Sökning: "APCI"

Visar resultat 1 - 5 av 9 avhandlingar innehållade ordet APCI.

  1. 1. Gas chromatography-atmospheric pressure chemical ionization-tandem mass spectrometry methods for the determination of environmental contaminants

    Detta är en avhandling från Örebro : Örebro university

    Författare :Dawei Geng; Örebro universitet.; [2016]

    Sammanfattning : The recent developments and improvements of instrumental methods for the analyses of the environmental contaminants, especially the persistent organic pollutants (POPs), have made it possible to detect and quantify these at very low concentrations in environmental and biotic matrices.The main objective of this thesis is to demonstrate the capability of the atmospheric pressure chemical ionization technique (APCI), using gas chromatography coupled to tandem mass spectrometry for the determination of a wide range of environmental contaminants, including the POPs regulated by Stockholm Convention, such as polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), but also the derivates of PBDEs and novel brominated flame retardants (NBFRs). LÄS MER

  2. 2. Packed Column Supercritical Fluid Chromatography Applications in Environmental Chemistry

    Detta är en avhandling från Örebro : Örebro University

    Författare :Nicole Riddell; Örebro universitet.; [2017]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Supercritical Fluid Chromatography; Mass Spectrometry; Ionization; POPs; APPI; APCI; chiral; achiral; packed column;

    Sammanfattning : Although gas and liquid chromatography have emerged as dominant separation techniques in environmental analytical chemistry, these methods do not allow for the concurrent analysis of chemically diverse groups of persistent organic pollutants (POPs). There are also a small number of compounds which are not easily amenable to either of these traditional separation techniques. LÄS MER

  3. 3. Novel Solid Phase Extraction and Mass Spectrometry Approaches to Multicomponent Analyses in Complex Matrices

    Detta är en avhandling från Stockholm : Department of Analytical Chemistry, Stockholm University

    Författare :Nahid Amini; Stockholms universitet.; [2010]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Sample preparation; SPE; RAM; GCB µ-trap; GCB disk; High temperature LC; LC MS; ESI; APCI; Matrix effects; LIT-MS; SALDI; Sample screening; Oxidized GCB; Silicon nitride; NATURAL SCIENCES Chemistry Analytical chemistry; NATURVETENSKAP Kemi Analytisk kemi; analytisk kemi; Analytical Chemistry;

    Sammanfattning : Analysis of compounds present in complex matrices is always a challenge, which can be partly overcome by applying various sample preparation techniques prior to detection. Ideally, the extraction techniques should be as selective as possible, to minimize the concentration of interfering substances. LÄS MER

  4. 4. Microdialysis Sampling, Electrochemical Detection and Mass Spectrometry of Carbohydrates in Monitoring Bioprocesses

    Detta är en avhandling från Department of Analytical Chemistry, Lund University

    Författare :Nelson Torto; Lunds universitet.; Lund University.; [1999]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; monosaccharides; membrane; IPED; ion spray; probe internal geometry; extraction fraction; electrochemical oxidation; electrochemical detection; disaccharides; desalting; carbohydrates; bioprocess monitoring; Cu; APCI; Au; MS; oligosaccharides; PAD; PEI; Analytical chemistry; Analytisk kemi;

    Sammanfattning : This thesis addresses; (1) the microdialysis experiment, application and methodology to maximise its performance when sampling from enzymatic bioprocesses, (2) electrochemical detection and electrochemical oxidation of carbohydrates on Au as well as Cu electrodes in alkaline solutions, and (3) coupling and maximising the performance of a microdialysis sampling based high performance anion exchange chromatography-integrated pulsed electrochemical detection-mass spectrometry system. Studies were carried out to investigate the effect of temperature, analyte as well as biomatrix complexity, analyte concentration, permeability factors, protein(enzyme)-membrane interaction and membrane material on the performance of microdialysis sampling. LÄS MER

  5. 5. Atmospheric pressure ionisation interface considerations for micro column separation with mass spectrometric detection

    Detta är en avhandling från Uppsala : Acta Universitatis Upsaliensis

    Författare :Per J. R. Sjöberg; Uppsala universitet.; [1999]
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry; Kemi; NATURAL SCIENCES Chemistry; NATURVETENSKAP Kemi; Analytical Chemistry; analytisk kemi;

    Sammanfattning : Two miniaturised atmospheric pressure chemical ionisation (APCI) interfaces were developed for micro column separation and their performances were investigated in high temperature open tubular column liquid chromatography and capillary supercritical fluid chromatography (SFC). The most influential parameters, for example, the interface probe position relative to the sampling orifice and the reagent ion plasma composition, were investigated to optimise the ion current signal and stability. LÄS MER