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Lesson 2-1


Various stains and solutions are utilized in routine hematological examinations.

These stains and solutions must be prepared with the utmost care and precisely according to formulations. Detailed directions for the preparation of all reagents that are required for performing procedures outlined throughout this subcourse are contained in the respective procedure. Careful attention should be given to precise measurements order in which reagents are added, control of temperature where indicated, filtration, and aging. Particular attention must be given to storage of reagents particularly with reference to requirements for refrigeration, incubation, and protection from intense light.


Proper labeling of reagents is an extremely important detail. Labels should be complete, securely attached, and neatly and legibly written or preferably typewritten. Items recorded on the label should include all constituents and quantities utilized, date of preparation, initials of the individual who prepared the reagent, and expiration date if the solution deteriorates with age. Labels should be protected against damage from water or other fluids by covering with a protective coating of cellophane tape over the surface of the label.


There are various precautions that must be taken in handling reagents in the hematology laboratory. Among the most important are the following:

  • Once a portion of a reagent has been removed from the original container, it should never be poured back because it can contaminate the remaining reagent.
  • Reagents are preferably stored in alphabetical order on shelving protected from dust, moisture, and direct sunlight.
  • Never use a reagent that cannot be clearly identified from the label on the container. Discard all reagents that cannot be accurately identified.
  • Always read the label before dispensing a reagent.
  • When working with newly prepared reagents, especially stains, ascertain whether desired results are being obtained. Unsatisfactory solutions should be discarded and replaced.
  • All mixing containers, stirring rods, and containers used for storage of reagents should be chemically cleaned prior to use.
  • During mixing and preparation, as well as in storage, it is good practice to avoid contact of reagents with metals. Many reagents contain substances that will react chemically with metals and produce changes that will render them unusable for laboratory work.
  • Do not allow inexperienced personnel to prepare reagents without close supervision.
  • Certain reagents are poisonous and adequate precautions should be taken to prevent accidental poisoning. All highly toxic reagents should be conspicuously labeled "POISON" and should be stored in a separate cabinet in the laboratory.
  • Commercial reagents should be checked with standards for purity. Record all lot numbers in case a reagent is not pure.
  • Test all new reagents to assure that proper results are attainable.

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