Calibration fluid by the bottle=bad idea?

[pjewett]

Hi All

Just calibrated my Apex PH probe recently using a bottle of Hanna PH 7 & 10. I just dip the probe in the bottle as apposed to the indivd packets.

I dip the probe in a cup of RO water before dipping in one or the other solution so as not to contaminate.

Anyway, couple questions.

Do these fluids have a shelf life?
Any reason I shouldn't be using full bottles of this stuff to calibrate..remember using the same solution again and again.

Best to be using "fresh" solution from unsealed packet each time?

Thanks

 

[pjewett]

err.. just realized i may have dipped the ph probe right into the first solution right out of the tank without rinsing first. would that screw up my solution?

 

[SteveZ15]

I use these at work we use the sealed packets they have exp date on them. rinse the probe dab dry dip in packet repeat for every one 4,7,10.. we calibrate ph meter every morning using new packets every time. I dont know how your ph meter works,but the one we use has a slope percentage if is not 95%or better we recalibrate or change probe. After machine is calibrated we probe 7 solution to test .05 is the allowable range,if it test good then we probe sample.I dont know how often you cal your probe,if it is not often I would use new packet.We have to use new and have strict guidlines because these are wastewater samples and are federally monitored because we have pass permit in order to discharge effluent into recieving waters

 

[Boomer]

You DO NOT EVER dip your probe into a bottle of cal solution EVER. You pour out enough in a small container/cup to cal the probe and discard it when done. You will contaminate the bottle doing what you are doing pj.. Packets are to be used ONCE ONLY.