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Selected papers from the latest issue:Multipesticide residue analysis in maize combining acetonitrile-based extraction with dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry
06 September 2011, 23:21:50
Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 6 September 2011
S.C., Cunha , J.O., Fernandes
A fast and simple gas chromatography-mass spectrometry (GC-MS) method for determination of forty-one pesticides residues in maize is introduced. The sample preparation involves liquid-liquid partitioning with acetonitrile in presence of anhydrous MgSO4 and NaCl (QuEChERS) followed by dispersive liquid-liquid microextraction (DLLME) using carbon tetrachloride as extractive solvent and the extract obtained by QuEChERS as dispersive solvent. The main factors influencing DLLME efficiency including extractive solvent type and volume as well as the volume of dispersive solvent were evaluated in this study. The DLLME procedure effectively provides an enrichment of the extract and a cleanup of certain polar matrix components, which...
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 6 September 2011
S.C., Cunha , J.O., Fernandes
A fast and simple gas chromatography-mass spectrometry (GC-MS) method for determination of forty-one pesticides residues in maize is introduced. The sample preparation involves liquid-liquid partitioning with acetonitrile in presence of anhydrous MgSO4 and NaCl (QuEChERS) followed by dispersive liquid-liquid microextraction (DLLME) using carbon tetrachloride as extractive solvent and the extract obtained by QuEChERS as dispersive solvent. The main factors influencing DLLME efficiency including extractive solvent type and volume as well as the volume of dispersive solvent were evaluated in this study. The DLLME procedure effectively provides an enrichment of the extract and a cleanup of certain polar matrix components, which...
SEC-Gradients, an alternative approach to polymer gradient chromatography: 2. Separation of Poly(meth)acrylates using a SEC-solvent/non-solvent gradient
06 September 2011, 23:21:50
Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 6 September 2011
Martin, Schollenberger , Wolfgang, Radke
A gradient ranging from methanol to tetrahydrofuran (THF) was applied to a series of poly(methyl methacrylate) (PMMA) standards, using the recently developed concept of SEC gradients. Contrasting to conventional gradients the samples eluted before the solvent, i.e. within the elution range typical for separations by SEC, however, the high molar mass PMMAs were retarded as compared to experiments on the same column using pure THF as the eluent. The molar mass dependence on retention volume showed a complex behaviour with a nearly molar mass independent elution for high molar masses. This molar mass dependence was explained in terms of solubility...
Highlights: ► The recently developed method of SEC-gradients was applied to the separation of poly(meth)acrylate blends. ► Separations of blends of PMMA and PtBA, respectively PMMA and PnBA were achieved in SEC gradients running from Methanol to THF ► The comparison of the eluent compositions at elution with cloud point measurements suggest that the separation is based on dissolution/precipitation.
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 6 September 2011
Martin, Schollenberger , Wolfgang, Radke
A gradient ranging from methanol to tetrahydrofuran (THF) was applied to a series of poly(methyl methacrylate) (PMMA) standards, using the recently developed concept of SEC gradients. Contrasting to conventional gradients the samples eluted before the solvent, i.e. within the elution range typical for separations by SEC, however, the high molar mass PMMAs were retarded as compared to experiments on the same column using pure THF as the eluent. The molar mass dependence on retention volume showed a complex behaviour with a nearly molar mass independent elution for high molar masses. This molar mass dependence was explained in terms of solubility...
Highlights: ► The recently developed method of SEC-gradients was applied to the separation of poly(meth)acrylate blends. ► Separations of blends of PMMA and PtBA, respectively PMMA and PnBA were achieved in SEC gradients running from Methanol to THF ► The comparison of the eluent compositions at elution with cloud point measurements suggest that the separation is based on dissolution/precipitation.
Rapid and simultaneous determination of hexa peptides (Ac-EEMQRR-amide and H2N-EEMQRR-amide) in anti-wrinkle cosmetics by hydrophilic interaction liquid chromatography - solid phase extraction preparation and hydrophilic interaction liquid chromatography with tandem mass spectrometry
06 September 2011, 23:21:50
Publication year: 2011
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 6 September 2011
Wanlong, Zhou , Perry G., Wang , Alexander J., Krynitsky , Jeanne I., Rader
A rapid method for the simultaneous determination of Ac-EEMQRR-amide and H2N-EEMQRR-amide in cosmetic products was developed and evaluated. This analytical procedure involved extracting samples with 0.1:0.1:85:15 (v:v) trifluoroacetic acid (TFA):formic acid:acetonitrile (ACN):water and determination by hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Samples showing serious ion suppression were further cleaned up using HILIC-SPE prior to HILIC-MS/MS analysis. Stable isotopically labeled peptides, corresponding to the above two peptides, were used as internal standards to correct for loss of recovery and matrix effects. Electrospray ionization (ESI) in the positive mode was used. The linear range was 2.0 - 1000ng/mL for...
Highlights: ► A rapid method for the simultaneous determination of Ac-EEMQRR-amide and H2N-EEMQRR-amide in cosmetic products ► Ac-EEMQRR-amide is an anti-aging/anti-wrinkle agent widely used in cosmetics. ► No methodology has previously been reported to quantitate these agents in cosmetic preparations and other products. ► This is the first paper using HILIC-SPE for preparation, analytical HILIC column for separation, and tandem mass spectrometry (MS/MS) with isotopically labeled internal standards for quantitation of peptides in cosmetic products. ► This method has been evaluated and successfully applied to several cosmetics products and may also be applicable for determination of peptides in other products.
Source: Journal of Chromatography A, In Press, Accepted Manuscript, Available online 6 September 2011
Wanlong, Zhou , Perry G., Wang , Alexander J., Krynitsky , Jeanne I., Rader
A rapid method for the simultaneous determination of Ac-EEMQRR-amide and H2N-EEMQRR-amide in cosmetic products was developed and evaluated. This analytical procedure involved extracting samples with 0.1:0.1:85:15 (v:v) trifluoroacetic acid (TFA):formic acid:acetonitrile (ACN):water and determination by hydrophilic interaction liquid chromatography with tandem mass spectrometry (HILIC-MS/MS). Samples showing serious ion suppression were further cleaned up using HILIC-SPE prior to HILIC-MS/MS analysis. Stable isotopically labeled peptides, corresponding to the above two peptides, were used as internal standards to correct for loss of recovery and matrix effects. Electrospray ionization (ESI) in the positive mode was used. The linear range was 2.0 - 1000ng/mL for...
Highlights: ► A rapid method for the simultaneous determination of Ac-EEMQRR-amide and H2N-EEMQRR-amide in cosmetic products ► Ac-EEMQRR-amide is an anti-aging/anti-wrinkle agent widely used in cosmetics. ► No methodology has previously been reported to quantitate these agents in cosmetic preparations and other products. ► This is the first paper using HILIC-SPE for preparation, analytical HILIC column for separation, and tandem mass spectrometry (MS/MS) with isotopically labeled internal standards for quantitation of peptides in cosmetic products. ► This method has been evaluated and successfully applied to several cosmetics products and may also be applicable for determination of peptides in other products.
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