Determination of δ¹³C of Trace Hydrocarbons in Natural Gas Using Syringe Solid Phase Extraction (SSPE) Coupled with Gas Chromatography/Isotope Ratio Mass Spectrometry (GC/IRMS)

Table 5

δ¹³C ratios (‰), (mV), and SD (‰) obtained from DI, SPME, and SSPE.

Compound	Direct injection		Solid phase microextraction			Syringe solid phase extraction
	δ^13C	Peak area	δ^13C	Peak area	Standard deviation	δ^13C	Peak area	Standard deviation
CH4	-48.20	1.02	—	—	—	-47.76	12.50	0.31
C2H6	-44.31	1.10	-44.82	0.24	0.36	-44.99	91.70	0.48
C3H8	-41.33	0.99	-42.86	0.28	1.08	-41.02	241.44	0.21
i-C4H10	—	—	-36.89	0.41	—	-39.42	35.90	—
n-C4H10	-37.28	0.91	-40.78	2.40	2.48	-36.84	170.06	0.31
i-C5H12	—	—	-38.58	0.58	—	-37.95	9.37	—
n-C5H12	-35.42	0.43	-37.76	2.64	1.65	-35.15	29.54	0.19
C6H14	—	—	-34.58	3.56	—	-36.53	2.82	—