It passes directly from the solid to the gas phase.
This usually requires separation of the solid and solution phases.
Adding more ice will just increase the amount of solid phase.
Some substances have more than one solid phase, depending upon the temperature and pressure.
Water, for example, has 13 solid phases at last count.
Ice for example, has at least 9 and possibly 11 solid phases.
Water has somewhere between 11 and 13 solid phases at high pressure, depending upon whose data you believe.
In some cases there is a chemical reaction between the water and the solid phase.
The analysis may also be in the solid or gas phase.
This means that in most environmental systems, 5β-coprostanol will be associated with the solid phase.