The unrepeatability of the results

Question

Hi, 
 We have a problem with repeatability of the results. Internal standard (Y) measurements are also unstable, eg for four samples the results are 1.05; 1.04, 1.04, 1.05 but for the next sample the result is 1.89. And I don't know why. Sometimes I have to repeat the sample twice to get the good value of the internal standard. This problem appears also for calibration standards. Mayby I should add that we use the online system for the internal. The second problem is unrepeatability of the results of our samples. For the three replicate from the same sample I got the different concenration (-0.127,0,25 and 4014). This problem appears not everyday but often and always for radial obserwation. Do you have any idea how to deal with these problems? Thank You for your help! 
 Sabina

vancleef · Accepted Answer

Hi Sabina, 
 This appears to be an instrument issue rather than a standards issue. I have reached out to them and they commented that the variability of the internal standard will affect the sample results. A ratio greater than 1.0 could indicate that either the internal standard tubing has come up out of the internal std solution, or there is some other issue with the sample intro delivery and air has gotten into the system. The other option is the ample has the internal std element present in it. Is your IS Yttrium? What are the part numbers for the IS and the calibration standards? Do you also use axial view, and does this happen with axial view too? It was recommended that a worksheet be included to see what is going on. 
 Best regards, 
 Trish

The unrepeatability of the results

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