Download An Example of the Application of Analytical Chemistry to

An Example of the Application of
Analytical Chemistry to
Environmental Science
Tongwen Wang
Virginia State University
May 5th, 2016
Analytical Chemistry
Chemical Analysis
Instrumental Analysis
Gas Chromatography (GC)
High Performance Liquid
Chromatography (HPLC)
Mass Spectrometry (MS)
Key Ideas in Water Treatment
 Transformation


Processes
Biological
Abiotic (Oxidative, reductive, hydrolytic, etc)
vs.
 Removal Processes


Destructive
Partitioning
• Solid phase
• Liquid phase
• Gas phase
Typical Oxidants Used in Water
Treatment
• Free chlorine (FC): ClO¯
• Monochloroamine (MCA): HOCl + NH3
NH2Cl + H2O
• Chlorine dioxide (ClO2): produced using a Bench-Scale ClO2
Generator
• Ozone (O3): generated using a Model GLS-1 PCI-WEDECO ozone
generator from compressed oxygen
• Hydrogen peroxide (H2O2)
• Permanganate (MnO4¯)
• UV: A 254-nm low-pressure mercury-vapor lamp
System 1: Diazinon
• Commonly used as a pesticide since 1952.
• Inhibition of the acetylcholinesterases of most kinds of
insects.
• Also affect the nervous systems of humans.
• Degradation by free chlorine (FC), hydrogen peroxide (H2O2),
monochloroamine (MCA), UV, chlorine dioxide (ClO2) and
ozone (O3).
Extracted ion chromatograms at (a) m/z 289 and (b) m/z
153
Mass Spectrum of (a) Diazoxon (MW: 288) and (b) IPMP (MW: 152)
Pathway of oxidation of diazinon
System 2: Fonofos
• To control lepidopterous insects
• Interferes with the nervous system by
inhibiting cholinesterase
• FC, H2O2 and permanganate oxidation were carried out
Total ion chromatograms of free chlorine and
H2O2 oxidation of fonofos at pH 7.0
Mass spectra for (a) fonofos (MW: 246) and (b) unknown
Pathway of oxidation of fonofos
LC/UV and GC/MS Analysis of Hydrolysis
Byproducts of Fonofos
A. Reaction mixture analyzed with direct
injection into HPLC/UV system after
spiking of internal standard.
B. Reaction mixture extracted into
hexane followed by GC/MS analysis.
UV spectra of fonofos hydrolysis product and
thiophenol standard extracted at the retention time of
the corresponding peaks
(a) GC/MS TIC of fonofos hydrolysis; (b) Mass spectra
of fonofos hydrylate and in the data base
Pathway of Fonofos hydrolysis
System 3: Aldicarb
Structure of Aldicarb Sulfoxide and
Aldoxycarb
TICs of Aldicarb standard and byproducts
under various oxidation systems
TICs of Aldoxycarb standard and its oxidation
byproduct under FC oxidation system
Mass spectrum of the unknown in the oxidation of
Aldoxycarb under FC oxidation system
Summary for Oxidation of Aldicarb
Acknowledgement
Dr. Yinfa Ma
Dr. Craig D. Adams
Dr. Paul Ki-souk Nam
Dr. Klaus Woelk
Dr. Honglan Shi
Financial Support
Awwa Research Foundation (project 3170)
Thank You!