Browsing by Author "Arancibia, Veronica"

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    ANTIPROLIFERATIVE ACTIVITY OF NEW 6-BROMINE DERIVATIVES OF 7-ANILINO-1-ARYLISOQUINOLINEQUINONES
    (2016) Andrea Ibacache, Juana; Valderrama, Jaime A.; Arancibia, Veronica; Theoduloz, Cristina; Muccioli, Giulio G.; Benites, Julio
    A variety of 6-bromine-containing 7-anilino-1-arylisoquinolinequinones 2a-g were synthesized to evaluate their half-wave potentials and in vitro antiproliferative activity on gastric and leukemia cancer cell lines. The new compounds displayed significant IC50 values in the range: 1.31 to 11.04 mu M. The structure activity relationship analysis of the new series suggest that the antiproliferative activity is dependent, in part, on the push-pull electronic effects of the nitrogen and bromine substituents inserted into the redox fragment of the 1-arylisoquinolinequinone scaffold. Linear regression analysis provided satisfactory relationships between the log IC50 and ClogP values for the AGS gastric cancer cell line.
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    Determination of a natural (17β-estradiol) and a synthetic (17α-ethinylestradiol) hormones in pharmaceutical formulations and urine by adsorptive stripping voltammetry
    (2019) Jose Trivino, Juan; Gomez, Marisol; Valenzuela, Javiera; Vera, Ariesny; Arancibia, Veronica
    An efficient, fast and sensitive method for the determination of 17 beta-estradiol, (E2) and 17 alpha-ethinylestradiol (EE2) in pharmaceutical formulations and in urine was developed and validated using a hanging mercury drop electrode (HMDE), screen printed carbon electrodes (SPCE), and screen printed carbon nanotube electrodes (SPCNTE). Both analyzes are adsorbed on the working electrodes. To obtain sensitive and selective methods, the effects of various parameters such as pH, adsorption potential, and time (E-ads, t(ads)) were optimized. The optimum experimental conditions chosen for the two analyzes were pH: 10.0; E-ads: - 0.60 and t(ads): 30 s, when HMDE was used. Under these conditions, one reduction signal was found at -1.31 V for E2 and two reduction signals at - 0.23 V and -1.20 V for EE2. The detection limits (DLs) were found to be 0.3 mu g L-1 for E2, 14.8 mu g L-1 for EE2 at - 0.23 V, and 9.7 mu g L-1 for EE2 at -1.20 V. On the other hand, in screen printed electrodes E2 and EE2 present oxidation of the phenolic hydroxyl groups at 0.30, 0.31, 0.32, and 0.33 V (pH:10) with DLs of 242, 277; 182, and 191 mu g L-1 for SPCE and SPCNTE, respectively. The method was successfully applied to the determination of these analyzes in Primaquin (R) (E2), Gynera (R) (EE2), spiked urine (with EE2), and urine samples of women who used Tinelle (R) (EE2) as contraceptive drug.
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    Development of a fast and sensitive method for the determination of As(III) at trace levels in urine by differential pulse anodic voltammetry using a simple graphene screen-printed electrode
    (2020) Nunez, Claudia; Jose Trivino, Juan; Segura, Rodrigo; Arancibia, Veronica
    A simple and fast anodic voltammetric method was employed to determine traces of As(III) in urine samples using commercial screen-printed graphene electrodes without subsequent modification. To obtain a sensitive and selective method for As(III) determination, the effects of various parameters such as pH, supporting electrolyte concentration, accumulation potential (E-acc), accumulation time (t(acc)), and potential scan conditions were studied. The optimum experimental conditions were chosen to be as follows: pH of 2.8 (0.01 mol L-1 phosphate buffer), scan increment of 4 mV, pulse width of 80 ms, pulse period of 0.5 s, and pulse amplitude of 200 mV. Differential pulse voltammograms were obtained by scanning from -0.80 V to 0.80 V without applying an accumulation step. Under these conditions, one peak was observed at 0.27 V due to As-0 oxidation. After optimizing the experimental conditions, the anodic peak current for As was found to be linearly related to its concentration up to ca. 5.0 mu g L-1, with detection and quantitation limits (DLs, QLs) of 0.28 mu g L-1 and 0.92 mu g L-1, respectively. The developed method was validated by the determination of As(III) in spiked tap water from our laboratory, which showed an As(III) concentration of 50.64 +/- 0.10 mu g L-1 (spiked with 50.0 mu g L-1); two urine samples (where As was not detected) spiked with As(III) 0.73 mu g L-1 and 0.91 mu g L-1 (in the cell) showed an As(III) concentration of 0.70 mu g L-1 and 0.91 mu g L-1, respectively. The method was successfully applied to the determination of As-total in 16 urine samples obtained from workers occupationally exposed to inorganic arsenic compounds without previous treatment. The results obtained for As-total were compared with measurements made by an external analytical laboratory, which used HG-AAS. To determine As-total, As(V) was reduced in the presence of thiosulfate in an acid medium. The electrode showed good stability and repeatability.
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    Development of Electroanalytical Methods Using Different Electrodes for the Determination of Progesterone (P4) in Pharmaceutical Formulations and Human, Cow and Goat Milk
    (2023) Cruz, Victoria; Trivino, Juan Jose; Arancibia, Veronica
    For the determination of progesterone (P4) electroanalytical studies were performed using mercury electrode (HMDE) and screen-printed boron-doped diamond electrode (BDD-SPE). The effects of pH, supporting electrolyte, accumulation potential and time (E-acc, t(acc)) were studied in both systems. The optimum conditions were: i) HMDE: pH 7,0; -0,1 V and t(acc): 40 s, ii) BDD-SPE: 0,5 mol L-1 H2S ; E-acc: 0,0 V and t(acc): 120 s. Under these conditions, the detection limit was 3.1 mu g L-1 for HMDE and 45.6 mu g L-1 for BDD-SPE. Both methods were validated and applied in the P4 determination on pharmaceutical formulations and milk samples.
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    Ex situ prepared nafion-coated antimony film electrode for adsorptive stripping voltammetry of model metal ions in the presence of pyrogallol red
    (2013) Arancibia, Veronica; Nagles, Edgar; Rojas, Carlos; Gomez, Marisol
    A nafion-coated antimony film electrode (NSbFE) was prepared ex situ and applied to the model metal ions Pb(II) and Cd(II) by adsorptive stripping voltammetry in the presence of pyrogallol red (PGR). To enhance the electroanalytical performance of the NSbFE, we optimized several operational parameters, including antimony concentration, deposition potential and time used in the preparation of the electrode, and effect of pH, ligand concentration (C-PGR), adsorptive potential, and time (E-ads, t(ads)). The NSbFE exhibited well developed signals for the reduction of the adsorbed complexes at -0.63 and -0.92 V for Pb-PGR and Cd-PGR, respectively, with higher current compared to unmodified electrodes. The optimum parameters for NSbFE preparation consisting of 100 mg L-1 Sb(III), 0.5 mol L-1 HCl at -1.5 V (150 s) and for the determination of Pb(II) and Cd(II) were pH = 4.5 (acetate buffer); C-PGR = 2.8 mu mol L-1; E-ads = -0.40 V and t(ads) = 100 s. The electrode presents good linear behavior in the examined concentration range from 0.9 to 12.0 mu g L-1 for both metal ions, with a limit of detection (3 sigma) of 0.4 and 0.9 mu g L-1 for Pb(II) and 0.5 and 1.0 mu g L-1 for Cd(II) using 2-mm and 3-mm diameter glassy carbon electrodes, respectively. The relative standard deviation for a Pb(II) a Cd(II) solution (9.8 mu g L-1) was 2.0% for six successive assays. The method was validated using certified reference water for trace elements (TMDA-61) with satisfactory results. Finally, the method was applied to the determination of Pb(II) and Cd(II) in tap and mineral water. (C) 2013 Elsevier B.V. All rights reserved.
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    Nafion-mercury coated film electrode for the adsorptive stripping voltammetric determination of lead and cadmium in the presence of pyrogallol red
    (2012) Nagles, Edgar; Arancibia, Veronica; Rojas, Carlos; Segura, Rodrigo
    An adsorptive stripping voltammetric (AdSV) method is presented for the simultaneous determination of Pb(II) and Cd(II) at trace levels in natural waters, based on metal complexation with pyrogallol red (PR) and subsequent adsorptive deposition on a Nation-mercury coated glassy carbon electrode (NHgFE). Pyrogallol red forms complexes with a metal:ligand stoichiometry of 1:1 with Pb(II) and of 1:2 with Cd(II). Optimal analytical conditions were pH 4.0 (acetate buffer); C-PR = 2.8 mu mol L-1; E-ads = -0.40 V vs. Ag/AgCl; t(ads) = 100 s. The linear calibration curves ranged from 1.0 mu g L-1 to 16.0 mu g L-1 for Pb(II) and from 1.0 mu g L-1 to 13.0 mg L-1 for Cd(II). The detection limits (S/N=3) were 0.05 mu g L-1 for Pb(II) and 0.01 mg L-1 for Cd(II). The relative standard deviation was 1.0% and 2.0% (n = 7), respectively, for a solution containing 5.0 mu g L-1 Pb(II) and Cd(II). The method was validated by determining Pb(II) and Cd(II) in certified reference waste water (SPS-WW1). Finally, the method was applied to the determination of Pb(II) and Cd(II) in commercial mineral water samples after UV digestion. (C) 2012 Elsevier B.V. All rights reserved.
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    Simultaneous Determination of Antimony(III) and Molybdenum(VI) by Adsorptive Stripping Voltammetry Using Quercetin as Complexing Agent
    (2013) Rojas, Carlos; Arancibia, Veronica; Gomez, Marisol; Nagles, Edgar
    A sensitive and selective voltammetric method for simultaneous determination of Sb(III) and Mo(VI) using Quercetin (Q) as complexing agent is described. Optimal conditions were found to be: pH3.7, CQ=6.0 mu molL1 and Eacc=0.10V. The LOD (3 sigma) for Sb(III) are 0.076 and 0.040 mu gL1, whereas for Mo(VI) are 0.086 and 0.048 mu gL1 with tacc of 60 and 120s, respectively. The method was validated using synthetic sea water (ASTM D665) and was applied to the determination of Sb(III) and Mo(VI) in natural waters with satisfactory results.
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    Simultaneous voltammetric determination of acetylsalicylic acid, caffeine and paracetamol in pharmaceutical formulations using screen-printed carbon electrode
    (2023) Cortes, Karla; Trivino, Juan Jose; Arancibia, Veronica
    Electrochemical oxidation of Paracetamol (PAR), Acetylsalicylic acid (ASA) and Caffeine (CAF) was investigated employing square wave stripping voltammetry (SWSV) using screen-printed carbon electrodes (SPCE). Determinations were performed in 0.1 mol L-1 BR buffer (pH 2.0) without accumulation step. SWV were obtained by scanning the potential from 0.00 to 1.40 V employing a scan increment of 4 mV, pulse amplitude 25 mV and frequency of 25 Hz. PAR, ASA and CAF presents oxidation signals at 0.45, 1.03 and 1.32 V. The detection limits were 1.2, 1.7 and 1.7 mg L-1, respectively. The method was applied in the PAR-ASA-CAF determination on pharmaceutical formulations.
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    Synthesis and in Vitro Antiproliferative Activity of New Phenylaminoisoquinolinequinones against Cancer Cell Lines
    (2013) Delgado, Virginia; Ibacache, Andrea; Arancibia, Veronica; Theoduloz, Cristina; Valderrama, Jaime A.
    A variety of phenylaminoisoquinolinequinones were synthesized and tested for their antiproliferative activity against three human-tumor derived cancer cell lines. The new aminoquinones were prepared from 4-methoxycarbonyl-3-methylisoquinoline-5,8-quinone (1) via acid-induced amination and bromination reactions. Remarkable differences in antiproliferative activity were observed depending upon the location and donor capacity of the substituted phenylamino group at the quinone nucleus. The effect of the substituents on the biological activity is discussed in terms of the donor-acceptor interactions which were evaluated through the redox properties of the aminoquinones.
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    Voltammetric method for the determination of Pb2+ and Cd2+ in water samples using a nafion-guanine-coated mercury film electrode
    (2022) Jose Trivino, Juan; Nunez, Claudia; Merino-San Martin, Ignacio; Zuniga, Manuel; Arancibia, Veronica
    A sensitive voltammetric method is reported for the simultaneous determination of Pb2+ and Cd2+ using a nafion-guanine-coated mercury film glassy carbon electrode. This modified electrode exhibited well-developed signals for the reduction of the adsorbed complexes Pb-Guanine and Cd-Guanine, at -0.59 and -0.76 V respectively. The effects of parameters such as pH, accumulation potential and time (E-acc, t(acc)) were optimized. These studies were done using metallic ions on their own and also mixed together. The best pH for the individual analysis of Pb2+ or Cd2+ were 2.2 and 6.1 respectively, whereas a pH of 5.0 (acetate buffer 0.01 mol L-1) was chosen for simultaneous determination. Under the optimized conditions (pH = 5.0; t(acc) = 60 s; E-acc = -1.0 V) reduction signal was found to be proportional to the concentration of Pb2+ and Cd2+ over the 6.6-35.0 mu g L-1 range, with 36 detection limits (DL) of 2.2 and 4.6 mu g L-1. However, for lower concentrations, a time of 120 s was applied, yielding a linear range from 0.5 to 12.0 mu g L-1 with DLs of 0.26 and 0.25 mu g L-1 for Pb2+ and Cd2+, respectively. If the guanine (G) is in the solution, the signals are much lower than in the modified electrode. The method was validated by determining Pb2+ and Cd2+ in certified reference material (GBW08607) and synthetic sea water (ASTM D665), spiked with 22 metal ions, with satisfactory results. Subsequently, the method was applied in bottled mineral waters and sea water samples without previous treatment.