Rta Ifpac 2012 Melamine Pesticides Sers

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  • 1. Detection of DEHP, Melamine & Pesticides in Liquid and Solid Field Samples by SERSRTA SERS Team: Stuart Farquharson (CEO), Frank Inscore (R&D Director), Chetan Shende & Atanu Sengupta (Senior Research Chemists), Hermes Huang (Application Scientist) • The Need/Challenges • Basic SERS Theory • SERS Sampling Devices • Applications • Illegal Drugs in Saliva/Surfaces • Poisons in Food • Explosives on Surfaces We havewww.rta.biz a Booth Providing Chemical Information When & Where You Need It
  • 2. Challenge: food contamination & adulteration • Need pesticides to meet food demand • 3 Million tons of contaminated fruits & vegetables reaches the US market/yr • Intentional adulteration/substitution - $ • Melamine – 50,000 hospitalizations • DEHP – replace palm oil as clouding agent in food Providing Chemical Information When & Where You Need It
  • 3. Challenge: minimize pesticide contamination Modern agriculture depends on pesticides to protect crops and to produce the quantity and quality of food demanded by todays society. Foods Animal Feeds Domestic Import Domestic ImportWith Residues 34.5% 29.6% 40.8% 45.9%Exceeding Guidance 0.8% 4.3% 1.6% 6.7% Food and Drug Administration Pesticide Program Providing Chemical Information When & Where You Need It
  • 4. Challenge: Detect Residues in Food & Feed Residues in Food Baby Food Feed (2003) DDT carbaryl malathion chlorpyrifos-methyl chlorpyrifos-methyl chlorpyrifos-methyl malathion malathion chlorpyrifos endosulfan permethrin methoxychlor dieldrin ethylenethiourea tribufos chlorpyrifos endosulfan pirimiphos-methyl chlorpropham chlorpyrifos diazon permethrin iprodione ethoxyquin iprodione thiabendazole ethion chlordane dimethoate gardona Requirements 0.1 to 50 ppm. Providing Chemical Information When & Where You Need It
  • 5. The Need & ChallengesVarious Agencies require a field-usable analyzer to identifytrace contaminants & adulterants in food.The analyzer must typically provide the following: • Specificity – Identify and discriminate the chemical from others (No False Positives!) • Sensitivity – Detect ~10-8 M or less (e.g. 25 ppb cocaine) • Reproducibility – Accurate and Repeatable (No False Negatives!) • Speed – Analysis within 10 minutes • Field Usable – Battery Operated and Rugged Providing Chemical Information When & Where You Need It
  • 6. The Solution: SERSSpecificity: Every chemical produces a unique Raman spectrumallowing unequivocal identification.Sensitivity: Silver and gold nanoparticles increase Raman signals by1 million times or more allowing 10-8M (ppb) detection. Melamine SERS: 1 mg/mL Raman: Pure
  • 7. How it works: RamanLight Chemical virt H H Transmittedhνo H H hνvib Absorbed (IR) hνo hνscat H H Raman Raman Scattered hνscat vib1 Rayleigh hνvib vib0 Laser light directed at a chemical generates Raman light. Providing Chemical Information When & Where You Need It
  • 8. Surface-enhanced Raman Spectroscopy When a molecule is within a plasmon field, the efficiency of Raman scattering can increase by 1 million times! Sub part-per million detection becomes possible. Single Molecule Detection: Chemical contribution requires 1012 -1014 Enhancement can provide additional 103 enhancement
  • 9. Dispersive Sample Raman Grating Phenylalanine O _ C O Raman Intensity + Filter H3N CH CH 2 Laser CCD 500 750 1000 1250 1500 1750 Bin Columns Raman Shift (cm-1)Limitations: 1) fluorescence, 2) unequal resolution, 3) x-axisinstability (laser shifting and expanding optics (temperature)will shift spectrum across CCD face like an accordion). Providing Chemical Information When & Where You Need It
  • 10. RTA’s SERSID - Trace Chemical Analyzer 2010 Patents: 6623977, 6943031, 6943032, 7312088, 7393691, 7393692, 7462492, 7462493, 7713914
  • 11. RTA’s SERS Sampling Systems 2001: Simple SERS Sample Vials Molecules Sol-Gel Matrix Raman in Solution Scattering 2001 Laser Adsorbed Molecules Metal Particle2003: SERS Microplate 2004: SERS-Active Capillary 1 10 Extraction and Pre-ConcentrationHigh Throughput Screening Providing Chemical Information When & Where You Need It
  • 12. Commercial SERS Substrates: Benzenthiol Concentration Enhancement Factor 10-3M 102 10-5M 104 10-8M (~10 ppb) 107
  • 13. Analysis: methyl parathion Normal Raman Normal Raman Surface-Enhanced Raman Surface-Enhanced Raman Providing Chemical Information When & Where You Need It
  • 14. Analysis: Fonofos Normal Raman Normal Raman Surface-Enhanced Raman Surface-Enhanced Raman Providing Chemical Information When & Where You Need It
  • 15. Sensitivity:10 ppb75 mW of 785 nm1 min Providing Chemical Information When & Where You Need It
  • 16. Standard Method: 1-2 hours Blank Sample: 1 ppm pesticide 100g sample + 200 mL 1 CH3CN 50% add 50 microg pesticide test 50% 100% 2 10g NaCl 10g NaCl test organic layer 3 Centrifuge Centrifuge test eluant 4a evap to 5 ml evap to 5 ml 4b SPE: C-18 SPE: C-18 4c add CH2Cl2/CH3OH add CH2Cl2/CH3OH test eluant 5a evap to 5 ml evap to 5 ml3 times 5b SPE: amino-propyl SPE: amino-propyl 5c add CH2Cl2/CH3OH add CH2Cl2/CH3OH test eluant 6a evap to 5 ml evap to 5 ml 6b SPE: carbon-black SPE: carbon-black 6c add CH3CN/Toluene add CH3CN/Toulene test eluant 7a evap to 5 ml evap to 5 ml 7b 1 microL in GC-FID 1 microL in GC-FID compare Providing Chemical Information When & Where You Need It
  • 17. Method: 10-minute analysis SG Plug SG Plug sma Providing Chemical Information When & Where You Need It
  • 18. Food Contamination: Pesticides 50 ppb Chlorpyrifos-methyl in Solvent, Ag-SG in Orange Juice OJ Blank400 800 1200 1600 Wavenumbers (cm-1) Sens & Instrumen Food Qual, 4, 101-107 (2010)
  • 19. Swab Test: carbaryl on an apple 1 Spray 2 Swab 3 Extract 4 Measure Providing Chemical Information When & Where You Need It
  • 20. Analysis: SERS of carbaryl on apple Providing Chemical Information When & Where You Need It
  • 21. Raman Spectra of Baby Milk Formula 785 nm Laser 1064 nm Laser Providing Chemical Information When & Where You Need It
  • 22. 1% Melamine in Baby Milk Formula 1% in Formula Pure Formula Difference spectrum Pure Melamine Providing Chemical Information When & Where You Need It
  • 23. Melamine: NR & SERS -785A) SERS spectrum of 1mg/mL melamine in water (80mW, 1 min.) B) Raman spectrum of pure melamine (200mW, 5 min). The enhancement factor is approximately 100,000. Providing Chemical Information When & Where You Need It
  • 24. Melamine: SERS at 785 nm FA) 1mg/mL B) 100 microg/mL C) 10 microg/mL D) 1 microg/mL (1 ppm) All spectra were taken at 80mW, 1min.Spectroscopy: April 2011, Applied Spectroscopy: May 2011 Providing Chemical Information When & Where You Need It
  • 25. SERS of Melamine 0.5 PPM (X20) Glass Luminescence 5 PPM Simple SERS Pure Melamine Sample Vial Providing Chemical Information When & Where You Need It
  • 26. SERS of Melamine 0.5 PPM in Solvent (X20) Glass Luminescence 5 PPM in Solvent 250 PPM extracted Simple SERS from Baby Formula Sample VialApplications of Vibrational Spectroscopy in Food Science, Wiley, 2010, p.663
  • 27. Food Contamination: Melamine 0.5 ppm in solvent glass bkg Ag-SG 5 ppm in solvent 250 ppm in Baby Formula 400 800 1200 1600 Wavenumbers (cm-1)Applications of Vibrational Spectroscopy in Food Science, Wiley, 2010, p.663
  • 28. Challenge: DEHP- Toxic Plasticizer June 2011: roughly 900 products have been recalled from nearly 40,000 Taiwanese retailers Bis(2-ethylhexyl)phthalate Providing Chemical Information When & Where You Need It
  • 29. Multiple, Fast Sample Analysis: 96-Well SERS-Active PlateWe develop SERS Sample Systems for You
  • 30. SERS Library 50 FoodContaminants & Adulterants
  • 31. SERSID – Trace Chemical Analyzer We have a Booth Providing Chemical Information When & Where You Need It