Ion Chromatography

AMI uses a Dionex ICS-1500 as our ion chromatography system. Typically this is used for fluoride, chloride, bromide, nitrate, nitrite, sulfate, and phosphate.

A liquid sample (or digested solid) is passed through the sample loop and injected into the eluent stream. This system is isocratic, so the eluent composition and concentration never changes throughout the test. The pumps push the eluent and sample through the guard and separator columns, and the sample ions are separated through ion exchange. This is based on the premise that different sample ions migrate through the IC column at different rates, depending upon their interactions with the ion exchange sites. After the eluent and sample ions leave the column, they flow through a suppressor that selectively enhances detection of the sample ions while suppressing the conductivity of the eluent. A conductivity cell measures the electrical conductance of the sample ions as they emerge from the suppressor and produces a signal based on a chemical or physical property of the analyte. The data collection system identifies the ions based on retention time, and quantifies each analyte by integrating the peak area or peak height. The data is quantified by comparing the sample peaks in a chromatogram to those produced from a standard solution to determine the sample concentration.

Typical methods include:

• EPA Method 9056A
• EPA Method 300.1
• ASTM D4208