Erwin Chargaff's research determined the percentage of the nitrogen bases within a strand of DNA. His work determined thatthe concentration of adenine is twice the concentration of thymine and the concentration of cytosine is twice the concentration of guanine.the percent of adenine is equal to the percent of guanine and the percent of cytosine is equal to the percent of thymine.the percent of adenine is equal to the percent of thymine and the percent of cytosine is equal to the percent of guanine.the concentrations of adenine, thymine, guanine, and cytosine are all equal.