Comprehensive Two-Dimensional Gas Chromatography and Chemometrics for the High-Speed Quantitative Analysis of Aromatic Isomers in a Jet Fuel Using the Standard Addition Method and an Objective Retention Time Alignment Algorithm

Abstract

A high-speed quantitative analysis of aromatic isomers in a jet fuel sample is performed using comprehensive two-dimensional gas chromatography (GC x GC) and chemometrics. A GC x GC separation time of 2.8 min is achieved for three aromatic isomers in jet fuel, which is 5 times faster than a reference method in which a singlecolumn separation resolves two of the three isomers of interest. The high-speed GC x GC separation is more than 10 times faster than a recent GC x GC separation that fully resolves the three components of interest in gasoline. The high-speed GC x GC analysis of jet fuel is accomplished through short GC columns, high gas velocities, and partial chromatographic peak resolution followed by chemometric resolution of overlapped peaks. The standard addition method and an objective retention time alignment algorithm are used to correct for retention time variations prior to the chemometric data analysis. The standard addition method corrects for chemical matrix effects that cause analytes in complex samples to have peak shapes, widths, and retention times that differ considerably from those of calibration standards in pure solvents. The retention time alignment algorithm corrects for the relatively small retention time variations caused by fluctuating instrumental parameters such as flow rate and temperature. The use of data point interpolation in the retention time alignment algorithm results in a more accurate retention time correction then previously achieved. The generalized rank annihilation method (GRAM) is the chemometric technique used to resolve the overlapped GC x GC peaks. The correction of retention time variations allows for successful GRAM signal deconvolution. Using the retention time alignment algorithm, GRAM quantification accuracy and precision are improved by a factor of 4. The methodology used in this paper should be applicable to other comprehensive separation methods, such as two-dimensional liquid chromatography, liquid chromatography coupled with capillary electrophoresis, and liquid chromatography coupled with gas chromatography.

Chemometric strategies for enhancing the chromatographic methodologies with second-order data analysis of compounds when peaks are overlapped

“…In our knowledge, only two papers reported the application of second-order methodologies in combination with standard addition to quantify analytes in complex samples that causes matrix effect in the GC responses. In this sense, Fraga et al [84] used GRAM with two-dimensional GC(GC-GC) coupled to a flame ionization detector (FID) for the determination of aromatic isomers in a jet fuel. The application of GRAM allowed for the separation of the overlapped GC×GC peaks, whereas the standard addition calibration corrected changes in peak widths and retention times between samples and standards.…”

Caracterização de amostras petroquímicas e derivados utilizando cromatografia gasosa bidimensional abrangente (GCxGC)

“…Fraga e colaboradores 22 relataram a rápida análise quantitativa de três isômeros aromáticos (isopropilbenzeno, propilbenzeno e 1,3,5-trimetilbenzeno) em combustível para jato por GCxGC-FID de alta velocidade, sendo a modulação realizada com válvula diafragma, utilizando o método da adição de padrão, um algoritmo de alinhamento objetivo do tempo de retenção e a técnica quimiométrica GRAM. Com o algoritmo de alinhamento foram realizadas correções de desvios causados por variações instrumentais (como oscilação da vazão da fase móvel ou da temperatura) antes da análise quimiométrica dos dados, pois, como a separação na von Mühlen et al…”

“…Posteriormente, são referidas as análises de etapas do processamento do petróleo bruto, os avanços nas análises de biomarcadores e, por fim, aplicações envolvendo poluentes ambientais provenientes de petróleo e seus derivados em amostras de ar, água e solo. Dentre as principais aplicações da GCxGC a amostras petroquímicas estão as análises de gasolina 13,14,18,[21][22][23][24][25][26][27][28][29][30] , combustíveis para jatos 22,31 , gasóleo leve 19,32 , óleo diesel 27,[33][34][35][36][37][38] , óleo bruto 20,[39][40][41] , solventes hidrocarbonetos não aromáticos 20 , querosene 15,20,28,32,42,43 , óleos de lavagem 44 , biomarcadores 40,[45][46][47] , poluentes ambientais em ar 10,16,26,34,41,45,[47]…”

Química Analítica de Processos

“…Uma exceção é a utilização de GCxGC como um analisador rápido "on-line" de nafta 28 , sendo 16 vezes mais rápido que o método padrão, que utiliza GC convencional. Para maiores detalhes sobre as características do equipamento utilizado, os autores citam trabalhos realizados anteriormente [36][37][38] .…”