A cleaner and simple spectrophotometric micro-fluidic procedure for copper determination using nitroso-R salt as chromogenic agent.

A cleaner and simple spectrophotometric method using microflow analysis (muFA) was performed. It consisted of a T-junction with microcoil on a polymethyl methacrylate (PMMA) chip which was fabricated by laser ablation and a molded polydimethylsiloxane (PDMS) as top plate. The fabricated PMMA chip was integrated with light emitting diode (LED) as light source and spectrometer as detector. The proposed device was applied to determining copper in water samples using nitroso-R salt as chromogenic reagent at 495 nm. It was found that the proposed muFA system was with less reagents and samples consumption with tiny waste generation. The relative standard deviation (R.S.D.) was less than 2% (n=11) with the percentage recovery of 98.0+/-1.7% (n=7). The linear range for determination of copper in water samples was over the range of 0.05-3.0 microg mL(-1) with a correlation coefficient (r2) of 0.999. The limit of detection (3sigma) was 47 ng mL(-1) with a sample throughput of 30 h(-1).

A simple flow injection spectrophotometric procedure for iron(III) determination using Phyllanthus emblica Linn. as a natural reagent.

The use of natural reagents from plant extracts for chemical analysis is one approach in the development of green analytical chemistry methodology. In this work, a natural reagent extracted from Phyllanthus emblica Linn. has been applied for the determination of iron(III) using a simple flow injection spectrophotometric method. The method was based on the measurement of a dark-purple complex formed by the reaction between iron(III) and the extracted solution in an acetate buffer (pH 5.6) at 570 nm. Under the optimum conditions, a linear calibration graph in the range of 0.50-20.0 mg L-1 iron(III) was obtained with a correlation coefficient (r2) of 0.9996. The limit of detection and limit of quantification were 0.31 and 0.50 mg L-1, respectively. The relative standard deviation was less than 2.50%. The proposed method was successfully applied for quantitative analysis of iron(III) in pharmaceutical preparations and water samples with a sampling rate of 90 samples h-1. The results are in good agreement with those obtained by the official ICP-OES technique at the 95% confidence level. The presented method provides a simple, cost-effective and environmentally friendly approach which is suitable and useful for determining iron(III). Therefore, it can be considered as an alternative analytical technique in green chemistry.

Deferiprone, a non-toxic reagent for determination of iron in samples via sequential injection analysis.

We present for the first time the use of deferiprone as a non-toxic complexing agent for the determination of iron by sequential injection analysis in pharmaceuticals and food samples. The method was based on the reaction of Fe(III) and deferiprone in phosphate buffer at pH 7.5 to give a Fe(III)-deferiprone complex, which showed a maximum absorption at 460nm. Under the optimum conditions, the linearity range for iron determination was found over the range of 0.05-3.0µgmL(-1) with a correlation coefficient (r(2)) of 0.9993. The limit of detection and limit of quantitation were 0.032µgmL(-1) and 0.055µgmL(-1), respectively. The relative standard deviation (%RSD) of the method was less than 5.0% (n=11), and the percentage recovery was found in the range of 96.0-104.0%. The proposed method was satisfactorily applied for the determination of Fe(III) in pharmaceuticals, water and food samples with a sampling rate of 60h(-1).

Synthesis and evaluation of simple naked-eye colorimetric chemosensors for anions based on azo dye-thiosemicarbazones.

A series of novel, highly selective azo dye-thiosemicarbazones based anion sensors (3e-f) have been synthesized from the condensation reaction between thiosemicarbazide and six different azo salicylaldehydes. The structure of the sensors was confirmed by spectroscopic methods. The selectivity and sensitivity in the recognition for acetate anion over other anions such as fluoride, chloride, iodide and dihydrogenphosphate anions were determined by naked-eyes and UV-vis spectra. The color of the solution containing sensor had an obvious change from light yellow to orange only after the addition of acetate anion in aqueous solution (water/dimethylsulfoxide, 7:3, v/v) while other anions did not cause obvious color change. The anion recognition property of the receptor via proton-transfer is monitored by UV-vis titration and (1)H NMR spectroscopy. Under condition in aqueous solution of sensor 3e (water/dimethylsulfoxide, 7:3, v/v), linearity range for the quantification of acetate anion was 1-22 µM and limit of detection (LOD) of acetate anion was 0.71 µM.

Sequential injection spectrophotometric determination of tetracycline antibiotics in pharmaceutical preparations and their residues in honey and milk samples using yttrium (III) and cationic surfactant.

A sequential injection analysis (SIA) spectrophotometric method for determining tetracycline (TC), chlortetracycline (CTC) and oxytetracycline (OTC) in different sample matrices were described. The method was based on the reaction between tetracyclines and yttrium (III) in weak basic micellar medium, yielding the light yellow complexes, which were monitored at 390, 392 and 395 nm, respectively. A cationic surfactant, cetyltrimethylammonium bromide (CTAB) was used to obtain the micellar system. The linear ranges of calibration graphs were between 1.0 × 10(-5) and 4 × 10(-4) mol L(-1), respectively. The molar absorptivities were 5.24 × 10(5), 4.98 × 10(4) and 4.78 × 10(4) L mol(-1)cm(-1). The detection limits (3σ) were between 4.9 × 10(-6) and 7.8 × 10(-6) mol L(-1) whereas the limit of quantitations (10σ) were between 1.63 × 10(-5) and 2.60 × 10(-5) mol L(-1) the interday and intraday precisions within a weak revealed as the relative standard deviations (R.S.D., n=11) were less than 4%. The method was rapid with a sampling rate of over 60 samples h(-1) for the three drugs. The proposed method has been satisfactorily applied for the determination of tetracycline and its derivatives in pharmaceutical preparations together with their residues in milk and honey samples collected in Chiang Mai Province. The accuracy was found to be high as the Student's t-values were found to be less than the theoretical ones. The results were compared favorably with those obtained by the conventional spectrophotometric method.

A simple and green analytical method for determination of iron based on micro flow analysis.

A simple, inexpensive and reagent-less colorimetric micro flow analysis (microFA) system was implemented in a polymethyl methacrylate (PMMA) micro fluidic manifold. A T-shaped micro channel on a PMMA chip was fabricated by laser ablation and topped with molded polydimethylsiloxane (PDMS). The fabricated microFA system was integrated with the optical components as detector and applied to the determination of iron in water samples. It is based on the measurement of Fe(III)-nitroso-R salt complex at 720 nm formed by the reaction between Fe(III) and nitroso-R salt in an acetate buffer solution pH 5. The proposed microFA consumed very small amount of reagent and sample, it released waste of less than 2.0 mL h(-1). The relative standard deviation (R.S.D.) was less than 2% (n=11) with the recovery of 98.7+/-0.12 (n=5). The linear range for the determination of iron in water samples was over the range of 0.05-4.0 microg mL(-1) with a correlation coefficient (r(2)) of 0.9994. The limit of detection (3sigma) and limit of quantitation (10sigma) were 0.021 microg mL(-1) and 0.081 microg mL(-1), respectively with a sample throughput of 40 h(-1).