The wiki on this product suggests to use a calibration solution with quinhydrone and a buffer solution of pH 4 but the method to prepare this solution is not given. Please provide it - you already suggested that it was attached. An alternative reference at: https://www.epa.gov/sites/production/files/2017-07/documents/field_measurement_of_orp113_af.r2.pdf does provide the method. quinhydrone is difficult to get - has any other calibration solution been tested at Seeed Studio?
Hi @dsrc34
Thanks for your offer the method to prepare a quinhydrone solution.
I will add this method to our wiki.
A quinhydrone calibration/verification solution is created by
adding 10g of quinhydrone to 1L of pH 4 or pH 7 buffer solution (ASTM D1498). The
solutions are mixed on a magnetic mixing plate for a minimum of 15 minutes to create
a saturated solution with undissolved crystals remaining. Quinhydrone solutions are
usable for 8 hrs from the time of mixing.
Sorry for we didn’t test other calibration before. Maybe you can help try other solutions like Zobell’s solution and Light’s solution.