Nidal A. Zatar

Spectrophotometric determination of nitrite and nitrate using phosphomolybdenum blue complex

A method for spectrophotometric determination of nitrite and nitrate is described. This method is based on the reduction of phosphomolybdic acid to phosphomolybdenum blue complex by sodium sulfide. The obtained phosphomolybdenum blue complex is oxidized by the addition of nitrite and this causes a reduction in intensity of the blue color. The absolute decrease in the absorbance of the blue color or the rate of its decrease is found to be directly proportional to the amount of nitrite added. The absorbance of the phosphomolybdenum blue complex is monitored spectrophotometrically at 814 nm and related to the concentration of nitrite present. The effect of different factors such as acidity, stability of the complex, time, temperature, phosphate concentration, molybdenum concentration, sodium sulfide concentration and the tolerance amount of other ions have been reported. Maximum absorbance is at 814 nm. The range of linearity using the conventional method is 0.5-2.0 ppm with molar absorptivity of 1.1 x 10(4) l mol(-1) cm(-1). and a relative standard deviation of 2.6% for five measurements. The range of linearity using the reaction rate method is 0.2-3.6 ppm with a relative standard deviation of 2.4% for five measurements. The method is applied for determination of nitrite and nitrate in water, meat products and vegetables.

Simultaneous Spectrophotometric Determination of Iron(II) and Iron(III) in Mixtures Using Di-2-pyridyl Ketone Benzoylhydrazone

Abstract A method for simultaneous spectrophotometric determination of total iron, iron(II) and iron(III) in mixtures containing other metal ions has been described. The method is based on the complexation of iron with di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution. Iron(II) complex with DPKBH exhibits two absorption maxima at 360 and 650 nm. meanwhile iron(II1) complex with DPKBH exhibits only one maximum at 360nm. Iron(II) and iron(III) complexes with DPKBH have similar behaviour at 360nm. Iron forms 1:2 complexes with the reagent. Beers laws are obeyed over the ranges 0.1–2 μgml-1 and 0.4–5 μgrn1-l for iron(II) complexes at 360 and 650nm respectively. Iron(III) showed results similar to those obtained for iron(II) at 360nm. The effect of pH, effect of excess reagent. the stability of complexes. and the tolerance limit of many metal ions have been reported. The method is applied to the determination of total iron, iron(I1). and iron(II1) in synthetic solutions.

Spectrophotemetric determination of cobalt in aqueous solution using di-2-pyridyl ketone derivatives

Abstract A method for the spectrophotometric determination of cobalt(II) is presented, with a comparison of the binary complexes formed by cobalt(II) with di-2-pyridyl ketone nicotinoylhydrazone (DPKNH), di-2-pyridyl ketone 2-thiophenoylhydrazone (DPKTH) and di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution. Cobalt(II) forms 1:2 complexes with the three reagents. Maximum absorbance is at 372 nm for Co(II)-DPKNH, at 389 nm for Co(II)-DPKTH and at 370 nm for Co(II)-DPKBH. Ranges of linearity, effects of pH and excess reagent, sensitivity, stability of the complexes and tolerance limits of ions are reported. It was concluded that the system with DPKTH is the best, followed by DPKNH and then DPKBH. The method was applied to the determination of cobalt in different alloys.

In vitro antioxidant and antitumor activities of six selected plants used in the Traditional Arabic Palestinian herbal medicine

Abstract Context: Despite several pharmacological applications of the medicinal plants in the Traditional Arabic Palestinian Herbal Medicine in Palestine (TAPHM), studies on their antioxidant properties are still scarce. Objective: This work evaluates the antioxidant and antitumor activities of the ethanol extracts from different parts of six plants: [Arum palaestinum Boiss (Araceae), Urtica pilulifera L. (Urticaceae), Coridothymus capitatus (L.) Reichb (Lamiaceae), Majorana syriaca (L.) Rafin. (Lamiaceae), Teucrium creticum L. (Lamiaceae), and Teucrium capitatum L. (Lamiaceae)] used in the TAPHM. Materials and methods: The antioxidant activity was evaluated for the ethanol extracts by DPPH and β-carotene–linoleic acid assays together with total contents of phenols and flavonoids. For the anti-carcinogenic evaluation, the extracts were tested for the ability to inhibit the proliferation of breast cancer cells (MCF-7) using the MTT reduction assay. Results: Among the extracts, the U. pilulifera had the highest amount of total phenolics, possessing the second highest total flavonoids. It also showed a maximum cytotoxic activity (IC50 = 63 µg/ml), followed by C. capitatus, and A. palaestinum. Otherwise, the extract of T. creticum was demonstrated to be an efficient scavenger of O2 (IC50 = 83 µg/ml), followed by M. syriaca, C. capitatus, T. capitatum, A. palaestinum, and U. pilulifera. Discussion and conclusion: The results suggest that the investigated plants have shown varied antioxidant capacities which were strongly correlated with their contents of phenolics. Accordingly, this study proposes that the therapeutic benefit of these plants can be, at least in part, attributed to its potential inhibition of oxidative processes.

Spectrophotometric determination of some aromatic amines

A method for spectrophotometric determination of four aromatic amines is described. The method is based on the reaction between the amine and the colorless Fe(III)-ferrozine complex. The amine reduces iron from Fe(III) to Fe(II) which forms a violet colored complex with ferrozine. The method is suitable for to the determination of 1,4-phenylenediamine, 2,4-diaminotoluene, 8-aminoquinoline and 2-amino-3-hydroxypyridine. The effect of different factors such as; pH, stability of the complex, temperature, ferrozine concentration, Fe(III) concentration and methanol concentration have been studied. The composition of the complex as well as the tolerance amount of other amines have been reported. Maximum absorbance is at 562 nm and Beers law is obeyed over the ranges 0.17-1.6 ppm for 1,4-phenylenediamine, 0.45-3.7 ppm for 2,4-diaminotoluene, 0.51-3.4 ppm for 8-aminoquinoline and 0.53-4.4 ppm for 2-amino-3-hydroxypyridine. The obtained molar absorbtivities were 4.7x10(4), 2.0x10(4), 1.6x10(4), 1.5x10(3) l mol(-1) cm(-1) respectively.

A selective spectrophotometric determination of europium in mixtures with other lanthanides,yttrium and scandium

Summary Spectrophotometric methods are presented for the determination of 0.04–5 mg of europium in rare earth mixtures, following a group separation, or in lanthanide compounds. Europium(III) is selectively reduced on a Jones reductor to europium(II) which in turn reduces molybdophosphoric acid to a molybdenum blue. The absorbance is measured at 810 nm in aqueous solution or at 790 nm after extraction into n-amyl alcohol; optimal reaction conditions and times are reported. Other rare earth elements, and chloride, bromide, perchlorate, acetate and sulphate, are without effect when present in gram amounts but nitrate and iodide must be absent. The method is applied to the determination of europium in various lanthanide oxides and bastnaesite.

Spectrophotometric Determination of Cobalt with Di-2-Pyridyl Ketone Benzoylhydrazone

Abstract A method for the spectrophotometric determination of cobalt (II) by complexation with di-2-pyridyl ketone benzoylhydrazone (DPKBH) in 50% (v/v) ethanolic solution is described. Cobalt (II) forms a 1:2 complex with DPKBH. The complex has maximum absorbance at 370 nm. Beers law is obeyed over the range 0.1 – 2.8 μg.ml−1. The effect of pH, effect of excess reagent, stability of the complex and the tolerance limit of many metal ions have been reported. The method is applied to the determination of cobalt in different alloys containing other metals ions.

A comparative study of some methods for the spectrofluorimetric determination of terbium in aqueous solutions containing other lanthanides and yttrium

Abstract Published methods based on the use of water-soluble binary and ternary complexes for the spectrofluorimetric determination of terbium(III) are compared. The complexes formed by terbium(III) with (1) ethylenediamine- N,N ′-bis- o -hydroxyphenylacetic acid, (2) o -hydroxyphenyliminodiacetic acid, (3) EDTA and sulphosalicylic acid, (4) EDTA and Tiron, and (5) iminodiacetic acid and Tiron were examined. In each system, the characteristic sharp-line emission from terbium(III) at around 545 nm is measured. On the basis of emission spectra from 400 to 600 nm, fluorescence intensity in relation to variation in terbium/reagent mole ratios, sensitivity and some interference tests involving other lanthanides, yttrium, thorium and dioxouranium(VI) ions, it is concluded that the system represented by (4) is best, followed by (1), (5) and (3) in that order; (2) is least satisfactory on account of the strong dependence of fluorescence intensity on the terbium(III)/reagent mole ratio.

Spectrofluorimetric determination of terbium as its ternary complex with edta and tiron Compositional studies, optimization of fluorescence output and conversion to a flow system

Abstract The spectrofluorimetric determination of terbium(III) as its ternary complex with EDTA and Tiron was studied further with regard to composition of the complex and the procedure was optimized by a simplex method. The results suggest a 1:1 molar ratio of terbium to Tiron for the ternary complex. The optimization study indicated that the three chosen variables (pH, and EDTA and Tiron concentration) are not interactive. The method was converted for use in a segmented-flow system with basic Technicon units and a spectrophotofluorimeter as detector. This procedure is satisfactory for the determination of terbium(III) in the range 0.03–0.24 μg ml −1 at a sampling rate of 30 h −1 . Results were satisfactory for the determination of terbium in lanthanide oxides, mixed oxides, the mineral bastnasite and a green phosphor (Gd 0.96 Ce 0.02 Tb 0.02 F 3 ).

Automatic spectrolfluorimetric method for the determination of dysprosium as its ternary complex with EDTA and Tiron

Abstract The automatic method is based on the ternary complex formed with EDTA and Tiron. The method is satisfactory or quantifying 0.1–1.2 μg ml−1 dysprosium under conditions similar to those used for terbium. The effect of other lanthanides, yttrium, thorium, and dioxouranium(VI) on the fluorescence intensity is described; the main interference is from terbium(III).