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New Method of Analysis of Lipids in Tribolium castaneum (Herbst) and Rhyzopertha dominica (Fabricius) Insects by Direct Immersion Solid-Phase Microextraction (DI-SPME) Coupled with GC–MS

by Ihab Alnajim 1,2,†, Xin Du 1,†, Byungho Lee 3, Manjree Agarwal 1,*, Tao Liu 4,* and Yonglin Ren 1
1
College of Science, Health, Engineering and Education, Murdoch University, Perth 6150, Australia
2
Date Palm Research Centre, University of Basrah, Basra 61004, Iraq
3
Research Institute of Life Science, GyeongSang National University, Jinju 52828, Korea
4
Institute of Equipment Technology, Chinese Academy of Inspection and Quarantine, No. A3, Gaobeidianbeilu, Chaoyang District, Beijing 100123, China
*
Authors to whom correspondence should be addressed.
Authors contributed to this work equally.
Insects 2019, 10(10), 363; https://doi.org/10.3390/insects10100363
Received: 3 July 2019 / Revised: 10 October 2019 / Accepted: 16 October 2019 / Published: 19 October 2019
Lipids play an essential role in providing energy and other physiological functions for insects. Therefore, it is important to determine the composition of insect lipids from cuticular and internal tissues for a better understanding of insect biology and physiology. A novel non-derivatization method for the analysis of lipids including fatty acids, hydrocarbon waxes, sterols in Tribolium castaneum (Herbst) and Rhyzopertha dominica (Fabricius) was explored using the direct immersion solid-phase microextraction (DI-SPME) coupled with gas chromatography–mass spectrometry (GC–MS). Nine extraction solvents, acetonitrile, methanol, hexane, ethanol, chloroform, acetonitrile and ethanol (1:1 v/v), acetonitrile and water (1:1 v/v), ethanol and water (1:1 v/v) and acetonitrile and ethanol and water (2:2:1 v/v/v) were selected and evaluated for the extraction of insect lipids with DI-SPME fiber. Acetonitrile extraction offered the best qualitative, quantitative, and number of lipids extracted from insects samples results. Acetonitrile extracted high-boiling point compounds from both species of tested insects. The range of hydrocarbons was C25 (pentacosane) to C32 (dotriacontane) for T. castaneum and C26 (11-methylpentacosane) to C34 (tetratriacontane) for R. dominica. The major compounds extracted from the cuticular surface of T. castaneum were 11-methylheptacosane (20.71%) and 3-methylheptacosane (12.37%), and from R. dominica were 10-methyldotriacontane (14.0%), and 15-methyltritriacontane (9.93%). The limit of detection (LOD) for the n-alkane compounds ranged between 0.08 (nonacosane) and 0.26 (dotriacontane) µg/g and for the fatty acids between 0.65 (arachidic acid) to 0.89 (oleic acid) µg/g. The study indicated that DI-SPME GC–MS is a highly efficient extraction and a sensitive analytical method for the determination of non-derivatized insect lipids in cuticular and homogenized body tissues. View Full-Text
Keywords: DI-SPME; GC–MS; insect lipids; insect hydrocarbons; T. castaneum; R. dominica DI-SPME; GC–MS; insect lipids; insect hydrocarbons; T. castaneum; R. dominica
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Alnajim, I.; Du, X.; Lee, B.; Agarwal, M.; Liu, T.; Ren, Y. New Method of Analysis of Lipids in Tribolium castaneum (Herbst) and Rhyzopertha dominica (Fabricius) Insects by Direct Immersion Solid-Phase Microextraction (DI-SPME) Coupled with GC–MS. Insects 2019, 10, 363.

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