30 research outputs found
Electroanalytical study of the antidepressant sertraline
Aflowinjection squarewave cathodic stripping voltammetric method has been developed for the determination of sertraline in a pharmaceutical
preparation. The method shows linearity between peak current intensity and sertraline concentration for the interval between 0.20×10−6
and 1.20×10−6 mol L−1. Limits of detection and quantification were found to be 1.5×10−7 and 5.0×10−7 mol L−1, respectively. Up to 70
samples per hour can be analysed with a good precision (R.S.D. = 2.5%). The proposed method was successfully applied to the determination
of sertraline in a commercial product. In the voltammetric determination of sertraline in flow, a high sample rate is obtained at reduced costs,
opening the possibility to compete with the chromatographic methods generally used for this analysis
Electroanalytical study of fluvoxamine
Fluvoxamine (FVX) can be reduced at a mercury-
drop electrode, with a maximum peak current
intensity being obtained at a potential of -0.7 V vs. Ag/
AgCl, in an aqueous electrolyte solution of pH 2. The
compound was determined in a pharmaceutical product
and in spiked human serum by square-wave adsorptivestripping
voltammetry (SWAdSV) after accumulation at
the electrode surface, under batch conditions. Because
the presence of dissolved oxygen did not interfere significantly
with the analysis, it was also possible to
determine FVX in the pharmaceutical product by use of
a flow-injection analysis (FIA) system with SWAdSV
detection. The methods developed were validated and
successfully applied to the quantification of FVX in a
pharmaceutical product. Recoveries between 76 and
89% were obtained in serum analysis. The FIA–
SWAdSV method enabled analysis of up to 120 samples
per hour at reduced cost, implying the possibility of
competing with the chromatographic methods usually
used for this analysis
Electrochemical determination of citalopram by adsorptive stripping voltammetry–determination in pharmaceutical products
The electrochemical behavior of citalopram was studied by square-wave and
square-wave adsorptive-stripping voltammetry (SWAdSV). Citalopram can be reduced
and accumulated at a mercury drop electrode, with a maximum peak current intensity
being obtained at a potential of approximately -1.25V vs. AgCl/Ag, in an aqueous
electrolyte solution of pH 12. A SWAdSV method has been developed for the
determination of citalopram in pharmaceutical preparations. The method shows a
linear range between 1.0x10-7 and 2.0x10-6 mol L-1 with a limit of detection
of 5x10-8 mol L-1 for an accumulation time of 30 s. The precision of the method
was evaluated by assessing the repeatability and intermediate precision, achieving
good relative standard deviations in all cases (≤2.3%). The proposed method was
applied to the determination of citalopram in five pharmaceutical products and the
results obtained are in good agreement with the labeled values
Brewer's spent grain from different types of malt: Evaluation of the antioxidant activity and identification of the major phenolic compounds
The antioxidant activity and phenolic composition of brewer's spent grain (BSG) extracts obtained by
microwave-assisted extraction from twomalt types (light and darkmalts) were investigated. The total phenolic
content (TPC) and antioxidant activity among the light BSG extracts (pilsen, melano, melano 80 and carared)were
significantly different (p b 0.05) compared to dark extracts (chocolate and black types), with the pilsen BSG
showing higher TPC (20 ± 1 mgGAE/g dry BSG). In addition, the antioxidant activity assessed by 2,2-diphenyl-
1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and deoxyribose assays decreased as
a result of increasing kilning temperatures in the following order: pilsen N melano N melano 80 N carared N
chocolate N black. HPLC-DAD/ESI-MS/MS analysis indicated the presence of phenolic acids, such as ferulic,
p-coumaric and syringic acids, as well as several isomeric ferulate dehydrodimers and one dehydrotrimer. Chocolate
and black extracts, obtained frommalts submitted to the highest kilning temperatures, showed the lowest levels of
ferulic and p-coumaric acids. These results suggested that BSG extracts from pilsen malt might be used as an
inexpensive and good natural source of antioxidants with potential interest for the food, pharmaceutical and/or
cosmetic industries after purification
Brewer's spent grain from different types of malt: Evaluation of the antioxidant activity and identification of the major phenolic compounds
The antioxidant activity and phenolic composition of brewer's spent grain (BSG) extracts obtained by
microwave-assisted extraction from twomalt types (light and darkmalts) were investigated. The total phenolic
content (TPC) and antioxidant activity among the light BSG extracts (pilsen, melano, melano 80 and carared)were
significantly different (p b 0.05) compared to dark extracts (chocolate and black types), with the pilsen BSG
showing higher TPC (20 ± 1 mgGAE/g dry BSG). In addition, the antioxidant activity assessed by 2,2-diphenyl-
1-picrylhydrazyl, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) and deoxyribose assays decreased as
a result of increasing kilning temperatures in the following order: pilsen N melano N melano 80 N carared N
chocolate N black. HPLC-DAD/ESI-MS/MS analysis indicated the presence of phenolic acids, such as ferulic,
p-coumaric and syringic acids, as well as several isomeric ferulate dehydrodimers and one dehydrotrimer. Chocolate
and black extracts, obtained frommalts submitted to the highest kilning temperatures, showed the lowest levels of
ferulic and p-coumaric acids. These results suggested that BSG extracts from pilsen malt might be used as an
inexpensive and good natural source of antioxidants with potential interest for the food, pharmaceutical and/or
cosmetic industries after purification