S. Podszun, P. Vulto, H. Heinz, S. Hakenberg, C. Hermann, T. Hankemeier, G.A. Urban
Macro- to micro-volume concentration of viable bacteria is performed in a microfluidic chip. The enrichment principle is based on free flow electrophoresis and is demonstrated for Gram positive bacteria. Bacteria from a suspension flow are trapped on a gel interface that separates the trapping location from integrated actuation electrodes in order to enable non-destructive trapping. The microfluidic chip contains integrated electrolytic gas expulsion structures and phaseguides for gel and liquid handling.
K.G.H. Janssen, J.J. Li, H.T. Hoang, P. Vulto, R. van den Berg, H.S. Overkleeft, J.C.T. Eijkel, N.R. Tas, H.J. van der Linden, T. Hankemeier
The feasibility of isotachophoresis in channels of sub micrometer and nanometer dimension is investigated. A sample injection volume of 0.4 pL is focused and separated in a 330 nm deep channel. The sample consists of a biomatrix containing the fluorescently-labeled amino acids glutamate and phenylalanine, 20 attomoles of each. Isotachophoretic focusing is successfully demonstrated in a 50 nm deep channel. Separation of the two amino acids in the 50 nm deep channel however, could not be performed as the maximum applicable voltage was insufficient.
C. Zhu, A. Dane, G. Spijksma, M. Wang, J. van der Greef, G.A. Luo, T. Hankemeier, R.J. Vreeken
A hydrophilic interaction liquid chromatography (HILIC) - ion trap mass spectrometry method was developed for separation of a wide range of phospholipids. A diol column which is often used with normal phase chromatography was adapted to separate different phospholipid classes in HILIC mode using a mobile phase system consisting of acetonitrile, water, ammonium formate and formic acid.
P.W. Lindenburg, F.W.A. Tempels, U.R. Tjaden, J. van der Greef, T. Hankemeier
Electroextraction (EE) takes place in a two-phase liquid-liquid system, consisting of an aqueous and an organic phase, where an applied electric field causes ions to be extracted from one phase into the other, to be concentrated close after the liquid-liquid interface. The extraction takes place in a wide-bore capillary that is connected to a 2-way 10-port switching valve, which serves to couple capillary EE (cEE) with LC-MS. In this set-up, volumes as high as 100 μL can be extracted, which is a ten times larger volume than has been reported, earlier.
P.W. Lindenburg, U.R. Tjaden, J. van der Greef, T. Hankemeier
In this work, we demonstrate the applicability of electroextraction (EE) to urine metabolites. To investigate which urine metabolite classes are susceptible to EE, off-line EE experiments were carried out with a prototype device, in which urine metabolites were electroextracted from ethyl acetate into water. The obtained extracts were examined with direct infusion MS and the results demonstrated that several compound classes could be extracted, amongst which amino acids and acylcarnitines.
J. Quist, P. Vulto, H.J. van der Linden, T. Hankemeier
We present a novel concept of filtering based on depletion zone isotachophoresis (dzITP). In the micro/nanofluidic filter, compounds are separated according to isotachophoretic principles and simultaneously released selectively along a nanochannel-induced depletion zone. Thus, a tunable low-pass ionic mobility filter is realized. We demonstrate quantitative control of the release of fluorescent compounds through the filter using current and voltage actuation. Two modes of operation are presented.
S. Krishnan, J.T. Vogels, L. Coulier, R.C. Bas, M.M.W.B. Hendriks, T. Hankemeier, U. Thissen
Setting appropriate bin sizes to aggregate hyphenated high-resolution mass spectrometry data, belonging to similar mass over charge (m/z) channels, is vital to metabolite quantification and further identification. In a high-resolution mass spectrometer when mass accuracy (ppm) varies as a function of molecular mass, which usually is the case while reading m/z from low to high values, it becomes a challenge to determine suitable bin sizes satisfying all m/z ranges.
F.M. van der Kloet, F.W. Tempels, N. Ismail, R. van der Heijden, P.T. Kasper, M. Rojas-Cherto, R. van Doorn, G. Spijksma, M. Koek, J. van der Greef, V.P. Mäkinen, C. Forsblom, H. Holthöfer, P.H. Groop, T. Reijmers, T. Hankemeier
Diabetic kidney disease (DKD) is a devastating complication that affects an estimated third of patients with type 1 diabetes mellitus (DM). There is no cure once the disease is diagnosed, but early treatment at a sub-clinical stage can prevent or at least halt the progression. DKD is clinically diagnosed as abnormally high urinary albumin excretion rate (AER). We hypothesize that subtle changes in the urine metabolome precede the clinically significant rise in AER. To test this, 52 type 1 diabetic patients were recruited by the FinnDiane study that had normal AER (normoalbuminuric).
The Netherlands Metabolomics Centre focusses on the development of metabolomics based technologies and instrumentation to address the current and future challenges in biology, biotechnology and biomedical research in order to improve personalised health and quality of life.