  We present two methods to extract the chemical potentials of quarks in high
energy collisions. The first method is based on the ratios of
negatively/positively charged particles, and the temperatures extracted from
the transverse momentum spectra of related hadrons are needed. The second
method is based on the chemical potentials of some particles, and we also need
the transverse momentum spectra of related hadrons. To extract the quark
chemical potentials, we would like to propose experimental collaborations to
measure simultaneously not only the transverse momentum spectra of anti-p, p,
K^-, K^+, pion^-, and pion^+, but also those of D^-, D^+, B^-, and B^+ (even
those of Delta^++, Delta^-, and Omega^-) in high energy nuclear collisions
