Reagent defined - Any substance in a test system other than a solvent or support material that is required for the target analyte to be detected and its value measured in a sample.

Clinical versus Research Reagents

The Laboratory of Pathology's (LP's) multi-faceted missions, inclusive of clinical and research functions, require the use of a wide array of reagents, test kits, stains, fixatives, and several other chemicals for clinical and research testing. Each LP section must establish their own policies and procedures for the handling, labeling, validations, and proper use of the reagents and chemicals. Because of the dual clinical-research functions in each LP section and due to the more strict regulatory requirements for maintaining clinical reagents, reagents that are used solely for either function must be clearly identified. For example, clinical reagents should be stored on separate shelves and on different levels within refrigerators if possible. Ideally, clinical and research reagents should be stored completely separate, but that might not be feasible in some areas. 'Research Only' labels should designate reagents and chemicals that are not to be reviewed during a clinical accreditation inspection, but it is important that research reagents NOT be used for clinical patient testing.

Reagent Labeling

  • Reagents, calibrators, controls, stains, chemicals, and solutions are properly labeled, as applicable and appropriate, with the following elements: Content and quantity; concentration or titer; storage requirements; date prepared or reconstituted by the laboratory; and expiration date. These elements can be recorded on a log (paper or electronic), and not necessarily on the containers.
  • It is not required to routinely label individual containers with 'date opened'. However, if the open date changes the expiration date (e.g. expires 30 days after opening or at room temperature), the new expiration date must be recorded on the container or log.
  • If the manufacturer defines a required storage temperature range, the temperature of storage areas must be monitored daily. 

Reagent Storage and Handling

  • If there are multiple components of a reagent kit, the laboratory must use components of reagent kits only within the kit lot unless otherwise specified by the manufacturer.

  • All reagents and media must be stored and handled as defined by the laboratory section and following the manufacturers' instructions in order to prevent environmentally-induced alterations that could affect reagent stability and test performance.
  • Special stains and solutions must be properly labeled and changed on a defined schedule. These solutions and stains must be properly labeled with the content, and date changed and expiration if applicable.
  • All reagents, chemicals, and media must be used within their indicated expiration date. If a reagent does not have a manufacturer-provided expiration date, the laboratory section should assign one based on known stability, frequency of use, storage conditions and risk of deterioration.
  • Prepared reagents must be properly stored, mixed when appropriate, and discarded when stability parameters are exceeded.
  • If the section identifies a problem with a reagent that was used for patient testing (e.g. expired vial or reagent subjected to unacceptable storage conditions, etc.), the laboratory must evaluate the potential impact on patient test results and maintain records of the evaluation and actions taken.

New Reagent Lot Confirmation of Acceptability

  • New reagent lots and shipments are checked against previous reagent lots or with suitable reference material before or concurrently with being placed in service. The purpose of this check is to confirm that the use of new reagent lots and shipments do not affect patient results. Matrix  interference between different lots of reagents may impact the calibration status of instruments and consistency of patient results. Improper storage conditions during shipping of reagents may have a negative impact on their ability to perform or exhibit the same levels of reactivity as intended. Testing of new reagent lots and shipments must follow manufacturer's instructions at a minimum.

  • Qualitative: For qualitative nonwaived tests, minimum cross-checking includes retesting at least one positive and negative sample with known reactivity against the new reagent lot. A weakly positive sample is recommended in systems where patient results are reported in that fashion.
    Examples of suitable reference materials for qualitative tests include:

    • Positive and negative patient samples tested on a previous lot;

    • Previously tested proficiency testing materials;

    • External QC materials tested on the previous lot;

    • Control strains of organisms or previously identified organisms

  • Quantitative: For quantitative nonwaived tests, patient specimens should be used to compare a new lot against the previous lot, when possible. Manufactured materials, such as proficiency testing (PT) or QC materials may be affected by matrix interference between different reagent
    lots, even if results show no change following a reagent lot change. The use of patient samples confirms the absence of matrix interference. The following materials may be used:

    • Patient samples tested on a previous lot;

    • Reference materials or QC products provided by the method manufacturer with method specific and reagent lot specific target values;

    • Proficiency testing materials with peer group established means;

    • QC materials with peer group established means based on interlaboratory comparison that is method specific and includes data from at least 10 laboratories;

    • Third party general purpose reference materials if the material is affirmed in the package insert or by the method manufacturer to be commutable with patient specimens for the method. 

    • QC material used to test the current lot is adequate alone to check a new shipment of the same reagent lot, as there should be no change in potential matrix interactions between the QC material and different shipments of the same lot number of reagents.

  • The performance of new lots of antibody and detection system reagents must be compared with old lots before or concurrently with being placed in use for patient testing. Parallel testing is required to control for variables such as disparity in the lots of detection reagents or instrument function. New lots of primary antibody and detection system reagents must be compared to the previous lot using at least one known positive control and one known negative control tissue. This comparison should be made on slides cut from the same control block.
  • New reagent lots of in-situ hybridization (ISH) probes must be checked for acceptable performance prior to use in patient testing. 

Chemical Safety

Laboratory reagents with chemicals must be handled in accordance with safety practices established in the NIH Chemical Hygiene Plan, and chemicals disposed in accordance with NIH Chemical Waste policies. All staff are required to complete annual mandatory NIH Safety Training. 

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Last updated by Lumelski, Victoria (NIH/NCI) [E] on Dec 28, 2023