermal Analysis, 1996

Thermal decomposition of various synthetic manganese oxides (MnO, Mn3O4, Mn2O3, MnOOH) and a natu... more Thermal decomposition of various synthetic manganese oxides (MnO, Mn3O4, Mn2O3, MnOOH) and a natural manganese dioxide (MnO2) from Gabon was studied with the help of termogravimetry in inert, oxidizing and reducing atmospheres. The compounds were characterized by XRD and electrochemical activity was tested by cyclic voltammetry using a carbon paste electrode. The natural manganese dioxide showed the best oxidizing and

Analytica Chimica Acta, 1999

An electroanalytical study of timolol in Britton±Robinson buffer is described. The reduction proc... more An electroanalytical study of timolol in Britton±Robinson buffer is described. The reduction process on the hanging mercury drop electrode gives rise to two adjacent peaks above À1.0 V (versus Ag/AgCl), the latter on the background discharge, within the entire pH range studied (1.8±10.5), the polarographic pK a value obtained was 6.75. The results proved that the reduction of timolol is irreversible and the limiting current is adsorption controlled. The dependence of the peak current on concentration was studied by means of different polarographic and voltammetric techniques. Using adsorptive stripping square wave voltammetry (AdS-SWV), the height for the ®rst peak was proportional to the concentration of timolol in two linear ranges: 1.0Â10 À9 to 1.2Â10 À8 M and 1.2Â10 À8 to 1.1Â10 À7 M, the 3' detection limit being 6.6Â10 À10 mol l À1. For square wave polarography (SWP) the linear range and the detection limit were 4.0Â10 À8 to 3.0Â10 À6 M with two different slopes and 2.5Â10 À8 M, respectively. A mechanism is proposed for the reduction of timolol. Two procedures, based on SWP and AdS-SWV, were developed for the determination of timolol in ophthalmologic drops.

Ecotoxicology, 2006

Acute pass/fail, multi-concentration tests, and 3-brood chronic toxicity tests with Daphnia magna... more Acute pass/fail, multi-concentration tests, and 3-brood chronic toxicity tests with Daphnia magna Straus (Cladocera, Crustacea) were used to characterise industrial and municipal effluents from various sources. The effluents that ''passed'' the pass/fail tests had 48-h EC 50 values >100% and reproduction No Observed Effect Concentration (NOECs) ‡100%, except for one effluent that had a reproduction NOEC of 31.6%. The acute multi-concentration toxicity tests allowed a rapid classification of effluents from Very Toxic (48-h EC 50 < 25%), to Non-Toxic (48-h EC 50 >100%). The acute-to-chronic ratio (ACR: 48-h EC 50 divided by the NOEC for reproduction) in the studied effluents ranged from 5 to about 100. From these results, we propose a step-wise protocol for assessing effluent toxicity. First, effluent is evaluated by means of simple and rapid pass/fail acute toxicity tests, to discriminate Non-Toxic from potentially Toxic effluents, thus facilitating the establishment of priority actions. Second, 48-h EC x is estimated to classify effluents on a toxicity scale from Non-Toxic to Very Toxic. Third, chronic multi-concentration tests are used to calculate reproduction NOECs. These parameters combined with data on effluent chemical composition, chemical and hydrological characteristics of receiving waters, and biological quality criteria can be jointly used for more rational regulatory practices and risk assessment of effluents.

Environmental Technology, 1998

The results from a study of the presence and temporal variability of linear alkylbenzenes (LABs) ... more The results from a study of the presence and temporal variability of linear alkylbenzenes (LABs) and polychlorinated biphenyls (PCBs) in sewage sludge are presented in this work. The sewage sludges, with anaerobic treatment, were originated in the Arazuri (Pamplona, Spain) wastewater primary treatment plant, which receives urban and industrial wastewaters. The organic pollutants extracted from the sewage sludge by a Soxhlet apparatus. Then, PCBs and LABs were separated from the rest of the pollutants on a chromatographic column. Some different detectors were flame ionization (FID), electron capture (ECD) and mass spectroscopy (MS). The results showed that LABs concentration varied between 1.4 and 73.0 mg kg−1 dry matter (d.m.). PCBs appear in smaller quantity, between 0.050 and 0.929 mg kg−1 (d.m.). The factor analysis of the results allowed verification of the different origin of PCBs and LABs.

… of Chromatography A, 2000

Capillary zone electrophoresis (CZE) was adapted to the simultaneous determination of a mixture o... more Capillary zone electrophoresis (CZE) was adapted to the simultaneous determination of a mixture of three imidazolic antifungal drugs. Separation was achieved by using a fused-silica capillary column with an acetic acid-Tris buffer at pH 5.18 and UV detection at 196 nm. Several electrophoretic parameters were investigated: pH and buffer concentration, applied voltage, temperature and injection conditions. The optimized CZE method was applied to the individual determination of ketoconazole, clotrimazole and econazole in pharmaceutical forms, after a previous single extraction step in methanol, with recoveries of 98.00, 99.96 and 99.58% respectively. The antifungal drugs can be determined at a concentration level lower 27 than 1.0?10 M.

The Science of the Total …, 1998

Ž. A simple chromatographic method, proposed by Aceves et al. 1988 , for the determination of ali... more Ž. A simple chromatographic method, proposed by Aceves et al. 1988 , for the determination of aliphatic hydrocar-Ž. bons and polyaromatic hydrocarbons PAHs was used. The results from a study of the presence and temporal Ž. variability of the aliphatic hydrocarbons and polyaromatic hydrocarbons PAHs in sewage sludge are shown in this Ž. work. The sewage sludges originated from the Arazuri waste water treatment plant site in Pamplona Spain. The organic pollutants have been extracted from the sewage sludge by a Soxhlet apparatus. Aliphatic hydrocarbons and Ž. PAHs are separated from the rest of the pollutants on a chromatographic column. Flame ionization FID and mass Ž. spectroscopy MS detectors have been used. The results showed that aliphatic hydrocarbons concentration varied y1 Ž. between 230 and 1420 mg kg dry matter DM. The PAHs appeared in smaller quantitie of between 128 and 482 y1 Ž. mg kg DM. The factor analysis of the results allowed us to verify the different origin of the aliphatic hydrocarbons and the PAHs.

Analytica Chimica Acta, 1997

Terbinafine is adsorbed on a hanging mercury drop electrode at pH 6.0 and gives a single wave at ... more Terbinafine is adsorbed on a hanging mercury drop electrode at pH 6.0 and gives a single wave at −1.47 vs.AgAgCl reference electrode, due to olefinic double bond reduction. The electrochemical process is irreversible and fundamentally controlled by adsorption. A systematic study of the several instrumental and accumulation variables affecting the adsorptive stripping (AdS) response was carried out using square wave

… of pharmaceutical and …, 1999

A sensitive method was developed to determine Prazosin using a nafion modified carbon paste elect... more A sensitive method was developed to determine Prazosin using a nafion modified carbon paste electrode (NMCPE). Prazosin was accumulated at a potential of 750 mV in Britton-Robinson buffer (pH 6.0) and then a negative sweep was made obtaining a cathodic peak close to 0 V. Cyclic voltammetric studies indicated that the process was quasi-reversible, and fundamentally controlled by adsorption. To obtain a good sensitivity, the instrumental and accumulation variables were studied using differential pulse voltammetry (DPV). Adsorptive voltammetric peak currents showed a linear response for Prazosin concentrations in the range between 4.0 × 10 − 11 and 4.0× 10 − 8 M with two different slopes, and a detection limit (LOD) of 3.1 × 10 − 11 M was obtained. The variation coefficient (CV) for a 8.0 × 10 − 10 M solution (n=10) was 4.08%. A spectrophotometric study of Prazosin was also carried out and two absorption bands were obtained at 246 and 329 nm (pH 1.8). The band at 329 nm was pH-dependent and its height and position changed with the pH values, so this allowed the pK a % determination (7.14 9 0.20) using different methods. The detection limit reached by means of UV-spectrophotometry was 0.9 ×10 − 7 M, and the variation coefficient for 1.5 × 10 − 5 M Prazosin solutions was 1.14% (n= 10). Although the sensitivity of the UV-spectrophotometric method was lower than that obtained using adsorptive stripping-differential pulse voltammetry (AdS-DPV), it could be applied to the determination of Prazosin in Minipres tablets. The voltammetric method was used for the determination of the drug in human urine samples at trace levels with good recoveries.

The Analyst, Sep 1, 1997

Page 1. Cathodic Stripping Voltammetric Determination of Doxazosin in Urine and Pharmaceutical Ta... more Page 1. Cathodic Stripping Voltammetric Determination of Doxazosin in Urine and Pharmaceutical Tablets Using Carbon Paste Electrodes Adela Arranz, Susana Fernández de Betono, José M. Moreda, Adolfo Cid and Juan ...

Journal of Pharmaceutical and Biomedical Analysis, 2003

The electroanalytical behaviour of ketoconazole in Britton Á/Robinson buffer is described. The re... more The electroanalytical behaviour of ketoconazole in Britton Á/Robinson buffer is described. The reduction process on the hanging mercury drop electrode (HMDE) gives rise to one peak over (/1.6 V (vs. Ag/AgCl/sat.KCl), within the pH range studied (4.7 Á/9.6). The results showed that the reduction of ketoconazole is irreversible and the limiting current is adsorption controlled. The dependence of the peak current on the concentration was studied by means of different polarographic and voltammetric techniques. Using adsorptive stripping differential pulse voltammetry (AdS-DPV), the detection limit (DL) reached was 5.3 )/10 (11 mol l (1 . Two procedures, based on differential pulse polarography (DPP) and AdS-DPV in aqueous medium were developed for the determination of ketoconazole in a gel formulation and spiked urine samples, respectively. #