LESSON 1: INTRODUCTION TO ANALYTICAL CHEMISTRY

• Analytical Chemistry


  A measurement science consisting of a set of powerful ideas and methods that are useful in all fields of science, engineering, and medicine
• Analyst


  • Must be able to design, carry out, and interpret measurements within the context of the fundamental technological problem
• Qualitative Analysis


  Reveals the identity of the constituents in a sample
• Quantitative analysis


  Indicates the amount of each substance in a sample
• Analytes


  The components of a sample that are determined either through qualitative or quantitative analysis
• GIVE 3 FUNCTION OF ANALYTICAL CHEMISTRY

  • Fundamental Research
  • Product Quality Control
  • Medical and Clinical Studies
• Accuracy


  The closeness of an experimental measurement or result to the true or accepted value
• Analyte


  Constituent of the sample which is to be studied by quantitative measurements or identified qualitatively
• Assay


  A highly accurate determination
• Background


  That proportion of a measurement which arises from sources other than the analyte itself. Individual contributions from instrumental sources, added reagents and the matrix can, if desired, be evaluated separately.
• Blank


  A measurement or observation in which the sample is replaced by a simulated matrix, the conditions otherwise being identical to those under which a sample would be analyzed. Thus, the blank can be used to correct for background effects and to take account of analyte other than that present in the sample which may be introduced during the analysis, e.g. from reagents.
• Calibration

  A procedure which enables the response of an instrument to be related to the mass, volume or concentration of an analyte in a sample.
• Concentration


  The amount of a substance present in a given mass or volume of another substance. The abbreviations w/w, w/v and v/v are sometimes used to indicate whether the concentration quoted is based on the weights or volumes of the two substances.
• Constituent


  A component of a sample.
• Detection Limit

  The smallest amount or concentration of an analyte that can be detected by a given procedure and with a given degree of confidence.
• Determination


  A quantitative measure of an analyte with an accuracy of considerably better than 10% of the amount present.
• Equivalent

  That amount of a substance which, in a specified chemical reaction, produces, reacts with or can be indirectly equated with one mole (6.023 × 1023) of hydrogen ions.
• Estimation


  A semi-quantitative measure of the amount of an analyte present in a sample, i.e. an approximate measurement having an accuracy no better than about 10% of the amount present.
• Interference

  An effect which alters or obscures the behavior of an analyte in an analytical procedure. It may arise from the sample itself, from contaminants or reagents introduced during the procedure or from the instrumentation used for the measurements.
• Internal Standard


  A compound or element added to all calibration standards and samples in a constant known amount.
• Masking


  Treatment of a sample with a reagent to prevent interference with the response of the analyte by other constituents of the sample
• Matrix


  The remainder of the sample of which the analyte forms a part.
• Method


  The overall description of the instructions for a particular analysis.
• Precision


  The random or indeterminate error associated with a measurement or result. Sometimes called the variability or reproducibility, it can be represented statistically by the standard deviation or relative standard deviation (coefficient of variation).
• Primary Standard


  A substance whose purity and stability are particularly well established and with which other standards may be compared.
• Procedure


  A description of the practical steps involved in an analysis.
• Reagent


  A chemical used to produce a specified reaction in relation to an analytical procedure.
• Sample


  A substance or portion of a substance about which analytical information is required.
• Sensitivity


  The change in the response from an analyte relative to a small variation in the amount being determined. The sensitivity is equal to the slope of the calibration curve, being constant if the curve is linear. The ability of a method to facilitate the detection or determination of an analyte (even the smallest concentration should be detected)
• Standard


  A pure substance which reacts in a quantitative and known stoichiometric manner with the analyte or a reagent. The pure analyte or a substance containing an accurately known amount of it which is used to calibrate an instrument or to standardize a reagent solution.
• Standard Addition


  A method of quantitative analysis whereby the response of the analyte in the sample is compared with the response obtained when known amounts of the analyte are added to the sample.
• Reagent


  A chemical used to produce a specified reaction in relation to an analytical procedure
• Sample


  A substance or portion of a substance about which analytical information is required
• Sensitivity


  The change in the response from an analyte relative to a small variation in the amount being determined. The sensitivity is equal to the slope of the calibration curve, being constant if the curve is linear
• The ability of a method to facilitate the detection or determination of an analyte (even the smallest concentration should be detected)
• Standard


  A pure substance which reacts in a quantitative and known stoichiometric manner with the analyte or a reagent. The pure analyte or a substance containing an accurately known amount of it which is used to calibrate an instrument or to standardize a reagent solution
• Standard Addition


  A method of quantitative analysis whereby the response from an analyte is measured before and after adding a known amount of that analyte to the sample
• Standardization


  Determination of the concentration of an analyte or reagent solution from its reaction with a standard or primary standard
• Technique


  The principle upon which a group of methods is based
• Validation of Methods


  It is essential to validate the method by analyzing standards which have an accepted analyte content, and a matrix similar to that of the sample. The accepted values for these validated standards are obtained by extensive analysis, using a range of different methods. Internationally accepted standards are available