“…Efficient and selective analytical methods for HA determination in plasma and urine samples are required for both dose regulation and clinical studies (pharmacokinetic–pharmacodynamic parameters, efficiency of the drugs) [ 6 , 7 ]. Up to date, several analytical methods have been used for HA determination: chromatographic [ 5 , 6 , 7 , 8 , 9 ], electrochemical [ 10 , 11 ], and spectrophotometric [ 12 , 13 ]. Some of the procedures are based on complexes formation between HA and metals [ 9 , 13 ].…”