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Träfflista för sökning "L773:1076 5174 OR L773:1096 9888 srt2:(1980-1984)"

Search: L773:1076 5174 OR L773:1096 9888 > (1980-1984)

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1.
  • Löfstedt, Christer, et al. (author)
  • Analysis of moth pheromone acetates by selected ion monitoring using electron impact and chemical ionization mass spectrometry
  • 1984
  • In: Biological Mass Spectrometry. - : Wiley. - 0306-042X .- 1096-9888. ; 11:3, s. 106-113
  • Journal article (peer-reviewed)abstract
    • Mass spectrometric determination of moth pheromone components by means of selected ion monitoring with electron impact and chemical ionization has been evaluated. For the analysis of acetates, chemical ionization with ammonia as reactant gas proved advantageous with respect to sensitivity and selectivity. A quantitative assay for determination of pheromone samples from individual turnip moth females (Agrotis segetum, Noctuidae), using internal standards, deuterated at the acyl group, was developed. The assay showed correct linearity in the investigated region (20–2000 pg). Signal to noise ratios for 100 pg of acetates using chemical ionization (ammonia as reactant gas) were in the range 10–50 depending on the degree of unsaturation. Conservative limits of detection (background signal + three times the standard deviation) and quantification (background signal + 10 times the standard deviation) were approximately 70 and 240 pg, respectively. A significant decrease in gland titre of (Z)‐5‐decenyl acetate and (Z)‐7‐dodecenyl acetate after mating was established.
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2.
  • Tunlid, Anders, et al. (author)
  • Diastereoisomeric determination of R‐alanine in bacteria using capillary gas chromatography and positive/negative ion mass spectrometry
  • 1984
  • In: Biological Mass Spectrometry. - : Wiley. - 0306-042X .- 1096-9888. ; 11:8, s. 428-434
  • Journal article (peer-reviewed)abstract
    • The possibilities of using combined capillary gas chromatography mass spectrometry for highly sensitive and selective determinations of enantiomeric alanines of bacterial origin have been evaluated. The alanines were separated as their diastereoisomeric N‐heptafluorobutyryl‐2‐butyl ester derivatives on a 25 m fused silica capillary column coated with SE‐54 as stationary phase. The mass spectra of the derivative obtained by chemical ionization using methane or ammonia (positive ions) and methane or Isobutane (negative ions) as reagent gases have been recorded. The highest sensitivity of detection was achieved by selected ion monitoring in the negative ion mode (detection limit about 0.8 pg). The method was tested by measuring the R‐alanine content in (a) Escherichia coli cultures and (b) natural bacterial communities associated with plant roots. In (a) the recorded detection limit implied possibilities to detect R‐alanine corresponding to 103−104 E. coli cells. The precision for quantifying R‐alanine in the cultures was 14% (coefficient of variation). (b) demonstrated an application where the R/(R + S) ratio of alanine is low. It was shown that accurate determinations of this ratio in the picogram range could be effected down to 0.4%.
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  • Result 1-2 of 2
Type of publication
journal article (2)
Type of content
peer-reviewed (2)
Author/Editor
Odham, Göran (2)
Löfstedt, Christer (1)
Tunlid, Anders (1)
University
Lund University (2)
Language
English (2)
Research subject (UKÄ/SCB)
Natural sciences (2)
Year
1984 (2)

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