HJ Cortes Consulting LLC

Midland, MI, United States

HJ Cortes Consulting LLC

Midland, MI, United States
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Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Gras R.,Dow Chemical Company | Cortes H.J.,University of Tasmania | And 3 more authors.
Analytica Chimica Acta | Year: 2013

A practical gas chromatographic approach is introduced for the characterization of trace ethylene glycol in industrial solvents and lubricants. The analytical approach employs single step derivatization technique that effectively converts ethylene glycol to the cyclic boronate ester (2-phenyl-1,3,2-dioxaborolane), using phenyl boronic acid as a derivatizing reagent. The separation of the derivatized product was achieved by using multidimensional gas chromatography. Heavy lubricant matrices like engine crankcase oil were back-flushed to improve sample throughput and system cleanliness. Detection and quantitation of 2-phenyl-1,3,2-dioxaborolane was conducted with mass spectrometry in selected ion monitoring mode.Complete analysis is conducted in less than 10min. Reproducibility of retention time was found to be less than 0.05% (n=20). Quantitative performance is highly satisfactory, viz. 0.49±0.02mgkg-1 (n=12) and 25.5±0.48mgkg-1 (n=12) for 0.5mgkg-1 and 25mgkg-1 spiked concentrations respectively. Over a range from 100μgkg-1 to 100mgkg-1, the response for 2-phenyl-1,3,2-dioxaborolane is linear with correlation coefficient of 0.998, a practical detection limit of 50μgkg-1, and average spiked recoveries for the analyte in the matrices tested range from 93 to 99%.Propylene glycol can also be analyzed using the same approach and water does not inhibit the formation of the derivatives, most probably owing to the use of 2,2-dimethoxypropane as a solvent for the derivatizing agent. © 2013 Elsevier B.V.


Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Gras R.,Dow Chemical Company | Hawryluk M.,Dow Chemical Company | And 3 more authors.
Journal of Chromatography A | Year: 2013

Volatile organic compounds such as light hydrocarbons, dienes, and aromatic compounds are often encountered in the manufacturing and processing environments of chemical and petrochemical segments. These compounds need to be closely monitored for process optimization, plant maintenance and industrial hygiene purposes. A high throughput analytical approach has been successfully developed and implemented for the accurate measurement of fourteen commonly encountered analytes. The approach incorporates a recently introduced 5-port planar microfluidic device configured for use as a Deans switch for multidimensional gas chromatography. The use of multidimensional gas chromatography allows the elimination of potential chromatographic contaminants with a substantial enhancement of stationary phase selectivity via the use of columns with different separation mechanisms, and the back-flushing of heavier undesired hydrocarbons. A low thermal mass gas chromatographic module was employed in the second dimension of the two-dimensional gas chromatography system and was used to provide independent temperature control, and rapid heating and cooling to meet the high throughput requirements. By successfully combining these concepts, complete analysis of fourteen targeted components can be conducted in less than 120s. Repeatability of retention times for all compounds was found to be less than 0.05% (n=20). Repeatability of area counts at two levels, namely 10ppmv and 1000ppmv over a period of two days was found to be less than 3% (n=20). Apart from methane, which has a detection limit of 0.4ppmv, the rest of the compounds were found to have detection limits of less than 0.2ppmv. Compounds of interest were found to be linear over a range of 500ppbv-3000ppmv with correlation coefficients greater than 0.999. © 2013 Elsevier B.V.


Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Gras R.,Dow Chemical Company | Cortes H.J.,University of Tasmania | And 2 more authors.
Analytical Chemistry | Year: 2013

A portable, fast gas chromatographic method for the direct measurement of the parts per billion level of sulfur-free odorants in commercially available natural gas is introduced. The approach incorporates a resistively heated, temperature-programmable silicon micromachined gas chromatograph that employs a standard capillary column for the fast separation of methyl and ethyl acrylate from the natural gas matrix. The separation approach is coupled to a micromachined differential mobility detector to enhance analyte detectability, and the overall selectivity obtained against the matrix is described. A complete analysis can be conducted in less than 70 s. Furthermore, these two compounds can be measured accurately in the presence of other common volatile sulfur-based odorants such as alkyl mercaptans and alkyl sulfides. Repeatability of less than 3% RSD (n = 20) over a range from 0.5 to 5 ppm was obtained with a limit of detection for the target compounds at 50 ppb (v/v) and a linear range from 0.5 to 50 ppm with a correlation coefficient of at least 0.997. © 2013 American Chemical Society.


Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Gras R.,Dow Chemical Company | Cortes H.J.,University of Tasmania | And 2 more authors.
Journal of Chromatography A | Year: 2013

An integrated gas chromatographic system has been successfully developed and implemented for the measurement of oxygen, nitrogen, carbon monoxide, carbon dioxide and light hydrocarbons in one single analysis. These analytes are frequently encountered in critical industrial petrochemical and chemical processes like catalytic cracking of naphtha or diesel fuel to lighter components used in gasoline. The system employs a practical, effective configuration consisting of two three-port planar microfluidic devices in series with each other, having built-in fluidic gates, and a mid-point pressure source. The use of planar microfluidic devices offers intangible advantages like in-oven switching with no mechanical moving parts, an inert sample flow path, and a leak-free operation even with multiple thermal cycles. In this way, necessary features such as selectivity enhancement, column isolation, column back-flushing, and improved system cleanliness were realized. Porous layer open tubular capillary columns were employed for the separation of hydrocarbons followed by flame ionization detection. After separation has occurred, carbon monoxide and carbon dioxide were converted to methane with the use of a nickel-based methanizer for detection with flame ionization. Flow modulated thermal conductivity detection was employed to measure oxygen and nitrogen. Separation of all the target analytes was achieved in one single analysis of less than 12min. Reproducibility of retention times for all compounds were found to be less than 0.1% (n=20). Reproducibility of area counts at two levels, namely 100ppmv and 1000ppmv over a period of two days were found to be less than 5.5% (n=20). Oxygen and nitrogen were found to be linear over a range from 20ppmv to 10,000ppmv with correlation coefficients of at least 0.998 and detection limits of less than 10ppmv. Hydrocarbons of interest were found to be linear over a range from 200ppbv to 1000ppmv with correlation coefficients of greater than 0.999 and detection limits of less than 100ppbv. © 2012 Elsevier B.V.


Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Gras R.,Dow Chemical Company | Shellie R.A.,Dow Chemical Company | And 2 more authors.
Journal of Chromatography A | Year: 2013

The detection of sulfur compounds in different hydrocarbon matrices, from light hydrocarbon feedstocks to medium synthetic crude oil feeds provides meaningful information for optimization of refining processes as well as demonstration of compliance with petroleum product specifications. With the incorporation of planar microfluidic devices in a novel chromatographic configuration, sulfur compounds from hydrogen sulfide to alkyl dibenzothiophenes and heavier distributions of sulfur compounds over a wide range of matrices spanning across a boiling point range of more than 650. °C can be characterized, using one single analytical configuration in less than 25. min. In tandem with a sulfur chemiluminescence detector for sulfur analysis is a flame ionization detector. The flame ionization detector can be used to establish the boiling point range of the sulfur compounds in various hydrocarbon fractions for elemental specific simulated distillation analysis as well as profiling the hydrocarbon matrices for process optimization. Repeatability of less than 3% RSD (n=. 20) over a range of 0.5-1000 parts per million (v/v) was obtained with a limit of detection of 50 parts per billion and a linear range of 0.5-1000 parts per million with a correlation co-efficient of 0.998. © 2013 Elsevier B.V.


Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Shellie R.A.,University of Tasmania | Cortes H.,University of Tasmania | And 3 more authors.
Journal of Chromatography A | Year: 2012

Steam condensate water treatment is a vital and integral part of the overall cooling water treatment process. Steam condensate often contains varying levels of carbon dioxide and oxygen which acts as an oxidizer. Carbon dioxide forms corrosive carbonic acid when dissolved in condensed steam. To neutralize the harmful effect of the carbonic acid, volatile amine compounds such as morpholine, cyclohexylamine, and diethylaminoethanol are often employed as part of a strategy to control corrosion in the water treatment process. Due to the high stability of these compounds in a water matrix, the indirect addition of such chemicals into the process via steam condensate often results in their presence throughout the process and even into the final product. It is therefore important to understand the impact of these chemicals and their fate within a chemical plant. The ability to analyze such compounds by gas chromatography has historically been difficult due to the lack of chromatographic system inertness at the trace level concentrations especially in an aqueous matrix. Here a highly sensitive, practical, and reliable gas chromatographic approach is described for the determination of morpholine, cyclohexylamine, and diethylaminoethanol in steam condensate at the part-per-billion (ppb) levels. The approach does not require any sample enrichment or derivatization. The technique employs a multi-mode inlet operating in pulsed splitless mode with programmed inlet temperature for sample introduction, an inert base-deactivated capillary column for solute separation and flame ionization detection. Chromatographic performance was further enhanced by the incorporation of 2-propanol as a co-solvent. Detection limits for morpholine, cyclohexylamine, diethylaminoethanol were established to be 100. ppb (v/v), with relative standard deviations (RSD) of less than 6% at the 95% confidence level (n= 20) and a percent recovery of 96% or higher for the solutes of interest over a range of 0.1-100. ppm (v/v). A complete analysis can be conducted in less than 10. min. © 2012 Elsevier B.V.


Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Gras R.,Dow Chemical Company | Cortes H.,University of Tasmania | And 2 more authors.
Journal of Chromatography A | Year: 2012

Oxygenated compounds like methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, acetaldehyde, crotonaldehyde, ethylene oxide, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, and 2-chloromethyl-1,3-dioxolane are commonly encountered in industrial manufacturing processes. Despite the availability of a variety of column stationary phases for chromatographic separation, it is difficult to separate these solutes from their respective matrices using single dimension gas chromatography. Implemented with a planar microfluidic device, conventional two-dimensional gas chromatography and the employment of chromatographic columns using dissimilar separation mechanisms like that of a selective wall-coated open tubular column and an ionic sorbent column have been successfully applied to resolve twelve industrially significant volatile oxygenated compounds in both gas and aqueous matrices. A Large Volume Gas Injection System (LVGIS) was also employed for sample introduction to enhance system automation and precision. By successfully integrating these concepts, in addition to having the capability to separate all twelve components in one single analysis, features associated with multi-dimensional gas chromatography like dual retention time capability, and the ability to quarantine undesired chromatographic contaminants or matrix components in the first dimension column to enhance overall system cleanliness were realized. With this technique, a complete separation for all the compounds mentioned can be carried out in less than 15. min. The compounds cited can be analyzed over a range of 250. ppm (v/v) to 100. ppm (v/v) with a relative standard deviation of less than 5% (n= 20) with high degree of reliability. © 2012 Elsevier B.V.


Causon T.J.,University of Tasmania | Cortes H.J.,University of Tasmania | Cortes H.J.,HJ Cortes Consulting LLC | Shellie R.A.,University of Tasmania | Hilder E.F.,University of Tasmania
Analytical Chemistry | Year: 2012

In this study we introduce the implementation of rapid temperature pulses for selectivity tuning in capillary liquid chromatography. Short temperature pulses improved resolution in discrete sections of chromatograms, demonstrated for ion-exchange chromatography (IC) and hydrophilic interaction chromatography (HILIC) modes. Using a resistively heated column module capable of accurate and rapid temperature changes, this concept is first illustrated with separations of small anions by IC using a packed capillary column as well as a series of nucleobases and nucleosides by HILIC using a silica monolithic column with zwitterionic functionality (ZIC-HILIC). Both positive (increasing temperature) and negative temperature pulses are demonstrated to produce significant changes in selectivity and are useful approaches for improving resolution between coeluted compounds. The approach was shown to be reproducible over a large number of replicates. Finally, the use of temperature gradients as well as other complex temperature profiles was also examined for both IC and HILIC separations. © 2012 American Chemical Society.


Luong J.,University of Tasmania | Luong J.,Dow Chemical Company | Gras R.,Dow Chemical Company | Cortes H.J.,University of Tasmania | And 2 more authors.
Analytical Chemistry | Year: 2013

The use of monoethylene glycol as an extraction medium for removing phenol and alkyl phenols in organic matrixes such as hydrocarbons is introduced and combined with a practical analytical multidimensional gas chromatography approach. The analytical approach has been successfully developed for the characterization of phenol, cresols, xylenols, and alkyl phenols like 4-ethylphenol and 2,3,5-trimethylphenol. The technique employs a single-step extraction of the analytes with monoethylene glycol and sonication, followed by multidimensional gas chromatography with mass spectrometry in selected ion monitoring mode for the detection and quantitation. Extraction efficiency of phenol approached 100% while cresols, xylenols, and 4-ethylphenol were 97% or higher and 2,3,5-trimethylphenol was better than 91% under the analytical conditions used. With the technique described, a complete analysis can be conducted in less than 16 min. Reproducibility of area counts at two levels, namely, 5 ppmw and 50 ppmw over a period of 2 days were found to be less than 4% (n = 20). The analytes of interest was found to be linear over a range from 100 ppbw to 250 ppmw with correlation coefficient of at least 0.999 and detection limit of 50 ppb w. Spike recoveries from 500 ppbw to 250 ppmw for all analytes range from 96 to 102%. © 2013 American Chemical Society.


Luong J.,Dow Chemical Company | Luong J.,University of Tasmania | Gras R.,Dow Chemical Company | Shellie R.A.,University of Tasmania | And 2 more authors.
Journal of Separation Science | Year: 2013

The application of planar microfluidic devices in GC for the separation of components of interest otherwise difficult to separate in a single analysis is presented. A variety of configurations were used for parallel chromatography, column effluent splitting, back flushing, selectivity tuning, valve less switching and column isolation, heart cutting, and comprehensive multidimensional chromatography. The synergies of recently commercialized planar microfluidic devices combined with the resolving power of fused-silica capillary columns are demonstrated. Difficult separations were accomplished in one single analysis, such as light hydrocarbons in air with high-moisture content, fixed gases in hydrocarbons, trace sulfur containing compounds in natural gas, and oxygenated compounds in hydrocarbons, among others. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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