Development of a sequential injection-liquid microextraction procedure with GC-FID for analysis of short-chain fatty acids in palm oil mill effluent.
Short-chain fatty acids, such as acetic, propionic, butyric, iso-valeric and valeric acids, play an important role in methanogenesis activity for biogas production processes. Thus, simple and rapid procedures for monitoring the levels of short-chain fatty acids are requisite for sustaining biogas production. This work presents the development of a sequential injection-liquid microextraction (SI-LME) procedure with GC-FID analysis for determination of short-chain fatty acids. GC-FID was employed for detection of the short-chain fatty acids. Calibration curves were linear with good coefficients of determination (r2>0.999), using methacrylic acid as the internal standard. Limits of quantification (LOQ) were in the range of 0.03-0.19mM. The SI-LME procedure employed tert-butyl methyl ether (TBME) as the extracting solvent. Various SI-LME conditions were investigated and optimized to obtain the highest recovery of extraction. With these optimized conditions, an extraction recovery of the five key short-chain fatty acids of 67-90% was obtained, with less than 2% RSD (n=3). The final SI-LME procedure employed two fluidic zones of TBME with a single aqueous fluidic zone of sample sandwiched between the TBME zones, with 5 cycles of flow reversal at a flow rate of 5µL/s for the extraction process. Intra- and inter-day precision values were 0.5-4.0% RSD and 3.3-4.8% RSD, respectively. Accuracy based on percentage of sample recovery were in the range of 69-96, 102-107, and 82-101% (n=4) for acetic, propionic and butyric acids, respectively. The proposed method was applied for the measurement of short-chain fatty acids in palm oil mill effluents used in biogas production in a factory performing palm oil extraction process. The SI-LME method provides improved extraction performance with high precision, and is both simple and rapid with its economical extraction technique. The SI-LME procedure with GC-FID has strong potential for use as a quality control process for monitoring short-chain fatty acid levels in biogas production.
Department of Chemistry and Center of Excellence for Innovation in Chemistry and Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs), Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
Thapanee
T
Pruksatrakul
Department of Chemistry and Center of Excellence for Innovation in Chemistry and Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs), Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
Pattamaporn
P
Phoopraintra
National Doping Control Centre, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
Prapin
P
Wilairat
Department of Biochemistry and Center for Excellence in Protein and Enzyme Technology, Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand.
Pimchai
P
Chaiyen
Department of Chemistry and Center of Excellence for Innovation in Chemistry and Flow Innovation-Research for Science and Technology Laboratories (FIRST Labs), Faculty of Science, Mahidol University, Rama VI Rd., Bangkok 10400, Thailand. Electronic address: rattikan.cha@mahidol.ac.th.
Rattikan
R
Chantiwas
D002849:Chromatography, Gas / Q000379:methods*; D005232:Fatty Acids, Volatile / Q000032:analysis*; D005410:Flame Ionization / Q000379:methods*; D059627:Liquid Phase Microextraction / Q000379:methods*; D000073878:Palm Oil / Q000032:analysis* / Q000737:chemistry; D014865:Waste Disposal, Fluid / Q000379:methods*
D005232:Fatty Acids, Volatile; D000073878:Palm Oil
Biogas; Gas chromatography; Palm oil mill effluent; Sequential injection-liquid microextraction; Short-chain fatty acids