Non-enzymatic and Electrochemical Detection of Creatine in Food Supplements

Creatine is a well-known member of supplement family and is widely preferred by consumers for therapeutic applications, muscle strength, and energy recovery. This study describes a new concept, which is based on a simple, one-step, and non-enzymatic creatine detection system on the Pt electrode. The creatine content of food supplements was determined using an elemental analyzer, and five different supplements were separated in terms of creatine. Three supplements were investigated as creatine sources, and the other two supplements were considered as branched-chain amino acid sources. For the electrochemical detection of creatine, cyclic voltammetry and square-wave voltammetry techniques were used. Graphene oxide and carbon nanotube-modified surfaces were applied in addition to bare Pt surface; however, bare Pt surface was found to be superior to the modified surfaces. Creatine was successfully detected using the proposed Pt electrode, and the limit of detection was calculated to be 36.0 mu g L-1. The obtained selectivity allowed performing a voltammetric comparison of creatine and branched-chain amino acid supplements. Real sample analysis was performed by analyzing milk powder; however, milk powder supplied only 32.4% of creatine content. This study presents a new method for detection of food supplements without the need for modification, high-cost, or pretreatment process.