Thanks again for the very helpful video workshop on image data processing with Iolite4, it has been so helpful. In that video you pointed out that one large advantage of cellspace images is that one can set up the laser pattern to cover only the crystal (or otolith) of interest, and not the surrounding epoxy, or matrix.
I have a project for which this would be very helpful, since it involves mineral separates in epoxy, but when I went to set it up, I realised that I have some questions about the best approach. Would you be willing to share your approach to setting up such an experiment?
We have used two different approaches in our lab to setting up rectangular maps for our experiments:
Many parallel lines are combined to a single laser shot, but to make certain that enough time elapses between the end of one line and the start of the next we changed the laser properties to have a slower maximum stage speed, so that there would be time for everything to wash out before the laser starts firing again.
Each line in the map pattern has its own laser spot number, and the built-in laser warm up and washout time is plenty to ensure that data from the end of one line doesn't mix with the start of the next.
Given that we are currently using 15 seconds each for warm up and washout, that adds up to a fair bit of extra time required for each map when using option 2, which limits the number of maps that can be run in one session, especially for the narrow ends of a crystal, where the short lines might need only 3 seconds of laser firing, which would mean 33 seconds for the line.
However, for option 1 it is necessary to be in the lab to change the maximum speed after it runs the standards and moves to the map area, as otherwise it would take a really long time to get to the map area, and, if the other maps planned for that session are not very near one another (and when are they?), it requires that the ICP-MS session stop after each so that we can once again change the speed to normal to get to the next area of interest, and then back to slow to run the map.
Needless to say, I am not so interested in doing this for a session that would involve 17 maps.
I rather suspect that the preferred approach when setting up cellspace images will be something different than either of those described above, and I would very much appreciate hearing your suggestion(s) for other approaches.
What do you feel is the best way to set up a cellspace image of the non-rectangle variety?
While I am asking, what is the most efficient way to determine how much time the ICP-MS needs to count for each laser pattern when the map is comprised of lines with very different lengths? With a rectangular map it is easy—every line needs the same amount of time for the corresponding ICP-MS sample number (assuming option 2 and each line has its own laser number). But if I go this route for lines of different lengths then either I count the same amount for every line, choosing a number that is long enough for the longest line (and have LOTS of blank before and after the short lines), or I have to calculate time for each line. This could be easily done in a spreadsheet with a formula that combines laser firing time, plus warmup, washout, and another 5 or 10 seconds, just to be certain that there is enough (since it is always frustrating when the laser is still firing after the ICP-MS is done counting). However, I have never seen a way to export the X-Y coordinates and estimated time the laser will be firing for a session that has not yet been run, so it seems to be that I need to click on each and every line and write down that information if I want to set up such a spreadsheet. This would add quite a bit of time to the experiment set-up, which is what has really prompted me to ask if there is a better way.
Thanks for sharing your thoughts and insights on this topic!
--Riia