Direct injection GC method for measuring light hydrocarbon emissions from cooling-tower water

Area of Science:

• Analytical Chemistry
• Environmental Science

Background:

• Current methods for quantifying light hydrocarbons in cooling water have limitations.
• Accurate monitoring of light hydrocarbons is crucial for emission control and leak detection.

Purpose of the Study:

• To develop and validate a Direct Injection Gas Chromatography (GC) method for quantifying light hydrocarbons (C6 and below) in cooling water.
• To overcome the limitations of existing technologies for light hydrocarbon analysis in aqueous samples.

Main Methods:

• Direct injection of water samples into a GC equipped with a stripper column to remove water before hydrocarbon separation.
• Validation of the method for precision, recovery, and detection limits.
• Validation of a sampling method using zero headspace VOA vials and a sample chiller.

Main Results:

• The Direct Injection GC method provides analysis in approximately 15 minutes with excellent precision and recovery.
• Method detection limits below 1 ppb (w/v) for ethylene, propylene, and benzene.
• Validated sampling method ensures minimal hydrocarbon loss, with over 93% recovery after 7 days at 4°C.

Conclusions:

• The Direct Injection GC method is a superior alternative to the El Paso stripper method for light hydrocarbon quantification in cooling water.
• This technique offers lower detection limits, better recoveries, and reduced maintenance compared to existing methods.
• The method is readily implementable for routine emission monitoring and leak detection of light hydrocarbons.