Simazine-d10 is intended for use as an internal standard for the quantification of simazine by GC- or LC-MS. Simazine is a triazine herbicide. Pre-emergent application of simazine (1 kg/ha) controls annual and perennial monocot and dicot weeds and increases crop yield in sorghum crops. It also controls weed emergence in kharif maize crops when applied at a concentration of 2 kg/ha. Simazine (200 and 400 mg/kg) induces spleen cell apoptosis and reduces the proliferation of B and T cells in mice. Formulations containing simazine have been used in the control of broadleaf weeds and annual grasses in agriculture.