Skarping, G; Renman, L; Dalene, M
Gas chromatography (GC) for the trace analysis of aromatic amines was developed. The chromatograph was equipped with an on column injection system and a thermionic specific detector. Aromatic amines were derivatized to their corresponding amides by reaction with a perfluorofatty acid anhydride. The amides were separated on a capillary column and detected by a thermionic specific detector. Amines investigated included aniline (62533), 2,6-toluenediamine (823405), 2,4-toluenediamine (95807), 2,4-diaminoanisole (615054), alpha-naphthylamine (134327), beta-naphthylamine (91598), 4-aminobiphenyl (92671), 1,5-naphthalenediamine (2243621), benzidine (92875), methylenedianiline (101779), o-tolidine (95534), methylene-bis-o-chloroaniline (27342752), and o-dianisidine (119904). Standard solutions of amines were prepared and amides were obtained by adding heptafluorobutyric-acid anhydride (HA), pentafluoropropionic-acid anhydride (PFA), monochloroacetic-acid anhydride (MCA), or acetic-acid anhydride (AA). The thermionic detector was optimized for maximum sensitivity by adjusting the hydrogen, air, and make up gas flow rates during injection of the derivatives. Quantitative analysis was based on peak area measurement. AA and MCA gave amides with much higher elution temperatures than the other anhydrides; AA was not suitable as an acylating agent because of the high elution temperatures and a tendency to cause tailing peaks at picogram concentrations. PFA and HA were suitable for general application, and MCA was useful for trace analysis of amines that did not have high boiling points. Injection of aromatic amine derivatives from PFA in toluene had a reproducibility of 0.8 to 1.7 percent. Columns that were not polar gave lower elution temperatures and greater resolution. Helium was the better carrier gas. The authors conclude that trace analysis of aromatic amines using capillary GC and a thermionic specific detector is a useful method for assaying amines.
