A new issue of this journal has just been published. To see abstracts of the papers it contains (with links through to the full papers) click here:
Selected papers from the latest issue:
Mixed-mode solid-phase extraction followed by dispersive liquid-liquid microextraction for the sensitive determination of ethylphenols in red wines
25 January 2012, 01:09:37
Publication year: 2012
Source: Journal of Chromatography A, Available online 24 January 2012
I. Carpinteiro, B. Abuín, I. Rodríguez, M. Ramil, R. Cela
Selectivity of mixed-mode solid-phase extraction (SPE) was combined with the concentration power of dispersive liquid-liquid microextraction (DLLME) to obtain a sensitive, low solvent consumption method for gas chromatography-mass spectrometry determination of ethylphenol off-flavours (4-ethylphenol, EP; 4-ethylguaicol, EG and 4-ethylcathecol, EC) in complex red wine samples. Under optimized conditions, limits of quantification (LOQs) between 0.3 and 0.8 ng mLwere obtained using just 5 mL of wine and 0.06 mL of 1,1,1-trichloroethane (TCE) as extractant in the DLLME step. Analytes were acetylated after SPE and previously to DLLME concentration to enhance the performance of their GC-MS determination. The overall extraction efficiency of the method was unaffected by the particular characteristics of each wine; thus, accurate results (relative recoveries from 89 to 109% for samples spiked at concentrations from 20 to 1000 ng mL) were obtained using matrix-matched standards, without requiring the use of the time consuming standard addition quantification methodology. The applicability of the method was demonstrated with the analysis of different red wines. Analytes concentrations varied from 6 to 2265 ng mL(EP), 0.8 to 251 ng mL(EG) and non-detected to 158 ng mL(EC).
Source: Journal of Chromatography A, Available online 24 January 2012
I. Carpinteiro, B. Abuín, I. Rodríguez, M. Ramil, R. Cela
Selectivity of mixed-mode solid-phase extraction (SPE) was combined with the concentration power of dispersive liquid-liquid microextraction (DLLME) to obtain a sensitive, low solvent consumption method for gas chromatography-mass spectrometry determination of ethylphenol off-flavours (4-ethylphenol, EP; 4-ethylguaicol, EG and 4-ethylcathecol, EC) in complex red wine samples. Under optimized conditions, limits of quantification (LOQs) between 0.3 and 0.8 ng mLwere obtained using just 5 mL of wine and 0.06 mL of 1,1,1-trichloroethane (TCE) as extractant in the DLLME step. Analytes were acetylated after SPE and previously to DLLME concentration to enhance the performance of their GC-MS determination. The overall extraction efficiency of the method was unaffected by the particular characteristics of each wine; thus, accurate results (relative recoveries from 89 to 109% for samples spiked at concentrations from 20 to 1000 ng mL) were obtained using matrix-matched standards, without requiring the use of the time consuming standard addition quantification methodology. The applicability of the method was demonstrated with the analysis of different red wines. Analytes concentrations varied from 6 to 2265 ng mL(EP), 0.8 to 251 ng mL(EG) and non-detected to 158 ng mL(EC).
Highlights
► Selective ethylphenols determination in red wines ► Wide linear response range ► Overall extraction yields not affected by wine sample characteristics ► High enrichment factors with low organic solvents and sample consumption.Development of a hydrophilic interaction liquid chromatography–mass spectrometry method for detection and quantification of urea thermal decomposition by-products in emission from diesel engine employing selective catalytic reduction technology
25 January 2012, 01:09:37
Publication year: 2012
Source: Journal of Chromatography A, Available online 24 January 2012
Mahmoud M. Yassine, Ewa Dabek-Zlotorzynska, Valbona Celo
The use of urea based selective catalytic reduction (SCR) technology for the reduction of NOx from the exhaust of diesel-powered vehicles has the potential to emit at least six thermal decomposition by-products, ammonia, and unreacted urea from the tailpipe. These compounds may include: biuret, dicyandiamine, cyanuric acid, ammelide, ammeline and melamine. In the present study, a simple, sensitive and reliable hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization (ESI)/mass spectrometry (MS) method without complex sample pre-treatment was developed for identification and determination of urea decomposition by-products in diesel exhaust. Gradient separation was performed on a SeQuant® ZIC-HILIC column with a highly polar zwitterionic stationary phase, and using a mobile phase consisting of acetonitrile (eluent A) and 15 mM ammonium formate (pH 6; eluent B). Detection and quantification were performed using a quadrupole ESI/MS operated simultaneously in negative and positive mode. With 10 μL injection volume, LODs for all target analytes were in the range of 0.2-3 μg/L. The method showed a good inter-day precision of retention time (RSD <0.5%) and peak area (RSD <3%). Satisfactory extraction recoveries from spiked blanks ranged between 96 and 98%. Analyses of samples collected during transient chassis dynamometer tests of a bus engine equipped with a diesel particulate filter (DPF) and urea based SCR technology showed the presence of five target analytes with cyanuric acid and ammelide the most abundant compounds in the exhaust.
Source: Journal of Chromatography A, Available online 24 January 2012
Mahmoud M. Yassine, Ewa Dabek-Zlotorzynska, Valbona Celo
The use of urea based selective catalytic reduction (SCR) technology for the reduction of NOx from the exhaust of diesel-powered vehicles has the potential to emit at least six thermal decomposition by-products, ammonia, and unreacted urea from the tailpipe. These compounds may include: biuret, dicyandiamine, cyanuric acid, ammelide, ammeline and melamine. In the present study, a simple, sensitive and reliable hydrophilic interaction liquid chromatography (HILIC)-electrospray ionization (ESI)/mass spectrometry (MS) method without complex sample pre-treatment was developed for identification and determination of urea decomposition by-products in diesel exhaust. Gradient separation was performed on a SeQuant® ZIC-HILIC column with a highly polar zwitterionic stationary phase, and using a mobile phase consisting of acetonitrile (eluent A) and 15 mM ammonium formate (pH 6; eluent B). Detection and quantification were performed using a quadrupole ESI/MS operated simultaneously in negative and positive mode. With 10 μL injection volume, LODs for all target analytes were in the range of 0.2-3 μg/L. The method showed a good inter-day precision of retention time (RSD <0.5%) and peak area (RSD <3%). Satisfactory extraction recoveries from spiked blanks ranged between 96 and 98%. Analyses of samples collected during transient chassis dynamometer tests of a bus engine equipped with a diesel particulate filter (DPF) and urea based SCR technology showed the presence of five target analytes with cyanuric acid and ammelide the most abundant compounds in the exhaust.
Highlights
► Exhaust from a bus engine equipped with diesel particulate filter and urea- selective reduction technology. ► Identification and quantification of urea thermal decomposition compounds in diesel emission were studied. ► A new HILIC-ESI/MS method has been developed. ► Five target analytes, with cyanuric acid and ammelide the most abundant compounds, were determined.Evaluation of a column classification method using the separation of alfuzosin from its related substances
25 January 2012, 01:09:37
Publication year: 2012
Source: Journal of Chromatography A, Available online 24 January 2012
Jarosław Szulfer, Alina Plenis, Tomasz Bączek
The popularity and commercial availability of reversed-phase liquid chromatographic (RP-LC) stationary phases cause analysts to be often confronted with the problem of column selection. For this reason, general test methods to characterize RP-LC columns have been extensively studied since the 1970s. This paper focuses on correlating the column classification based on a method developed at the Katholieke Universiteit Leuven (KUL method) with the selectivity obtained for a real separation. The analysis of alfuzosin hydrochloride and related compounds was carried out according to the method prescribed in the European Pharmacopoeia (Ph. Eur.) monograph. This separation was performed on 36 new RP-LC stationary phases which had been previously characterized chromatographically. For deeper comparative analysis of KUL classification of the stationary RP-LC brands and their column performance in pharmaceutical practice two chemometric tools, such as principal component analysis (PCA) and cluster analysis (CA), have been used. It was shown that stationary phase classes closely related by KUL method gave comparable separation for alfuzosin and related compounds. Therefore, the column ranking system based on the evaluation ofF-values can be considered as a helpful tool in the selection of a suitable column for pharmaceutical analyses.
Source: Journal of Chromatography A, Available online 24 January 2012
Jarosław Szulfer, Alina Plenis, Tomasz Bączek
The popularity and commercial availability of reversed-phase liquid chromatographic (RP-LC) stationary phases cause analysts to be often confronted with the problem of column selection. For this reason, general test methods to characterize RP-LC columns have been extensively studied since the 1970s. This paper focuses on correlating the column classification based on a method developed at the Katholieke Universiteit Leuven (KUL method) with the selectivity obtained for a real separation. The analysis of alfuzosin hydrochloride and related compounds was carried out according to the method prescribed in the European Pharmacopoeia (Ph. Eur.) monograph. This separation was performed on 36 new RP-LC stationary phases which had been previously characterized chromatographically. For deeper comparative analysis of KUL classification of the stationary RP-LC brands and their column performance in pharmaceutical practice two chemometric tools, such as principal component analysis (PCA) and cluster analysis (CA), have been used. It was shown that stationary phase classes closely related by KUL method gave comparable separation for alfuzosin and related compounds. Therefore, the column ranking system based on the evaluation ofF-values can be considered as a helpful tool in the selection of a suitable column for pharmaceutical analyses.
Highlights
► Column classification was carried out in view of LC separation of alfuzosin and related compounds. ► We performed LC column classification based on KUL method. ► We evaluated column classification system using chemometric techniques. ► Principal component analysis and cluster analysis were applied. ► The tested classification system can be considered as efficient tools.Ultra-Trace Level Analysis of Morpholine, Cyclohexylamine, and Diethylaminoethanol in Steam Condensate by Gas Chromatography with Multi-Mode Inlet, and Flame Ionization Detection
25 January 2012, 01:09:37
Publication year: 2012
Source: Journal of Chromatography A, Available online 24 January 2012
J. Luong, R.A. Shellie, H. Cortes, R. Gras, T. Hayward
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 to 100 ppm (v/v). A complete analysis can be conducted in less than ten minutes.
Source: Journal of Chromatography A, Available online 24 January 2012
J. Luong, R.A. Shellie, H. Cortes, R. Gras, T. Hayward
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 to 100 ppm (v/v). A complete analysis can be conducted in less than ten minutes.
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