Biotage ELSD-A120 - Cartridge Considerations; Sample Preparation

Biotage
®
ELSD-A120 User Manual 37
Using the Detector
4
General Considerations
Sample Preparation
Samples containing particulate matter should be filtered through a
0.45 µm filter prior to analysis.
Cartridge Considerations
ELSD-A120 will detect all non-volatile components in the mobile
phase, which includes cartridge-packing material. Cartridge packing
material will become chemically and mechanically broken down over
the lifetime of the cartridge, causing particles to enter the detector.
This cartridge “shedding” will lead to extremely high baseline.
Amino cartridges used with aqueous mobile phase are particularly
prone to this type of shedding and should be checked regularly. To
minimize cartridge breakdown always follow the manufacturer’s
instruction supplied with the cartridge.
Table 4 Volatile Mobile Additives Compatible With ELS Detection
Mobile Phase Additive pKa pKb Bp (°C) Mp (°C)
Acids
Trifluoroacetic Acid (TFA) 0.3 13.70 72.4 -15.4
Formic Acid 3.75 10.25 100.7 8.3
Acetic Acid 4.75 9.25 116.0 16.6
Bases
Ammonia 9.25 4.75 -33.4 -77.7
Methylamine 10.66 3.34 -6.6 -94.0
Ethylamine 10.81 3.19 16.6 -81.0
Triethylamine 11.01 2.99 89.3 -114.7
Ion-Pair Reagent
Pentafluoropropionic acid
(PFPA)
~0.6 97
Heptafluorobutyric acid (HFBA) ~0.6 120
Nonafluoropropionic acid (NFPA) ~0.6 140
Tridecafluoroheptanoic acid ~0.6 175