Patent ID: 8043564

Claim:
A needle for solid-phase microextraction of a sample to be analyzed, wherein the needle is packed with an adsorbent or concentrating medium comprising a copolymer of methacrylic acid and ethylene glycol dimethacrylate, wherein the molar ratio of methacrylic acid and ethylene glycol dimethacrylate in said copolymer ranges from 1:1 to 1:10; wherein the needle is a metal needle; wherein the needle has an inner diameter ranging from 0.2 to 0.6 mm; an outer diameter ranging from 0.5 to 0.8 mm; and a length ranging from 3 to 10 cm; and wherein the copolymer is in the form of beads each (1) having a particle size ranging from about 20 μm to about 100 μm, (2) having fine pores therein, and (3) having been prepared by copolymerizing methacrylic acid and ethylene glycol dimethacrylate in the absence of another monomer and in the presence of a dispersing agent.