In this work, direct and indirect methods for determination of vitamin K3 were developed using differential pulse polarography. The reaction between sulfite and the quinone (Q) form of vitamin K3 was used for indirect determination, since the sulfite peak at -0.7 V is sharp and very reproducible in 0.1 M HAc NaAc (pH = 5.5). It was found that at pH 4.5-5.5, this reaction was quantitative and very fast when the temperature was 45 °C. For its direct determination, on the other hand, vitamin K3 was standardized by the indirect method using standard sulfite as the reducing agent. The calibration graph for vitamin K3 (in Q form), using the peak at -1.0 V in a HAc-NaAc medium with a pH of 5.5, was linear for concentrations ranging from 5 \times 10-7 to 3 \times 10-5 M, and the limit of detection (LOD) was 1.5 \times 10-7 M. The proposed methods were successfully applied to the determination of vitamin K3 in a clinical injection solution and in blood serum.

In this work, direct and indirect methods for determination of vitamin K3 were developed using differential pulse polarography. The reaction between sulfite and the quinone (Q) form of vitamin K3 was used for indirect determination, since the sulfite peak at -0.7 V is sharp and very reproducible in 0.1 M HAc NaAc (pH = 5.5). It was found that at pH 4.5-5.5, this reaction was quantitative and very fast when the temperature was 45 °C. For its direct determination, on the other hand, vitamin K3 was standardized by the indirect method using standard sulfite as the reducing agent. The calibration graph for vitamin K3 (in Q form), using the peak at -1.0 V in a HAc-NaAc medium with a pH of 5.5, was linear for concentrations ranging from 5 \times 10-7 to 3 \times 10-5 M, and the limit of detection (LOD) was 1.5 \times 10-7 M. The proposed methods were successfully applied to the determination of vitamin K3 in a clinical injection solution and in blood serum.