A device is provided for delivering gases to an analyzer, such as an isotopic ratio mass spectrometer. The device includes first and second reactors, preferably arranged in parallel. At least one of the reactors may be selectively activated, or means may be incorporated to circumvent one of the reactors, such that different types of gas conversions may be achieved.

A method for analyzing light n-alkane components and carbon isotopes in deep and ultra-deep source rocks includes: (S1) subjecting a 5A molecular sieve column to aging; (S2) pyrolyzing a source rock; and allowing a pyrolysis product to enter the 5A molecular sieve column; where n-alkanes are adsorbed and retained by the 5A molecular sieve column; allowing an outflow to pass through a fractionation plate and an empty column or a weak polarity column to be discharged; and (S3) performing programmed heating such that the n-alkanes adsorbed on the 5A molecular sieve column are successively desorbed according to molecular weight, and then pass through the fractionation plate and the HP-5 or DB-5 column to enter a mass spectrometer for composition analysis or isotopic analysis. An analysis system is further provided.

A method for analyzing light n-alkane components and carbon isotopes in deep and ultra-deep source rocks includes: (S1) subjecting a 5 A molecular sieve column to aging; (S2) pyrolyzing a source rock; and allowing a pyrolysis product to enter the 5 A molecular sieve column; where n-alkanes are adsorbed and retained by the 5 A molecular sieve column; allowing an outflow to pass through a dividing plate and an empty column or a weak polarity column to be discharged; and (S3) performing programmed heating such that the n-alkanes adsorbed on the 5A molecular sieve column are successively desorbed according to molecular weight, and then pass through the dividing plate and the HP-5 or DB-5 column to enter a mass spectrometer for composition analysis or isotopic analysis.