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Jace James & Lauren Erland.  Separation based on charge & frictional force Capillary Electrophoresis (CE)

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Presentation on theme: "Jace James & Lauren Erland.  Separation based on charge & frictional force Capillary Electrophoresis (CE)"— Presentation transcript:

1 Jace James & Lauren Erland

2  Separation based on charge & frictional force Capillary Electrophoresis (CE)

3 CE  Capillary zone electrophoresis (CZE) Separation of charged molecules based on electrophoretic mobilities & migration velocities Detection INORGANIC compounds  Micellar electrokinetic chromatography (MEKC) Combines electrophoresis and chromatography Simultaneous separation of neutral and charged molecules Detection ORGANIC compounds  Microchip CE Portable Presence explosive-compound residues

4 Detection of Separated Compounds  CE can be coupled with diverse detection devices depending on the analyte of interest UV-Vis Laser induced fluorescence (LIF) Electrospray Ionization (ESI) ○ Allows coupling with MS NMR Chemiluminescence

5 Advantages  Simple instrumentation  Exceptional power & resolution  Rapid analysis time  Highly versatile Same instrument, often same capillary can be used to run diverse samples (change only running buffer) Can be coupled with many different detection devices  Separation of charged, neutral and volatile molecules  Low mass limits of detection Nanograms or picograms of sample Minimal damage to sample  Inexpensive reagents Waste is mostly aqueous, environmentally friendly  Minimal sample requirements  Direct sample injection In many cases no sample prep required

6 Gunshot Residue (GSR) & Explosives  Produced when a firearm is discharged Deposited on hands of the perpetrator  Components include: Unburned powder Heavy metals from the barrel of the gun, primer and cartridge  Determination if firearm has been fired identify bullet holes estimate firing distance  Detection military, industrial and home- made explosives


8 Current Methods for Detection  Most common: Scanning Electron Microscopy with Energy Dispersive X- ray Analysis (SEM-EDX)  moderate sensitivity, requires expensive instrumentation, is highly demanding in terms of professional skills, and is a very time consuming process.  Identification INORGANIC compounds ONLY Push towards ORGANIC primers False Negatives!!!

9 SEM-EDX: A case study  2001  Identification of a single, partially burnt gunpowder grain on a suspect’s clothing  SEM unsuccessful  CE was able to identify and individualize the gunpowder grain MEKC can be used to detect ORGANIC compounds CZE for INORGANIC compounds


11 Ink Analysis  Separation is a vital step in ink analysis Ink components vary widely with manufacturer, colour Possibility of contamination from writing surface Chemical changes as ink ages  Results can be stored electronically Development reference libraries  Difficult to find a single method for separation of such diverse mixtures


13 Current Techniques  TLC Low resolution Low power of differentiation  GC & HPLC commonly used Greater technical skill required Large sample size Costly Extensive sample prep Difficult for complex samples Destructive Time consuming

14 CE & Ink Analysis  CE appropriate for many different types of analyte Organic, inorganic, volatile Need only change running buffer Quick, easy and inexpensive!  Extraordinarily small quantities required Pico or nanoliters Virtually non-destructive  Detection generally by UV-Vis  Has been applied to many types of pens and inks Fountain-pen, ballpoint, water-soluble, red, blue and black inks

15 CE readily differentiates inks originating from different manufacturers Reproducible migration times and relative peak areas

16 Capillary Electrophoresis  Simple  Low Cost  Short analysis time  Non-destructive  High power resolution and separation  Potential to expand to many other applications  Eco-Friendly!

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