Samples for alkalinity are collected with a peristaltic pump and tubing into new, 20 ml HDPE plastic containers with conical caps. The samples are stored refrigerated at 4 degrees Celsius until analysis, which should occur within 2 weeks. The samples are warmed to room temperature and then analyzed with an Orion 720A pH meter and Radiometer combination electrode. The sample is titrated to an endpoint pH of approximately 3.557 by adding 0.05N HCl to 16 mls sample at the Hasler Lab (or 0.01N HCl to 4 mls sample at Trout Lake Station Lab) in 10 microliter increments using a micro-pipette. The pH meter millivolt readings (along with the corresponding the amount of acid added) of the last 10 acid additions prior to the endpoint are recorded.
The detection limit for the gran alkalinity titration is approximately 5 micro-equivalents per liter of CO3 and the analytical range for the method extends to 4000 micro-equivalents per liter of CO3.
Method Log: Prior to 1986 and since 2002, alkalinity titrations were performed as described above. During the period of February 1986 – November 2001, the alkalinity determinations for Trout, Sparkling, Allequash and Big Muskellunge Lakes were made by a Brinkmann 636 Titroprocessor using 0.05N HCl with 16 mls of sample.
field & laboratory