Monitoring of linear alkyl benzenes (LABs) in riverine and estuarine sediments in Malaysia.

The aim of this a pioneering research is to investigate linear alkylbenzenes (LABs) as biomarkers of sewage pollution in sediments collected from four rivers and estuaries of the south and east of Peninsular Malaysia. The sediment samples went through soxhlet extraction, two-step column chromatography purification, fractionation and gas chromatography-mass spectrometry (GC-MS) analysis. Principal component analysis (PCA) with multivariate linear regression (MLR) was used as well for source apportionment of LABs. The results of this study showed that total LAB concentration was 36-1196 ng g-1dw. The internal to external isomer ratios (I/E ratio) of LABs were from 0.56 to 3.12 indicated release of raw sewage and primary and secondary effluents into the environment of south and east of Peninsular Malaysia. Our research supported that continuous monitoring of sewage pollution to limit the environmental pollution in riverine and estuarine ecosystem.

A P212121 polymorph of (+)-clusianone.

The title compound, C33H42O4 [systematic name: (1S,5S,7R)-3-benzoyl-4-hy-droxy-8,8-dimethyl-1,5,7-tris-(3-methyl-but-2--enyl)bi-cyclo-[3.3.1]nona-3-ene-2,9-dione], has a central bi-cyclo-[3.3.1]nonane-2,4,9-trione surrounded by tetra-prenyl-ated and benzoyl groups. The compound was recrystallized several times in methanol using both a slow evaporation method and with a crystal-seeding technique. This subsequently produced diffraction-quality crystals which crystallize in the ortho-rhom-bic space group P212121, in contrast to a previous report of a structure determination in the Pna21 space group [McCandlish et al. (1976 ▶). Acta Cryst. B32, 1793-1801]. The title compound has a melting point of 365-366 K, and a specific rotation [α](20) value of +51.94°. A strong intra-molecular O-H⋯O hydrogen bond is noted. In the crystal, mol-ecules are assembled in the ab plane by weak C-H⋯O inter-actions.