RESUMEN
A micro flow analysis (µFA) system has been designed and fabricated for determination of total iron. The system consists of a microchannels fabricated by etching the polymethyl methacrylate (PMMA) by using laser ablation techniques and a sealed polydimethylsiloxane (PDMS) as top plate. The PMMA micro-flow was topped with a home-made polydimethylsiloxane (PDMS) micro-flow through cell, which was integrated with light emitting diode (LED) as light source and a USB 2000 spectrometer as detector. The proposed µFA system was applied to determination of Fe(III) using norfloxacin as a less-toxic complexing agent in an acetate buffer solution pH 4.0, resulting in a yellow colored complex which gave the maximum absorption at 430nm. Under the optimum conditions, a linear calibration graph was obtained in the concentration range of 0.20-5.00mgL(-1). The limit of detection (LOD, defined as 3σ) and limit of quantification (LOQ, defined as 10σ) were 0.12 and 0.45mgL(-1), respectively. The relative standard deviation (R.S.D.) for repeatability and reproducibility were less than 1.50% and 1.24% (n=11) for 0.2mgL(-1) and 1.0mgL(-1) Fe(III), respectively. The proposed method was successfully applied to the determination of total iron in water samples, validated by the FAAS standard method after digestion by HNO3 and H2O2.
Asunto(s)
Análisis de Inyección de Flujo/métodos , Hierro/análisis , Miniaturización/métodos , Norfloxacino/química , Contaminantes Químicos del Agua/análisis , Concentración de Iones de Hidrógeno , Espectrofotometría , Inhibidores de Topoisomerasa II/análisisRESUMEN
A reverse flow injection analysis (rFIA) spectrophotometric method has been developed for the determination of aluminium(III). The method was based on the reaction of Al(III), quercetin and cetyltrimethylammonium bromide (CTAB), yielding a yellow colored complex in an acetate buffer medium (pH 5.5) with absorption maximum at 428 nm. The rFIA parameters that influence the FIA peak height have been optimized in order to obtain the best sensitivity and minimum reagent consumption. A linear relationship between the relative peak height and Al(III) concentrations were obtained over the concentration range of 0.02-0.50 mg L(-1) with a correlation coefficient of 0.9998. The limit of detection (LOD, defined as 3sigma) and limit of quantification (LOQ, defined as 10sigma) were 0.007 and 0.024 mg L(-1), respectively. The repeatability was 1.10% (n=11) for 0.2 mg L(-1) Al(III). The proposed method was applied to the determination of Al(III) in tap water samples with a sampling rate of 60 h(-1). Results obtained were in good agreement with those obtained by the official ICP-MS method at the 95% confidence level.