title: Direct injection versus liquid-liquid extraction for plasma sample analysis by high performance liquid chromatography with tandem mass spectrometry.
abstract: Direct injection versus liquid-liquid extraction for post-dose human plasma sample analysis by high performance liquid chromatography with tandem mass spectrometry (LC/MS/MS) have been studied using a drug candidate compound. For the direct-injection method, an Oasis(R) HLB column (1 x 50 mm, 30 micrometer) was used as the on-line extraction column and a conventional Waters symmetry C18 column (3.9 x 50 mm, 5 micrometer) was used as the analytical column. Each plasma sample (100 microL) was mixed with 100 microL of a working solution of the internal standard in aqueous 0.05 M ammonium acetate (pH 6.9), and portions (10 microL) of these samples were then injected into the LC/MS/MS system. For the liquid-liquid extraction method, a YMC Basic C18 column (2.0 x 50 mm, 5 micrometer) was used as the analytical column. Each sample (0.5 mL) was extracted with methyl tert-butyl ether and the extract was reconstituted and injected into the LC/MS/MS system. The total analysis time for both methods was 2.0 min per sample. The accuracy, inter-day precision and intra-day precision obtained from the quality control samples were within 8% for both methods. The analysis results of post-dose human plasma samples showed that the deviations of 91% of the concentrations obtained using the direct-injection method were within +/-20% from the concentrations obtained using the liquid-liquid extraction method, and the overall average percentage deviation was -1.5%. The results showed that the two methods were equivalent in terms of total chromatographic run time, accuracy and precision. However, for a batch of 100 samples, the sample preparation time for the direct-injection method was only about 25% of the time required for liquid-liquid extraction. This decrease in sample preparation time resulted in the doubling of the overall sample analysis throughput.
authors.affiliation: Bristol-Myers Squibb Pharmaceutical Research Institute, Bioanalytical Research, Metabolism and Pharmacokinetics, New Brunswick, NJ 08903-0191, USA. jemalm@bms.com
authors.forename: M
authors.initials: M
authors.lastname: Jemal
authors.forename: M
authors.initials: M
authors.lastname: Huang
authors.forename: X
authors.initials: X
authors.lastname: Jiang
authors.forename: Y
authors.initials: Y
authors.lastname: Mao
authors.forename: M L
authors.initials: ML
authors.lastname: Powell
mesh_terms: D002851:Chromatography, High Pressure Liquid; D006801:Humans; D007202:Indicators and Reagents; D013058:Mass Spectrometry; D010949:Plasma / Q000737:chemistry*; D011786:Quality Control
chemical_list: D007202:Indicators and Reagents