A comparison of techniques for analysing 90Y-Zevalin thin-layer chromatography plates

OBJECTIVESTo simulate Y-Zevalin thin-layer chromatograms representing a range of radiochemical purities, to compare the radiochemical purities obtained with five techniques used to quantify Y on the plates and to measure the reproducibility of the five techniques at the minimum acceptable radiochemical purity of 95%. METHODSYttrium-90 solutions were pipetted onto the origin and solvent front lines of thin-layer chromatography (TLC) plates to simulate radiochemical purities of 90%, 92%, 94%, 95%, 96%, 98% and 100%. Each plate was analysed using three TLC scanners (Bioscan AR2000, Bioscan Mini-scan and an instrument constructed in-house) and two cut-and-count techniquesone using a sodium iodide well detector and the other a liquid scintillation counter. The reproducibility of each technique was measured by analysing the 95% plate 10 times. RESULTSThe radiochemical purities measured by the five techniques agreed well. The means of the seven results obtained with each agreed within 0.7%. The reproducibility of each technique was excellent. The coefficient of variation for 10 measurements was ≤0.3%. The signal to background ratios were satisfactory, ranging from 24 to 2.1×10. CONCLUSIONEach technique is suitable for analysing Y-Zevalin TLC plates.