Manual and semiautomated spectrophotometric determination of vitamin K3 by reactions wih piperidine and malononitrile.

: Simple, rapid, selective, and sensitive spectrophotometric methods are described for manual and semiautomated determination of vitamin K3. These methods are based on reactions with piperidine and malononitrile whereby intense red and blue colors with maximum absorption at 510 nm (E(1%) 1 cm 150) and 580 nm (E(1%) 1 cm 155), respectively, are developed. The reactions are sensitive enough to permit the determination of 2-100 micrograms vitamin K3/mL with an average recovery of 98% and a standard deviation of 1%. There is no interference from vitamin K1 and K2, and the reduced forms of K vitamins, or from many common pharmaceutical diluents and additives.