Interactions of Transition Metal Ions with Organophosphorus Pesticides Probed by Electrospray Ionisation Mass Spectrometry Bernd O. Keller, Department of Pathology and Laboratory Medicine, UBC 48th Annual Western Canada Trace Organic Workshop, Vancouver, BC, May 13, 2013. Ag + Cu 2+ Hg 2+ 1
Topics: • What are Organophosphorus Pesticides (OPs)? • What is the relevance of the interactions of OPs with transition metal ions? • What information can Electrospray Ionisation Mass Spectrometry (ESI ‐ MS, ESI ‐ MS/MS) provide? 2
Diazinon Quinalphos • 40 OPs registered in US • Use of >32,000 tons p.a. Fenitrothion 3
http://www.ecifm.rdg.ac.uk/pesticides.htm 4
Degradation of OPs: Hydrolysis of Quinalphos (PA ‐ Q) PA ‐ Q • Microbiologically H 5 C 2 O O N P • Photo ‐ catalytically O S C 2 H 5 N • Hydrolysis +H 2 O H 5 C 2 O OH H O N P O S C 2 H 5 N PA ‐ OH HQ Diethyl ‐ 2 ‐ Hyroxyquinoxaline phosphorthioic acid (HQ) (PA) 5
Hydrolysis of Quinalphos – Half ‐ life Determination dd H 2 O Na + , K + Hg 2+ Ag + Cu 2+ Half ‐ 119 d 119 d 19 sec 9 h 27 d life PA ‐ Q • HPLC ‐ UV H 5 C 2 O O N P • pH 4.0 (dil. HNO 3 ) O S C 2 H 5 N salts added as nitrates • +H 2 O • 1 ‐ 30 molar excess of salts H 5 C 2 O OH H O N P O S Hamid Esbata, Thesis, Queen’s University 2005 C 2 H 5 N PA ‐ OH HQ 6
Entry into the environment, besides chemical manufacturing and wastewater: Silver: mining, photo ‐ processing, use as Ag + antibiotic Copper: fertilizer, e.g. foliar sprays (Cu(OH) 2 ), Cu 2+ mining Hg 2+ Mercury: deposition from atmosphere (coal combustion), seedling protection, other agricultural uses, gold amalgamation 7
ELEMENTS September 2005 v. 1 no. 4 p. 205 ‐ 210 • Transition metal ions are tightly bound to soil solids • They can be very mobile if bound to colloids (<1 um) • Distribution with ground ‐ and surface ‐ waters Presence of >10 pesticides and heavy metal ions in Rankala Lake (India) reported at medium to high ppb levels J Bioremed Biodegrad 2012 ;3:143 8
• Q 1 : Single isotope selection • In ‐ source fragmentation: allows “pseudo ‐ MS 3 ” • TOF ‐ analyzer: accurate mass measurement (< 5 ppm) • Direct infusion of low μ M solution mixtures at pH 4 9
107/109 Ag + 1:1 [HQ+Ag] + 253 1.0 Ag + [PA ‐ Q + 107 Ag + ] Signal Intensity (Arb. Units) 107 405 0.8 0.6 S [ ] + Ag P O 0.4 O C 2 H 5 ‐ C 2 H 4 [HQ+H + ] 231 203 147 0.2 ‐ C 2 H 4 ‐ C 2 H 4 0.0 50 100 150 200 250 300 350 400 M/Z 255 1.0 109 [PA ‐ Q + 109 Ag + ] Signal Intensity (Arb. Units) 0.8 407 0.6 0.4 [HQ+H + ] 233 147 205 0.2 0.0 100 200 300 400 M/Z Isotope selection in Q 1 allows discerning of Ag + ‐ containing fragments 10
253 (A) 1.0 ‐ [PA ‐ H] [PA ‐ Q + Ag + ] [HQ+Ag + ] 0.9 107 405 m/z 405 m/z 253 0.8 Signal Intensity (Arb. Units) ‐ [(PA ‐ 2H) ‐ + Ag + ] 0.7 ‐ [HQ] ‐ [PA ‐ Q] 0.6 ‐ [HQ] ‐ [C 2 H 5 ] 0.5 [HQ+H + ] 0.4 ‐ 28 231 0.3 m/z 147 ‐ [PA ‐ C 2 H 5 ] [Ag + ] 147 0.2 m/z 107 ‐ 28 [PA ‐ C 2 H 5 + Ag + ] ‐ 28 0.1 m/z 231 0.0 50 100 150 200 250 300 350 400 450 M/Z 147 (B) 1.0 ‐ [PA ‐ H] [PA ‐ Q + Cu + ] [HQ+Cu + ] 0.9 m/z 361 m/z 209 361 0.8 Signal Intensity (Arb. Units) ‐ [(PA ‐ 2H) ‐ + Cu + ] 0.7 63 Cu + 2.5 ‐ [HQ] ‐ [PA ‐ Q] 0.6 2.0 ‐ [HQ] ‐ [C 2 H 5 ] 0.5 -3 1.5 x10 209 1.0 ‐ 28 0.4 [HQ+H + ] 0.5 0.3 ‐ 28 ‐ [PA ‐ C 2 H 5 ] m/z 147 60 65 [Cu + ] 0.2 187 m/z 63 [PA ‐ C 2 H 5 + Cu + ] 0.1 63 ‐ 28 0.0 m/z 187 40 80 120 160 200 240 280 320 360 M/Z Cu(I) 11
Charge reduction mechanisms in ESI: Predominantly detection of singly charged ions • Me 2+ An ‐ H 2 O L An ‐ 1. [Me 2+ + L + An ‐ ] overall charge: +1 2. [Me 2+ + (L ‐ H) ‐ ] overall charge: +1 3. Me 2+ +An ‐ Me + + An* [Me + + L] overall charge: +1 12
Acridine Ligands ‐ Same Molecular Formula + Cu 2+ m/z 658 m/z 659 Cu(II) Mostly Cu(I) Tintaru et. al. J. Phys. Org. Chem. 2009 , 22 : 229 ‐ 233 13
Cu(I) Cu(II) HCl Cl* Cu(II) Cu(I) charge state reduction in the absence of easily removable protons Tintaru et. al. J. Phys. Org. Chem. 2009 , 22 : 229 ‐ 233 14
Quinalphos • Cu(II) Cu(I) due to lack of removable protons in vicinity • It is not an electrochemical process at the ESI tip 15
Change of solvent system from MeOH/H 2 O to dry nitromethane (CH 3 ‐ NO 2 ) for Hg 2+ study ACN MeOH H 2 O Dry CH 3 NO 2 16
Hg 2+ 17
• No Hg(II) Hg(I) charge state reduction observed (Hg has a lower second ionisation potential compared to Cu) 18
Summary: • ESI ‐ MS and ESI ‐ MS/MS gives insights into structures of rapidly formed transition metal ion – OP complexes • Observed Cu(II) Cu(I) charge state reduction in gas ‐ phase allows statements on removable proton locations in solution complexes • Ag + binds to S > N, Cu 2+ binds N > S, Hg 2+ binds S>>>N 19
Future Work: • Studies of interaction of transition metal ions bound to highly mobile colloidal particles with OPs • Studies of fate, distribution of OPs and transition metal ions in the environment • Development of detoxification strategies of OP stockpiles 20
Rapid Communications in Mass Spectrometry June 30 th edition, 2013 berndkel@mail.ubc.ca 21
Thank you! Hamid & Family in Libya Gary van Loon Erwin Buncel 22
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