Adjustable volume pipette sampler

Claim 1

An adjustable volume sampler or syringe, useful for the introduction and the dispension of liquid samples therefrom comprising: an upper hollow tubular member having a central longitudinal axis and a first inner diameter along a majority of the length thereof, and upper and lower ends, said upper member including an inwardly projecting internally threaded region of short length near its said lower end, said internally threaded region having a second inner diameter smaller than said first inner diameter; a lower hollow tubular member coaxial with said upper tubular member, and having upper and lower ends, said lower member including a partially externally threaded region near its said upper end, said lower member being partially received within and threadedly fastened coaxially within said upper member to define an adjustable volumetric capacity barrel, said lower end of said tubular member having an introduction and discharge opening; plunger means, coaxial with said upper and lower tubular members, for the introduction or dispension of liquid samples from within said barrel, said plunger means extending from outside of said upper tubular member along and within said upper tubular member and into the interior of said lower tubular member, and having a slidable sealing means at the bottom thereof for sliding contact with an interior of said lower tubular member; spring biasing means for urging said plunger means in an upward axial direction and comprising a coil spring residing within said upper tubular member above said internally threaded region and encircling a portion of said plunger means, an upper end of said coil spring abutting against an upper portion of said plunger means, and a lower end of said coil spring abutting against said lower tubular member; and stop means at the upper end of said upper tubular member for limiting the upward axial travel of said plunger means.