Assembly of a new gas-diffusion unit and its application to the determination of total carbonate and ammoniacal nitrogen by FIA.

Sanada, Masahiro; Oshima, Mitsuko; Motomizu, Shoji

doi:10.2116/bunsekikagaku.42.9_t123

Cited by 12 publications

(7 citation statements)

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“…1,3,12 For a sensitive determination, the difference in the molar absorptivity (ε) between a protonated form (HR) and a deprotonated form (R -) and the ratio of εHR to εR-must be large. However, as shown in Table 1, the difference between εHR and εR-at 450 nm and the ratio of εHR to εR-are not very large.…”

Section: Selection Of Color-developing Reagentmentioning

confidence: 99%

“…This meant that the efficiency of the diffusion of the gaseous substance through the PTFE membrane was improved so as to be higher than in the previous system. 3 To improve the permeable efficiency, a back-pressure coil was connected just after the GD unit. The length of the back-pressure coil (0.25 mm i.d.)…”

Section: Optimization Of Fia Conditions For a Sensitivity Improvementmentioning

confidence: 99%

“…By using a glass tube, the aqueous streams became stable, and furthermore the assembly became easier than that in the previous one. [1][2][3] Two tee connectors were changed for Y connectors made of PEEK for lowering the dead volume in the connectors. Ferrules made of silicon material were used for easier and more reliable connections; the flow-in and flow-out tubes for the reagent stream could be inserted directly into the inner tube of the PTFE membrane, and fastened tightly.…”

Section: Improvement Of Gas-diffusion Unitmentioning

confidence: 99%

“…Aoki et al 6 improved a conductometric method based on continuous flow reported by Carlson. 11 The limit of detection corresponding to a signal-to-noise ratio of three was 1 × 10 -5 M. Motomizu et al reported a gas-diffusion-FIA for carbonate [1][2][3] and ammonium. 7,8 However, in the methods reported so far, the sensitivity was not sufficient for determining TC at low concentrations in such samples as rain water and purified water, in which TC is less than, or around, 10 -5 M, 9 because the contamination of water from CO2 in air was unavoidable.…”

Section: Introductionmentioning

confidence: 99%

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Highly Sensitive Determination Method for Total Carbonate in Water Samples by Flow Injection Analysis Coupled with Gas-Diffusion Separation

et al. 2001

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A spectrophotometric method for the determination of total carbonate in water samples was developed. The method is based on the color change of an acid-base indicator in relation to the concentration of permeable gas substances through a membrane. By using a new portable FIA system equipped with a gas-diffusion unit, a highly sensitive and on-site determination of total carbonate in aqueous solutions was investigated. A new color-change system with 4-(2′,4′-dinitrophenylazo)-1-naphthol-5-sulfonic acid (DNN5S) was developed. Absorbance changes of the reagent solution were measured at 450 nm with a light-emitting diode (LED) as a light source. A new type of gas-diffusion unit was used, and was constructed with double tubing: the inner tubing was a micro porous PTFE (polytetrafluoroethylene) tubing (1.0 mm inner diameter and 1.8 mm outer diameter, pore size 2 µm, porosity 50%); the outer tubing was made of glass with 2.0 mm inner diameter. The optimized system conditions were as follows: the sample size was 200 µl, the temperature of the air bath for the gas-diffusion unit was 25˚C, and the length of the gas-diffusion unit was 15 cm; each flow rate was 0.3 ml min -1 . For measuring carbonate at low concentrations, a method for preparing water with less carbonate was proposed: the carbonate content of the water was decreased down to 5 × 10 -7 M. The calibration graph was rectilinear from 1 × 10 -6M to 10 -3 M, and the detection limit (corresponding to a signal-to-noise ratio of 3) was 1 × 10 -6 M of carbonate. The relative standard deviation (RSD) of ten measurements of 2.3 × 10 -5 M Na2CO3 solution was 1.9%. The total carbonate in various kinds of water (such as river, sea, rain, distilled and ultra purified) was determined.

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Section: Selection Of Color-developing Reagentmentioning

confidence: 99%

Section: Optimization Of Fia Conditions For a Sensitivity Improvementmentioning

confidence: 99%

Section: Improvement Of Gas-diffusion Unitmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Highly Sensitive Determination Method for Total Carbonate in Water Samples by Flow Injection Analysis Coupled with Gas-Diffusion Separation

et al. 2001

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“…Employment of a GD unit enables colored samples, or samples which differ in refractive index from the reagent, to be analyzed without optical interference. Motomizu and his group reported a number of GD applications in flow injection (FI) analysis [12,13,14,15,16,17] including application to iodide and other halogens [15]. In 1997, Hakedal and Egeberg [18] proposed an FI system for determination of iodide in brine.…”

Section: Introductionmentioning

confidence: 99%

Simple and selective method for determination of iodide in pharmaceutical products by flow injection analysis using the iodine?starch reaction

Nacapricha

Uraisin

Ratanawimarnwong

et al. 2004

Analytical and Bioanalytical Chemistry

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This work exploited the well-known iodine-starch reaction for development of a simple flow-injection (FI) method for determination of iodide in pharmaceutical samples. Iodide in an injected zone was oxidized to iodine. A gas diffusion unit enables selective permeation of iodine through a hydrophobic membrane. Detection was made very selective for elemental iodine by employing formation of the I(3)(-)-starch complex. The detection limit (3 S/ N) of the system was 1 mg I L(-1). For a liquid patent medicine used for asthma treatment we suggested modification of the system. Direct injection of this sample, which contains a particularly high concentration level of iodide (ca. 9000 mg I L(-1)), can be achieved by coupling a dialysis unit to the FI system. This has increased the working range to 6000-10,000 mg I L(-1) without employing complicated nanoliter injection.

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Environmental Applications of Flow Analysis

Motomizu

2008

Advances in Flow Analysis

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Assembly of a new gas-diffusion unit and its application to the determination of total carbonate and ammoniacal nitrogen by FIA.

Cited by 12 publications

References 0 publications

Highly Sensitive Determination Method for Total Carbonate in Water Samples by Flow Injection Analysis Coupled with Gas-Diffusion Separation

Highly Sensitive Determination Method for Total Carbonate in Water Samples by Flow Injection Analysis Coupled with Gas-Diffusion Separation

Simple and selective method for determination of iodide in pharmaceutical products by flow injection analysis using the iodine?starch reaction

Environmental Applications of Flow Analysis

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