Prieto-Blanco, M. C., N. Jornet-Martínez, Y. Moliner-Martínez, C. Molins-Legua, R. Herráez-Hernández, V. J. Andrés, and P. Campins-Falcó,
"Development of a polydimethylsiloxane–thymol/nitroprusside composite based sensor involving thymol derivatization for ammonium monitoring in water samples",
Science of The Total Environment, vol. 503–504, pp. 105 - 112, 2015.
AbstractAbstract This report describes a polydimethylsiloxane (PDMS)-thymol/nitroprusside delivery composite sensor for direct monitoring of ammonium in environmental water samples. The sensor is based on a \{PDMS\} support that contains the Berthelot's reaction reagents. To prepare the PDMS–thymol/nitroprusside composite discs, thymol and nitroprusside have been encapsulated in the \{PDMS\} matrix, forming a reagent release support which significantly simplifies the analytical measurements, since it avoids the need to prepare derivatizing reagents and sample handling is reduced to the sampling step. When, the PDMS–thymol/nitroprusside composite was introduced in water samples spontaneous release of the chromophore and catalyst was produced, and the derivatization reaction took place to form the indothymol blue. Thus, qualitative analysis of NH4+ could be carried out by visual inspection, but also, it can be quantified by measuring the absorbance at 690 nm. These portable devices provided good sensitivity (LOD < 0.4 mg L− 1) and reproducibility (RSD < 10%) for the rapid detection of ammonium. The PDMS–NH4+ sensor has been successfully applied to determine ammonium in water samples and in the aqueous extracts of particulate matter \{PM10\} samples. Moreover, the reliability of the method for qualitative analysis has been demonstrated. Finally, the advantages of the PDMS–NH4+ sensor have been examined by comparing some analytical and complementary characteristics with the properties of well-established ammonium determination methods.
Elzanfaly, E. S., S. A. Hassan, M. Y. Salem, and B. A. El-Zeany,
"Different signal processing techniques of ratio spectra for spectrophotometric resolution of binary mixture of bisoprolol and hydrochlorothiazide; a comparative study",
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, vol. 140, pp. 334 - 343, 2015.
AbstractAbstract Five signal processing techniques were applied to ratio spectra for quantitative determination of bisoprolol (BIS) and hydrochlorothiazide (HCT) in their binary mixture. The proposed techniques are Numerical Differentiation of Ratio Spectra (ND-RS), Savitsky–Golay of Ratio Spectra (SG-RS), Continuous Wavelet Transform of Ratio Spectra (CWT-RS), Mean Centering of Ratio Spectra (MC-RS) and Discrete Fourier Transform of Ratio Spectra (DFT-RS). The linearity of the proposed methods was investigated in the range of 2–40 and 1–22 μg/mL for \{BIS\} and HCT, respectively. The proposed methods were applied successfully for the determination of the drugs in laboratory prepared mixtures and in commercial pharmaceutical preparations and standard deviation was less than 1.5. The five signal processing techniques were compared to each other and validated according to the İCH\} guidelines and accuracy, precision, repeatability and robustness were found to be within the acceptable limit.
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