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Objective: To study the chemical constituents from the aerial part of Sibiraea angustata., Methods: The constituents were isolated by various chromatographic techniques (HP-20 macroporous absorption resin, Sephadex LH-20 gel, RP-MPLC and PHPLC)and their structures were determined on the basis of physicochemical properties and their spectroscopic data,as well as literatures., Results: Eleven compounds were separated and identified as p-methoxycinnamic acid(I), protocatechuic aldehyde(II), quercetin(III), isorhamnetin(IV), quercetin 3-O-beta-D-galactopyranoside (V),9-0-[beta-D-glucopyranoside]-3,4,5-trimethoxy cinnamyl alcohol(VI), syringaresinol-4'-O-beta-D-monoglucoside(VII), ntin(VIII), sibiraic acid(IX), sibiscolacton(X), methyl ferulic acid(XI)., Conclusion: Compounds I-XIII are isolated from the genus of Sibiraea for the first time.

The analysis of seven aliphatic carboxylic acids (formic, acetic, propionic, iso-butyric, n-butyric, iso-valeric and n-valeric acid) in anaerobic digestion process waters for biogas production was examined by ion-exclusion chromatography with dilute acidic eluents (benzoic acid, perfluorobutyric acid (PFBA) and sulfuric acid) and non-suppressed conductivity/ultraviolet (UV) detection. The columns used were a styrene/divinylbenzene-based strongly acidic cation-exchange resin column (TSKgel SCX) and a polymethacrylate-based weakly acidic cation-exchange resin column (TSKgel Super IC-A/C). Good separation was performed on the TSKgel SCX in shorter retention times. For the TSKgel Super IC-A/C, peak shape of the acids was sharp and symmetrical in spite of longer retention times. In addition, the mutual separation of the acids was good except for iso- and n-butyric acids. The better separation and good detection was achieved by using the two columns (TSKgel SCX and TSKgel Super IC-A/C connected in series), lower concentrations of PFBA and sulfuric acid as eluents, non-suppressed conductivity detection and UV detection at 210 nm. This analysis was applied to anaerobic digestion process waters. The chromatograms with conductivity detection were relatively simpler compared with those of UV detection. The use of two columns with different selectivities for the aliphatic carboxylic acids and the two detection modes was effective for the determination and identification of the analytes in anaerobic digestion process waters containing complex matrices.