The analysis of major impurities of lipophilic-conjugated phosphorothioate oligonucleotides by ion-pair reversed-phase HPLC combined with MALDI-TOF-MS.

A simple and rapid ion-pair reversed phase high-performance liquid chromatography (IP-RP-HPLC) method was developed to analyse the major impurities of lipophilic-conjugated phosphorothioate oligonucleotides (ODNs), which provided better separation performance than capillary gel electrophoresis and ion exchange chromatograph methods. The study showed that covalent conjugations of lipophilic group (docosanyl, C(22)) to ODN at 5'-termini (denoted as 5'C(22)-Flu) or 3'-termini (denoted as 3'C(22)-Flu) exhibited similar chromatographic retention behavior. Some important analytical conditions of IP-RP-HPLC, including column type, ion-pairing buffer composition, and separation temperature, were investigated for the effects on the separation of crude 5'C(22)-Flu.

Determination of deoxyschizandrin in rat plasma by LC-MS.

A simple, rapid and sensitive LC-MS method was developed for quantification of deoxyschizandrin in rat plasma. A 50 miccrol plasma sample was extracted by ether and performed on Elite Hypersil C(18) column (200 mm x 4.6 mm, 5 microm) with the mobile phase of methanol-water (84:16, v/v) in a run time of 6.

Determination of five components in Ixeris sonchifolia by high performance liquid chromatography.

A high performance liquid chromatography (HPLC) method was developed for the simultaneous quantification of five major active ingredients (markers) in Ixeris sonchifolia (Bge.) Hance, namely chlorogenic acid, caffeic acid, luteolin-7-O-beta-D-glucuronide, luteolin-7-O-beta-D-glucoside and luteolin. Samples were extracted with 70% methanol.