This assay has high sensitivity and excellent specificity for detection of Glutamine synthetase. No significant cross-reactivity or interference between Glutamine synthetase and analogues was observed. Sample types: serum, plasma, tissue homogenates, cell lysates and other biological fluids. Range: 15.62-1000 pg/mL. Sensitivity: 6.2 pg/mL. Intra-assay Precision (Precision within an assay): 3 samples with low, middle and high level Glutamine synthetase were tested 20 times on one plate, respectively. Inter-assay Precision (Precision between assays): 3 samples with low, middle and high level Glutamine synthetase were tested on 3 different plates, 8 replicates in each plate.CV (%) = SD/meanX100;Intra-Assay: CV<10%;Inter-Assay: CV<12%. Time: 3 hours