Hi everyone!
I prepared a 100ppm solution by dissolving 100ml of B into 1L of distilled water following the same procedure that was done in many other case studies. and based on that, I wrote that in my methods!
I did the other required tests and sent all my samples together for ICP-test including the control.
The results showed that my B-prepared stock solution was 160ppm and not 100ppm.
Is it useful to re-calculate all the results to make them all of 100ppm? or just I should proceed like that and keep it as it is (160ppm)?
if I just need to keep it as 160ppm, how can I refer to that in my methodology? and based on what shall I write that I prepared 160ppm??
looking forward to hearing from you! - Thanks
Firstly to do with your data:
- DO NOT change your results to read something else: that is almost certainly fraudulent and likely to have serious consequences for you and possibly everybody in your laboratory. Keep the data as they are, refer to it as such in your report's method. No one will punish you for being honest.
Next: Just to be sure: B for Boron? not "solution B" or some other lab shorthand ?
Boron is notorious for contaminating ICP instruments, sticking to tubing and the interior of the machinery. 100 ppm in an ICPMS could require strenuous efforts to clean it up in the first instance, followed by months of washout to reduce the last few ppm. If someone after you tries to measure a low concentration of B, they could be measuring your carryover for weeks.
The biggest problem is that you proceeded with experiments before confirming you had accurately prepared your 100 ppm stock:
- what was the compound you used to prepare the 100ml of B ? Was it the same as the papers you based it on? Boric acid mw 61.8, borax (anhydrous sodium tetraborate, Na2B4O7, sodium tetraborate pentahydrate, Na2B4O7·5H2O or sodium tetraborate decahydrate, Na2B4O7·10H2O ) or something else?
- If you miscalculated the mass and weighed out a less hydrated form, that might account for the difference.
- How was the B calibrated for the ICP? You say you used water; ICP solutions regularly use acidified solutions to keep elements in solution. This may be the single most important difference.
- Was there a density issue with either the water, B compound or the calibration solutions?
- Did you use borosilicate glassware? That could contribute some B, but probably not 60 ppm worth.
- Distilled water: did you check that for B concentration? I have seen B increase in 18mega-ohm.cm water: because it is not ionic it isn't extracted by the purification system. If your source water is not clean, B will readily build up. Distilled water (heated and recondensed) may be even more prone to this.
Check with the ICP staff to see whether the water is an issue (contamination and acid in calibrations). Double check how much B per g of stock compound there was. Report everything truthfully.
Hello,
Firstly, if B is for boron, I would suggest you to make your stock solution in 2% HNO3 so it is more stable.
Secondly, as I understand, you are not the one who directly analysis the sample, right? If you are, it would be better if you can provide information about your calibration standard. In order to have accurate results, I suggest that your sample concentration should not be more than double of highest calibration level. For example, if your calibration level is 1, 5, 20 ppm, then dilution is needed for your 100ppm solution.
Also, from my experience, 100ppm Boron is really high concentration for ICPMS. I have experienced running 2ppm boron sample, it took me quite a long time for rinsing.
- Badges
- Science method