quantification of the concentration of vocs in gasoline and diesel
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www.estcal.comwww.estcal.comElectronic Sensor Technology, Inc.
Quantification of the concentration of VOCs in gasoline and diesel
www.estcal.comwww.estcal.comElectronic Sensor Technology, Inc.
Quantification of the concentration of VOCs in gasoline and diesel
www.estcal.comwww.estcal.comElectronic Sensor Technology, Inc.
4 News that have shocked us in the past!
• Fuel contamination incident in Bangor, County Down lead Tesco to pay the claims of about £8m.
• ASDA sent cheques to about 3,000 customers who collectively claimed £1.4m in compensation.
• In 2009, Fatty Acid Methyl Ester, a harmful component for engines found in jet fuel of U.S Air Force’s C-130 USAF.
• Fleet Readiness Center (FRC) East discarded about 12,000 gallons of fuel in December, 2014.
Fuel contamination is creating major problems for the globe
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The increasing number of fuel contamination cases every year arises a need for a technology to detect impurities in the fuel.
Introducing…zNose®
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7 Unique features of EST zNose®
Uses Surface Acoustic Wave (SAW) sensor and
ultra-fast Gas Chromatography (GC)
technology.
Rapidly provides complete
chemical profile.
Software of zNose® includes expandable library
of over 700 chemicals & odor signatures.
Operates within a wireless network.
www.estcal.comwww.estcal.comElectronic Sensor Technology, Inc.
4 steps to quantify the Chemistry of Gasoline Vapors!
Step 1 -Ambient air (vapor) is first sampled
and organic vapors collected on the trap
that acts as a pre-concentrator.
Step 2- The trap is switched into the
helium section where the collected organic
compounds are injected into flowing helium gas.
Step 3- The organic compounds pass through a
capillary column with different velocities and thus
individual chemicals exit the column at specific
times.
Step 4- As they exit the column they are
detected and quantified by a solid
state detector.
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6 Samples of Pemex gasoline (87 and 92 octane) & 5 samples of diesel were taken from various service stations across US and subjected to a 4-step GC
method.
Testing Gasoline and Diesel Samples from service stations!
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4-step GC method
Step1: Sample Preparation Fully vaporized samples and headspace vapors of gasoline and diesel collected.
Step 2: Sample Pre-concentration Time: Required sample volume of 1-0.5 milliliter from the concentration of vapor samples from gasoline and diesel.
Step 3 - Column Ramping: Used a db624 column and temperature ramping rates varied from zero (isothermal) to as high as 18o C/second.
Step 4 - Detector Response: Detector temperature of 10o C used for optimum response to the most volatile compounds, such as benzene.
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• Calibration standards made by injecting known concentrations of benzene, toluene, ethylbenzene, o-xylene, and n-alkanes into septa sealed 40 milliliter vials and 250 milliliter bottles.
• Vapor standards used to verify system linearity and to provide reference retention times for indexing peak retention times.
• Standard deviation of replicate measurements using vapor standards was typically 1-5%.
• Using BTEX calibration standards used to test system linearity for vapor concentrations up to approximately 50 ppm.
4 Key Matrices to Set Calibration Standards
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