A procedure is presented for determining the concentration of polymer lithium, alkyllithium, and monomer by use of small-molecule GPC. The system poly(styryllithium), butyllithium, styrene, and benzene are used to illustrate the method. The method as presented has a lower limit on the direct measurement of butyllithium concentration of 0.00005 molar. If the total carbon-bound lithium is to be determined, the limit can be appreciably lowered. The styrenebenzene separation was obtained for concentration ratios of 1:5 or greater. Several suggestions are presented for improving these analyses.