Narong Chimpalee

Flow-injection extraction-spectrophotometric determination of perchlorate with brilliant green

Abstract Perchlorate (0-2.5 μg ml −1 ) is determined spectrophotometrically at 640 nm after extraction into benzene of its ion-associate with Brilliant Green in a flow-injection manifold with a membrane separator. The injection rate is 20 h −1 . The detection limit is 36 ng ml −1 , based on 250-μl injections. The system is applied to the determination of perchlorate in potassium chlorate after prior selective destruction of chlorate.

Flow-injection extraction spectrophotometric determination of bismuth as tetraiodobismuthate(III) with the tetramethylenebis(triphenylphosphonium) cation

Bismuth can be determined spectrophotometrically at 495 nm after its extraction as tetramethylenebis(triphenylphosphonium) tetraiodobismuthate(III) into dichloromethane. The carrier stream is 2 M sulphuric acid and the reagent stream contains 2% (w/v) potassium iodine and 0.4% (w/v) tetramethylenebis(triphenylphosphonium) bromide. The injection rate is 20 h-1. The calibration graph is linear up to 20 μ ml-1 bismuth and the detection limit is 0.24 μ ml-1 bismuth, based on injection volumes of 250μl. The system has been applied to determination of bismuth in pharmaceutical samples.

Flow-injection spectrophotometric determination of cobalt by extraction as tetrathiocyanatocobaltate(II) with the ethylenebis(triphenylphosphoniu) cation

Abstract Cobalt (0–10 μg) may be determined spectrophotometrically at 625 nm after flow-injection extraction into chloroform of the ion associate ethylenebis(triphenylphosphonium) tetrathiocyanatocobaltate(II). The carrier stream contained 10% (w/v) ammonium fluoride and the reagent stream contained 0.5% (w/v) ethylenebis (triphenylphosphonium) bromide and 5% (w/v) ammonium thiocyanate. The injection rate was 20 h −1 . The calibration graph is linear up to 20 μg ml −1 and detection limit is 0.23 μg ml −1 cobalt, based on injection volumes of 500 μl. The system has been applied to the determination of cobalt in a range of tool steels.

Flow-injection extraction-spectrophotometric determination of permanganate with the ethylene-bis(triphenylphosphonium) cation

Abstract Permanganate is determined spectrophotometrically at 545 nm after extraction into chloroform of the ion-associate, ethylene -bis (triphenylphosphonium) permanganate. The carrier stream is pH 6 buffer containing 10% (w/v) ammonium fluoride and the reagent stream is 0.25% (w/v) ethylene-bis (triphenylphosphonium) bromide. The injection rate is 24 h−1. Th calibration graph is linear up to 25 μg ml−1 and the detection limit is 0.58 μg m−1 Mn (VII), based on 250- μl injections. The system is applied to the determination of manganese in a range of steels.

Flow-injection extraction spectrophotometric determination of dichromate with the tetramethylenebis(triphenylphosphonium)cation

Abstract Chromium(VI) (0–5 μg) can be determined spectrophotometrically at 365 nm after flow-injection extraction into chloroform of the ion-associate, tetramethylenebis(triphenylphosphonium) dichromate. The carrier stream is distilled water and the reagent stream contains 1 M sulphuric acid and 0.5% (w/v) tetramethylenebis(triphenylphosphonium) bromide. The sampling rate is 24 h −1 . The calibration graph is linear up to 20 μg ml −1 and the detection limit is 0.44 μg ml−1 chromium, based on injection volumes of 250 μl. The system has been applied to the determination of chromium in a range of steels.

Applications of a slotted tube atom trap and flame atomic absorption spectrometry : determination of bismuth in copper-based alloys with and without hydride generation

Abstract Improved systems are reported for the determination of bismuth (0-0.1%, w/w) in copper-based alloys by flame atomic absorption spectrometry. The use of a slotted quartz tube atom trap (STAT) with nebulised solutions or coupled with hydride generation decreases the characteristic concentrations (nebulized solution, 0.44/0.25, without/with STAT; hydride, 0.022/0.014, without/with STAT) and improved precisions by factors of two compared with those obtained without the use of the STAT. Determination of bismuth in a series of reference materials demonstrates the usefulness of STAT systems for the analysis of metallurgical samples.

Determination of lead in copper based alloys using a modified quartz tube atom trap and flame atomic-absorption spectrometry

SummaryStudies have been carried out on a series of quartz tube atom traps designed to increase the sensitivity of the flame atomic absorption spectrophotometry for lead. A significant improvement has been achieved and is illustrated by the determination of lead in copper based alloys.

Determination of lead in copper based alloys using a modified quartz atom trap and flow injection flame atomic absorption spectrometry

SummaryAn improved system has been developed for the determination of lead in copper based alloys by flame atomic-absorption spectrophotometry. The system is based on flow injection coupled to flame-AAS with the STAT technique. The system improves the sensitivity and increases sample throughput compared to conventional flame-AAS; it also enhanced STAT working life times.

Determination of tin in copper based alloys using a modified quartz atom-trap (STAT) and flame-atomic absorption spectrophotometry

SummaryAn improved system is reported for the determination of tin in copper-based alloys by flame-atomic absorption specved sensitivity and precision by factors of 2–3 compared to that obtained using conventional flame AAS. Determination of tin in a series of certified references samples demonstrates the improved precision of the proposed procedure.

The spectrophotometric determination of manganese(VII) after extraction with the trimethylene-bis(triphenylphosphonium) cation with microcrystalline naphthalene

SummaryManganese(VII) (0–120 μg) can be determined spectrophotometrically at 548 nm after its adsorptive extraction at pH 6 as its trimethylene-bis(triphenylphosphonium) ion pair with microcrystalline naphthalene after dissolution of the solid phase in 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 0.61%.