9.3 Acid-Base Forms of Organic Analytes

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 salt form.

• 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 H$_{\textrm{2}}$SO$_{\textrm{4}}$. 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.