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:
Determination of sulfonamides in food samples by membrane-protected micro-solid phase extraction coupled with high performance liquid chromatography
20 November 2011, 23:45:07
Publication year: 2011
Source: Journal of Chromatography A, Available online 19 November 2011
Jiangeng Huang, Juanjuan Liu, Cong Zhang, Jiaojiao Wei, Li Mei, ...
In the present study, a simple and sensitive extraction method based on polypropylene membrane-protected micro-solid phase extraction (MP-μ-SPE) has been developed for analysis of sulfonamides in food samples. Poly (methacrylic acid-ethylene glycol dimethacrylate) (p-MAA-EDMA) was synthesized using orthogonal array experimental design, optimized with three factors at four levels and evaluated on yield, hydrophobic and cation-exchange properties. The optimized p-MAA-EDMA was then employed as the sorbent in the MP-μ-SPE for extraction of sulfonamides from milk and chicken muscle samples, followed by high performance liquid chromatographic analysis with ultraviolet detection. Under optimized extraction conditions, good linearities (0.010-1.0 μg mLwith r>0.9900), low limits of detection (0.38-0.62 ng mL), and acceptable intra-day (2.7-13.7%) and inter-day (6.7-15.2%) relative standard deviations were obtained. It was demonstrated to be an effective approach to handle semi-solid/solid samples with good resistance to interference from “dirty” samples.
Source: Journal of Chromatography A, Available online 19 November 2011
Jiangeng Huang, Juanjuan Liu, Cong Zhang, Jiaojiao Wei, Li Mei, ...
In the present study, a simple and sensitive extraction method based on polypropylene membrane-protected micro-solid phase extraction (MP-μ-SPE) has been developed for analysis of sulfonamides in food samples. Poly (methacrylic acid-ethylene glycol dimethacrylate) (p-MAA-EDMA) was synthesized using orthogonal array experimental design, optimized with three factors at four levels and evaluated on yield, hydrophobic and cation-exchange properties. The optimized p-MAA-EDMA was then employed as the sorbent in the MP-μ-SPE for extraction of sulfonamides from milk and chicken muscle samples, followed by high performance liquid chromatographic analysis with ultraviolet detection. Under optimized extraction conditions, good linearities (0.010-1.0 μg mLwith r>0.9900), low limits of detection (0.38-0.62 ng mL), and acceptable intra-day (2.7-13.7%) and inter-day (6.7-15.2%) relative standard deviations were obtained. It was demonstrated to be an effective approach to handle semi-solid/solid samples with good resistance to interference from “dirty” samples.
Highlights
► MP-μ-SPE was developed for food analysis. ► Synthesis of P-MAA-EDMA was optimized using orthogonal array experimental design. ► The materials were evaluated by the yield, hydrophobic and ion-exchange properties. ► The optimized p-MAA-EDMA was used as the sorbent in MP-μ-SPE of sulfonamides. ► It was effective to handle semi-solid/solid samples with good resistance to matrix.COMBINED USE OF ISOPROPYLAMINE AND TRIFLUOROACETIC ACID IN METHANOL-CONTAINING MOBILE PHASES FOR CHIRAL SUPERCRITICAL FLUID CHROMATOGRAPHYs
20 November 2011, 23:45:07
Publication year: 2011
Source: Journal of Chromatography A, Available online 19 November 2011
Katrijn De Klerck, Debby Mangelings, David Clicq, Filip De Boever, Yvan Vander Heyden
In chiral supercritical fluid chromatography (SFC), mobile-phase additives are often used to improve enantioseparations and peak shapes. An acidic or basic additive is chosen, depending on the nature of the compound. This work highlights the simultaneous use of the acidic additive trifluoroacetic acid (TFA) and the basic additive isopropylamine (IPA) in supercritical fluid chromatography for enantioseparations. To evaluate the combination of TFA and IPA, 59 chiral pharmaceutical compounds were analyzed on four polysaccharide-based chiral stationary phases (CSPs):LuxCellulose-1, LuxCellulose-2, LuxCellulose-4 and LuxAmylose-2. The results show that an important increase in enantioselectivity of the chromatographic system can occur when combining trifluoroacetic acid and isopropylamine in the mobile phase (MP), compared to the individual use of these additives. However, the combination of isopropylamine and trifluoroacetic acid in a supercritical methanol-containing mobile phase can also lead to problems as a result of the formation of salt complexes between the two additives. Combining the additives trifluoroacetic acid and isopropylamine and taking the appropriate measures to avoid salt formation,i.e.reducing the additives’ concentrations, can lead to simpler chiral SFC screening conditions that display even broader enantioselectivity.
Source: Journal of Chromatography A, Available online 19 November 2011
Katrijn De Klerck, Debby Mangelings, David Clicq, Filip De Boever, Yvan Vander Heyden
In chiral supercritical fluid chromatography (SFC), mobile-phase additives are often used to improve enantioseparations and peak shapes. An acidic or basic additive is chosen, depending on the nature of the compound. This work highlights the simultaneous use of the acidic additive trifluoroacetic acid (TFA) and the basic additive isopropylamine (IPA) in supercritical fluid chromatography for enantioseparations. To evaluate the combination of TFA and IPA, 59 chiral pharmaceutical compounds were analyzed on four polysaccharide-based chiral stationary phases (CSPs):LuxCellulose-1, LuxCellulose-2, LuxCellulose-4 and LuxAmylose-2. The results show that an important increase in enantioselectivity of the chromatographic system can occur when combining trifluoroacetic acid and isopropylamine in the mobile phase (MP), compared to the individual use of these additives. However, the combination of isopropylamine and trifluoroacetic acid in a supercritical methanol-containing mobile phase can also lead to problems as a result of the formation of salt complexes between the two additives. Combining the additives trifluoroacetic acid and isopropylamine and taking the appropriate measures to avoid salt formation,i.e.reducing the additives’ concentrations, can lead to simpler chiral SFC screening conditions that display even broader enantioselectivity.
Highlights
► Investigation of isopropylamine and trifluoroacetic acid as additives in SFC ► Additives combined together in methanol-based mobile phase for chiral screenings ► Broader enantioselectivity is achieved compared to individual use of the additives ► Formation of salt complexes between additives, their precipitation is problematic ► Lowering the concentration allows combined use of isopropylamine and trifluoroacetic acidEffect of varying flow regimes upon elution behaviour and apparent molecular characteristics and hydrodynamic properties of amylopectin isolated from normal corn starch using Asymmetrical Flow Field-Flow Fractionation
20 November 2011, 23:45:07
Publication year: 2011
Source: Journal of Chromatography A, Available online 19 November 2011
Shazia Juna, Anton Huber
A detailed study of the elution behaviour, apparent molecular characteristics and hydrodynamic properties of amylopectin-type fraction (isolated from normal corn starch) in aqueous media employing asymmetrical flow field-flow fractionation (AF4) was undertaken by systematically varying the channel flow (Fch), cross flow (Fcr) and Fcr/Fchratios. Distributions of apparent molar masses and radii of gyration, mass recoveries and hydrodynamic radii decreased as a function of increasing Fcrat a fixed Fch, due to the increase in the retention of amylopectin-type fraction in the AF4 channel. Increased retention of the amylopectin-type fraction in the AF4 channel was also observed at low Fchand high Fcr/Fchratios. Large amylopectin-type molecules/particles (possibly aggregates) eluted at high Fch, low Fcrand low Fcr/Fchratios.
Source: Journal of Chromatography A, Available online 19 November 2011
Shazia Juna, Anton Huber
A detailed study of the elution behaviour, apparent molecular characteristics and hydrodynamic properties of amylopectin-type fraction (isolated from normal corn starch) in aqueous media employing asymmetrical flow field-flow fractionation (AF4) was undertaken by systematically varying the channel flow (Fch), cross flow (Fcr) and Fcr/Fchratios. Distributions of apparent molar masses and radii of gyration, mass recoveries and hydrodynamic radii decreased as a function of increasing Fcrat a fixed Fch, due to the increase in the retention of amylopectin-type fraction in the AF4 channel. Increased retention of the amylopectin-type fraction in the AF4 channel was also observed at low Fchand high Fcr/Fchratios. Large amylopectin-type molecules/particles (possibly aggregates) eluted at high Fch, low Fcrand low Fcr/Fchratios.
Highlights
► Elution behaviour of amylopectin (normal corn) using AF4. ► Influence of cross flow rates upon retention of amylopectin ► Effect of flow rates on the aggregation and hydrodynamic properties of amylopectinUltra-preconcentration and determination of thirteen organophosphorus pesticides in water samples using solid-phase extraction followed by dispersive liquid-liquid microextraction and gas chromatography with flame photometric detection
20 November 2011, 23:45:07
Publication year: 2011
Source: Journal of Chromatography A, Available online 19 November 2011
Soheila Samadi, Hassan Sereshti, Yaghoub Assadi
An ultra-preconcentration technique composed of solid-phase extraction (SPE)anddispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-flame photometric detection (GC-FPD) was used for determination of thirteen organophosphorus pesticides(OPPs) includingphorate, diazinon, disolfotane, methyl parathion, sumithion, chloropyrifos, malathion, fenthion, profenphose, ethion, phosalone, azinphose-methyl and co-ral in aqueous samples. The analytes were collected from large volumes of aqueous solutions (100 mL) into 100 mg of a SPE C18sorbent.. The effective variables of SPE including type and volume of elution solvent, volume and flow rate of sample solution, and salt concentration were investigated and optimized.Acetone was selected as eluent in SPE and disperser solvent in DLLME and chlorobenzene was used as extraction solvent. Under the optimal conditions, the enrichment factors were between 15160-21000 and extraction recoveries were 75.8 to 105.0%. The linear range was 1-10000 ngLand limits of detection(LODs) were between 0.2 and 1.5 ngL. The relative standard deviations (RSDs) for 50 ngLof OPPs in water with and without an internal standard, were in the range of 1.4-7.9% (n = 5) and 4.0-11.6%, respectively. The relative recoveries of OPPs from well and farm watersat spiking levels of 25 and 250 ngLwere 88-109%.
Source: Journal of Chromatography A, Available online 19 November 2011
Soheila Samadi, Hassan Sereshti, Yaghoub Assadi
An ultra-preconcentration technique composed of solid-phase extraction (SPE)anddispersive liquid-liquid microextraction (DLLME) coupled with gas chromatography-flame photometric detection (GC-FPD) was used for determination of thirteen organophosphorus pesticides(OPPs) includingphorate, diazinon, disolfotane, methyl parathion, sumithion, chloropyrifos, malathion, fenthion, profenphose, ethion, phosalone, azinphose-methyl and co-ral in aqueous samples. The analytes were collected from large volumes of aqueous solutions (100 mL) into 100 mg of a SPE C18sorbent.. The effective variables of SPE including type and volume of elution solvent, volume and flow rate of sample solution, and salt concentration were investigated and optimized.Acetone was selected as eluent in SPE and disperser solvent in DLLME and chlorobenzene was used as extraction solvent. Under the optimal conditions, the enrichment factors were between 15160-21000 and extraction recoveries were 75.8 to 105.0%. The linear range was 1-10000 ngLand limits of detection(LODs) were between 0.2 and 1.5 ngL. The relative standard deviations (RSDs) for 50 ngLof OPPs in water with and without an internal standard, were in the range of 1.4-7.9% (n = 5) and 4.0-11.6%, respectively. The relative recoveries of OPPs from well and farm watersat spiking levels of 25 and 250 ngLwere 88-109%.
Highlights
► We introduced SPE-DLLME-GC-FPD for determination of OPPs in water samples. ► The method's advantages are high EF, low LOD, wide LDR and short analysis time. ► It offers ultra preconcentration factor and excellent performance in complex matrices.Purification of Coomassie Brilliant Blue G-250 by Multiple Dual Mode Countercurrent Chromatography
20 November 2011, 23:45:07
Publication year: 2011
Source: Journal of Chromatography A, Available online 19 November 2011
Nazim Mekaoui, Joseph Chamieh, Vincent Dugas, Claire Demesmay, Alain Berthod
Commercial samples of Coomassie Brilliant Blue G 250 (CBB) were not pure enough to give reliable results when used as indicator of amine content in biological material. The polar and apolar impurities produce unacceptable biases in the results. Counter current chromatography (CCC) was used to purify significant amounts of CBB. The liquid system heptane/1-butanol/water 2:3:4 v/v was appropriate to separate crude CBB in three groups of components: polar, partitioning in the aqueous lower phase, intermediate, partitioning well between the aqueous and organic phases, and apolar, preferring greatly the organic phase. The dual-mode way of using a CCC chromatograph was found appropriate for the separation injecting the crude CBB in the middle of a two coil CCC instrument. A multi dual-mode purification was performed allowing to eliminate the polar impurities in the aqueous phase at the column tail and the apolar ones in the organic phase at the column head, trapping the purified dye inside the CCC column. 200 mg of purified CBB were obtained from 1 g of crude CBB in 3 hours using as little as 150 mL of butanol and 70 mL of heptane with 200 mL of water. The purified CBB gave total satisfaction in testing amine content in polyclonal antibody containing monolith pipettes.
Source: Journal of Chromatography A, Available online 19 November 2011
Nazim Mekaoui, Joseph Chamieh, Vincent Dugas, Claire Demesmay, Alain Berthod
Commercial samples of Coomassie Brilliant Blue G 250 (CBB) were not pure enough to give reliable results when used as indicator of amine content in biological material. The polar and apolar impurities produce unacceptable biases in the results. Counter current chromatography (CCC) was used to purify significant amounts of CBB. The liquid system heptane/1-butanol/water 2:3:4 v/v was appropriate to separate crude CBB in three groups of components: polar, partitioning in the aqueous lower phase, intermediate, partitioning well between the aqueous and organic phases, and apolar, preferring greatly the organic phase. The dual-mode way of using a CCC chromatograph was found appropriate for the separation injecting the crude CBB in the middle of a two coil CCC instrument. A multi dual-mode purification was performed allowing to eliminate the polar impurities in the aqueous phase at the column tail and the apolar ones in the organic phase at the column head, trapping the purified dye inside the CCC column. 200 mg of purified CBB were obtained from 1 g of crude CBB in 3 hours using as little as 150 mL of butanol and 70 mL of heptane with 200 mL of water. The purified CBB gave total satisfaction in testing amine content in polyclonal antibody containing monolith pipettes.
No comments:
Post a Comment