Instrumental Methods of Analysis

- Chromatography
- Electrophoresis

seperation techniques in instrumental method

Internal Standard

substance that is added in a constant amount to standards in an analysis

Signal

analytical measurement that carries information about the analyte that is of interest to the scientist

Specification

a list of tests, references to analytical procedures, and appropriate acceptance criteria that are numerical limits, ranges, or other criteria for the test described

F - Specification

[T/F] The standard establishes the set of criteria to which a material should conform to be considered acceptable for its intended use.

Classical/Wet-Chemical Method

measurements depend on the chemical properties of the sample

F - Chemical Stoichiometry

[T/F] In classical or wet-chemical method, the reagent is made to react completely with the analyte. The relationship between the measured signal and analyte concentration is determined by chemical spectometry.

Volume of Standard

the measured signal in the classical or wet-chemical method pertains to the _ used to measure the analyte concentration

- Precipitation
- Extraction
- Distillation

separation techniques in classical or wet-chemical method

- Colors
- BP/MP
- Solubility
- Odors
- Optical Activity
- Refractive Index

qualitative analyses in classical or wet-chemical method

- Gravimetric
- Volumetric

quantitative analyses in classical or wet-chemical method

T

[T/F] Classical or wet-chemical method is more suitable for analysis of major constituents. This method is used if the analyte in the sample is present in large amount.

F - Cheaper

[T/F] Classical or wet-chemical method is used to certify analytical standards, but generally expensive than other methods.

T

[T/F] Classical or wet-chemical method provides more accurate, precise, and robust results and is less susceptible to environmental fluctuations.

Instrumental Method

measurement of physical or chemical properties of the analyte

- Conductivity
- Electrode Potential
- Light Absorption or Emission
- Mass-to-charge Ratio
- Fluorescence

quantitative analyses in instrumental method

T

[T/F] Instrumental method is suitable for trace analyses.

T

[T/F] Instrumental methods are mostly multi-channel and amenable to automation; thus, the time for analysis is shorter.

F - Less

[T/F] More skills and training are required when performing instrumental methods.

- Spectrometric Methods
- Chromatographic Methods
- Electrochemical Methods
- Miscellaneous

types of instrumental methods

Emission

[Spectrometric]

- Emission Spectroscopy
- Fluorescence
- Phosphorescence and Luminescence

Absorption

[Spectrometric]

- Spectrophotometry and Photometry
- Photoacoustic Spectroscopy
- Nuclear Magnetic Resonance
- Electron Spin Resonance Spectroscopy

Scattering

[Spectrometric]

- Turbidimetry
- Nephelometry
- Raman Spectroscopy

Refraction

[Spectrometric]

- Refractometry
- Interferometry

Diffraction

[Spectrometric]

- X-Ray
- Electron Diffraction

Rotation

[Spectrometric]

- Polarimetry
- Optical Rotary Dispersion
- Circular Dichroism

- GC (Gas)
- HPLC

types of chromatographic methods

Conductometry

[Electrochemical]

resistance

Coulometry

[Electrochemical]

charge

Polarography

[Electrochemical]

current

Potentiometry

[Electrochemical]

potential

Mass-to-charge Ratio

[Miscellaneous]

mass spectrometry

Thermal Characteristics

[Miscellaneous]

- Thermal gravimetry and titrimetry
- Differential scanning calorimetry
- Differential thermal analyses Thermal conductometric methods

Radioactivity

[Miscellaneous]

- Activation
- Isotope Dilution

F - Can be

[T/F] Analytical Instruments connvert information about the physical of chemical characteristics of the analyte to information that cannot be manipulated and interpreted by man.

- Signal Generator
- Transducer or Detector
- Signal Processor
- Read-Out Device

general components of instrumental measurement

- Energy Source (Light)
- Chemical System (Matter)

parts of signal generator

Signal Generator

consists of the chemical system interacting with the stimulus from the energy source producing an analytical signal reflecting the presence and conc. of the analyte

F - Electrical

[T/F] The transducer or detector transforms the analytical signal produced by the signal generator into a mechanical signal.

Signal Processor

modifies and cleans up the electrical signal to make it more convenient to interpret

1) Attenuation
2) Amplification
3) Filtration (Noise Removal)

3 processes involved in signal processor

Read-Out Device

converts the electrical signal to a form usable to the analyst

F - Read-Out Device

[T/F] Digital timer or display is an example of signal processor.

T

[T/F] Amplifier is an example of signal processor.

Calibration

determines the relationship between analytical response and the analyte conc.

- Comparison with standards
- External standard calibration
- Standard addition method
- Internal standard method

calibration of instrumental methods

Direct Comparison

[Comparison With Standards]

property of the analyte is compared with standards such that the property being tested matches the standard

Direct Comparison

[Comparison With Standards]

concentration of the analyte was then equal to the concentration of the standard after dilution

F - Most Accurate

[Comparison With Standards]

[T/F] Titration is the least accurate method among all analytical procedures.

Titration

[Comparison With Standards]

analyte reacts with a standardized reagent in a reaction of known stoichiometry

External Standard

used to calibrate instruments and procedures when there are no interference effects from matrix components in the analyte solution

T

[T/F] External standards are prepared separately from the samples.

Calibration Curve

in external standard, _ is prepared by plotting the data or by fitting them to a suitable mathematical equation like slope-intercept form

Standard Addition Method

useful for analyzing complex samples in which the likelihood of matrix effects if substantial

Spiking

procedure in standard addition method wherein there is an addition of one or more increments of a standard solution to sample aliquots containing identical columes

T

[T/F] Internal standards are added in a constant amount to all samples including blank and calibration standards.

UV:
- Absorbance

FTIR:
- Peak Area
- Peak Location
- Peak Height

HPLC:
- Retention Time

examples of signals

Noise

analytical measurement made up of extraneous information that is unwanted

F- Noise Only

[T/F] Both signal and noise degrade the accuracy and precision of an analysis and also places a lower limit of analyte that can be detected.

Chemical Noise

arise from a host of uncontrollable variables that affect the chemistry of the system being analyzed; changes in the chemical system

- Undetected variations in temp. or pressure
- Fluctuation in relative humidity
- Vibrations leading to stratification of powdered solids
- Changes in light intensity
- Laboratory fumes

examples of chemical noise

T

[T/F] Instrumental noise is associated with each component of an instrument and can be filtered.

Signal-to-Noise (S/N) Ratio

equation that indicates the magnitude of an experimental effect above the effect of experimental error due to chance fluctuations

International Council for Harmonisation (ICH

an international non-profit organization that aims to develop guidelines via a process of scientific consensus with regulatory and industry experts working together

F - Cannot be attributed

[T/F] Out-of-Control Process is a process in which variations among the observed sampling results can be attributed to a constant system of chance causes.

Out of Specification (OOS) Result

a result that falls outside established acceptance criteria which have been established in official compendia and/or by company documentation

Out of Trend (OOT) Result

a time-dependent result which falls outside a prediction interval or fails a statistical process control criterion

Standard

the metric, specification, gauge, statement, category or physical product sample against which the outputs of a process are compared and declared acceptable or unacceptable

System Suitability Test

used to verify that the test system will perform in accordance with the criteria set forth in the procedure