Institute of Chemistry, University of Białystok, Białystok, Poland.
Talanta. 2012 Jul 15;96:223-9. doi: 10.1016/j.talanta.2012.02.064. Epub 2012 Mar 15.
A new flow-injection (FI) and high performance liquid chromatography (HPLC) with chemiluminescence detection method has been proposed for the determination of α-lipoic acid (LA). The assay is based on the measurement of chemiluminescence (CL) produced during the reaction of α-lipoic acid with potassium permanganate in a sodium hexametaphosphate medium (pH 3). This reaction is accompanied by a weak CL, which is greatly increased in the presence of a formaldehyde solution. The proposed FI method allows the determination of LA over the range: 0.5-20μgmL(-1) with LOD 4×10(-3)μgmL(-1). An introduction of HPLC into the flow manifold improves selectivity of the method and allows the determination of LA in a complex sample. The chromatographic linear range is 2.5-30μgmL(-1) with LOD 1.774μgmL(-1). Chromatographic separation was achieved by isocratic elution (acetonitrile/potassium dihydrogen phosphate, pH 3, adjusted with phosphoric acid): 30/70 using a Cosmosil 5C(18)-MS-II (4.6mm×150mm I.D.) column at a flow rate of 1.0mLmin(-1). The presented methods were utilized to determine the α-lipoic acid content in "Alfa-lipoic acid" capsules and in food products.
一种新的流动注射（FI）和高效液相色谱（HPLC）化学发光检测法已被提出用于测定α-硫辛酸（LA）。该测定法基于在偏磷酸钠介质（pH 3）中，α-硫辛酸与高锰酸钾反应过程中产生的化学发光（CL）的测量。该反应伴随着微弱的 CL，当存在甲醛溶液时，CL 会大大增强。所提出的 FI 方法允许在 0.5-20μgmL（-1）范围内测定 LA，LOD 为 4×10（-3）μgmL（-1）。将 HPLC 引入流动系统可提高方法的选择性，并允许在复杂样品中测定 LA。色谱线性范围为 2.5-30μgmL（-1），LOD 为 1.774μgmL（-1）。通过等度洗脱（乙腈/磷酸二氢钾，pH 3，用磷酸调节）实现色谱分离：30/70，使用 Cosmosil 5C（18）-MS-II（4.6mm×150mm ID）柱，流速为 1.0mLmin（-1）。所提出的方法用于测定“α-硫辛酸”胶囊和食品中α-硫辛酸的含量。
