The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Tyge Greibrokk - One of the best experts on this subject based on the ideXlab platform.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Andersen, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:In the present work, isoelectric point (pl) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5-4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm x 0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 microm Mono P from Amersham Biosciences and 10 microm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of beta-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the beta-Lactoglobulins was investigated, e.g. a 100 microl sample of dilute beta-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Anderse, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:Abstract In the present work, isoelectric point (pI) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5–4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm ×0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 μm Mono P from Amersham Biosciences and 10 μm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of β-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the β-Lactoglobulins was investigated, e.g. a 100 μl sample of dilute β-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
Helena Cacote - One of the best experts on this subject based on the ideXlab platform.
-
detection and quantification of bovine ovine and caprine milk percentages in protected denomination of origin cheeses by reversed phase high performance liquid chromatography of beta Lactoglobulins
Journal of Chromatography A, 2003Co-Authors: Isabel M P L V O Ferreira, Helena CacoteAbstract:Abstract A method for detecting and quantifying bovine, ovine and caprine milk mixtures in milk and cheeses by means of reversed-phase high-performance liquid chromatography (RP-HPLC) of β-Lactoglobulins is described. Gradient elution was carried out with a flow rate of 0.5 ml/min and a temperature of 45 °C, using a mixture of two solvents: solvent A (0.1% TFA in water) and solvent B (0.09% TFA in 80% aqueous acetonitrile, v/v). The effluent was monitored at 215 nm. Under the conditions used different chromatographic patterns were obtained for bovine, ovine and caprine whey proteins. Each milk type presented different retention times for β-lactoglobulin peaks. Binary mixtures of bovine and ovine or bovine and caprine raw milks containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of bovine milk, as well as ovine and caprine milk mixtures containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of ovine milk were used for cheese making. Cheeses were prepared and ripened, according to traditional methods. Milk mixtures, fresh and ripened cheeses were analyzed. A linear relationship was established between log 10 of β-lactoglobulin peaks ratio (calculated as peak area values ratio) and log 10 of the relative percentage of bovine or ovine milk. The ratio between β-lactoglobulin peaks was not affected by the degree of ripening. Thus, enabling the quantification of milk type percentage, with a detection limit of 2%. This technique allowed quantification of milk species within the concentration range of 5–95%. The method was successfully applied for authenticity evaluation and quantitative determination of ovine and caprine milk percentages of commercial protected denomination of origin (PDO) cheeses.
-
Detection and quantification of bovine, ovine and caprine milk percentages in protected denomination of origin cheeses by reversed-phase high-performance liquid chromatography of beta-Lactoglobulins.
Journal of chromatography. A, 2003Co-Authors: Isabel M P L V O Ferreira, Helena CacoteAbstract:A method for detecting and quantifying bovine, ovine and caprine milk mixtures in milk and cheeses by means of reversed-phase high-performance liquid chromatography (RP-HPLC) of beta-Lactoglobulins is described. Gradient elution was carried out with a flow rate of 0.5 ml/min and a temperature of 45 degrees C, using a mixture of two solvents: solvent A (0.1% TFA in water) and solvent B (0.09% TFA in 80% aqueous acetonitrile, v/v). The effluent was monitored at 215 nm. Under the conditions used different chromatographic patterns were obtained for bovine, ovine and caprine whey proteins. Each milk type presented different retention times for beta-lactoglobulin peaks. Binary mixtures of bovine and ovine or bovine and caprine raw milks containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of bovine milk, as well as ovine and caprine milk mixtures containing 1, 2, 5, 10, 20, 30, 50, 75 and 95% (v/v) of ovine milk were used for cheese making. Cheeses were prepared and ripened, according to traditional methods. Milk mixtures, fresh and ripened cheeses were analyzed. A linear relationship was established between log 10 of beta-lactoglobulin peaks ratio (calculated as peak area values ratio) and log 10 of the relative percentage of bovine or ovine milk. The ratio between beta-lactoglobulin peaks was not affected by the degree of ripening. Thus, enabling the quantification of milk type percentage, with a detection limit of 2%. This technique allowed quantification of milk species within the concentration range of 5-95%. The method was successfully applied for authenticity evaluation and quantitative determination of ovine and caprine milk percentages of commercial protected denomination of origin (PDO) cheeses.
Milaim Pepaj - One of the best experts on this subject based on the ideXlab platform.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Andersen, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:In the present work, isoelectric point (pl) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5-4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm x 0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 microm Mono P from Amersham Biosciences and 10 microm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of beta-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the beta-Lactoglobulins was investigated, e.g. a 100 microl sample of dilute beta-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Anderse, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:Abstract In the present work, isoelectric point (pI) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5–4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm ×0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 μm Mono P from Amersham Biosciences and 10 μm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of β-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the β-Lactoglobulins was investigated, e.g. a 100 μl sample of dilute β-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
Roger Trones - One of the best experts on this subject based on the ideXlab platform.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Andersen, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:In the present work, isoelectric point (pl) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5-4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm x 0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 microm Mono P from Amersham Biosciences and 10 microm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of beta-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the beta-Lactoglobulins was investigated, e.g. a 100 microl sample of dilute beta-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Anderse, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:Abstract In the present work, isoelectric point (pI) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5–4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm ×0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 μm Mono P from Amersham Biosciences and 10 μm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of β-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the β-Lactoglobulins was investigated, e.g. a 100 μl sample of dilute β-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
Elsa Lundanes - One of the best experts on this subject based on the ideXlab platform.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Andersen, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:In the present work, isoelectric point (pl) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5-4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm x 0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 microm Mono P from Amersham Biosciences and 10 microm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of beta-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the beta-Lactoglobulins was investigated, e.g. a 100 microl sample of dilute beta-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
-
isoelectric point separation of proteins by capillary ph gradient ion exchange chromatography
Journal of Chromatography A, 2004Co-Authors: Thomas Anderse, Milaim Pepaj, Roger Trones, Elsa Lundanes, Tyge GreibrokkAbstract:Abstract In the present work, isoelectric point (pI) separation of proteins by pH-gradient ion-exchange chromatography (IEC) on packed capillary columns is demonstrated. The development of a miniaturized flow-through pH probe for reliable pH monitoring of the column effluent, which was an important technical challenge for adapting this technique to capillary dimensions, was solved by designing a low microliter per minute flow rate housing to a commercially available micro pH probe. Highly linear outlet pH-gradients within the pH range 8.5–4.0 were obtained when applying simple inexpensive buffers consisting solely of piperazine, N-methylpiperazine and imidazole on 10 cm ×0.32 mm i.d. fused silica capillaries packed with anion-exchange poly(styrene divinylbenzene)-based macroporous materials, i.e. 10 μm Mono P from Amersham Biosciences and 10 μm PL-SAX from PolymerLabs. Furthermore, when using a pH-gradient from 6.8 to 4.3, both columns were able to baseline separate the A and B genetic variants of β-lactoglobulin, which differ with two amino acid residues only, but the PL-SAX column provided almost a two-fold decrease in peak widths compared to the Mono P column. The influence of varying the buffer concentration, injection volume and column temperature on the peak widths and resolution of the β-Lactoglobulins was investigated, e.g. a 100 μl sample of dilute β-Lactoglobulins was injected directly on the column with practically no increase in peak width as compared to what obtained with conventional injection volumes. Finally, a pH-gradient from 6.8 to 4.3 was used to separate proteins in skimmed bovine milk on the PL-SAX column. The milk was simply diluted 1:10 (v/v) with water and filtrated before injection.
