LC Technical Note

Analysis of Iodide Ions in Seawater by HPLC with ECDLT106

GL Sciences Inc.

Analysis of iodide ions typically requires separation by ion chromatography followed bydetection and quantification using an electrochemical detector (ECD) with a silver electrode, or an
inductively coupled plasma mass spectrometer (ICP-MS). However, when using a typical ECD, thesilver electrode requires periodic polishing. Both ion chromatography and ICP-MS have thedisadvantage of high equipment cost. In this report, an analytical method that combines reversedphase HPLC and an electrochemical detector with a diamond electrode is shown to be a moreconvenient method. For separation, iodide ions are successfully retained on an ODS column usinga mobile phase with an ion pair reagent. For detection, an electrochemical detector with diamondelectrode (that does not require polishing and needs little maintenance) was used. Using thismethod, it is possible to detect and quantify the iodide ion concentration in seawater.
(C. Aoyama)

Example: Measurement of standardnA
100 120 140 160 180

1. Iodide ion (I-) 1 μmol/L
HPLC conditions
Column: Inertsil ODS-4(5 μm, 150 x 3.0 mm I.D.)
Eluent: A) Phosphate buffer *B) CH3CN
A/B = 65/35, v/v(Mixed by a gradient mixer)
Flow rate: 0.4 mL/min
Column temperature : 35 ˚C
Detected: ECD 1000 mV vs. Ag/AgClDetected: (ED723,Diamond)
Injection volume : 10 μL

6080

140

* Phosphate buffer:
1.56 g disodium dihydrogen phosphate (dihydrate) 3.58 g
Disodium hydrogen phosphate (12 hydrate) and 0.32 gchloride Hexadecyltrimethylammonium were dissolved in
1 L of ultrapure water.

0246810Time (min)Relationship between potential and peak area

Calibration curve

ピーク面積PeakArea

ピーク面積PeakArea

R2 = 0.999

600

800

1000

1200

電位（mVvs. vsAg/AgCl）
Potential(mVAg/AgCl)

1400

00.5

11.5Concentration (µmol/L)
濃度 (μmol/L)

22.5

GL Sciences LC Technical Note

<Example Chromatograms of sea water analysis>
The seawater was filtered through a 0.45 μm membrane filter, which served as a sample solution.

Seawater sampled at a tourist beach

1. Iodide ion (I-)

1. Iodide ion (I-)

Quantitative results: 201 nmol/LQuantitative results: 93 nmol/L

100100

Seawater sampled at an urban fishing port

160

60

80

80nAnA

10246Time (min)8100246Time (min)810GL Sciences disclaims any and all responsibility for any injury or damage which may be caused by this data directly or indirectly.
We reserve the right to amend this information or data at any time and without any prior announcement.

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