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The establishment of EVISA is funded by the EU through the Fifth Framework Programme (G7RT- CT- 2002- 05112).


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Name:
Entwisle John
Position:
Research analyst
Address:
LGC Ltd, Queens Road, Teddington, Middlesex, TW11 OLY, United Kingdom
Telephone:  +44(0)20 8943 7306
Fax:  + 44(0) 20 8943 2767
Entwisle John

E-Mail:  John.Entwisle@lgcgroup.com
Homepage:  http://www.lgc.co.uk
Interests:
Development of methodologies for the determination of species/total elements in food/environmental sample types at a metrological level in order to improve measurement capabilities. Where, possible using isotope dilution techniques including species-specific IDMS to provide primary reference values for the certification of reference materials and CCQM studies. Some examples of method development:
  • Enzymatic extraction and chromatography for mercury and methyl-mercury using HPLC-ICP-MS species specific isotope dilution  to provide primary reference values.
  • Procedure for the determination of total arsenic in food matrices (fish, bovine liver, herbal medicine) using high accuracy standard addition technique.
  • LC separation which enables the rapid determination of ultra trace levels of plutonium and uranium isotopes in food and environmental samples.
  • Microwave assisted acid hydrolysis for the accurate determination of methionine and selenomethionine in animal feed and selenium yeast supplements. Using HPLC-ICP-MS with Xe collision gas enabling species specific isotope dilution analysis.
  • A method for the simultaneous determination of total P, S, Se and As in food samples  employing  methane addition to the plasma gas and Xe/hydrogen mix in the collision cell.
  • A novel ion pair liquid chromatography separation of strontium from rubidium (wine digests).  Enabling accurate isotopic Strontium measurements to be made using a multi-collector ICP-MS.
  • A procedure for the determination of  PBDE and PBB (brominated flame retardants) in polymer using ASE extraction and HPLC-ICP-MS detection.
  •  Chromatography and extraction for the simultaneous determination of Cr(VI) and Cr(III) in Cr enriched yeast using isotope pattern de-convolution with double spiking species-specific isotope dilution mass spectrometry (IDMS).

Instrumentation:
  • GC, HPLC, nano-LC hyphenated    
  • Collision cell ICP-MS (Agilent 7500, Agilent 7700)
  • High resolution ICP-MS (Thermo Element 2)
  • Electrospray ion trap MS (Agilent 6300)
Occurence of this scientist in other parts of the EVISA webportal:



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Events
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EMEC 24: European Meeting on Environmental Chemistry
26.11.2024
Alicante, Spain
23rd ICFIA: International Conference on Flow Injection Analysis and FRelated Techniques
03.12.2024
The Empress Hotel, Mueang, Chiang Mai, Thailand
PittCon 2025
01.03.2025
Boston, Massachusetts
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News
What's new on EVISA's web site ?
Liquid chromatography hyphenated with inductively coupled plasma optical emission spectrometry (LC-ICP-OES) for speciation analysis
Ion chromatography hyphenated with inductively coupled plasma optical emission spectrometry (IC-ICP-OES) for the determination of inositol phosphates in food and feed
Mercury-Contaminated Tuna: An Unprecedented Health Scandal
Quantification of Technetium-99 in Wastewater Using Online Preconcentration and Anion-Exchange Chromatography Coupled with Inductively Coupled Plasma-Mass Spectrometry
... more News




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