An in situ autosampling method and associated sampling device for capturing a material sample from a vessel. Methods of the present invention make use of a sampling device having an extendable sample capture element with a concave sample capture pocket located near a distal end thereof. The sample capture pocket is adapted to capture a known volume of material when the sample capture element is extended into said material. The material sample remains trapped in the sample capture pocket upon sample capture element retraction. Ports in the sample capture pocket may be placed in communication with corresponding material transfer channels extending through the sample capture element to allow for the in situ processing of a material sample, and the subsequent discharge of the sample to an analyzer or another downstream location.