Eco-Friendly and Practical Electrochemical Determination of Lactic Acid in Milk Using Boron Doped Diamond Electrode

In this study, an economical, environmentally friendly, sensitive, selective, and rapid voltammetric quantitative analysis method was developed using a boron doped diamond electrode to determine lactic acid (LA). Two linear working ranges were determined for LA determination in phosphate buffer solution (PBS, pH of 2). The first linear working range (LR1) was between concentrations of 1.5 × 10−6–8 × 10−6 mol· L−1, with a detection limit of 1.3 × 10−6 mol·L−1, and the limit of quantification (LOQ) was found to be 4.4 µmol· L−1. The second linear working range (LR2) was determined in the concentration range of 8.0–89.2 µmol·L−1. LOD was calculated as 15.8 µmol·L−1, and the LOQ value was calculated as 52.6 µmol·L−1 in the LR2. Intraday repeatability of the BDD electrode for LA determination was (RSD) 6.8% in LR1 and 11.8% in LR2. The interday repeatabilities of the BDD electrode in LR1 and LR2 were calculated as 7.7% and 4.7%, respectively. The developed electrochemical sensor was successfully applied for the determination of LA in milk sample. The sensor exhibited a short response time of about 10 s in PBS at pH 2. The recovery values of LA in PBS and milk sample were 97.3% and 96.1%, respectively.