[Contrastive study of two methods("programmed temperature vaporization with back flushing" and "head space") for...

Area of Science:

• Petroleum Geochemistry
• Analytical Chemistry

Context:

• Accurate analysis of light hydrocarbons is crucial for petroleum geochemistry.
• Existing analytical methods may have limitations in terms of accuracy and reliability for complex oil samples.

Purpose:

• To present and compare two light hydrocarbon analytical methods: PTV with Back Flushing and Head Space.
• To evaluate the reliability and applicability of these methods for geochemistry studies.
• To determine the suitability of combining data from different analytical techniques.

Summary:

• A "PTV with Back Flushing" method using temperature-programmed inlets and gas back flushing was developed for direct oil sample injection, efficiently removing heavy components.
• "Head Space" analytical method was also established.
• Both methods offer advantages like extended column life and reduced analysis time, meeting ASTM D5134-98 resolution criteria for components < C9 with good repeatability.
• Analysis of ten oil samples revealed relative deviations of +/- (1%-25%) for 19 geochemistry parameters between the two methods.
• Direct injection of crude oil using PTV with Back Flushing yields more reliable results.

Impact:

• Highlights the unacceptability of combining data from PTV with Back Flushing and Head Space methods in geochemistry.
• Recommends calibration for "Head Space" results in geochemistry studies.
• Provides insights into selecting appropriate analytical techniques for reliable geochemical analysis of light hydrocarbons in crude oil.