This section of the website contains information concerning specific methods investigated by members of the Round Robin Group, and/or by the Group itself. The immediate goal of the RR Group is to submit one or more methods to the American Society of Testing and Materials (ASTM) by December, 2005.
The methods described below are candidates for round-robin studies. The “Status” line indicates the developmental stage of each method according to the following letter codes:
Method CGC.RR.2005-01.0 Group Type Analysis of Finished Diesel Fuel by GC x GC x FID/SCD.
Submitting Members: Mario Ibarra, Frank DiSanzo, Randy Shearer, Ed Ledford, Lawrence Matengula
This method will employ GC x GC in combination with Flame Ionization and Sulfur Chemiluminesence Detectors to speciate and quantify paraffins, isoparaffins, napthenes, aromatics and sulfur-containing compounds in finished diesel fuels. The method will call for group type reports according to carbon number. The method will be extensible to variety of petroleum derived non-olefinic matrices, including light crude oil and petroleum distillates, and raw or finished gasolines, kerosenes, jet fuels, and fuel oils.
Status Detail: Several laboratories have validated similar methods. Both qualitative and quantitative aspects of the analysis are established by multiple laboratories who have published their work individually or reported their work at professional meetings. Full method specification in preparation; to be submitted to RR Group and ASTM by December 2005.
Method CGC.RR.2005-02.0 BTEX, Higher Aromatics, and Oxygenates in Finished Gasolines by GC x GC x FID.
Submitting Members: Ed Ledford, Lawrence Matengula
This method will employ GC x GC x FID to separate and quantify aromatics and oxygenates in finished gasoline. At present the method calls for a highly polar first column, followed by a non-polar second column.
Status Detail: Validation of BTEX and higher aromatics in gasolines has been completed by two laboratories working independently. Nine of 12 key oxygenate compounds are resolved from hydrocarbon matrix; three light ethers are obscured by light hydrocarbon interferences. Approaches to resolving these interferences are available and are being investigated.
Method CGC.RR.2005-03.0 Thermodynamics of individual compounds and numerical GC x GC Modeling
Submitting Members: Stephen E. Reichenbach, Edward B. Ledford, Jr.
This method is directed toward the development of predictive models of the GC x GC process. The method involves presenting sample continuously to a modulated capillary column to determine vant Hoff parameters for individual compounds on the column stationary phase. This method is not a chromatographic separation. It employs an uncoated transfer line in place of a primary column. The method features a standard split-splitless inlet configured to retain for a long period of time (hours) sample material introduced by an autoinjector, and to “bleed” the retained material continuously into the carrier gas flow, thereby permitting retention behavior on a short analytical column to be measured at numerous temperatures during a single run. Provision is made for measuring carrier gas velocity, so that k values for the compound can be determined at various temperatures. From this data, vant Hoff plots are constructed. The vant Hoff parameters are then used by predictive models of the chromatographic process. The goal is numerical optimization of GC x GC methods prior to actual construction and testing of GC x GC column sets.
Status Detail: The continuous injection method is operational in the proposers laboratory. Linear vant Hoff plots are readily obtained. A computer model for predicting retention time on the basis of vant Hoff parameters is under development. Full method specification to be submitted to the RR Group pending successful prediction of GC x GC test chromatograms. Submission of this method to ASTM or other standards organizations is not anticipated. RR Group members and others would employ compound database and predictive chromatography derived from this method to accelerate the development of other methods.
Method RR-2005-04.0 Determination of Heteroatomic Hydrocarbons and Hydrocarbon Groups in Diesel Range Petrochemical Fractions by GC x GC x MS.
Submitting Member: Gianluca Stani
This method will employ GC x GC x MS to identify and quantify selected heteroatomic hydrocarbons, including pyrroles, pyridines, amines, nitriles, quinolines, carbazoles, benzothiophenes, dibenzothiophenes, sulfides, and thiols, and to identify and quantify hydrocarbon groups including non-aromatics, mono-aromatics, di-aromatics, and tri-armoatcs in diesel range petroleum fractions.
Status Detail: Some 130 heteroatomic hydrocarbons have been resolved from complex diesel range petroleum matrices, and identified. Some 27 hydrocarbon group types have been separated and identified in the same fractions. This completes a single laboratory validation for the qualitative portion of the analysis. Quantiative studies are currently in progress. Full method specification to be submitted to the RR group pending completion of single laboratory validation of quantitative analysis and justification based upon industry survey or study requests from recognized standards bodies.
Several members of the GC x GC Round Robin Group have completed single laboratory validation of methods in the areas of flavors and fragrances, dioxins/PCBs in biological matrices, characterization of hydrocarbons in ocean and river sediments, and forensics. These methods will be described as they become available.