Stockholm university
Denna sida på svenska

Jan Holmbäck

About me

We are studying lipids from their different appearances in biological systems, e.g. barrier lipids, storage lipids and membrane lipids. The basic methods for characterization of lipids are based on chromatography, both HPLC (intact lipids) and GC (fatty acids), and there is a need to improve chromatographic separation performance as well as the detection techniques (ELSD, CAD and MS). NMR is also an important tool for characterization of lipids. Different techniques to assess oxidation of lipid products are also developed.

 

On-going projects

  • Investigation of the potential of using porous graphitized carbon (PGC) as stationary phase for lipid class and molecular species analysis.
  • Profiling of phospholipid materials during storage at different conditions using chromatographic and spectroscopic techniques.
  • Multivariate characterization and identification of surface extracts and total extracts from plant leaves by NMR spectroscopy.
  • Optimization of analytical procedures involved in the fatty acid composition analysis of complex biological matrices.

Publications

A selection from Stockholm University publication database

  • Sorptive Capacities of Nonpolymeric Plant Lipids for Hydrophobic Chemicals Determined by Passive Dosing

    2019. Damien Johann Bolinius (et al.). Environmental Science and Technology 53 (3), 1278-1286

    Article

    Vegetation plays an important role in the partitioning, transport, and fate of semivolatile hydrophobic organic chemicals (HOCs) in the environment. Leaf/air partition ratios (K-leaf/air) of HOCs are highly variable for different plant species. The differences cannot be fully explained by the fraction of lipids in the leaves or the thickness of the cuticle. Our goal was to elucidate the importance of non polymeric lipids in determining K-leaf/air To do this, we extracted organic matter from 7 plant species using solvents that do not extract the polymeric lipids cutin and cutan, to yield extractable organic matter (EOM). We used passive dosing to determine the partition ratios of selected HOCs between the EOM of the leaves and our reference lipid, olive oil (K-EOM/olive oil) In addition, we measured analogous partition ratios for three lipid standards. Proton nuclear magnetic resonance (NMR) spectroscopy was used to characterize the composition of lipids. Differences in K-EOM/olive oil of two polychlorinated biphenyls and four chlorinated benzenes were below a factor of 2 in the plant species studied, indicating that the reported differences in K-leaf/air are not caused by differences in the sorptive capacities of nonpolymeric lipids or that our EOM is not representative of all nonpolymeric leaf lipids.

    Read more about Sorptive Capacities of Nonpolymeric Plant Lipids for Hydrophobic Chemicals Determined by Passive Dosing

  • Chemicals from textiles to skin

    2018. Francesco Iadaresta (et al.). Environmental science and pollution research international 25 (25), 24629-24638

    Article

    Despite the possible impact on human health, few studies have been conducted to assess the penetration and accumulation of contaminants in the skin after a prolonged contact with textile materials. In previous studies, we have shown that benzothiazole and its derivatives, as well as other potentially hazardous chemicals, often are present as textile contaminants in clothes available on the retail market. Since benzothiazole is a common contaminant in clothes, these can be a possible route for human chemical exposure, both systemic and onto the skin. To investigate this potential exposure, Franz-type and flow-through cells were used for the permeation studies together with a Strat-MA (R) artificial membranes. Experiments were performed using solutions of benzothiazole, as well as contaminated textile samples in the donor chamber. Benzothiazole was demonstrated to penetrate through, as well as being accumulated in the membrane mimicking the skin. After 24 h, up to 62% of benzothiazole was found in the acceptor cell, while up to 37% was found absorbed in the skin mimicking membrane. It also was shown that there was release and permeation from contaminated fabrics. The results indicate that benzothiazole can be released from textile materials, penetrate through the skin, and further enter the human body. This will possibly also apply to other chemical contaminants in textiles, and the results of this study indicate that the presence of these textile contaminants entails potential health risks. A rough risk assessment was made for clothing textiles according to Environmental Protection Agency (EPA) and European regulations for carcinogenic and non-carcinogenic compounds, using literature data for benzothiazole.

    Read more about Chemicals from textiles to skin

  • Differences between Lipids Extracted from Five Species Are Not Sufficient To Explain Biomagnification of Nonpolar Organic Chemicals

    2015. Annika Jahnke (et al.). Environmental Science and Technology Letters 2 (7), 193-197

    Article

    Lipids are the major sorptive phase for many organic chemicals that bioaccumulate in foodwebs. However, lipids are usually operationally defined by the extraction protocol. Large differences in sorptive capacities between species would violate assumptions implicit in widely used lipid-normalization procedures and invalidate generic bioaccumulation factors. We extracted lipids from five species from different trophic levels and domains and determined fractions of triglycerides, phospholipids, and cholesterol. We passively dosed the lipids with cyclic volatile methylsiloxanes and chlorobenzenes via headspace from spiked olive oil to determine their sorptive capacities. Lipids from seal blubber and pork bacon solely composed of triglycerides had capacities similar to that of olive oil; lipids from mussels, herring, and guillemot egg had quantifiable fractions of phospholipids and cholesterol and showed capacities reduced by factors of up to 2.3-fold. Generally, the sorptive capacities of the lipids were not elevated relative to the olive oil controls and are unlikely to explain a substantial part of biomagnification.

    Read more about Differences between Lipids Extracted from Five Species Are Not Sufficient To Explain Biomagnification of Nonpolar Organic Chemicals

  • A single step reversed-phase high performance liquid chromatography separation of polar and non-polar lipids

    2014. Petter Olsson, Jan Holmbäck, Bengt Herslöf. Journal of Chromatography A 1369, 105-115

    Article

    This paper reports a simple chromatographic system to separate lipids classes as well as their molecular species. By the use of phenyl coated silica as stationary phase in combination with a simple mobile phase consisting of methanol and water, all tested lipid classes elute within 30min. Furthermore, a method to accurately predict retention times of specific lipid components for this type of chromatography is presented. Common detection systems were used, namely evaporative light scattering detection (ELSD), charged aerosol detection (CAD), electrospray mass spectrometry (ESI-MS), and UV detection.

    Read more about A single step reversed-phase high performance liquid chromatography separation of polar and non-polar lipids

  • Class separation of lipids and polycyclic aromatic hydrocarbons in normal phase high performance liquid chromatography - A prospect for analysis of aromatics in edible vegetable oils and biodiesel exhaust particulates

    2014. Petter Olsson (et al.). Journal of Chromatography A 1360, 39-46

    Article

    The retention characteristics of the major lipid components in biodiesels and edible oils as well as representative polycyclic aromatic compounds (PAHs) have been investigated on five different normal phase HPLC stationary phases, in order to optimize class separation for an automatized online HPLC cleanup of PAHs prior GC-MS analysis. By stepwise comparison of different hexane/MTBE compositions as mobile phases on cyano-, phenyl-, pentabromobenzyl-, nitrophenyl- and amino- modified silica columns, the capacity and selectivity factors for each analyte and column could be calculated. It was concluded that the most suitable column for backflush isolation of PAHs in biodiesel and edible oil matrices was the pentabromobenzyl-modified silica (PBB). A previously described online HPLC-GC-MS system using the PBB column was then evaluated by qualitative and quantitative analysis of a biodiesel exhaust particulate extract and a vegetable oil reference material. The GC-MS full scan analysis of the biodiesel particulate extract showed that the lipids had been removed from the sample and a fraction containing PAHs and oxygenated derivatives thereof had been isolated. Quantified mass fractions of PAHs of the reference material BCR-458 agreed well for most of the certified PAH mass fractions in the spiked coconut oil reference material.

    Read more about Class separation of lipids and polycyclic aromatic hydrocarbons in normal phase high performance liquid chromatography - A prospect for analysis of aromatics in edible vegetable oils and biodiesel exhaust particulates

  • Separation And Identification Of Lipid Classes By Normal Phase Lc-Esi/Ms/Ms On A Cyanopropyl Column

    2014. Petter Olsson (et al.). European Journal of Lipid Science and Technology 116 (5), 653-658

    Article

    In order to establish a versatile and convenient method for the analysis of lipids, electrospray ionization tandem mass spectrometry (ESI-MS/MS) was applied to a HPLC separation on a cyanopropyl-bonded stationary phase. A binary gradient mobile phase system consisting of hexane, toluene, methanol and a stable electrospray yielding sodium adduct ions could be used to generate specific product ions in MS/MS mode. By applying the LC/ESI-MS/MS method on an egg yolk sample, 29 different molecular species of phosphatidylethanolamines, phosphatidylcholines, and lysophosphatidylcholines could be detected within 25 min.

    Read more about Separation And Identification Of Lipid Classes By Normal Phase Lc-Esi/Ms/Ms On A Cyanopropyl Column

  • Separation of Lipid Classes by HPLC on a Cyanopropyl Column

    2012. Petter Olsson, Jan Holmbäck, Bengt Herslöf. Lipids 47 (1), 93-99

    Article

    A new method for the separation and identification of lipid classes by normal-phase HPLC on a cyanopropyl column is described. The use of a simple binary gradient, with toluene as a component, provided a rapid separation of non-polar as well as phospholipid classes. The inherent small differences in performances between possible non-polar eluent components of the gradient, such as hexane, heptane, and iso-octane, had a pronounced impact on retention times for individual phospholipid classes. Separation of molecular species within a lipid class could also be observed.

    Read more about Separation of Lipid Classes by HPLC on a Cyanopropyl Column

Show all publications by Jan Holmbäck at Stockholm University

Edit the profile