Sarcosine has been identified as a potential prostate cancer marker. To provide determination of this compound, a number of methods are developing. In this study, we optimized a method for its separation by hydrophilic interaction liquid chromatography with electrochemical detection. Due to the fact that mobile phases commonly used for this type of separation altered the LODs measured by electrochemical detectors, we applied postcolumn dosing of buffer suitable for electrochemical detection. The optimized conditions were mobile phase A acetonitrile, mobile phase B water in the ratio A/B 70: 30, with postcolumn addition of mobile phase C (200 mM phosphate buffer pH 9). The optimal mixing ratio was A+B/C 1:1 with a flow rate of 0.80 mL.min(-1) (0.40 + 0.40 mL.min(-1) ) and detection potential of 1000 mV. Due to the optimization of the parameters for effective separation, which had to meet the optimal parameters of electrochemical detection, we reached the good resolution for separation also with a good LOD (100 nM). In addition, we successfully carried out sarcosine analysis bound on our modified paramagnetic microparticles with the ability to preconcentrate sarcosine isolated from artificial urine. This article is protected by copyright. All rights reserved.