Analysis of manufacturing by-products and impurities in illicit cocaine via high-performance liquid chromatography and photodiode array detection.

An high-performance liquid chromatography (HPLC) method is reported for the detection of manufacturing by-products and impurities in illicitly produced cocaine. For the first time peak enriched chromatograms were obtained using HPLC, and were accomplished using reversed-phase chromatography and photodiode array detection. The use of sodium dodecylsulfate as an ion-pairing reagent permitted the simultaneous separation of acids, mono-protic amines and di-protic amines, and, in combination with gradient elution, greatly increased the number of compounds separated. A mixed binary-ternary gradient was used to further optimize the separation. Dual UV detection at 215 and 277 nm was used. The chromatogram at 215 nm consisted first of carboxylic acids such as benzoic acid, cinnamic acid (cis and trans) and several isomers of truxillic and truxinic acid; next the mono-protic amines benzoylecgonine and cinnamoylcocaine (cis and trans); and last a group of compounds which are believed to be isomers of the di-protic amine truxilline. In addition, simultaneous detection at 277 nm permitted the selective detection of various compounds, some of which are additional components. The rapid acquisition of UV spectra greatly facilitated compound identification.