Performance of three enzymic methods for filter paper glucose determination

Area of Science:

• Clinical Chemistry
• Biochemical Analysis

Background:

• Filter paper blood collection is a practical method for home monitoring of diabetic patients.
• Accurate glucose quantitation from blood spots requires optimized elution and enzymatic methods.

Purpose of the Study:

• To compare three protein precipitants (trichloracetic acid, perchloric acid, sulphosalicylic acid) for glucose elution from filter paper.
• To evaluate the effects of these precipitants on three enzymatic glucose determination methods (glucose dehydrogenase, hexokinase, glucose oxidase).
• To identify the optimal combination for robust glucose quantitation in blood spots.

Main Methods:

• Comparison of trichloracetic acid (TCA), perchloric acid (PCA), and sulphosalicylic acid (SSA) for glucose elution from filter paper.
• Assessment of the impact of elutants on glucose dehydrogenase (GDH), hexokinase (HK), and glucose oxidase (GOD) enzymatic assays.
• Evaluation of reaction time, elution time, precision, and glucose recovery using a microcentrifugal analyser.

Main Results:

• The combination of TCA elutant with the GDH method demonstrated superior performance in terms of reaction and elution times.
• Within- and between-batch precision for the TCA-GDH method were 2.7% and 3.2%, respectively.
• Glucose recovery was 110 +/- 5%, and comparison with an automated GOD method showed high correlation (r=0.9).

Conclusions:

• The TCA-GDH method provides a robust, precise, and accurate means for quantifying glucose in filter-paper blood spots.
• This method offers improved sensitivity and precision compared to glucose oxidase (GOD) methods.
• TCA as an elutant results in faster elution and minimal interference with enzymatic assays.