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All samples should be in solution in an organic solvent. Often,
this will involve extraction, via acid-base extraction, from an aqueous
solvent into an organic one. It is much better to use the free acid
or free base form of an organic compound in solution rather than the
- The salts decompose in the GC injector, which is heated to around
250 C, so the retention time and mass spectrum will be of the free
acid or base form anyway.
- The conjugate acid of many organic salts of bases are strong acids,
such as HCl or HSO. The may lead to
primary or secondary contamination problems as they accumulate in
the GC inlet. Therefore, it is better from an instrument maintenance
standpoint to avoid the injection of such salts.
John S. Riley, DSB Scientific Consulting