Improved enzymic assay for serum formate with colorimetric endpoint

Area of Science:

• Clinical Chemistry
• Biochemical Assays
• Analytical Chemistry

Background:

• Fluorometric assays for serum formate can suffer from nonlinear calibration and require specialized equipment.
• Existing methods may necessitate complex sample preparation and lack broad dynamic range.

Purpose of the Study:

• To develop a modified, more robust, and user-friendly fluorometric assay for quantifying formate in serum.
• To overcome limitations of previous formate detection methods, enhancing accuracy and efficiency.

Main Methods:

• Serum samples were pretreated with acetonitrile for protein precipitation.
• A new reagent combining nicotinamide adenine dinucleotide (NAD), diaphorase, and p-iodonitrotetrazolium violet (INT) was utilized.
• Formate oxidation by formate dehydrogenase produced NADH, which reduced INT to a colored product measured spectrophotometrically at 500 nm.

Main Results:

• The modified assay demonstrated linear calibration, unlike previous nonlinear methods.
• Acetonitrile pretreatment minimized the need for blanking, and the dynamic range was expanded up to 10-fold.
• The assay proved to be linear, specific, sensitive, precise, and accurate, using a standard spectrophotometer.

Conclusions:

• The modified fluorometric assay offers significant improvements over existing methods for serum formate determination.
• This enhanced procedure simplifies measurement, expands dynamic range, and ensures reliable, accurate results for clinical applications.