Dipotassium ethylenediaminetetraacetic acid is better than tripotassium salt for electrochemiluminescence insulin measurement

Previous studies reported that stability of insulin was better on ethylenediaminetetraacetic acid (EDTA) plasma sample than serum sample. However, those studies used tripotassium EDTA (K3-EDTA) tubes, rather than dipotassium EDTA (K2-EDTA) tubes which are more commonly used in laboratories. We investigated the impact of preservative type of EDTA (K2 or K3) on the stability of C-peptide and insulin at 4 °C and at room temperature room. Our study has identified that K2-EDTA achieves longer stability of insulin but does not improve the stability of C-peptide. Insulin and C-peptide are stable 24 h on the same K2-EDTA sample at room temperature.