Setting AVS 7 for trace element analysis

Question

Hello, i'm working on developing methode of chromium in milk powder by ICP-OES 5110, i used to set up the AVS 7 as attached on pic and it have been having bad replicates, it's always on 3rd replicates meanwhile on 1st and 2nd replicates is fine. Anyone had this issue, I've already try another setting for avs but nothing changed. Can you give me some recomendation for this issue?

evanclay · Accepted Answer

Hello, 
 The intensity reading for the 3rd replicate is very low. This suggests there is no sample left in the loop when you are measuring the 3rd replicate. You did not state what size loop you are working with - but this is too small for the conditions you are working with. 
 So you either need to use a larger loop size - or you need to modify the conditions so that you can measure the 3 replicates with the current loop. I can't see all the method conditions you are working with - but to work with the smaller loop size, you may need to reduce the read time (per replicate - if you want to continue to use 3 replicates), or else you would need to reduce the inject pump rate (which will reduce signal slightly). Otherwise, you could leave the read time unchanged and go back to 2 replicates. 
 If you go to a larger loop size, remember that you will need to allow more time for the loop to be filled prior to the reading - and you will need to check the rinse time to ensure the remaining sample in the loop (if any) is washed out before reloading. 
 Hope those comments help you, Cheers Eric

almander · Answer

Hello, 
 I recommend trying the following: 
 1. under "Measurement Conditions" set the stabilization time to 5 sec. From your picture, I can't see what your stabilization time is currently set to. 
 2. under "Common Conditions" deselect the Fast pump check box and set the rinse time to 0s. 
 3. Click the small rectangular calculator icon (to the right of Pump rate - Uptake) to access the AVS Parameter Calculator. Select the sample pump tube type, enter the Autosampler tube length (measured from the tip of the probe to the valve), and select the volume of the loop you have installed. Then click 'Apply' to apply the Recommended Configuration and try running the worksheet with the recommended configuration conditions.

Setting AVS 7 for trace element analysis

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