Any tips on analysing calcium on a 240FS with a nitrous oxide/acetylene flame?
I set up our new nitrous burner and have been exploring calcium at 239.9nm. First time, the signal looked awful (0.1-0.2 absorbance units of noise bouncing around), instrument wouldn't calibrate, and the gain was spiked in the 90+% range. The next day, I did a little cleaning of the burner head (minimal), made some very minor optimization changes (burner, lamps, signal), and the signal was beautiful with gain in the 35-40% range. Then I stepped away for a week or so…
The past couple days I've been looking at higher concentration calcium samples at 239.9nm, and I'm back to a noisy signal with 90+% gains and poor calibration. I have added 2200ppm potassium to try and improve the calcium signal in the most recent samples.
I'm planning to take everything apart and give it a good cleaning in the morning, but if anyone else has tips I'd appreciate any input. I am able to get the absorbance readings from the calcium standard, and although it isn't the prettiest calibration curve, it at least looks like it's trying to be linear... the noisy signal is just throwing it off.
Thanks again. That one magical day with pristine data got my hopes up.