Efficacy of head space solid-phase microextraction coupled to gas chromatography–mass spectrometry method for determination of the trace extracellular hydrocarbons of cyanobacteria

• A HS-SPME-GC–MS method was developed for determination of trace level extracellular hydrocarbons of cyanobacteria.
• The sensitivity of HS-SPME method was significantly higher than traditional liquid–liquid extraction (LLE) method.
• Heptadecane in the culture media of Synechocystis sp. PCC 6803 was first be quantified.

Hydrocarbons are widespread in cyanobacteria, and the biochemical synthetic pathways were recently identified. Intracellular fatty alka(e)nes of cyanobacteria have been detected by liquid–liquid extraction (LLE) coupled to gas chromatography–mass spectrometry (GC/MS). However, whether fatty alka(e)nes can be released to cyanobacterial culture media remains to be clarified. This work develops a sensitive method for analyzing the trace level of extracellular hydrocarbons in cyanobacterial culture media by head space solid-phase microextraction (HS-SPME) coupled to GC/MS. Headspace (HS) extraction mode using polydimethylsiloxane fiber to extract for 30 min at 50 °C was employed as the optimal extraction conditions. Five cyanobacterial fatty alka(e)nes analogs including pentadecene (C15:1), pentadecane (C15:0), heptadecene (C17:1), heptadecane (C17:0), nonadecane (C19:0) were analyzed, and the data obtained from HS-SPME-GC/MS method were quantified using internal standard peak area comparisons. Limits of detection (LOD), limits of quantitation (LOQ), linear dynamic range, precisions (RSD) and recovery for the analysis of extracellular fatty alka(e)nes of cyanobacteria by HS-SPME–GC/MS were evaluated. The LODs limits of detection (S/N = 3) varied from 10 to 21 ng L−1. The correlation coefficients (r) of the calibration curves ranged from 0.9873 to 0.9977 with a linearity from 0.1 to 50 μg L−1. The RSD values were ranging from 7.8 to 14.0% and from 4.0 to 8.8% at 1.0 μg L−1 and 10.0 μg L−1 standard solutions, respectively. Comparative analysis of extracellular fatty alka(e)nes in the culture media of model cyanobacteria Synechocystis sp. PCC 6803 demonstrated that sensitivity of HS-SPME–GC/MS method was significantly higher than LLE method. Finally, we found that heptadecane can be released into the culture media of Synechocystis sp. PCC 6803 at the later growth period.