title: Development and validation of a gas chromatography/mass spectrometry method for the metabolic profiling of human colon tissue.
abstract: In this study, a gas chromatography/mass spectrometry (GC/MS) method was developed and validated for the metabolic profiling of human colon tissue. Each colon tissue sample (20 mg) was ultra-sonicated with 1 mL of a mixture of chloroform/methanol/water in the ratio of 20:50:20 (v/v/v), followed by centrifugation, collection of supernatant, drying, removal of moisture using anhydrous toluene and finally derivatization using N-methyl-N-trifluoroacetamide (MSTFA) with 1% trimethylchlorosilane (TMCS). A volume of 1 microL of the derivatized mixture was injected into the GC/MS system. A total of 53 endogenous metabolites were separated and identified in the GC/MS chromatogram, all of which were selected to evaluate the sample stability and precision of the method. Of the identified endogenous metabolites 19 belonging to diverse chemical classes and covering a wide range of the GC retention times (Rt) were selected to investigate the quantitative linearity of the method. The developed GC/MS method demonstrated good reproducibility with intra- and inter-day precision within relative standard deviation (RSD) of +/-15%. The metabolic profiles of the intact tissue were determined to be stable (100 +/- 15%) for up to 90 days at -80 degrees C. Satisfactory results were also obtained in the case of other stability-indicating studies such as freeze/thaw cycle stability, bench-top stability and autosampler stability. The developed method showed a good linear response for each of the 19 analytes tested (r(2) > 0.99). Our GC/MS metabolic profiling method was successfully applied to discriminate biopsied colorectal cancer (CRC) tissue from their matched normal tissue obtained from six CRC patients using orthogonal partial least-squares discriminant analysis [two latent variables, R(2)Y = 0.977 and Q(2) (cumulative) = 0.877].
authors.affiliation: Department of Pharmacy, Faculty of Science, National University of Singapore, 18 Science Drive 4, Singapore 117543.
authors.forename: Mainak
authors.initials: M
authors.lastname: Mal
authors.forename: Poh Koon
authors.initials: PK
authors.lastname: Koh
authors.forename: Peh Yean
authors.initials: PY
authors.lastname: Cheah
authors.forename: Eric Chun Yong
authors.initials: EC
authors.lastname: Chan
mesh_terms: D001704:Biopolymers / Q000032:analysis*; D003106:Colon / Q000378:metabolism*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D020869:Gene Expression Profiling / Q000379:methods*; D020543:Proteome / Q000032:analysis*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013048:Specimen Handling / Q000379:methods*
chemical_list: D001704:Biopolymers; D020543:Proteome