Edited by AMitchell, 24 March 2005 - 06:23 AM.
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Problem Positive Control Sample in ELISA
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Posted 24 March 2005 - 06:20 AM
Please help....I am running an indirect ELISA for anti-rPA Total IgG. I have recieved from an outside source a positive serum sample (polycolonal rabbit sera) to use in my assay until I can stock pile my own. So far I conducted 5 ELISA and I am observing alot of variation in the OD405 readings of the positive control. The first time a ran a set of ELISA's the readings were 0.844, 0.786. The second time the reading was 1.600. THe third time the readings were 3.227, and 2.105. I did change lots for the ABTS substrate that I use between the first and second time I ran an ELISA. I think it would be plausible to expect some variation in OD readings but not as much as I have observed (approx. difference 0.8). The lot number was the same for the third ELISA and the readings are much higher than before and there is considerable variation just between two plates (3.227 and 2.105). I use a fresh aliquot of the positive sera each time to prepare my control which I dilute to 1:1600. Any and all suggestions are greatly appreaciated. Thanks in advance!!!