Beschreibung:
<jats:title>Abstract</jats:title><jats:p>In the present study, the impact of pH of both the leading electrolyte and the sample on the separation capacity of an isotachophoretic system, used for the analysis of organic acids in human seminal plasma and prostatic fluid, was assessed. Generally, maximum separable amounts of eleven equimolar pairs of anions decreased within a pH range of 2.90–4.25 of the leading electrolyte due to increasing net mobilities of the analytes with rising pH. The values obtained under equimolar conditions were also valid for nonequimolar mixtures as long as the buffer capacity of the leading electrolyte was sufficient to maintain constant mobilities of the ionic species to be separated throughout the capillary. However, when the sample injected has a buffer capacity of its own and a pH higher than that of the leading electrolyte, separation capacity will vary. For that reason, the maximum separable amount of an aqueous solution of phosphate and citrate was higher than that obtained for seminal plasma. Hence, the injection volume had to be reduced in order to ensure complete resolution. Besides phosphate and citrate, which was the prime component of prostatic fluid, lactate, aspartate and glutamate could be quantitatively determined in seminal plasma with a precision of ± 1.5%.</jats:p>