Research Institute for Chromatography RIC

Kortrijk, Belgium

Research Institute for Chromatography RIC

Kortrijk, Belgium
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Verstraeten M.,Vrije Universiteit Brussel | Broeckhoven K.,Vrije Universiteit Brussel | Lynen F.,Ghent University | Choikhet K.,Hewlett - Packard | And 5 more authors.
Journal of Chromatography A | Year: 2012

This contribution discusses the difference in chromatographic performance when switching from the customary employed constant flow rate gradient elution mode to the recently re-introduced constant pressure gradient elution mode. In this mode, the inlet pressure is maintained at a set value even when the mobile phase viscosity becomes lower than the maximum mobile phase viscosity encountered during the gradient program. This leads to a higher average flow rate compared to the constant flow rate mode and results in a shorter analysis time. When both modes carry out the same mobile phase gradient program in volumetric units, normally identical selectivities are obtained. However, small deviations in selectivity are found due to the differences in pressure and viscous heating effects. These selectivity differences are of the same type as those observed when switching from HPLC to UHPLC and are inevitable when speeding up the analysis by applying a higher pressure. It was also found that, when using concentration-sensitive detectors, the constant pressure elution mode leads to identical peak areas as the constant flow rate mode. Also the linearity is maintained. In addition, the repeatability of the peak area and retention time remains the same when switching between both elution modes. © 2011 Elsevier B.V.

Gansbeke W.V.,Ghent University | Polet M.,Ghent University | Hooghe F.,Ghent University | Devos C.,Research Institute for Chromatography RIC | Eenoo P.V.,Ghent University
Journal of Chromatography B: Analytical Technologies in the Biomedical and Life Sciences | Year: 2015

In 2013, the World Anti-Doping Agency (WADA) drastically lowered the minimum required performance levels (MRPLs) of most doping substances, demanding a substantial increase in sensitivity of the existing methods. For a number of compounds, conventional electron impact ionization gas chromatography tandem mass spectrometry (GC-EI-MS/MS) is often no longer sufficient to reach these MRPLs and new strategies are required. In this study, the capabilities of positive ion chemical ionization (PICI) GC-MS/MS are investigated for a wide range of drug related compounds of various classes by injection of silylated reference standards. Ammonia as PICI reagent gas had superior characteristics for GC-MS/MS purposes than methane. Compared to GC-EI-MS/MS, PICI (with ammonia as reagent gas) provided more selective ion transitions and consequently, increased sensitivity by an average factor of 50. The maximum increase (by factor of 500-1000) was observed in the analysis of stimulants, namely chlorprenaline, furfenorex and phentermine. In total, improved sensitivity was obtained for 113 out of 120 compounds. A new GC-PICI-MS/MS method has been developed and evaluated for the detection of a wide variety of exogenous doping substances and the quantification of endogenous steroids in urine in compliance with the required MRPLs established by WADA in 2013. The method consists of a hydrolysis and extraction step, followed by derivatization and subsequent 1μL pulsed splitless injection on GC-PICI-MS/MS (16min run). The increased sensitivity allows the set up of a balanced screening method that meets the requirements for both quantitative and qualitative compounds: sufficient capacity and resolution in combination with high sensitivity and short analysis time. This resulted in calibration curves with a wide linear range (e.g., 48-9600ng/mL for androsterone and etiochanolone; all r20.99) without compromising the requirements for the qualitative compounds. © 2015 Elsevier B.V.

De Vrieze M.,Ghent University | Lynen F.,Ghent University | Chen K.,Ghent University | Szucs R.,Pfizer | And 2 more authors.
Analytical and Bioanalytical Chemistry | Year: 2013

Several in vitro methods have been tested for their ability to predict drug penetration across the blood-brain barrier (BBB) into the central nervous system (CNS). In this article, the performance of a variety of micellar liquid chromatographic (MLC) methods and immobilized artificial membrane (IAM) liquid chromatographic approaches were compared for a set of 45 solutes. MLC measurements were performed on a C18 column with sodium dodecyl sulfate (SDS), polyoxyethylene (23) lauryl ether (Brij35), or sodium deoxycholate (SDC) as surfactant in the micellar mobile phase. IAM liquid chromatography measurements were performed with Dulbecco's phosphate-buffered saline (DPBS) and methanol as organic modifier in the mobile phase. The corresponding retention and computed descriptor data for each solute were used for construction of models to predict transport across the blood-brain barrier (log BB). All data were correlated with experimental log BB values and the relative performance of the models was studied. SDS-based models proved most suitable for prediction of log BB values, followed closely by a simplified IAM method, in which it could be observed that extrapolation of retention data to 0 % modifier in the mobile phase was unnecessary. © 2013 Springer-Verlag Berlin Heidelberg.

David F.,Research Institute for Chromatography RIC | Tienpont B.,Research Institute for Chromatography RIC | Devos C.,Research Institute for Chromatography RIC | Lerch O.,GERSTEL GmbH and Co. KG | Sandra P.,Research Institute for Chromatography RIC
Journal of Chromatography A | Year: 2013

Laboratories focusing on residue analysis in food are continuously seeking to increase sample throughput by minimizing sample preparation. Generic sample extraction methods such as QuEChERS lack selectivity and consequently extracts are not free from non-volatile material that contaminates the analytical system. Co-extracted matrix constituents interfere with target analytes, even if highly sensitive and selective GC-MS/MS is used. A number of GC approaches are described that can be used to increase laboratory productivity. These techniques include automated inlet liner exchange and column backflushing for preservation of the performance of the analytical system and heart-cutting two-dimensional GC for increasing sensitivity and selectivity. The application of these tools is illustrated by the analysis of pesticides in vegetables and fruits, PCBs in milk powder and coplanar PCBs in fish. It is demonstrated that considerable increase in productivity can be achieved by decreasing instrument down-time, while analytical performance is equal or better compared to conventional trace contaminant analysis. © 2013 Elsevier B.V.

PubMed | Japan Tobacco Inc. and Research Institute for Chromatography RIC
Type: | Journal: Journal of chromatography. A | Year: 2016

Detailed lipidomics experiments were performed on the extracts of cured tobacco leaf and of cigarette smoke condensate (CSC) using high-resolution liquid chromatography coupled to quadrupole time-of-flight mass spectrometry (LC-Q-TOF MS). Following automated solid-phase extraction (SPE) fractionation of the lipid extracts, over 350 lipids could be annotated. From a large-scale study on 22 different leaf samples, it was determined that differentiation based on curing type was possible for both the tobacco leaf and the CSC extracts. Lipids responsible for the classification were identified and the findings were correlated to proteomics data acquired from the same tobacco leaf samples. Prediction models were constructed based on the lipid profiles observed in the 22 leaf samples and successfully allowed for curing type classification of new tobacco leaves. A comparison of the leaf and CSC data provided insight into the lipidome changes that occur during the smoking process. It was determined that lipids which survive the smoking process retain the same curing type trends in both the tobacco leaf and CSC data.

Sandra K.,Metablys | Sandra K.,Research Institute for Chromatography RIC | Pereira A.D.S.,Research Institute for Chromatography RIC | Vanhoenacker G.,Research Institute for Chromatography RIC | And 3 more authors.
Journal of Chromatography A | Year: 2010

A lipidomics strategy, combining high resolution reversed-phase liquid chromatography (RPLC) with high resolution quadrupole time-of-flight mass spectrometry (QqTOF), is described. The method has carefully been assessed in both a qualitative and a quantitative fashion utilizing human blood plasma. The inherent low technical variability associated with the lipidomics method allows to measure 65% of the features with an intensity RSD value below 10%. Blood plasma lipid spike-in experiments demonstrate that relative concentration differences smaller than 25% can readily be revealed by means of a t-test. Utilizing an advanced identification strategy, it is shown that the detected features mainly originate from (lyso-)phospholipids, sphingolipids, mono-, di- and triacylglycerols and cholesterol esters. The high resolution offered by the up-front RPLC step further allows to discriminate various isomeric species associated with the different lipid classes. The added value of utilizing a Jetstream electrospray ionization (ESI) source over a regular ESI source in lipidomics is for the first time demonstrated. In addition, the application of ultra high performance LC (UHPLC) up to 1200. bar to extend the peak capacity or increase productivity is discussed. © 2010 Elsevier B.V.

Ochiai N.,GERSTEL K.K. | Sasamoto K.,GERSTEL K.K. | Ieda T.,GERSTEL K.K. | David F.,Research Institute for Chromatography RIC | Sandra P.,Research Institute for Chromatography RIC
Journal of Chromatography A | Year: 2013

As reproducible coating of stir bars with more polar phases was found to be very difficult, a supporting grid was used in the development of an ethyleneglycol-modified Silicone (EG Silicone) coated stir bar. This new polar coating showed good performance for the extraction of polar solutes, but long term use also showed degradation of the coating due to friction while stirring. In order to address the lower robustness of the EG Silicone stir bar which has a much softer coating compared to a conventional polydimethylsiloxane (PDMS) stir bar, a novel SBSE procedure termed multi-SBSE (mSBSE) was developed. mSBSE consists of the robust PDMS stir bar stirring at the bottom of the vial and the EG Silicone stir bar attached on the inner side wall of the vial (a magnetic clip is used for the set-up). After extraction, the two stir bars are placed in a single glass desorption liner and are simultaneously thermally desorbed. The desorbed compounds were analyzed by thermal desorption-gas chromatography-mass spectrometry (TD-GC-MS). Compared to conventional SBSE, mSBSE provides more uniform enrichment of a wide range of odor compounds in aqueous sample since both stir bars can complement each other, while eliminating the damage of the EG Silicone phase during the extraction. The robustness of the EG Silicone stir bar was dramatically increased and more than 30 extraction and desorption cycles were possible without loss in performance. The recoveries for polar solutes such as 2-acetyl pyrrole (logKow: 0.55), benzyl alcohol (logKow: 1.08), guaiacol (logKow: 1.34), and indole (logKow: 2.05) were increased by a factor of about 2-7. The mSBSE-TD-GC-MS method showed good linearity (r2>0.9913) and high sensitivity (limit of detection: 0.011-0.071ngmL-1) for the test compounds spiked in water. The feasibility and benefit of the method was demonstrated with analysis of odor compounds in roasted green tea. The normalized areas obtained from mSBSE showed the best enrichment for most of the selected compounds compared to conventional SBSE using the PDMS stir bar or the EG Silicone stir bar. Fifteen compounds were determined in the range of 0.15-210ngmL-1 (RSD<14%, n=6). © 2013 Elsevier B.V.

Sandra K.,Research Institute for Chromatography RIC | Vandenheede I.,Research Institute for Chromatography RIC | Sandra P.,Research Institute for Chromatography RIC
Journal of Chromatography A | Year: 2014

Protein biopharmaceuticals such as monoclonal antibodies and therapeutic proteins are currently in widespread use for the treatment of various life-threatening diseases including cancer, autoimmune disorders, diabetes and anemia. The complexity of protein therapeutics is far exceeding that of small molecule drugs; hence, unraveling this complexity represents an analytical challenge. The current review provides the reader with state-of-the-art chromatographic and mass spectrometric tools available to dissect primary and higher order structures, post-translational modifications, purity and impurity profiles and pharmacokinetic properties of protein therapeutics. © 2013 Elsevier B.V.

Devos C.,Research Institute for Chromatography RIC | David F.,Research Institute for Chromatography RIC | Sandra P.,Research Institute for Chromatography RIC
Journal of Chromatography A | Year: 2012

According to recent directives of the European Union (EU), limits of quantification (LOQ) for the determination of tributyltin (TBT) in surface waters should be ca. 60. pg/L (ppq). This put very stringent requirements on analytical methodologies; definitely when they have to be applied in a routine environment. Stir bar sorptive extraction (SBSE), followed by thermal desorption (TD) and capillary gas chromatography-triple quadrupole mass spectrometry (GC-MS/MS) can provide accurate and precise data at the 2. ng/L level (ppt). For lower concentrations, matrix and reagent interferences together with contamination may provide too high TBT values. A two-dimensional heart-cut GC method was developed to fractionate TBT from interferences. The GC-GC-MS/MS method shows excellent linearity in the range 50. pg/L-4. ng/L, good repeatability (RSD < 20% at 200. pg/L), and a limit of detection of 11. pg/L. The method performance is demonstrated with representative samples i.e. harbor water and waste water samples. © 2012 Elsevier B.V.

Devos C.,Research Institute for Chromatography RIC | Ochiai N.,Gerstel K.K. | Sasamoto K.,Gerstel K.K. | Sandra P.,Research Institute for Chromatography RIC | David F.,Research Institute for Chromatography RIC
Journal of Chromatography A | Year: 2012

Suspected fragrance allergens were determined in cosmetic products using a combination of full evaporation-dynamic headspace (FEDHS) with selectable one-dimensional/two-dimensional GC-MS. The full evaporation dynamic headspace approach allows the non-discriminating extraction and injection of both apolar and polar fragrance compounds, without contamination of the analytical system by high molecular weight non-volatile matrix compounds. The method can be applied to all classes of cosmetic samples, including water containing matrices such as shower gels or body creams. In combination with selectable 1D/2D GC-MS, consisting of a dedicated heart-cutting GC-MS configuration using capillary flow technology (CFT) and low thermal mass GC (LTM-GC), a highly flexible and easy-to-use analytical solution is offered. Depending on the complexity of the perfume fraction, analyses can be performed in one-dimensional GC-MS mode or in heart-cutting two-dimensional GC-MS mode, without the need of hardware reconfiguration. The two-dimensional mode with independent temperature control of the first and second dimension column is especially useful to confirm the presence of detected allergen compounds when mass spectral deconvolution is not possible. © 2012 Elsevier B.V.

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