ABSTRACT
This work describes rapid, sensitive and highly precise methods for the determination of total iron in blood serum and water samples, using batch, nFIA and rFIA techniques. The proposed methods are based on the selective oxidation of 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) (ABTS) by iron(III). The absorbance of the resultant green solution of radical cation (ABTS(·+)) was monitored spectrophotometrically at λ max=415 nm. The reaction is stoichiometric with a ratio of 1:1 (Fe(III):ABTS) as determined by Job's and molar ratio methods. The proposed methods allow for the determination of Fe(III) in the ranges 0-4.5 mg L(-1) (LOD 25.5 µg L(-1), %RSD 0.97%, n=7); 0 to 4.5 mg L(-1) (LOD 370 µg L(-1), %RSD 1.28%, n=7) and 0 to 2.7 mg L(-1) (81.6 µg L(-1), %RSD 0.76%, n=6) for batch, nFIA and rFIA techniques, respectively. The proposed methods show high selectivity to Fe(III), as indicated by the high tolerance limits for common interfering ions. The nFIA method was applied in total iron assay in camel blood serum, whereas batch and rFIA methods were successful in the determination of total iron in municipal pipeline water and spiked groundwater. Statistical analysis indicated insignificant differences in accuracy and precision between the results obtained by the developed methods and ICP-AES or phenanthroline methods.
Subject(s)
Flow Injection Analysis/methods , Iron/analysis , Serum/chemistry , Water/chemistry , Animals , Benzothiazoles/chemistry , Camelus , Oxidation-Reduction , Spectrophotometry , Sulfonic Acids/chemistryABSTRACT
Ipratropium (IP(+)) ion-selective electrode (ISE) has been constructed from poly(vinyl chloride) matrix membrane containing Ipratropium-tetraphenylborate (IP-TPB) as the electroactive component using 2-nitrophenyloctylether as plasticizer. The electrode exhibits near Nernstian response to Ipratropium bromide (IPBr) over the concentration range 10(-5) to 10(-2) mol L(-1) and detection limit 5.1x10(-6) mol L(-1). The electrode offers significant advantages including long lifetime (>2 months), excellent stability and reproducibility, fast response time (<10 s), wide pH working range (pH 2-9), high thermal stability (isothermal coefficient 0.37 mV/degrees C) and superior selectivity for IPBr over a large number of inorganic and organic substances. The electrode was successfully used as indicator electrode in the potentiometric titration of IPBr versus sodium tetraphenylborate (NaTPB) and in the determination of IPBr in Atrovent vials and spiked urine samples applying batch and flow injection techniques, with satisfactory results.
Subject(s)
Bronchodilator Agents/analysis , Flow Injection Analysis/methods , Ipratropium/analysis , Pharmaceutical Preparations/analysis , Polyvinyl Chloride/chemistry , Bronchodilator Agents/chemistry , Electrodes , Ipratropium/chemistry , Pharmaceutical Preparations/chemistry , Potentiometry , Reproducibility of Results , Sensitivity and SpecificityABSTRACT
A new kinetic spectrophotometric method for the determination of oxalate has been described, based on its enhancing effect on the oxidation of Mn(II) to MnO(4)(-), which is measured at 525 nm, by potassium periodate. Under the optimum conditions of 20 mugml(-1) Mn(II) in MnSO(4).H(2)O/0.015 moll(-1) H(3)PO(4)/0.013 moll(-1) sodium acetate and 3x10(-3) moll(-1) KIO(4) at 35 degrees C, calibration graphs in the range of 0.05-1.25 and 0.05-1.75 mugml(-1) oxalate concentration were obtained with detection limits of 27 and 5 ngml(-1) by the fixed time and the induction period methods, respectively. No serious interference was identified. The proposed method is simple, inexpensive, sensitive and accurate. The applicability of the method was demonstrated by the determination of the oxalate in spinach and urine samples.
