GE Healthcare of Piscataway, NJ, has received US Patent No. 8,507,197, "Quality control methods for arrayed oligonucleotides." The provided method involves synthesizing a complement probe oligonucleotide for each oligonucleotide being tested. Probe oligonucleotides are optionally grouped. They are then hybridized to test oligonucleotides, and the hybridized pair is subject to single base extension and detection.