To prepare the 10 mM ACh standard solution, dissolve 245 mg acetylcholine

perchlorate in 100 mL of 20 mM phosphate buffer, pH 3.5 (including 25

mM Na2EDTA-2H2O). Please store this 10 mM ACh solution at 4 ºC. When

making dilutions for a standard curve, use the 20 mM phosphate buffer, pH

3.5 (including 25 mM Na2EDTA-2H2O). Be very careful to never inject a high

concentration (mM or μM). This will necessitate disassembling the injector

and possible other parts to thoroughly clean them.