The Effects of Operating Conditions on Semivolatile Organic Compounds Emitted from Light-Duty, Gasoline-Powered Motor Vehicles

Author(s): Jason S. Herringtona, Michael D. Haysa, Barbara J. Georgeb, Richard W. Baldaufa,c

a Office of Research and Development, National Risk Management Research Laboratory, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, E343-02, Research Triangle Park, NC 27711, USA
b Office of Research and Development, National Exposure Research Laboratory, U.S. Environmental Protection Agency, 109 T.W. Alexander Drive, Research Triangle Park, NC 27711, USA
c Office of Transportation and Air Quality, National Vehicle and Fuel Emissions Laboratory, U.S. Environmental Protection Agency, 2000 Traverwood Drive, Ann Arbor, MI 48105, USA

Published By: Atmospheric Environment

Issue: vol. 54

Year of Publication: 2012

Link: http://www.sciencedirect.com/science/article/pii/S1352231012001586?v=s5

Abstract: A thermal extraction-gas chromatography-mass spectrometry (TE-GC-MS) method was utilized to quantitatively examine semivolatile organic compounds (SVOCs) in fine particulate matter (PM2.5) collected from light-duty, gasoline-powered vehicle (LDGV) exhaust. Emissions were analyzed from a subset of 18 vehicles tested in the Kansas City Light-Duty Vehicle Emissions Study (KCVES). The KCVES applied the LA92 Unified Driving Cycle (UDC), consisting of “cold start”, “hot stabilized running”, and “warm start” phases. The sensitivity of the TE-GC-MS analysis provided the opportunity to examine the emission rates and proportions of SVOCs (including polycyclic aromatic hydrocarbons (PAHs), hopanes, and steranes) in PM2.5 on an individual vehicle basis for each UDC phase. Mean target SVOC emissions rates of 5.01 μg km−1, 0.28 μg km−1, and 0.63 μg km−1 were reported for the cold start, hot stabilized running, and warm start phases, respectively. Operating conditions as depicted by each UDC phase significantly affected SVOC emission rates and proportions in PM2.5. The cold start phase emission rates were significantly higher than the hot stabilized running and warm start phases for 89% of the target SVOCs. An increase in SVOC proportions in PM2.5 was observed during the warm start phase compared with the cold start and hot stabilized running phase. This observation was significant for 31% of the target compounds, including chrysene, benzo[a]anthracene, and pyrene. Vehicles tested in both summer and winter provided emissions data describing ambient temperature effects. Emission rates were significantly higher in the winter for 92% of the target SVOCs. Until now, observations of specific SVOCs in motor vehicle emissions produced under changing operating conditions were scant. Such emissions data may be useful for emissions modeling, source apportionment studies, and human exposure assessments.

Developing New Methods for Pesticides in Dietary Supplements

Author(s): Julie Kowalski, Michelle Misselwitz, Jason Thomas,  Jack Cochran

Published By: Food Safety Magazine

Issue: February/March 2012

Year of Publication: 2012

Link: http://www.foodsafetymagazine.com/article.asp?id=3876&sub=sub1

Abstract: New requirements for dietary supplements to be manufactured under current Good Manufacturing Practices (cGMP) regulations have created a need for methods to detect pesticides in these complex, largely botanical products. QuEChERS offers a simple, cost-effective approach that can reduce matrix interferences as well as variation among technicians. Here we demonstrate a procedure that incorporates a QuEChERS extraction, cartridge solid-phase extraction (cSPE) cleanup and gas chromatography-time-of-flight mass spectrometry (GC-TOFMS), resulting in good recoveries for a wide range of pesticide chemistries in dandelion root powder.

Activity in the FID Detection Port: A Big Problem if Underestimated

Author(s): Jaap de Zeeuw

Published By: Separation Science

Issue: vol. 3, issue 14

Year of Publication: 2011

Link: http://www.sepscience.com/emails/sepsci1211eu.pdf

Abstract: It is commonly known in gas chromatography, that many problems can be traced to the injection system (e.g. sample, syringe, inlet). This is a valid statement, as 80% of “trouble” is related to injection conditions. One must also be aware that activity may be caused by other contributions. For instance, if we look at non-symmetrical peaks, there are more important areas to look at. Not only can the column be overloaded or poorly deactivated, but the detector also has a huge impact on peak shape and response. Here it is shown that flame tips can adsorb up to 90% of a component and cause tailing of polar as well as base/acidic compounds. Although it looks like the column is not performing, it’s the detector that is the problem.

Analysis of Trace Hydrocarbon Impurities in 1,3-Butadiene Using Optimized Rt®-Alumina BOND/MAPD PLOT Columns

Author(s): Rick Morehead, Jan Pijpelink, Jaap de Zeeuw, Tom Vezza

Published By: Restek Corporation

Year of Publication: 2011

Link: http://www.restek.com/Technical-Resources/Technical-Library/Petroleum-Petrochemical/petro_PCAN1434

Abstract: Impurity analysis of 1,3-butadiene on an Rt®-Alumina BOND/MAPD column results in good separation of both light polar impurities (methyl acetylene, propadiene) and  4-vinylcyclohexene, a heavier contaminant that often requires testing on a second column.

Improve Trace Analysis of Acetylene, Propadiene, and Methyl Acetylene Impurities With Higher Capacity Alumina MAPD Columns

Author(s): Rick Morehead, Jan Pijpelink, Jaap de Zeeuw

Published By: Petro Industry News

Year of Publication: 2011

Link: http://www.restek.com/Technical-Resources/Technical-Library/Petroleum-Petrochemical/petro_PCAN1537-UNV

Abstract: When analysing trace impurities in petroleum gases, such as propylene, ethylene, or 1,3-butadiene, column capacity (loadability) is an important factor in obtaining accurate data. Phase overload results in peak tailing, which can be problematic when trace level impurities elute near the main component where they may be obscured by the larger peak. Peak tailing can be further exacerbated by residual activity on the adsorbent surface. Using a higher capacity column with an appropriate deactivation is a good strategy for reducing tailing and improving accurate quantification of low level polar impurities in volatile petroleum streams.

How to Get More Analysis out of Your GC System

Author(s): Jaap de Zeeuw

Published By: Separation Science

Issue: vol. 3, issue 11

Year of Publication: 2011

Link: http://www.sepscience.com/emails/sepsci1011eu.pdf

Abstract: A common question we get asked by our customers is how they can get a longer column lifetime. This can be from a cost perspective (column price) or from a maintenance perspective (downtime, labour, calibration). Of course, the investment in a new column is large, around $500, but one thing that we should keep in mind is that we have to spread this investment over the total number of analyses. With typically 2000-5000 analysis per column the cost of the column per analyses is 10-25 cents. This must be put in contrast to downtime and sample preparation time. Column lifetime is defined by several factors and ways to extend it are discussed here.

A Primer on Control Systems

Author(s): Brandon Tarr

Published By: Restek Corporation

Year of Publication: 2011

Link:http://www.restek.com/Technical-Resources/Technical-Library/General-Interest/general_GNAN1401

Abstract: This article provides an introduction to control systems and discusses how control variables influence process variables. Topics include open loop, closed loop, and PID control systems. Simulations illustrate overshoot and undershoot around the setpoint during process control.

A Primer on Gas Flow

Author(s): Brandon Tarr

Published By: Restek Corporation

Year of Publication: 2011

Link:http://www.restek.com/Technical-Resources/Technical-Library/General-Interest/general_GNAN1402

Abstract: A basic understanding of gas flow principles is fundamental to obtaining accurate flow measurements. This primer contrasts mass flow and volumetric flow regimes, and illustrates the effect of flow impedance and loading on the flow source in gas chromatography.

Analysis of Pesticides in Dietary Supplements: Evaluation of QuEChERS, Cartridge SPE Clean-Up, and Gas Chromatography Time-of-Flight Mass Spectrometry

Author(s): Julie Kowalski, Michelle Misselwitz, Jason Thomas, Jack Cochran

Published By: Agro FOOD INDUSTRY Hi-tech today

Issue: Sept./Oct. Focus on Food Analysis supplement, vol. 22, no. 5

Year of Publication: 2011

Abstract: New requirements for dietary supplements to be manufactured under cGMP regulations have created a need for methods to detect pesticides in these complex, largely botanical products (e.g. vitamins, herbal and botanical pills, etc.) Since dietary supplements contain natural products where pesticides have been employed, methods for pesticide analysis must be evaluated, including sample extraction and cleanup, as well as instrumental techniques such as gas chromatography (GC). The QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation method offers a rapid way to prepare samples for analysis, but dietary supplement extracts can be so complex as to make trace-level pesticide determinations problematic. In this work, we evaluate a method involving QuEChERS extraction and dispersive solid phase extraction (dSPE) cleanup, cartridge SPE (cSPE) cleanup, and GC- time-of-flight mass spectrometry (TOFMS) to detect pesticide residues in dandelion root powder obtained from a dietary supplement vendor.

Extending the Power of Stabilized PLOT Column Technology to Process GC Analyzers

Author(s): Jaap de Zeeuw, Rick Morehead, Tom Vezza, Gary Stidsen

Published By: Petro Industry News

Year of Publication: 2011

Link: http://www.restek.com/Technical-Resources/Technical-Library/Petroleum-Petrochemical/petro_0021

Abstract: New metal MXT® PLOT columns offer greater stability than conventional PLOT columns, making them a better choice for process GC analyzer applications. New bonding techniques result in highly reproducible flow characteristics, improved layer stability, and excellent separation efficiencies.