Renewable Resources Robert-Jan van Putten,†,‡ Jan C. van der Waal,† Ed de Jong,*,† Carolus B. Rasrendra,‡,⊥ Hero J. Heeres,*,‡ and Johannes G. de Vries* †Avantium Chemicals, Zekeringstraat 29, 1014 BV Amsterdam, the Netherlands ‡Department of Chemical Engineering, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands DSM Innovative Synthesis BV, P.O. Box 18, 6160 MD Geleen, the Netherlands Department of Chemical Engineering, Institut Teknologi Bandung, Ganesha 10, Bandung 40132, Indonesia

Hydroxymethylfurfural, A Versatile Platform Chemical Made from Renewable Resources

5-Hydroxymethylfurfural (HMF) as a building block platform: Biological properties, synthesis and synthetic applications

Some Typical Advances in the Synthetic Applications of Allenes

Separation of polar compounds on polar stationary phases with partly aqueous eluents is by no means a new separation mode in LC. The first HPLC applications were published more than 30 years ago, and were for a long time mostly confined to carbohydrate analysis. In the early 1990s new phases started to emerge, and the practice was given a name, hydrophilic interaction chromatography (HILIC). Although the use of this separation mode has been relatively limited, we have seen a sudden increase in popularity over the last few years, promoted by the need to analyze polar compounds in increasingly complex mixtures. Another reason for the increase in popularity is the widespread use of MS coupled to LC. The partly aqueous eluents high in ACN with a limited need of adding salt is almost ideal for ESI. The applications now encompass most categories of polar compounds, charged as well as uncharged, although HILIC is particularly well suited for solutes lacking charge where coulombic interactions cannot be used to mediate retention. The review attempts to summarize the ongoing discussion on the separation mechanism and gives an overview of the stationary phases used and the applications addressed with this separation mode in LC.

Hydrophilic interaction chromatography.

Hydrophilic interaction liquid chromatography (HILIC) provides an alternative approach to effectively separate small polar compounds on polar stationary phases. The purpose of this work was to review the options for the characterization of HILIC stationary phases and their applications for separations of polar compounds in complex matrices. The characteristics of the hydrophilic stationary phase may affect and in some cases limit the choices of mobile phase composition, ion strength or buffer pH value available, since mechanisms other than hydrophilic partitioning could potentially occur. Enhancing our understanding of retention behavior in HILIC increases the scope of possible applications of liquid chromatography. One interesting option may also be to use HILIC in orthogonal and/or two-dimensional separations. Bioapplications of HILIC systems are also presented.

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Hydrophilic interaction liquid chromatography (HILIC)—a powerful separation technique

Determination of polyethylene glycol in low-density polyethylene by large volume injection temperature gradient packed capillary liquid chromatography.

Problems occurring during operation of a 2-D LC-MS system for separation and identification of neuropeptides, such as contamination of the used salts and column bleed, are described. When using polysulfoethyl aspartamide, which is widely used as a strong cation exchange stationary phase in the first dimension, interfering peaks were observed in the second-dimension reversed-phase chromatograms. The observed peaks, found to be caused by column bleeding, had abundance above the threshold value and influenced the quality of the analyses. The origin of the peaks was verified and appropriate measures are proposed. Additionally, peaks caused by polyethylene glycols (PEGs), covering approximately 5 min of feasible chromatographic time in every fraction, were observed. The commercial ammonium formate salts used to prepare the first-dimension mobile phase were found to contain PEG impurities, and in subsequent work the salt solutions were prepared from formic acid and ammonia to avoid any additional contaminations.

Determination and removal of impurities in 2-D LC-MS of peptides.

Molecular imprinting in Separation Science

A reliable, sensitive, and robust two-valve column-switching temperature-programmed packed capillary liquid chromatography method with on-column ultraviolet detection has been developed and validated for the simultaneous determination of 2,4-toluene-diisocyanate, 2,6-toluene-diisocyanate, hexamethylene-diisocyanate, and 4,4-methylene-bisphenyl-diisocyanate in workroom air, based on an established 1-(2-methoxyphenyl)-piperazine derivatization filter sampling method. The isocyanate derivatives were enriched on a 0.32×30 mm 5 μm Inertsil C8 pre-column using a non-eluting solvent composition of acetonitrile-10 mM ammonium formate (pH 4.0) (4 : 96, v/v) at a flow rate of 50 μL/min, prior to back-flushing on a 0.32 × 250 mm 3-μm Hypersil ODS column, using a mobile phase composition of acetonitrile-10 mM ammonium formate (pH 6.0) (40 : 60, v/v) at a flow rate of 5 μL/min. Injection volumes up to 1.0 mL were loaded onto the pre-column. An initial temperature of 80°C provided beneficial selectivity effects as compared to ambient temperature, providing baseline separation of the 2,6-toluene-diisocyanate and hexamethylene-diisocyanate derivatives. Temperature programming from 80 to 95°C provided efficient elution of late eluting 4,4-methylene-bisphenyl-diisocyanate. The method was validated using spiked filters with 5 to 250 ng of the 2,4-toluene-diisocyanate derivative, yielding a coefficient of correlation of 0.997 when using an injection volume of 1.0 mL. The within-assay (n = 4) and between-assay (n = 4) precisions were in the range 2.7–29.0 and 2.0–18.0%, respectively, and the within- and between-assay recoveries of the isocyanate derivatives were 92.3–97.8 and 95.4–96.7% for all concentrations except for the lowest level. The mass limit of detection of the isocyanate derivatives for the LC method was in the range 0.12–0.25 ng, corresponding to a concentration limit of detection of 12–23 ng/m3 total isocyanate groups in air using a 15-L air sampling volume, with 20% sample exploitation, 100% sampling efficiency, and 50% recovery at low concentrations.

Determination of 1‐(2‐methoxyphenyl)‐piperazine derivatives of airborne diisocyanates by packed capillary liquid chromatography with pre‐column large‐volume enrichment

Tyge Greibrokk

Papers

Determination of polyethylene glycol in low-density polyethylene by large volume injection temperature gradient packed capillary liquid chromatography.

Determination and removal of impurities in 2-D LC-MS of peptides.

Molecular imprinting in Separation Science

Determination of 1‐(2‐methoxyphenyl)‐piperazine derivatives of airborne diisocyanates by packed capillary liquid chromatography with pre‐column large‐volume enrichment

Characterization of polymer additives by supercritical fluid chromatography and by liquid chromatography