  HD 22128 and HD 56495 are both double-lined spectroscopic binary systems with
short orbital periods, which have been proposed to host magnetic Ap stars. Ap
stars in short period binary systems are very rare, and may provide insight
into the origin of magnetism in A-type stars. We study these two systems using
high-resolution MuSiCoS spectropolarimetric data, in order to asses the
presence of magnetic fields and study the atmospheric chemistry of the
components. This represents the first modern magnetic measurements and careful
spectroscopic analyses of these stars. We find no evidence of a magnetic field
in any of the stars, with precise uncertainties on the longitudinal magnetic
field of 50 and 80 G in the components of HD 22128, and 80 and 100 G in the
components of HD 56495. We performed detailed abundance analyses of both stars
in both systems, finding clear evidence of Am chemical peculiarities in both
components of HD 22128, and in the brighter component of HD 56495, with
overabundant iron peak elements and underabundant Sc and Ca. The less luminous
component of HD 56495 is chemically normal. The atmospheric chemistry is
consistent with the absence of magnetic fields, and consistent with the theory
of Am star formation proposing that tidal interactions slow the rotation rate
of the star, allowing atomic diffusion to proceed efficiently.
