Waters Sep-Pak DNPH-Silica Cartridges - Manual (Page 7)

[ Care and Use ManUal ]
Waters Sep-Pak DNPH-Silica Cartridge
7
VI. trouBLesHootInG
Use Table 5 to solve common problems that may arise while using
the cartridges. Most errors occur as a result of contamination during
sample preparation. If resolution problems persist, validate the HPLC
system
5 .
Table 5: Troubleshooting Common Problems
VII. reFerenCes And BIBLIoGrAPHY
1. Committee on Aldehydes, Board of Toxicology and
Environmental Hazards, National Research Council,
Formaldehyde and Other Aldehydes; National Academy Press,
Washington, DC, 1981.
2. Tejada, S.B., “Evaluation of Silica Gel Cartridges Coated In
Situ With Acidified 2,4-Dinitrophenylhydrazine for Sampling
Aldehydes with Ketones in Air”, Intern. J. Environ. Chem. 1986,
26, 167-185.
3. Riggins, R. M., “Compendium of Methods for the Determination
of Toxic Organic Compounds in Ambient Air”, US Environmental
Protection Agency Report EPA-600/4-84-041, US
Environmental Protection Agency: Research Triangle Park, NC,
1984.
V. storAGe And dIsPosAL oF used CArtrIdGes
Storing unused Cartridges
Always store any unused Waters Sep-Pak DNPH-Silica cartridges in
their protective pouches to prevent contamination.
Store the sealed pouches in a refrigerator at (4 °C or lower) for up to
six months. Cartridges may be stored in their unopened pouches at
room temperature (20 to 25 °C) for up to two weeks.
Background levels of hydrazone derivatives increase slightly with
time and temperature. Before using cartridges exposed to high
temperatures or stored longer than the recommended periods, run a
blank.
Storing Exposed Cartridges
Once a cartridge has been used to collect a sample, be careful to
cap and seal it until it is time to elute it. Inadvertent exposure of an
exposed cartridge can ruin a carefully collected sample. Elute the
derivatives from the cartridge within two weeks.
Disposing of Used Cartridges
Dispose of used cartridges according to applicable government
regulations.
Symptom Possible Cause Solution
High carbonyl values
in unused cartridges Contaminated acetonitrile Certify acetonitrile quality prior
to use, see Appendix A
Contaminated glassware Use only pre-cleaned glassware.
Air contamination of
sample during elution
Prepare sample in a glove box.
Cartridge age and storage
conditions
Buy new cartridges. Refrigerate
unused cartridges. Rotate stock.
Improper mobile phase
composition
Prepare fresh mobile phase,
decrease acetonitrile content.
Formaldehyde
coelutes with other
peaks Separation conditions Check separation conditions. Use
a gradient separation.
Broad peaks Injection volume too high Use injection volume appropriate
to column (≤ 20 µL for 150 mm
or ≤ 10 µL for 75 mm Nova-Pak
C
18
columns).