GC columns vary considerably in their polarity and affinity for different chemical functional groups. Compound separation is largely dependent on the affinity each sample compound has for the stationary phase (column coating material) relative to the mobile phase (nitrogen, hydrogen or helium carrier gas). A standard column is a DB-1 column (30 m long x 0.25 mm ID x 0.25 μm coating thickness), a column with a nonpolar stationary phase (a column whose inner surface is lined with a nonpolar matrix such as dimethylpolysiloxane) which is an excellent general purpose column that separates nonpolar and slightly polar compounds very well. Polar compounds such as organic acids chromatograph poorly on this column. Similar nonpolar dimethylpolysiloxane (PDMS) columns, such as HP-1 and SPB-1, also separate most volatiles associated with honey bees quite well. For polar compounds, a better alternative is the DB-35 ((35 % Phenyl)-methylpolysiloxane) column.