Post on 20-Dec-2015
Technique: Titration
Measures: Concentration
Quantitative Yes
Qualitative Sometimes: precipitation
Sensitivity: Low
Precision: Typically mMolar. Depends on standards
Accuracy: Depends on endpoint determination and standards
Ease: Very simple
Pro Very simple
Con Need to know analyte. Limited sens/prec/acc
Technique: Titration
Measures: Concentration
Quantitative Yes
Qualitative Sometimes: precipitation
Sensitivity: Low
Precision: Typically mMolar. Depends on standards
Accuracy: Depends on endpoint determination and standards
Ease: Very simple
Pro Very simple
Con Need to know analyte. Limited sens/prec/acc
Technique: Electrochemistry: galvanic cell
Measures: Concentration
Quantitative Yes
Qualitative No
Sensitivity: good
Precision: good
Accuracy: good
Ease: Simple
Pro Measures current. Small devices
Con Only for ReDox reactions. Need to know analyte
Technique: Electrochemistry: galvanic cell
Measures: Concentration
Quantitative Yes
Qualitative No
Sensitivity: good
Precision: good
Accuracy: good
Ease: Simple
Pro Measures current. Small devices
Con Only for ReDox reactions. Need to know analyte
Technique: Electrochemistry: ion selective electrode
Measures: Concentration
Quantitative Yes
Qualitative No
Sensitivity: good
Precision: good
Accuracy: Limited by interference
Ease: Simple
Pro Measures current
Con Only for ReDox reactions. Need to know analyte
Technique: Spectrophotometry: UV-VIS absorption
Measures: Concentration
Quantitative Yes
Qualitative Spectral signature
Sensitivity: Moderate
Precision: Moderate (contamination)
Accuracy: Moderate (need to subtract blank)
Ease: Simple
Pro Molecule specific
Con Need rather pure sample and know spectrum
Technique: Spectrophotometry: UV-VIS absorption
Measures: Concentration
Quantitative Yes
Qualitative Spectral signature
Sensitivity: Moderate
Precision: Moderate (contamination)
Accuracy: Moderate (need to subtract blank)
Ease: Simple
Pro Molecule specific
Con Need rather pure sample and know spectrum
Technique: Spectrophotometry: Atomic flames
Measures: Concentration
Quantitative Yes
Qualitative Element specific
Sensitivity: Good
Precision: Better in absorption than in emission (T)
Accuracy: Good
Ease: Yes
Pro Specificity
Con Only elemental
Technique: Spectrophotometry: Atomic flames
Measures: Concentration
Quantitative Yes
Qualitative Element specific
Sensitivity: Good
Precision: Better in absorption than in emission (T)
Accuracy: Good
Ease: Yes
Pro Specificity
Con Only elemental
Technique: Mass spectrometry
Measures: mass
Quantitative Somewhat with standards
Qualitative Molecular identification
Sensitivity: Very good (sometimes attomoles)
Precision: Resolution 500-106 (FT-ICR)
Accuracy: Depends on resolution and calibration
Ease: Complex apparatus
Pro Sensitive. Informative
Con Complex. More qualitative than quantitatve
Technique: Mass spectrometry
Measures: mass
Quantitative Somewhat with standards
Qualitative Molecular identification
Sensitivity: Very good (sometimes attomoles)
Precision: Resolution 500-106 (FT-ICR)
Accuracy: Depends on resolution and calibration
Ease: Complex apparatus
Pro Sensitive. Informative
Con Complex. More qualitative than quantitatve
Technique: Chromatography
Measures: Separation of compounds
Quantitative With internal standards
Qualitative Yes but need more information
Sensitivity: Very good; depends on detector
Precision: Resolution increases with square root of length
Accuracy: See resolution, depends on standards
Ease: Routine
Pro Ubiquitous and routine
Con Needs combination with other info, e.g. GC-MS
Technique: Chromatography
Measures: Separation of compounds
Quantitative With internal standards
Qualitative Yes but need more information
Sensitivity: Very good; depends on detector
Precision: Resolution increases with square root of length
Accuracy: See resolution, depends on standards
Ease: Routine
Pro Ubiquitous and routine
Con Needs combination with other info, e.g. GC-MS
Technique: NMR
Measures: Molecular structure
Quantitative No
Qualitative Yes
Sensitivity: Low
Precision: High
Accuracy: High
Ease: Complex apparatus
Pro Detailed structure info
Con Expensive, low sensitivity
Technique: X-Rays
Measures: Structure
Quantitative No
Qualitative Yes
Sensitivity: Good but needs crystal
Precision: Very good
Accuracy: Very good
Ease: Sample prep. Sophisticated analysis
Pro Detailed structure information
Con Crystal growth. Complexity
Technique: Microscopy
Measures: Geometry
Quantitative No
Qualitative Yes
Sensitivity: New techniques for single molecule
Precision: STM>electon microscopy>Optical
Accuracy:
Ease: Sophisticated apparatus
Pro Detailed
Con Not quantitative. Interpretation can be difficult
Technique: DNA Sequencing
Measures: DNA sequence
Quantitative No
Qualitative Yes
Sensitivity: Single DNA by PCR
Precision: Very high
Accuracy: Limited by genetics statistics only
Ease: Robotic automation
Pro Sensitive and specific
Con Need to match
Surface analytical techniques
• UPS• XPS• LEED• AUGER• Second harmonic generation• SIMS• SERS
http://www.udel.edu/chem/beebe/surface.htm
http://www.uksaf.org/tech/list.html
Novel “Micro” techniques
• Single molecule fluorescence microscopy• Biosensors• Nanotech sensors• Microfluidics
Immunoassays
Selection by specific antibody-antigen affinity
Novel “Micro” techniques
• electronic nose
Nov 14, 2003Nanotube sensor detects nerve
agentsResearchers in the US have made a
nerve agent detector using single-walled carbon nanotubes. Eric Snow and colleagues at the Naval Research
Laboratory (NRL) in Washington say that their device is simple to fabricate,
extremely sensitive and intrinsically selective to specific gases. The sensor could be used in industrial and military applications (J Novak et al. 2003 Appl.
Phys. Lett. 83 4026).
I ~ f (receptor Q)
Chemical and nucleic acid receptors
Chemical and nucleic acid receptors
Figure 1. Gate-biased nanowire sensor