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Blank not reading "0"
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What instrument and methods are you running?
AA 400, looking at Na and K. With K, I have a filter insert.
ATOMIC ABSORTION is a very sensitive method and anything could cause these type of problems. Check your furnace for possible contamination, also inspect the graphite tube or replace it and see the difference. Make fresh new calibration blanks and standards, as well as the matrix modifier.
If your blank wasn't reading zero maybe the furnace needed to be aligned, also sometimes its normal reading numbers outside zero when running blanks. What I usually do is create a setup for blanks only and perform calibration and eventually perform regular analysis and see if there are any positive changes.
HectorAtlas at what levels are your energy readings for Na and K?
We dont test for Sodium or Potassium via AA. However, anything above 1ppm seems to be very high levels for this instrument. the highest standard I make is 500ppb and from there the instrumnet dilutes to multiple calibration points.
I didnt know much when I started using the AA, I still dont know a lot, but i understand much of the work needed to analyze Lead, Bismuth and Selenium and one of the things that help me a lot was the Cookbook that was included in the files plus all the tools that PinAAcle900z has such as the recommended conditions, the characteristic mass, check method, etc.
Look at the recommended conditions for these elements and compare it to the settings you have when analyzing. Write down eveything the way you have now so if you make any adjustments, then you can see the positive or negative results you are obtaining.
ok make a list of all consumables/standards such as matrix modifiers, acids, graphite tubes, graphite contacts, you use and mark the ones that are new. Replace what you havent yet and verify if it makes a difference.
How is the current lifetime of your lamps or lamp? The instrument must have an option to see these data. If you have an spare lamp available, try it and see if it makes a difference.
Some instruments have the options for aligning the furnace, check manual if yours has this option and see if your instrument needs it.
Contamination in the furnace or in the lenses could be another possible cause. Your manual should have a page for troubleshooting with different possible options, check for this if you havent yet.
Mine has these locks underneath the furnace so before I adjust anything, I open the window for Lamp current and then I see how the current increases or decreases according to the adjustment is being applied. Again, im not sure if all instruments are the same but mine has two locks, one is for front-back movement, and other for angle. it also has a camera where I can see the direction the adjustment is going. Current will increase to highest point possible before decreasing as I keep adjusting, then I try to find the middle point by finding the highest lowest point of these adjustments. I also mark the position as is now so in case I want to start over.
Sorry my friend but that is the best solution I can think at the moment. Good luck.
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