Fast and quantitative high-performance liquid chromatography method for the determination of 9-fluorenylmethoxycarbonyl release from solid-phase synthesis resins

Base catalyzed cleavage of 9-fluorenylmethoxycarbonyl (FMOC) group and subs equent analysis by UV spectrophotometry is a commonly used technique for me asuring the loading of functional groups on solid supports. Recent works su ggest that using 1,8-diazabicyclo[5,4,0]undec-7-ene (DBU) instead of piperi dine makes it possible to use gas chromatography for quantitation, but due to the long deprotection time used, the method is not high-throughput. We o bserved that the dibenzofulvene released after DBU deprotection could be me asured by reversed-phase (RP) HPLC. We have optimized the concentration of DBU as well as the time of the deprotection and coupled with a fast RP-HPLC separation results in a highly reproducible, high-throughput method. The m easured loading correspond well with the manufacturer's data on several com mercial resins. Using this method we have quantitated the amine loading on several polystyrene resins and we have found that the total amount of funct ional group can be more than twice the amount of the available ones. We con cluded that the differences were the function of the resin loading as well as the level of crosslinking. (C) 2000 Elsevier Science B.V. All rights res erved.