- #1
DeepThinking
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Hi, I'm trying to calculate the slope of a pH probe using 7.0 and 10.0 buffer solutions. I've been searching for hours but all examples use 7.0 and 4.0. I've calibrated my probe using the 7.0 and 4.0 buffers and calculated the slope, then I used 7.0 and 10.0, used the same math for the slope and it was quite different so I don't know if that's normal or I'm doing something wrong.
This is using 7.0 and 4.0 and confident its correct.
pH electrode generated –5 mV in pH 7.00 buffer and +165 mV in pH 4.00 buffer.
165 mV – (-5 mV) = 170 mV
170mv/3 = 56.66mV/pH unit
56.66/59.16 x 100 = 95.8% slope
Now this is an example with 7.0 and 10.0, is this correct?
pH electrode generated –5 mV in pH 7.00 buffer and -165 mV in pH 10.00 buffer.
-165 mV – (-5 mV) = -160 mV
-160mv/3 = -53.33mV/pH unit
53.33/59.16 x 100 = -90.15% slope
Obviously with a 2nd buffer over 7.0 the slope always comes out as a negative number, would I just invert it to a positive number?
Thanks
This is using 7.0 and 4.0 and confident its correct.
pH electrode generated –5 mV in pH 7.00 buffer and +165 mV in pH 4.00 buffer.
165 mV – (-5 mV) = 170 mV
170mv/3 = 56.66mV/pH unit
56.66/59.16 x 100 = 95.8% slope
Now this is an example with 7.0 and 10.0, is this correct?
pH electrode generated –5 mV in pH 7.00 buffer and -165 mV in pH 10.00 buffer.
-165 mV – (-5 mV) = -160 mV
-160mv/3 = -53.33mV/pH unit
53.33/59.16 x 100 = -90.15% slope
Obviously with a 2nd buffer over 7.0 the slope always comes out as a negative number, would I just invert it to a positive number?
Thanks