217 / 582
Important Quality Parameter for
DHA Analysis
• The column must not only elute hydrocarbons
• Also need to elute
alcohols
This is a big challenge and that’s why
Rtx-DHA 100 columns are preferred
1. ethanol
2. pentane
3. t-butanol
4. 2-methylbutene-2
Elution of Alcohols on the DHA-type
Columns ASTM Method D6730
Position of alcohols depend
on the activity of the surface..
Correct positions, Good deactivation
Column : 100m x 0.25mm PONA/DHA-type
Conditions : acc to ASTM 6730
Concentration: The SAME amount injected on every column
Rtx-DHA-100
Impact of a Tailing Alcohol Peak
Supplier 1 type DHA column
7.0
8.0
9.0
10.0
11.0
Time (min)
1
2
3
4
5
1. ethanol
2. C5
3. 2 methyl butene 2
4. t butanol
# 24160U
Oven: 5 ºC → 8.23 min., 22ºC/min → 48 ºC
Alcohol peaks are retained by column
activity / adsorption;
They elute at wrong position..
Risk: Misidentification and possible wrong data