1. Selecting an analytical method
1.1. Speed
1.2. Ease
1.3. Cost
1.4. Detection Limit
1.5. sample size
2. Signal
2.1. The instrument response produced from the analyte or a solution of known concentration
2.2. Types
2.2.1. Analog
2.2.1.1. Continuous
2.2.2. Digital
2.2.2.1. Count
2.2.2.2. Binary
2.2.3. Time
2.2.3.1. Frequency
2.2.3.2. Pulse Duration
2.2.3.3. Time/ avg rate of pulses
3. Noise
3.1. Random fluctuation present in the baseline where no analytical signal is present
3.2. P-p ot RMS
3.2.1. p-p usually 5X greater
3.3. Signal to noise ratio (S/N)
3.3.1. a figure of merit for the quality of data with respect to confidence limits
3.3.2. mean/standard deviation
3.3.3. 1/RSD
3.4. Chemical Sources
3.4.1. Effect of T or p on chemical equilibrium
3.4.2. change in moisture content of a hygroscopic sample
3.4.3. laboratory fumes condensing or reacting in a sample
3.4.4. photosensitive samples
3.5. Types of Instrumental/ Electronic
3.5.1. Thermal
3.5.1.1. Agitation of electrons (charge carries)
3.5.1.2. Independent of frequency
3.5.1.3. Dependent on T, R, and bandwidth
3.5.2. Shot
3.5.2.1. Type of white noise
3.5.2.2. because charge and energy are quantized
3.5.3. Flicker
3.5.3.1. pink noise
3.5.3.2. significant at frequencies lower than 100 Hz
3.5.3.3. proportional to signal and inversely dependent on absolute frequencies
3.5.3.4. 1/f
3.5.4. Environmental
3.5.4.1. Reduction
3.5.4.1.1. shield circuits and wires
3.5.4.1.2. good grounding
3.5.4.1.3. reduce vibrations
3.5.4.1.4. insulate
3.5.4.1.5. reduce radiant energy
3.5.4.2. Interferes with analytical measurements
3.5.5. Noise Reduction
3.5.5.1. Grounding/ Shielding
3.5.5.1.1. Surround circuits with conducting material
3.5.5.1.2. absorb electromagnetic radiation by the shield
3.5.5.2. Filtering
3.5.5.2.1. Noise at high frequencies, signals at low frequencies
3.5.5.2.2. take the output voltage across the capacitor
3.5.5.2.3. let low frequencies pass
3.5.5.3. ensemble average
3.5.5.3.1. noise is randomly distributed but signal is not
3.5.5.3.2. average successive sets of data
3.5.5.3.3. noise smooths out
4. Caibration
4.1. Comparison with Standards
4.1.1. Direct comparison
4.1.2. Titrations
4.2. External- Standard Calibration
4.2.1. Calibration curve relate known concentrations of standards to instrument/ method response
4.2.2. Errors: Matrix effects, systematic, and random
4.3. Standard Addition Methods
4.3.1. Employed when the matriculates of an unknown can not be duplicated
4.3.2. Add a small aliquot of a high concentration standard to the unknown so the solution matrix is not affected
4.4. Internal- Standard Method
4.4.1. Plot ratio of the analyze signal to the internal standard signal as a function of the analyze conc. of the standards
4.4.2. Compensates for random and systematic errors
4.4.3. Used when the sample volume is not constant, instrument response varies from run to run, or when sample loss occurs during sample introduction
5. Figures of Merit
5.1. Precision
5.1.1. Abs Standard Deviation
5.1.1.1. s
5.1.2. Relative standard Deviation
5.1.2.1. s/xbar
5.1.3. Coefficient of variation
5.1.3.1. s/x*100%
5.1.4. Variance
5.1.4.1. s^2
5.2. Bias
5.2.1. Absolute systematic error
5.2.2. Reative systematic error
5.3. Sensitivity
5.3.1. Calibration Sensitivity
5.3.1.1. the rate of change of the analytical signal for each concentration unit (m)
5.3.2. Analytical Sensitivity
5.3.2.1. m/s where s is std dev of the measurement
5.4. Detection Limit
5.4.1. Ybl+ 3StDevbl/sensitivity
5.4.2. The smallest concentration of analyte that can be certified as being statistically different from the blank
5.5. Dynamic Range
5.5.1. LOQ to LOL
5.6. Selectivity
5.6.1. Coefficient of Selectivity
5.6.1.1. K(b,a)= m(b)/m(a)
5.6.2. S= m(a)c(a)+ m(b)c(b)+ s(bl)
5.6.3. The ability of a technique to respond specifically to the analyze of interest