analytical 1

Selectivity is the ability to distinguish diferent components of a sample.

Sensitivity is the ability of an instrument to descriminate between small difference in [analyte].

Slope/Standard deviation, defined from concentration.

• 1) precision
• 2) Slope of Calibration Curve

Linearity is in reference to the plots of a calibration curve to be one dimensional in respect to eachother with a high r^2 value close to 1.

Range is the area of variation in the upper and lower limits of the detection limit.

When discussing the sensitvity of an instrument the two things to be considered are:

Limit of Detection:


Limit of quantification:

The limit of dection is the minimum amount of analyte that can be detected by a method @ a known confidence level.

The limit of quantification is the smallest amount that the researcher can measure with reasonable accuracy with that instrument.

The minimal extinguishable signal of an instrament is determined by



This is also known as calculating the figures of Marrit (FOM)

Polarization is the deviation of electric potential from the predicted value of the nernst equation.

• Attributed to 2 things:
• 1. concentration polarization
• 2. kinetic polarization

The over potential required to overcome the activation energy

moles reacted =

• Working electrode: where rxn of interest occurs
• Auxillary electrode: Completes circuit w/o adding additional
• elecrons
• Reference electrode: measures potential directly at the working electrode

• Strengths:
• fast

• Weaknesses:
• charging current
• can only distinguish peaks of 0.02 V apart
• sensitivity of 10^-4

• Strengths:
• Peaks are more easily distinguished
• enables the ability to distinguish peaks from 0.04 V from eachother
• Sensivity of 10^-7 to 10^-9

Weaknesses:

Strengths:

• 1)most effective excitation signal
• 2) Very fast 10ms to yield data
• 3) Same sensitivity as DPP (10^-7 to 10^-9)
• 4) high [ ] of analyte at surface

strengths:

• 1) Mostly qualitative, can be quantitative
• 2) studies redox reactions and intermediate

Weaknesses:

1) not as sensitivity as pulse methods

Strengths:

• 1) great for small amounts of sample
• 2) Sensitivity of ^-6 to 10^-9

the number of oscillations of the electric field vector per unit time

units: 1/p

The velocity of a wave is the length the wave travels over time.

This value is known as the speed of light, 3.0x10^8 m/s or 3.0x10^10 cm/s

The linear distance between successive maxima or minima of a waves

Units: cm s^-1

Wave number is defined as the number of waves per centimeter and is equal to

Units: cm^-1

Plank's Constant 6.63x10^-34

Emission spectroscopy is the excitation by heat or a chemical rxn (chemiluminescence) to monitor wavelengths of light that is emitted.

excitation by electromagnetic radiation, 2 types

• 1) fluorescence
• 2) phosphorescence

emission occurring fro s1 to s0, 10^-4 sec to 10^-8

emission occurring from T1 to S0 between states of different mutiplicity

pass light through a sample and measure absorbance as a funcition of wavelength

Beers Law's limitations are:

• 1) only work ok dilute samples
• 2) If particles are close, they will affect eatchothers charge distrucbution.
• 3) if close, it will aslo affect the spectrum and linearity
• 4)can get complexs and ppt that affect spectrum (chemical deviations)
• 5) association and dissociation rxns with solvents or other molecules in matrix
• 6) Instrument deviation, quality of monochrometer