Comparison of standardization techniques for manual colorimetric analyses

Area of Science:

• Analytical Chemistry
• Clinical Chemistry

Background:

• Colorimetric methods are widely used in various analytical applications.
• The precision of these methods can be influenced by standardization procedures.
• Understanding these influences is key for reliable diagnostic and research outcomes.

Purpose of the Study:

• To investigate the impact of standardization modes and standard types on the precision of manual colorimetric methods.
• To introduce and define 'variable calibration mode' and 'constant calibration mode' for standardization.
• To provide evidence-based recommendations for method evaluation and quality control.

Main Methods:

• Evaluation of four manual colorimetric methods under optimal conditions.
• Analysis of variance to assess precision.
• Introduction of 'variable calibration mode' (within-run standards) and 'constant calibration mode' (predetermined calibration).

Main Results:

• Both the mode of standardization and the type of standard significantly affect method precision.
• Calibration relationships and standardization modes require method-specific, objective validation.
• Careful selection of within-run standards is essential when this mode is employed.

Conclusions:

• The choice of standardization strategy and standards critically influences colorimetric assay precision.
• Method-specific, evidence-based calibration and standardization are necessary.
• These findings have direct implications for improving method evaluation and ensuring robust quality control in laboratory settings.