A 5.00 kg batch of crude penicillin was assayed by isotope dilution. To a 1.00 g sample of this batch was added 10.0 mg of 35S-labled penicillin having an activity of 10600 cpm. Only 1.40 mg of pure penicillin having an activity of 280 cpm was recovered. What was the penicillin content of the original 5.00 kg of crude penicillin?