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Selected papers from the latest issue:
Packed Column Supercritical Fluid Chromatography (pcSFC) of Hydrophilic Analytes via Water-Rich Modifiers
22 February 2012, 21:55:48
Publication year: 2012
Source: Journal of Chromatography A, Available online 22 February 2012
Larry T. Taylor
The use of additives to dramatically extend the range of solute polarity amenable to CO2based supercritical fluid chromatography (pcSFC) was predicted over twenty years ago. At that time additives were predicted to have multiple functions such as enhancement of mobile phase solvating power, ion suppression, and ion pairing. The adsorption of mobile phase components on the stationary phase causing a modification of its surface was predicted, but the implications for separations were not defined. Reports published in the late 1980‘s showed that while water could not function as a primary modifier due to it poor solubility in carbon dioxide, its use as an additive was more promising. The past decade has seen very little published work concerning water and pcSFC. Now reports are beginning to appear that demonstrate enhanced selectivity with water, and application of the technology to polypeptide salts, drug molecules, and nucleobases. This review attempts to bridge the past with the present. As evidenced by the studies described in this review, water may offer much potential as an additive in that it could (a) enhance the solvating power of the mobile phase, (b) introduce HILIC-like analyte partitioning, (c) simplify preparative purifications, and (d) offer a more mass spectrometrically compatible interface.
Source: Journal of Chromatography A, Available online 22 February 2012
Larry T. Taylor
The use of additives to dramatically extend the range of solute polarity amenable to CO2based supercritical fluid chromatography (pcSFC) was predicted over twenty years ago. At that time additives were predicted to have multiple functions such as enhancement of mobile phase solvating power, ion suppression, and ion pairing. The adsorption of mobile phase components on the stationary phase causing a modification of its surface was predicted, but the implications for separations were not defined. Reports published in the late 1980‘s showed that while water could not function as a primary modifier due to it poor solubility in carbon dioxide, its use as an additive was more promising. The past decade has seen very little published work concerning water and pcSFC. Now reports are beginning to appear that demonstrate enhanced selectivity with water, and application of the technology to polypeptide salts, drug molecules, and nucleobases. This review attempts to bridge the past with the present. As evidenced by the studies described in this review, water may offer much potential as an additive in that it could (a) enhance the solvating power of the mobile phase, (b) introduce HILIC-like analyte partitioning, (c) simplify preparative purifications, and (d) offer a more mass spectrometrically compatible interface.
Highlights
► Water as a neutral additive has been shown to enhance pcSFC selectivity. ► Water enhances solvation of polar analytes and the stationary phase. ► After 20 years, water is finding new applications in pcSFC.Determination of Tropane Alkaloids Atropine and Scopolamine by Liquid Chromatography-Mass Spectrometry in Plant Organs of Datura Species
22 February 2012, 21:55:48
Publication year: 2012
Source: Journal of Chromatography A, Available online 22 February 2012
Silvia Jakabová, Lajos Vincze, Ágnes Farkas, Ferenc Kilár, Borbála Boros, ...
Hyoscyamine (atropine) and scopolamine are the predominant tropane alkaloids in theDaturagenus, occurring in all plant organs. The assessment of the alkaloid content of various plant parts is essential from the viewpoint of medical use, but also as a potential risk of toxicity for humans and animals. Therefore, a reliable method for the determination of tropane alkaloid content is of high importance.The present work aimed at the elaboration of a rapid method for determination of the most abundantDaturaalkaloids by LC-MS technique using a new generation of core-shell particle packed column. Tropane alkaloid content was investigated in various plant organs of fourDaturataxa (D. innoxia, D. metel, D. stramonium, andD. stramoniumvar.tatula), grown under the same conditions, in two developmental stages.We have developed a rapid LC-MS method for the quantitative determination of atropine and scopolamine, which was successfully applied to quantify the alkaloids in different plant organs (leaves, flowers, stems, seeds) of thorn apples after a simple sample preparation step. Elaboration and validation of the method and analysis of plant extracts were done by UFLC-MS technique, employing an Ascentis Express C18 column. Detection was done in positive ionization mode (ESI + ) and the method suitability was evaluated by several validation characteristics. Quantitation limits are 333 and 167 pg mLfor scopolamine and atropine, respectively, and the method shows very good repeatability.The analysis ofDaturaextracts revealed significant differences depending on the species, the organ and the sampling period. Atropine was found to be dominant over scopolamine in three out of the four taxa investigated.D. innoxiashowed the highest concentrations of scopolamine in all organs examined, whereasD. metelaccumulated the lowest scopolamine levels. Hyoscyamine, measured as atropine, was the highest inD. stramoniumvar.tatula, and the lowest inD. innoxia. Samples collected in summer had higher scopolamine levels than autumn samples, concerning both stems and leaves.
Source: Journal of Chromatography A, Available online 22 February 2012
Silvia Jakabová, Lajos Vincze, Ágnes Farkas, Ferenc Kilár, Borbála Boros, ...
Hyoscyamine (atropine) and scopolamine are the predominant tropane alkaloids in theDaturagenus, occurring in all plant organs. The assessment of the alkaloid content of various plant parts is essential from the viewpoint of medical use, but also as a potential risk of toxicity for humans and animals. Therefore, a reliable method for the determination of tropane alkaloid content is of high importance.The present work aimed at the elaboration of a rapid method for determination of the most abundantDaturaalkaloids by LC-MS technique using a new generation of core-shell particle packed column. Tropane alkaloid content was investigated in various plant organs of fourDaturataxa (D. innoxia, D. metel, D. stramonium, andD. stramoniumvar.tatula), grown under the same conditions, in two developmental stages.We have developed a rapid LC-MS method for the quantitative determination of atropine and scopolamine, which was successfully applied to quantify the alkaloids in different plant organs (leaves, flowers, stems, seeds) of thorn apples after a simple sample preparation step. Elaboration and validation of the method and analysis of plant extracts were done by UFLC-MS technique, employing an Ascentis Express C18 column. Detection was done in positive ionization mode (ESI + ) and the method suitability was evaluated by several validation characteristics. Quantitation limits are 333 and 167 pg mLfor scopolamine and atropine, respectively, and the method shows very good repeatability.The analysis ofDaturaextracts revealed significant differences depending on the species, the organ and the sampling period. Atropine was found to be dominant over scopolamine in three out of the four taxa investigated.D. innoxiashowed the highest concentrations of scopolamine in all organs examined, whereasD. metelaccumulated the lowest scopolamine levels. Hyoscyamine, measured as atropine, was the highest inD. stramoniumvar.tatula, and the lowest inD. innoxia. Samples collected in summer had higher scopolamine levels than autumn samples, concerning both stems and leaves.
Highlights
► We have developed a rapid LC-MS method for the quantitative determination of atropine and scopolamine. ► The method was successfully applied to quantify the alkaloids in different plant organs (leaves, flowers, stems, seeds) of thorn apples after a simple sample preparation step. ► Lower limits of quantitation are 333 and 167 pg mL-1 for scopolamine and atropine, respectively, and the method shows very good repeatability. ► The analysis ofDaturaextracts revealed significant differences depending on the species, the organ and the sampling period.Determination of triazine herbicides in cereals using dynamic microwave-assisted extraction with solidification of floating organic drop followed by high-performance liquid chromatography
22 February 2012, 21:55:48
Publication year: 2012
Source: Journal of Chromatography A, Available online 21 February 2012
Hui Wang, Guijie Li, Yiqun Zhang, Haiyan Chen, Qi Zhao, ...
A simple and cost-effective method of dynamic microwave-assisted extraction (DMAE) combined with solidification of floating organic drop (SFO) was developed for determining the five triazine herbicides in cereals. The approach combines the advantages of DMAE and SFO technique, and up to 15 samples can be treated simultaneously in 16 min. Firstly, triazine herbicides were extracted with 1 mL of methanol containing 90 μL of 1-dodecanol and following with 10 mL of water under the action of microwave energy. After that, 1.5 g sodium chloride was added into the obtained extract, and the mixture was centrifuged and cooled. The 1-dodecanol drop which contained the target analytes was solidified and transferred for analysis by HPLC-UV. Limits of detection of the five triazines obtained were in the range of 1.1-1.5 ng g. Relative standard deviations of intra- and inter-day tests ranging from 5% to 7% were obtained. The method was successfully applied to the analysis of ten cereals and the recoveries of the triazines for the spiked samples were in the range of 80-102%. The proposed method is an alternative approach to the analysis of triazine herbicides in complex solid samples, being more rapid and simpler compared with the traditional extraction method.
Source: Journal of Chromatography A, Available online 21 February 2012
Hui Wang, Guijie Li, Yiqun Zhang, Haiyan Chen, Qi Zhao, ...
A simple and cost-effective method of dynamic microwave-assisted extraction (DMAE) combined with solidification of floating organic drop (SFO) was developed for determining the five triazine herbicides in cereals. The approach combines the advantages of DMAE and SFO technique, and up to 15 samples can be treated simultaneously in 16 min. Firstly, triazine herbicides were extracted with 1 mL of methanol containing 90 μL of 1-dodecanol and following with 10 mL of water under the action of microwave energy. After that, 1.5 g sodium chloride was added into the obtained extract, and the mixture was centrifuged and cooled. The 1-dodecanol drop which contained the target analytes was solidified and transferred for analysis by HPLC-UV. Limits of detection of the five triazines obtained were in the range of 1.1-1.5 ng g. Relative standard deviations of intra- and inter-day tests ranging from 5% to 7% were obtained. The method was successfully applied to the analysis of ten cereals and the recoveries of the triazines for the spiked samples were in the range of 80-102%. The proposed method is an alternative approach to the analysis of triazine herbicides in complex solid samples, being more rapid and simpler compared with the traditional extraction method.
Highlights
► Cereal samples were extracted by dynamic microwave-assisted extraction technology. ► Triazine herbicides in the extract were enriched by 90 μL of 1–dodecanol. ► Extraction and enrichment were completed in a single step. ► The solidified 1–dodecanol contained triazines was analyzed by HPLC–UV. ► Up to 15 samples can be treated simultaneously in 16 min.Liquid chromatography-flame ionisation detection using a nebuliser/spray chamber interface. Part 2. Comparison of functional group responses
22 February 2012, 21:55:48
Publication year: 2012
Source: Journal of Chromatography A, Available online 21 February 2012
Erepamowei Young, Roger M. Smith, Barry L. Sharp, Joanne R. Bone
The application of a LC-nebuliser/spray chamber interface-flame ionization detection has been demonstrated for the superheated water liquid chromatography of a wide range of aliphatic and aromatic analytes. The linearity and sensitivity of the response of volatile and involatile analytes have been compared. The response of the detector towards different analytes is similar to that in GC-FID and for volatile analytes was comparable to UV detection. However, the responses from involatile analytes, such as amino-acids and carbohydrates, was poor and often lower than for a refractive index detector.
Source: Journal of Chromatography A, Available online 21 February 2012
Erepamowei Young, Roger M. Smith, Barry L. Sharp, Joanne R. Bone
The application of a LC-nebuliser/spray chamber interface-flame ionization detection has been demonstrated for the superheated water liquid chromatography of a wide range of aliphatic and aromatic analytes. The linearity and sensitivity of the response of volatile and involatile analytes have been compared. The response of the detector towards different analytes is similar to that in GC-FID and for volatile analytes was comparable to UV detection. However, the responses from involatile analytes, such as amino-acids and carbohydrates, was poor and often lower than for a refractive index detector.
Highlights
► A LC-nebuliser/spray chamber interface-flame ionization detection for superheated water liquid chromatography ► responds to a wide range of aliphatic and aromatic analytes ► linearity and sensitivity of the response of volatile and involatile analytes compared ► response of detector compared to GC-FID ► compared to UV and RI detectorsErratum to “Processing nanoparticles with A4F-SAXS for toxicological studies: Iron oxide in cell-based assays” [J. Chromatogr. A 1218 (2011) 4160–4166]
22 February 2012, 21:55:48
Publication year: 2012
Source: Journal of Chromatography A, Available online 21 February 2012
Patrick Knappe, Linda Boehmert, Ralf Bienert, Silvana Kamutzki, Birgit Niemann, ...
Source: Journal of Chromatography A, Available online 21 February 2012
Patrick Knappe, Linda Boehmert, Ralf Bienert, Silvana Kamutzki, Birgit Niemann, ...
Predictions of comprehensive two-dimensional gas chromatography separations from isothermal data
20 February 2012, 22:49:46
Publication year: 2012
Source: Journal of Chromatography A, Available online 18 February 2012
Shukui Zhu, Sheng He, David R. Worton, Allen H. Goldstein
Two-dimensional retention times and peak widths in temperature programmed comprehensive two-dimensional gas chromatography were predicted using a theoretical model developed from experimental data obtained under isothermal conditions. A Matlab program was written to calculate the following parameters: dead time (tM), elution temperature (Te), retention time (tR), hold-up width (wM) and peak width (wR). The two-dimensional retention times of a sample mixture that contained n-alkanes and polyaromatic hydrocarbons (PAHs) were predicted and were observed to be in excellent agreement with experimentally determined values. The relative deviation between the model and the experimental data was less than 2 and 7% for the primary and secondary retention times, respectively. The relative deviation of peak width was less than 7 and 10% in the primary and secondary dimensions, respectively. The advantage of this model was its simplicity, informed entirely from experimental data, with no reliance on theoretical parameters. This prediction model would be useful for optimizing GC × GC separation conditions and for confirming compound identifications of components that are chromatographically resolved but that have nearly identical mass spectra.
Source: Journal of Chromatography A, Available online 18 February 2012
Shukui Zhu, Sheng He, David R. Worton, Allen H. Goldstein
Two-dimensional retention times and peak widths in temperature programmed comprehensive two-dimensional gas chromatography were predicted using a theoretical model developed from experimental data obtained under isothermal conditions. A Matlab program was written to calculate the following parameters: dead time (tM), elution temperature (Te), retention time (tR), hold-up width (wM) and peak width (wR). The two-dimensional retention times of a sample mixture that contained n-alkanes and polyaromatic hydrocarbons (PAHs) were predicted and were observed to be in excellent agreement with experimentally determined values. The relative deviation between the model and the experimental data was less than 2 and 7% for the primary and secondary retention times, respectively. The relative deviation of peak width was less than 7 and 10% in the primary and secondary dimensions, respectively. The advantage of this model was its simplicity, informed entirely from experimental data, with no reliance on theoretical parameters. This prediction model would be useful for optimizing GC × GC separation conditions and for confirming compound identifications of components that are chromatographically resolved but that have nearly identical mass spectra.
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