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Simultaneous analysis of first-line anti-tuberculosis drugs in tablets by UV spectrophotometry compared to capillary zone electrophoresis

100%

Marcellos L., Faria A., Souza M., Almeida M., Sabin G., Poppi R., Oliveira M.

Open Chemistry

2012

vol. 10

issue 6

1808-1816

The development and optimization of a novel UV spectrophotometric methodology was proposed for simultaneous analysis of ethambutol (ETB), isoniazid (ISO), rifampicin (RIF) and pyrazinamide (PYR), using multivariate calibration based on the partial least squares method (PLS). The methodology was successfully applied for analysis of four-drug fixed dose combination (4-FDC) tablets used for tuberculosis treatment. A 34 Box-Behnken design, with triplicate in central point, was used for sample preparation in the calibration step. In the present case, nine latent variables were chosen for the model development that presented the smallest RMSECV and explain 98.76% of data variance in Y block (concentrations of ETB ISO, RIF and PYR) and 99.93% of data variance in X block (spectral data). PLS models for ETB, ISO, RIF and PYR presented RMSEP and R2 values of 0.23 mg L−1 and 0.971; 0.14 mg L−1 and 0.731; 0.11 mg L−1 and 0.990 and 0.57 mg L−1 and 0.972, respectively. A validation step was performed based on the comparison between the UV spectrophotometric proposed methodology and capillary zone electrophoresis (CZE) in 4-FDC real samples and no significant difference was found between two methodologies at 95% of confidence level. [...]

Detection of Nitrate(NO-2) Ions Produced in Disproportionation of Nitrogen(II) Oxide in Aqueous Solution

51%

Kufelnicki A., Jaciubek-Rosińska J.

Ecological Chemistry and Engineering S

2012

vol. 19

issue 1

39-46

The nitrate ions (NO-2), products of disproportionation of NO in aqueous solution, were detected by an Orion Nitrite Electrode 97-46. Calibrations by means of standard NaNO2 solutions within the range 0.001÷100 ppm indicated linear dependence of EMF on ppm within 1÷100 ppm. Measurements justified the usefulness of this detection method of NO in solutions of OH- concentration lower than 10-2 mol dm-3 since at higher concentrations the EMF values exceeded the measurement range of the electrode. Occurrence of nitrate ions produced in the disproportionation reaction was additionally confirmed in dependence of OH- concentration by near UV and fluorescence spectra. The calibrated ion-selective nitrate electrode has also been shown, on the basis of Co(II)-dipeptide-OH- systems, as a useful tool in studying reversible NO uptake by Co(II) chelates in aqueous solution. Such a reaction may be regarded as simulating the harmful binding of NO by hemoglobin, where it substitutes the isoelectronic dioxygen.

Jony azotanowe (NO-2), produkty dysproporcjonowania NO w roztworze wodnym, oznaczano za pomocą jonoselektywnej elektrody Orion Nitride Electrode 97-46. Kalibracje za pomocą standardowych roztworów NaNO2 w zakresie 0.001÷100 ppm wskazywały liniową zależność SEM od ppm w zakresie 1÷100 ppm. Pomiary uzasadniły użyteczność tej metody wykrywania NO w roztworach o stężeniu OH- mniejszym niż 10-2 mol dm-3, ponieważ przy większych stężeniach wartości SEM przekraczały zakres pomiarowy elektrody. Występowanie jonów azotanowych tworzonych w reakcji dysproporcjonowania było dodatkowo potwierdzane, w zależności od stężenia OH-, za pomocą widm w bliskim UV i widm fluorescencyjnych. Wykazano także, na przykładzie układów Co(II)-dipeptyd-OH-, że kalibrowana jonoselektywna elektroda na jony azotanowe (NO-2) może być użytecznym narzędziem w badaniu odwracalnego wiązania NO przez chelaty Co(II) w roztworze wodnym, reakcji symulującej szkodliwe działanie tlenku azotu(II) na hemoglobinę.

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1 Ecological Chemistry and Engineering S

1 Open Chemistry

2 2012

1 Almeida M.

1 Faria A.

1 Jaciubek-Rosińska J.

1 Kufelnicki A.

1 Marcellos L.

1 Oliveira M.

1 Poppi R.

1 Sabin G.

1 Souza M.

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Simultaneous analysis of first-line anti-tuberculosis drugs in tablets by UV spectrophotometry compared to capillary zone electrophoresis

Detection of Nitrate(NO-2) Ions Produced in Disproportionation of Nitrogen(II) Oxide in Aqueous Solution