Hart J P, Wring S A, Morgan I C
Analyst. 1989 Aug;114(8):933-7. doi: 10.1039/an9891400933.
Linear sweep voltammetry was used to study the accumulation behaviour of vitamin K1 at carbon paste electrodes prepared with different types of graphite and pasting agents. The vitamin was found to undergo strong accumulation, but this depended on the type of graphite and pasting agent used. A carbon paste electrode containing Nujol - Ultra Carbon Ultra Superior Purity graphite (25 + 75 m/m) gave the highest sensitivity with adsorptive stripping voltammetry; the optimum accumulation time was 15 min at an open circuit. A variety of procedures were investigated in order to separate vitamin K1 from plasma prior to adsorptive stripping analysis. These procedures were evaluated for plasma levels of the vitamin that are likely to be encountered in pharmacokinetic studies. A solvent extraction method using hexane and ethanol gave the best recovery (91%) and detection limits [180 ng ml-1 in the supporting electrolyte (450 ng ml-1 in plasma)]. However, the analysis time could be reduced by 50% (with some loss of sensitivity) by using ethanol to deproteinate the plasma with the measurement being made directly on the resulting supernatant. As the calibration graphs are linear, quantification can be performed by the method of single standard additions; therefore, relatively short analysis times are feasible.
采用线性扫描伏安法研究了维生素K1在不同类型石墨和糊剂制备的碳糊电极上的富集行为。发现该维生素会发生强烈富集，但这取决于所用石墨和糊剂的类型。含有氢化蓖麻油 - 超纯碳（25 + 75 m/m）的碳糊电极在吸附溶出伏安法中具有最高灵敏度；开路时的最佳富集时间为15分钟。为了在吸附溶出分析之前从血浆中分离维生素K1，研究了多种方法。对这些方法在药代动力学研究中可能遇到的血浆维生素水平进行了评估。使用己烷和乙醇的溶剂萃取法回收率最高（91%），检测限为[在支持电解质中为180 ng/ml（在血浆中为450 ng/ml）]。然而，通过使用乙醇使血浆脱蛋白并直接对所得上清液进行测量，分析时间可减少50%（灵敏度略有损失）。由于校准曲线是线性的，因此可以通过单标准加入法进行定量；因此，相对较短的分析时间是可行的。
