4
–
Example Applications
Thermo Scientific
Product Manual for IonPac AS31 Columns
Page 24 of 45
155007-01
For Research Use Only. Not for use in diagnostic procedures.
4.7
Separation and Detection of 9 HAAs, Bromate, and Dalapon using IC-MS
The Dionex IonPac AS31 provides good separation of common inorganic anions, monochloroacetic acid,
monobromoacetic acid, dichloroacetic acid, chlorobromoacetic acid, dibromoacetic acid, trichloroacetic acid,
dichlorobromoacetic acid, chlorodibromoacetic acid, tribromoacetic acid, bromate, and dalapon using a potassium
hydroxide eluent and mass spectrometric detection. Please note that IC analysis was performed on a Thermo Scientific
Dionex ICS-5000
+
HPIC System and matrix ions were diverted to waste, with only the ions of interest sent to the Mass
Spectrometer. The separation of all nine haloacetic acids, bromate, and dalapon in the EPA Method 557 LSSM matrix
is shown in Figures 6 and 7.
For these analyses, we used negative ion, Full Scan Mode with 330 ms max inject time. Good extracted ion
chromatograms were produced from both SIM and Full Scan Modes. S/N values for MCAA and MBAA were better in
SIM mode, while S/N values for all other ions were better in Full Scan mode. In both modes, we observed highly
accurate mass values allowing resolution of molecular ions differing in m/z by 0.032 (Bromate and DCAA). With
minor
In-Source
fragmentation, we observed diagnostic fragments for all components.
The following table can provide initial guidance on setting up time windows for matrix diversion based on the retention
times of chloride, carbonate/sulfate, and nitrate. The recommendations below can be adjusted based on the gradient
delay volume of the HPIC system and the retention times of the Dionex IonPac AG31/AS31 columns to ensure analytes
of interest are not diverted to waste. Please note that on some occasions, chloride, carbonate, and sulfate could co-elute
as a single peak. Example 2 below shows how to setup the matrix diversion window when this occurs.
Retention Time
Chloride
Retention Time
Carbonate/Sulfate
Retention Time
Nitrate
Matrix diversion window plus
+ 1.0 min
+ 1.5 min
Matrix diversion window minus
– 1.0 min
– 1.5 min
Example 1:
Retention Time
Chloride
Retention Time
Carbonate/Sulfate
Retention Time
Nitrate
Dionex IonPac AG31/AS31 set #1
9.58 min
10.08 min
20.3 min
Start
diverting flow to waste
8.58 min
18.8 min
Stop
diverting flow to waste
11.08 min
21.8 min
Example 2:
Retention Time
Chloride
Retention Time
Carbonate/Sulfate
Retention Time
Nitrate
Dionex IonPac AG31/AS31 set #2
9.93 min
9.93 min
20.7 min
Start
diverting flow to waste
8.93 min
19.2 min
Stop
diverting flow to waste
10.93 min
22.2 min
