Measurement of Acetate Concentrations in Marine Pore Waters by Using an Enzymatic Approach

Acetate concentrations in marine and freshwater matrices were measured by an enzymatic technique which coupled the synthesis of acetyl coenzyme A to AMP production. The resulting AMP was assayed by a sensitive and relatively rapid high-pressure liquid chromatography method, using an aqueous, isocratic mobile phase for elution. The method was insensitive to the presence of seawater salts and required no sample prepurification or distillation. Propionate caused a minor, but statistically insignificant, interference when equimolar with acetate; butyrate caused no interference, even at relatively high concentrations. Detection limits for acetate were approximately 100 nM with a precision of about 5%. Pore waters from two intertidal sediments contained approximately 1 to 12 μM acetate; the concentrations were linearly but inversely correlated with porewater sulfate.