Iara Lúcia Tescarollo Dias

Solid-phase spectrofluorimetric determination of acetylsalicylic acid and caffeine in pharmaceutical preparations using partial least-squares multivariate calibration.

PLS-1, a variant of the partial least-squares algorithm was used for the solid-phase spectrofluorimetric determination of acetylsalicylic acid (ASA) and caffeine (CF) in pharmaceutical formulations. The method allows the simultaneous quantification of the analytes, as the closely overlapping spectral bands are efficiently solved. Sample preparation prior to analysis is not required. The calibration set consisted of 83 samples with 50-170mgg(-1) ASA plus 5-20mgg(-1) CF; another set of 25 samples was used for external validation. Agreement between predicted and experimental concentrations was fair (r=0.987 and 0.974 for ASA and CF models). For both models, the prediction performance was evaluated in terms of the coefficient of variability (CV), relative predictive determination (RPD), and ratio error range (RER). The final PLS-1 models were used for the determination of ASA and CF in pharmaceutical formulations.

Electrochemical sensor highly selective for estradiol valerate determination based on a modified carbon paste with iron tetrapyridinoporphyrazine

This work reports the use of iron tetrapyridinoporphyrazine (FeTPyPz) as a highly selective catalyst in the construction of an electrochemical sensor for estradiol valerate (EV) determination. The sensor was prepared by modifying a carbon paste with FeTPyPz. The best results were obtained in a mixture of acetonitrile (MeCN) and 0.1 mol L(-1) phosphate buffer solution (pH 6.0) in a volume ratio of 47 : 53. A linear response range was observed between 45 and 450 micromol L(-1) with a sensitivity of 12160 +/- 306 microA L mol(-1) and quantification and detection limits of 45 and 13 micromol L(-1), respectively. The repeatability, expressed as the relative standard deviation (RSD) for n = 10, was 5.9% ([EV] = 50 micromol L(-1)). The reproducibility (RSD) for the sensor construction was better than 4% and the operational stability (RSD) over 50 measurements was 1.8%. A detailed investigation regarding the selectivity and electrochemical characteristics was carried out. Finally, in a first step to evaluate the application potential of the sensor, it was successfully applied to determine EV in a commercial formulation.

A Poly(Vinyl Chloride) Membrane Electrode for the Determination of the Diuretic Furosemide

ABSTRACT New polymeric electrode responding to furosemide was constructed by incorporating the furosemide–aliquat ion pair complex into a poly(vinyl chloride) (PVC) membrane. The electrode exhibited a linear response over the concentration range 1.59 × 10−4–1.00 × 10−2 mol L−1, a detection limit of 1.19 × 10−4 mol L−1 with E = −245.6 − 58.9log[Fur]. The pH did not affect the response of the electrode within the range 7.0–10.0. Direct potentiometry was used to assay furosemide in pharmaceutical preparations. The results were compared with those obtained with spectrophotometric and chromatographic reference methods.

Furosemide Determination by First‐Derivative Spectrophotometric Method

Abstract Furosemide was analyzed in tablet and liquid pharmaceutical preparations entirely and after photolitic degradation, by direct ultraviolet first derivative spectrophotometry 1 D at 262 nm. At this wavelength, it was possible to eliminate the decomposition product interference. A linear response range between 1.0 and 10.0 µg mL−1 was obtained in optimized conditions. The estimation of relative standard deviation was within the range 0.37–2.4% (n=10). The method was applied in pharmaceutical preparation samples, and the results were compared with those obtained with normal spectrophotometric method to determine furosemide with advantages as high selective, accuracy and precision

Simultaneous spectrofluorimetric determination of paracetamol and caffeine in pharmaceutical preparations in solid-phase using partial least squares multivariate calibration

Abstract Partial least‐squares algorithm (PLS)‐1 was used for the solid‐phase spectrofluorimetric determination of paracetamol (PA) and caffeine (CF) in pharmaceutical formulations. In despite of the closely overlapping spectral bands, the method allows the simultaneous quantification and sample preparation prior to analysis is not required. The calibration set consisted of 96 samples with 100–400 mg/g−1 PA plus 10–65 mg/g−1 CF; another set of 25 samples was used for external validation. Agreement between predicted and experimental concentrations was fair (r=0.993 and 0.964 for PA and CF models). Prediction performance was evaluated in terms of the coefficient of variability (CV), relative predictive determination (RPD), and ratio error range (RER). The PLS‐1 model was used for the determination of PA and CF in pharmaceutical formulations.

Aplicação e avanços da espectroscopia de luminescência em análises farmacêuticas

This paper provides a review on the latest advances and applications of the luminescence spectroscopy for the development of pharmaceuticals analyses methods, basically based on the photo- and chemiluminescence. The different forms of the drugs determination on pharmaceuticals through the fluorescence and chemiluminescence are discussed. The analyses include the drugs native fluorescence (liquid and solid-phases); the fluorescence from the oxidizing or reducing forms of the drug; the fluorescence from the chemical derivatization and their photochemistry and hydrolysis reactions. The quenching of luminescence and chemiluminescence generation for the pharmaceutical quantification are also shown. Finally, the trends and future perspectives of the luminescence spectroscopy in the field of the pharmaceutical research are discussed.

Carbamide Peroxide Determination in Tooth Whitening Using a Reagentless HRP-Biosensor

Abstract A rapid and effective method for carbamide peroxide (CP) quantification in pharmaceuticals is proposed. The reagentless biosensor was prepared by using lyophilized turnip extract as horseradish peroxidase (HRP) enzyme source. The biosensor presented the best performance. The measurements were carried out in 0.1 mol L−1 Pipes buffer (pH 6.0). At −100 mV vs. Ag|AgCl, a linear response range from 3.0 to 25.0 mmol L−1 was obtained. The quantification and detection limits were 1.2 and 0.4 mmol L−1, respectively, and the response time was 0.5 s. The biosensor repeatability, storage, and lifetime were excellent, allowing a satisfactory CP quantification in real pharmaceutical samples, when compared with those obtained by the official method.