I'm going to assume the advice is still to store in the cap with some water.
I tried doing a stability test last night and realized how much of a noob I am at this. I have a few questions I was hoping to get answered.
1) If my storage water dries up, what is the best way to rehydrate the bulb? 10-15 minutes in tap water?
2) I'm using
premixed buffers and I realize that for calibrating I will always want fresh buffers however for the stability test do I need fresh buffers for each testing? If so, it seems like I'll use my whole bottle before the stability test is through!
3) How do I know when a reading is stabilized? When I put my meter into the 7 solution for calibration it started at 7.12 and gradually kept climbing down and never seemed to stop. I gave up when it was at 6.91. Every time I thought it had stabilized it would drop another tenth. This was over the course of about 5 minutes. It never stayed on any given reading for longer than a minute though.
4) When rinsing with DI water, how important is it to get all the water out of the sample cup? I've been pretty OCD about it but I'm wondering if I need to be...is it the PH of any risidual water we're worried about affecting the buffer or the dilution of it? As for the meter itself, I've been spraying it and as AJ mentioned just using a paper towel to wick at it without putting any pressure on the bulb.
5) Once I calibrate 7 and 4 and save, shouldn't my reading be 4.00 if it's still sitting in the buffer? I was getting 3.99 (which I realize is within the accuracy range just thought it would show exact right after calibration).
6) When I put the meter in the sample, should I move it around before locking the cap on or lock the cap on and then shake it around?
7) I RTFM and didn't see anywhere that mentioned where we could find the slope/offset values on this meter...correct me if I'm wrong. If we don't know what it's using, how do I know that the meter is calibrated any given time I turn it on? Do I just plan on calibrating every day/time I use it?
8) with ATC, do I need to be concerned with the temperature at all when recording the readings? I will always cool my samples down to room temp (~70F) but want to make sure that the slight variances shouldn't matter. Assuming ATC accounts for temp differences, why do we need to chart temp when doing a stabilization test?
9) Other than spraying with DI water right after use, is there any need for cleaning solution? I think I read in this thread it was unneeded but just wanted to verify.
I think that's all for now. Thanks in advance.
-pHNoob