Ion-pair
chromato~2phy offers attractive possibilities in pharmaceutical z~~&si~. The specificity of the separation ~pist~~~ CZII be W&C? OVZ~ a wide range by zppropri2te selection of the stationary phazc 'Be choice of 2 suitable counter-ion can also dr2sticxlIy improve the detection !imit, permitting the determination of drug subsfinces in Iow dosage 2nd possibly of by-products or breakdo%<-products. fonpair chromato_erapby of tropane 2nd ergot alkaloids has been investigated using picr2te as counter-ion. Alumina, Kieselguhr 2nd various _mdes of silica gel have been tested 2s supports. PartiEion properties studied in a b2tch procedure has-e been compared with -the actual chromztograpbic conditions. Columns (IO cm) fiEled with silica gef @article site, 5pm; pore size, 1000 A) show the best performance in the separation of hybscyamine, scopofamine 2nd ergo&nine 2s picrate ion-pairs. C&e wntrol of@ 2nd temperature is essential for reproducibIe separations. Improvements in detectioa limits between 100 2nd 300 times have been observed with these systems. Ion-pair extractions of these alkaloids from dosage forms can be used for sample preparation prior to injection OR to the column. This provides an added degree of s&cGvity 2nd sensitivity.
The b&t detectors currently 2v2ilabfe in high-pressure liquid chromatography PLCj -2re spec~ruphoEometric and also spectrofftroriietric and it seems Iogical .refore to solve the current detection problems at least partially by ultr2vio:et (Vu; i fluorescence derivatization methods. Recent activities show indeed the increased =R% in such an approach L.2. Another import2nt argument for derivatization is the :cificity of detection. This is 2n import2nt factor for analysis in 2 complex matrix % 2s polluted w2~eer SourCeSI biolo$caf materials or compficated pharmaceutical mufations where marry interfering substances are encormtered. By using spxific semispe&ie 12belhg re2gents, derivatization caz~ be e_+oyed 2~ 2 clean-up step.