Observation: MS-222 (3-Aminobenzoic Acid Ethyl Ester C₉H₁₁NO₂ * CH₄SO₃) affects pH of solutions. It is an acid.

Question: Does our water here in San Marcos, TX, have any buffering capacity?

Experiment: Make a 1.0% stock solution of MS-222 using 5g MS-222 salt to 500ml conditioned water (tap water with prescribed amount of Jungle Brand Start Right added.) Test the pH of this 1% stock solution and of varying dilutions made from this 1% solution. Also test the pH of the conditioned water with out and MS-222 added. The following dilutions were used: 1%, 0.80%, 0.50%, 0.20%, 0.15%, 0.10%, 0.08%, 0.06%, 0.04%, 0.01% and 0.00%.

Observations: The pH almost seems to decrease linearly as the amount of MS-222 increases.

pH	1.54	1.68	1.9	2.85	3.7	5.25	5.67	5.94	6.32	7.22	7.74
% solution	1.0%	0.8%	0.5%	0.2%	0.15%	0.1%	0.08%	0.06%	0.04%	0.01%	0.0%

Conclusions: 

The addition of MS-222 does have a significant effect on the pH when added to the water here. This is especially true when it is used in higher concentrations. This could easily affect the health of fish when they are anesthetized in such solutions.

Contributed by Leona C. Hazlewood, Steven Kazianis, D. Trono and Ronald Walter. Experiment performed by Leona C. Hazlewood, Xiphophorus Genetic Stock Center.

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