Hello, I work in a lab which is new to ICP-OES and I would ask for help from more experienced users. We use iCAP 7200 Radial and Qtegra software.
1. Can we import calibration curve from previous measurement or we need to run standards every single time?
2. How many 9's should be in R2.
3. What about RSE. We asume it should be the lowest, but how low, like 5%? What determines it's value?
4. What determines range of standards taken to make calibration curve? I mean like 0,1 ppm - 100 ppm, 0,05 ppm - 20 ppm.
5. What would you do with situation presented in attached screenshot. It's line 220 for Pb, as you can see the center of peak for sample (blue) is slightly moved to the right compared to standard. Is there interference?
Hi Magdalena,
I will try to answer some of your questions.
1. Every time you make an analysis, you need to perform a previous calibration step. This step is mandatory for any spectrometric technique since the measured analytical signals may change considerably for both short and long terms. In some cases, for example in a long run, depending on the matrix and other conditions, you also may need an additional calibrations in order to obtain quality results.
2. A good calibration fit for ICP OES is often higher than 0.9980, but you can get acceptable results with lower values. All depends on how careful you need to be in your analysis.
3. Did you mean "RSD" (relative standard deviation)? If is this the case, lower RSD means better precision. In general, the ICP OES analysis present typical RSD values below 5%, depending on matrix and operating conditions.
4. Calibration range is a characteristic of the element and the emission line you ar measuring. For example, the main wavelenght for Pb is around 405 nm and less intense lines may be found at 220 nm or 283 nm. In this case, 405 nm is the most sensitive, thus it is most probable that you have a linear range at lower concentrations (just guessing, 0.01 - 5 ppm). On the other hand, less sensitive lines will give you higher ranges (for example, 0.1 ppm - 20 ppm or higher).
5. I´m not sure about the software you are using since I never worked with it but generally one of the peaks is the analyte signal and the other is the correct background. I believe that C letter is the center of the peak (which you can displace to right or left to fit it properly) and L/R are the left or right end of the peak (peak wings), where the baseline is set.
I hope it can help will with your questions.
Sincerely
Alex