Chemical Warfare Agents. Hanna Hunziker, Céline Prange Analy:cal Strategy, 13. October 2015

Transcription

1 Chemical Warfare Agents Hanna Hunziker, Céline Prange Analy:cal Strategy, 13. October 2015

2 World War I tons of gas Aerosols or vapours Ethylbromoacetate Chloroacetone Xylylbromide Chlorine Gas Phosgene Mustard Gases Cl Lewisites (contain Arsenic) O Me O Cl O Cl Cl Br Br Cl S As Cl Cl Cl 2 O Cl Wikipedia, Chemical Warfare,

3 Post WWI Nerve gases Tabun O O O Sarin N P O P O P Soman CN F F Biological agents Saxitoxin (Natural product) Ricin (Protein) Wikipedia, Chemical Warfare,

4 Chemical Weapons Conven:on (CWC) OPCW (Organisa:on for the prohibi:on of chemical weapons) Chemical Weapons: Toxic chemicals and their precursors (key components) Toxic chemicals: can cause death, temporary incapacita:on and permanent harm to humans or animals Prohibited to develop, acquire, stockpile and transfer chemical weapons Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

5 Classifica:on of Chemical Warfare Agents (Toxins and Precursors) Schedule 1 Only research and pharmaceu:cal purposes, >100 g must be reported to OPCW E.g. Nerve gases, S+N mustards, Saxitoxin, Ricin Schedule 2 Only small scale use E.g. Precursor of Sarin used as a flame retardant Schedule 3 Large scale use: > 30 t plants inspected by OPCW E.g. Phosgene, HCN, PCl 3, SCl 2, N- (CH 2 CH 2 OH) 3 etc. Wikipedia, Chemical Weapons Conven:on,

6 Number of Inves:gated Chemicals P- atom bound to alkyl group (Me, Et, n- Pr, i- Pr), but no further directly bound C- Atoms Nerve gas deriva:ves Schedules 1.A.1, 1.A.3: > possibili:es Schedule 2.B.4: millions of possibili:es It is impossible to look for all of them! Follow regula:ons: 1. Sample Prepara:on, 2. Screening and Analysis, 3. Data evalua:on and Iden:fica:on Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

7 Liquid and Solid Samples Liquid- liquid or solid- liquid extrac:on Extrac:on into CH 2 Cl 2 for non- polar molecules Aqueous solu:on in three parts Evapora:on of solvent and deriva:za:on with BSTFA (N,O- Bis(trimethylsilyl)trifluoroacetamide) for polar compounds including aminoalcohols Ca:on exchange, evapora:on of solvent and deriva:za:on with BSTFA, for alkylphosphonic acids Deriva:za:on with DMT (Dimercaptotoluene) for lewisites Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

8 Air Samples Collec:on with solid adsorbents (Resins, graphite, ac:ve charcoal or porous polymers) Extrac:on with ethyl- acetate followed by LC- or GC- MS or Thermal desorp:on directly coupled to GC Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

9 On- site analysis Confirma:on of declared chemical and Confirma:on of absence of any undeclared scheduled chemicals (in par:cular Schedule 1 chemicals) Portable GC- MS Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

10 Analy:cal methods GC with selec:ve detectors (FID, NPD, FPD), GC/MS, GC/FTIR LC/MS NMR: 31 P and 19 F (for screening), 1 H, 13 C Capillary electrophoresis OPCW central analy:cal database: NMR, IR, GC/ MS, GC(RI)

11 Comparison: GC and LC GC Deriva:sa:on of polar chemicals Isola:on from water Requirement of vola:lity More suitable for mustards, lewisite and halogenated precursors of some nerve agents Unequivocal iden:fica:on of unknown substances Large database of GC/EI/MS spectra Lower limit of detec:on LC Direct applicability to aqueous samples CW agents in environment and decontamina:on solu:ons hydrolysis and oxida:on more polar, less reac:ve suitable for LC Sulfur mustards and lewisite are too reac:ve with water and some column phases Only method suitable to more complex toxins and pep:des

12 GC in screening Most of the chemical warfare (CW) related agents have suitable high vapor pressure and thermal stability for GC or can be deriva:sed to a vola:le form Good resolu:on, inertness, high sensi:vity, possibili:es for selec:ve detec:on CW related chemicals are rich in heteroatoms: P, S, O, N, Cl, As, F selec:ve detectors

13 Need for selec:ve detectors Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

14 Need for selective detectors NPD FPD-S NPD: nitrogen-phosphorous detector FPD: flame photometric detector FPD-P Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

15 GC in screening Iden:fica:on: Absolute and rela:ve reten:on :mes, reten:on indices (RI's) C- series: homologue series of n- alkanes M- series: (CF 3 ) 2 P(S)(CH 2 ) n CH 3, where n= (alkyl bis(trifluoromethyl)phosphine sulfides)

16 GC/MS: Soman Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

17 Reproducibility of mass spectra Mesilaakso, M. Chemical Weapons Conven0on Chemical Analysis, John Wiley & Sons, 2005.

18 FTIR Chromatography necessary for environmental samples GC/FTIR Func:onal group monitoring GC/FTIR and GC/EI/MS complement each other - Cases where EI/MS cannot differen:ate btw. Isomers but FTIR can - Cases in which FTIR cannot tell exact size of alkyl group but EI/MS can - Overlapping structural info increase reliability

19 LC/MS Analytes: - polar degrada:on products of CW agents - Nerve agents (hydrolise sufficiently slowly) - Bio. Ac:ve pep:des - Bio. Markers of CW exposure in blood, urine Screening of aqueous soil- extracts and water samples

20 NMR Pro: Fingerprint nature of spectra iden:fica:on of known chemicals Structural specificity of spectra structural elucida:on of unknown chemicals Majority of scheduled chemicals are analyzable by NMR Nondestruc:ve further analysis by other techniques Con: Background resonances possible interference with chemicals of interest No separa:on method comparable to GC for MS or FTIR Sensi:vity is low: High detec:on limits compared to MS and FTIR Not suitable for on- site analysis

21 Analysis of Chemical Warfare agents Ques:ons? Thank you for your aqen:on!