A solid phase microextraction sampling instrument for inserting into or through a solid or semisolid material to extract a component of interest from a sample, comprising: a support structure at least partially coated with an extraction phase for extracting the component of interest, the support structure having: an insertion portion for inserting into or through the material and into the sample, the insertion portion comprising: a protrusion defining a leading protrusion side and a trailing protrusion side of the insertion portion, wherein the protrusion preferably extends around the circumference of the insertion portion of the support structure, and the height of the protrusion is preferably from about 1μm to about 1.0cm, wherein the protrusion projects with a height from the support structure that is approximately equal to the thickness of the extraction phase where the extraction phase abuts the protrusion to shield the coating during insertion in a direction along the axis of insertion of the support structure, and wherein the sampling instrument has multiple cross-sectional planes in the insertion portion that each extend about perpendicular from the axis of insertion, each cross-sectional plane having distances between the axis of insertion and the outer edge of the sampling instrument, wherein each distance in the cross-sectional plane of interest is greater than or equal to the corresponding distances in all of the cross-sectional planes located between the cross-sectional plane of interest and the insertion end of the insertion portion, characterized in that the extraction phase is located_at least on the trailing protrusion side of the protrusion and abuts a trailing side edge of the protrusion, wherein the trailing side edge of the protrusion is preferably substantially perpendicular to the support structure. a support structure at least partially coated with an extraction phase for extracting the component of interest, the support structure having: an insertion portion for inserting into or through the material and into the sample, the insertion portion comprising: a protrusion defining a leading protrusion side and a trailing protrusion side of the insertion portion, wherein the protrusion preferably extends around the circumference of the insertion portion of the support structure, and the height of the protrusion is preferably from about 1μm to about 1.0cm, wherein the protrusion projects with a height from the support structure that is approximately equal to the thickness of the extraction phase where the extraction phase abuts the protrusion to shield the coating during insertion in a direction along the axis of insertion of the support structure, and wherein the sampling instrument has multiple cross-sectional planes in the insertion portion that each extend about perpendicular from the axis of insertion, each cross-sectional plane having distances between the axis of insertion and the outer edge of the sampling instrument, wherein each distance in the cross-sectional plane of interest is greater than or equal to the corresponding distances in all of the cross-sectional planes located between the cross-sectional plane of interest and the insertion end of the insertion portion, characterized in that the extraction phase is located_at least on the trailing protrusion side of the protrusion and abuts a trailing side edge of the protrusion, wherein the trailing side edge of the protrusion is preferably substantially perpendicular to the support structure.