Hanne Devle

A GC – magnetic sector MS method for identification and quantification of fatty acids in ewe milk by different acquisition modes

A general method for qualitative and quantitative determination of fatty acids (FAs) using GC-MS was developed and tested on ewe milk. A total number of 38 poly unsaturated FAs, monounsaturated FAs and saturated FAs, from C6:0 to C24:1, were used in a comparative study of scan, reconstructed ion chromatogram and SIM. Fatty acid methyl esters in standard solutions as well as in milk from ewe were analyzed by these techniques, using a sector instrument. Instrument precision, linearity, LOD and LOQ, as well as calibration behavior and response factors were investigated for each approach. The quantitative results obtained by each technique were compared. All techniques had values for LOD and LOQ in the ng/mL region.

Identification of Brominated Flame Retardants in Sediment and Soil by Cyclohexane Extraction and Gas Chromatography Mass Spectrometry

The accumulation of brominated fl ame retardants (BFRs) in the environment raises concern in light of observed detrimental effects on wildlife as well as on public health. We here present a recently modi fi ed method for the identi fi cation and quanti fi cation of the following selection of bromodiphenyl ether (BDE) fl ame retardants: BDE-17, -47, -66, -100, -153 and -183, in soil and sediments, using a new extraction procedure followed by gas chromatography mass spectrometry (GC-MS). Low- and high- resolution mass spectrometry (LRMS and HRMS, respectively) were compared and the latter was found to be superior with respect to both sensitivity and linear range. At LRMS mode the linear range was 3.8 – 19.2 ng/g dry weight (dw), while the use of HRMS more than doubled the linear range to 1.9 – 38.4 ng/g dry weight. Both methods were tested with regards to matrix associated effects on the limit of detection and quantitation. The use of HRMS yielded equal sensitivity for standards in solution and matrix. This was not the case when using LRMS. Here the limits of detection and quantitation were severely elevated by the matrix. Recoveries were comparable, but slightly higher at LRMS mode (77.0 – 121.9%) compared to HRMS (83.2 – 115.3%). The method described here is high throughput, low cost and will prove valuable in monitoring the levels of BFRs in the environment.

Identification and Quantification of Fatty Acids in T. viridissima, C. biguttulus, and C. brunneus by GC-MS

Fatty acid (FA) profiles of the species Tettigonia viridissima, Chorthippus biguttulus, and Chorthippus brunneus were determined and quantitated. Extracted lipids were derivatized into FA methyl esters (FAMEs) prior to analysis by GC-MS. A total of 37 different FAs were identified in T. viridissima, yielding a total FA content of 10.4 g/100 g of dry matter. The contents of saturated FAs, monounsaturated FAs, and polyunsaturated FAs were 31.1, 35.9, and 33.0%, respectively. Lipids from T. viridissima were also fractioned into neutral lipids, free fatty acids, and polar lipids by offline solid phase extraction. For C. brunneus and C. biguttulus, 33 FAs were identified, yielding a total FA content of 6.14 g/100 g of dry matter. SFAs, MUFAs, and PUFAs, respectively, constituted 32.7, 25.1, and 42.1% of the total FA content. The contents of MUFAs, PUFAs, n-3 FAs, and n-6 FAs of each species, and the n-6/n-3 ratio, were subsequently discussed.

Fatty Acid Profiles of Stipe and Blade from the Norwegian Brown Macroalgae Laminaria hyperborea with Special Reference to Acyl Glycerides, Polar Lipids, and Free Fatty Acids

A thorough analysis of the fatty acid profiles of stipe and blade from the kelp species Laminaria hyperborea is presented. Lipid extracts were fractionated into neutral lipids, free fatty acids, and polar lipids, prior to derivatization and GC-MS analysis. A total of 42 fatty acids were identified and quantified, including the n-3 fatty acids α-linolenic acid, stearidonic acid, and eicosapentaenoic acid. The fatty acid amounts are higher in blade than in stipe (7.42 mg/g dry weight and 2.57 mg/g dry weight, resp.). The highest amounts of n-3 fatty acids are found within the neutral lipid fractions with 590.6 ug/g dry weight and 100.9 ug/g dry weight for blade and stipe, respectively. The amounts of polyunsaturated fatty acids are 3.4 times higher in blade than stipe. The blade had the highest PUFA/SFA ratio compared to stipe (1.02 versus 0.76) and the lowest n-6/n-3 ratio (0.8 versus 3.5). This study highlights the compositional differences between the lipid fractions of stipe and blade from L. hyperborea. The amount of polyunsaturated fatty acids compared to saturated- and monounsaturated fatty acids is known to influence human health. In the pharmaceutical, food, and feed industries, this can be of importance for production of different health products.