Conventional silica columns dynamically modified with cetyltrimethylammonium ions were evaluated for the determination of UV-absorbing bromide, nitrate, and nitrite in seawater samples. Cetyltrimethylammonium, which is a quaternary ammonium ion, was dynamically introduced onto silica surfaces. The first layer of the modifier was introduced by electrostatic interaction, whereas the second layer was introduced by hydrophobic interaction. The latter layer worked as the anion-exchange sites. The modified conventional silica columns could be used for separation of inorganic anions. Separation of authentic mixture of five anions was achieved within 17 min. The addition of 0.1 mM cetyltrimethylammonium ion to the eluent improved the repeatability of the retention time. Seawater samples could be directly injected onto the prepared conventional silica columns, and bromide, nitrate, and nitrite levels were determined to be 69, 0.13, and 0.016 ppm, respectively.

Determination of trace inorganic anions in seawater samples by ion chromatography using silica columns modified with cetyltrimethylammonium ion

Application of flowing-stream techniques to water analysis Part II. General quality parameters and anionic compounds: halogenated, sulphur and metalloid species.

https://ousar.lib.okayama-u.ac.jp/files/public/3/33014/20160528030919178420/fulltext.pdf

Flow injection spectrophotometry coupled with a crushed barium sulfate reactor column for the determination of sulfate ion in water samples

Structural alterations of humic acid fractions in a steel slag-compost fertilizer during fertilization. Analysis by pyrolysis/methylation-gas chromatography/mass spectrometry

A new flow-injection analysis (FIA) system with detection by an electrode-separated piezoelectric quartz crystal (ESPQC) was developed for sulphate determination in water. The method was based on the decrease in conductivity upon precipitation of barium sulphate due to the mixing between reagent and sample with change indicated by the frequency shift in the ESPQC sensor. The best performance was achieved using a three-channel FI system consisted of a carrier stream of water, a buffer stream containing 0.05% KCl, 10 mM acetic acid and l mM sodium acetate, and a reagent stream of 0.1% BaCl2. Under the optimized conditions, the linear range for sulphate determination was 0.5–50 ppm with a correlation coefficient of 0.9991, detection limit 0.3 ppm (S/N = 2) and sample throughput 50 samples/h. The effect of co-existing cations and anions were investigated and found not to cause interference for most samples except those with very high salt content. The reliability of the method was established by parallel determination using standard turbidimetric method for sulphate in drinking and pond water samples with results within statistical variation. The method developed was shown to provide a simple, sensitive, rapid and reproducible FIA detection method for ionic compounds in the liquid medium.

Determination of sulphate in water by flow-injection analysis with electrode-separated piezoelectric quartz crystal sensor

A rapid and simple flow-injection method using a reaction column packed with barium chromate powder is described for the determination of micro amounts of sulfate ion in surface- and sea-water samples. An aqueous solution containing 4.5mM sodium acetate and 4% ethanol was used as a carrier solution at a flow rate of 0.8ml/min. The absorbance of the chromate ion (which corresponds to the sulfate ion concentration) in the carrier solution from the reaction column was measured using a photometric detector at 370nm. Interference from some cations was eliminated by the use of a cation-exchange resin column installed in front of the reaction column; interference from some anions was reduced by using the carrier solution mentioned above. The concentration range from 0.5 to 5ppm of the sulfate ion in practical water samples can be determined by the proposed method with good reproducibility.

Flow-injection spectrophotometric determination of micro amounts of sulfate ion in surface- and sea-water samples with a barium chromate reaction column

Satoshi Nakayama

Papers

Flow-injection spectrophotometric determination of micro amounts of sulfate ion in surface- and sea-water samples with a barium chromate reaction column