Atmospheric heterogeneous photoreactions occur between formaldehyde and hydroxyl radicals to produce formic acid. These photoreactions not only occur in clouds, but also in other tropospheric hydrometeors such as precipitation and dew droplets. Experiments were performed by irradiating Teflon tubes containing nanomole concentrations of formaldehyde and hydrogen peroxide. Following irradiation at a wavelength of 313 nanometers, the concentrations of formaldehyde and formate ion were analyzed using High Pressure Liquid Chromatography and Ion Chromatography. Data are presented to illustrate how nitrate and sulfate anions effect the photo-oxidation of formaldehyde in the aqueous-phase, as well as the effects of these anions on the formate ion which is a product of this photo-oxidation.