S.A. Barakat

Spectrophotometric determination of chromium(VI) by extraction of benzyltributylammonium dichromate

Abstract Chromium(VI) (–100 μg) can be determined spectrophotometrically at 365 nm after its extraction as benzyltributylammonium dichromate into chloroform. The effects of acidity, diverse ions and masking studies are reported.

Flow-injection extraction-spectrophotometric determination of manganese(VII) with benzyltributylammonium cations

Abstract A flow-injection manifold has been developed for the spectrophotometric determination of manganese(VII) at 548 nm after extraction into chloroform of the ion-associate, benzyltributylammonium permanganate. The carrier stream was a pH 6 buffer containing 10% (w/v) ammonium fluoride and the reagent stream was 0.10% (w/v) benzyltributylammonium chloride. The injection rate was 20 h −1 . The calibration graph is linear up to 25 μg ml −1 and the detection limit (3 × baseline noise) is 0.91 μg ml −1 Mn(VII), based on 250-μl injection volumes. The system has been aplied to the determination of manganese in steels and a cupro-nickel alloy.

Flow-injection extraction spectrophotometric determinatin of chromium(VI) with the benzyltributylammonium cation

Abstract Chromium(VI) can be determined spectrophotometrically at 365 nm after flow-injection extraction into chloroform of the ion associate benzyltributylammonium dichromate. The carrier stream was distilled water, merged with 1.0 M sulphuric acid solution, the reagent stream was 0.5% (w/v) benzyltributylammonium chloride solution. The injection rate was 20 h −1 . The calibration graph was linear up to 20 μg ml −1 and the detection limit (3 × baseline noise) was 0.5 μg ml −1 Cr(VI) based on 250-μl injection volumes. The system has been applied to the determination of chromium in steels.

Chemical amplification methods for the sequential determination of trace amounts of ruthenium by titrimetric and spectrophotometric procedures.

Two simple, inexpensive and rapid iodometric and spectrophotometric procedures were developed for trace amount determination of ruthenium. The proposed methods were based on the oxidation of ruthenium(II or III) with sodium periodate at pH 2.4-3.6, masking the excess periodate with sodium molybdate. The released iodate was then allowed to react with KI at pH 3, with subsequent determination of the released iodine spectrophotometry as triiodide at 350 nm or iodometry with 0.005 M sodium thiosulphate. This procedure offers an 18- and 15-fold amplification per Ru(II) or Ru(III) ion, respectively. Alternatively, the produced iodine was extracted with CHCl(3), shaken with an aqueous solution of sodium sulphite and the produced iodide ion was then allowed to react with bromine (or sodium periodate). The released iodate was subsequently determined by iodometry or spectrophotometry after addition of KI. The bromine and sodium periodate oxidation procedures offered 90- and 360-fold amplification per ruthenium(III) ion, and 108- and 432-fold amplification per ruthenium(II) ion. Ruthenium(IV) content was determined by these procedures after prior reduction to Ru(III) with sulphurous acid. The binary mixtures Ru(II)-Ru(III); Ru(III)-Ru(IV) and Ru(II)-Ru(IV) in aqueous solution at concentration 0.05 mug ml(-1) were successfully analyzed by the developed procedures. The utility of the proposed methods for the analysis of ruthenium in its complexes was demonstrated. Natural seawater and seawater spiked with ruthenium were analyzed satisfactorily.

Flow-injection extraction-spectrophotometric determination of permanganate with the triphenylsulphonium cation

SummaryPermanganate can be determined spectrophotometrically at 548 nm after flow-injection extraction into chloroform of the ion-associate triphenylsulphonium permanganate. The carrier stream was a pH 6 buffer containing 10% (w/v) ammonium fluoride and the reagent stream was 0.10% (w/v) triphenylsulphonium chloride. The injection rate was 20 h−1. The calibration graph is linear up to 40 μg ml−1 and the detection limit is 1.10 μg ml−1 Mn(VII), based on injection volumes of 250 μl. The system has been applied to the determination of manganese in steels and a cupro-nickel alloy.

Spectrophotometric determination of manganese in steels after extraction of permanganate with benzyltributylammonium chloride

Abstract Manganese(VII) (0–100 μg) can be determined spectrophotometrically at 548 nm after its extraction as benzyltributlammonium permanganate, at pH 6, into chloroform. The effects of pH, reagent concentrations and diverse ions are reported. The system has been applied to the determination of manganese in a variety of steels. For the determination of 60 μg of manganese the relative standard deviation was 0.19% (7 measurements).

Spectrophotometric determination of manganese in low-alloy steels after its extraction as triphenylsulphonium permanganate

SummaryManganese(VII) (0–100 μg) can be determined spectrophotometrically at 548 nm after its extraction as triphenylsulphonium permanganate into chloroform. The effects of pH, reagent conditions and diverse ions are reported. The system has been applied to the determination of manganese in a range of steels. For the determination of 60 μg of manganese the relative standard deviation was 0.5% (n=7).

New Compounds in Extract of Eryngium Creticum Lam and Preliminary Biological Activity Evaluation = المركبات الجديدة في نبات قرصعنة (Eryngium Creticum Lam) وتقييم الأنشطة البيولوجية

The identification of 6, not previously recorded, compounds, in an extract of Eryngium creticum lam, native in Jordan, have been observed using LC-MS/MS. The compounds are isobutyl 3-(diheptylcarbamoyl) benzoate, 3-Nitrophthalic anhydride, Metamitron, 1, 3-Diacetylindole, The baine and Clemizole. The extract was evaluated for cytotoxicity against human colorectal cancer cells HT29 and SW480.