The analysis of wax esters,very long mid-chain ketones and sterol ethers isolated from walvis bay diatomaceous ooze

Wax esters (ranging from C₃₂ to C₄₄), very long mid-chain ketones (ranging from C₃₁ to C₄₃) and sterol ethers were isolated from Walvis Bay diatomaceous ooze and identified by glass capillary gas chromatography/mass spectrometry and direct probe high-resolution mass spectrometry.The wax ester compositions of co-eluting wax esters with the same molecular weight were determined from fragment ions characteristic for the alcohol and fatty acid moieties. Dominant wax esters are the C₃(16F-20A), C₃₆(18F-18A), C₃₈(16F-22A), C₃₈(18F-20A), C₄₀(18F-22A), C₄₀(20F-20A) and C₄₀(24F-16A).The presence of isoprenoid wax esters and the chain length distributions of alcohol and fatty acid moieties point to an origin from zooplankton. The position of the ketogroup in the mid-chain ketones is determined from characteristic fragment ions. Major ketones are the C₃₈(C₁₈H₃₇-CO-C₁₉H₃₉) and C₄₀(C₁₈H₃₇-CO-C₂₁H₄₃).The sterol ethers have C₈ and C₉ ether moieties and C₂₇, C₂₈, and C₂₉ steroid moieties. The origin and significance of the ketones and the sterol ethers is obscure.