Measurement of faecal ammonia

Area of Science:

• Biochemistry
• Clinical Chemistry
• Analytical Chemistry

Background:

• Accurate measurement of ammonia in biological samples is crucial for diagnosing various medical conditions.
• Existing methods for stool ammonia analysis may be affected by interfering enzymes.
• Urease and other fecal enzymes can interfere with NADH-based enzymatic assays.

Purpose of the Study:

• To develop and validate a modified end-point enzymatic method for quantifying ammonia in stool water.
• To improve the reliability and accuracy of stool ammonia measurements.
• To address the issue of enzymatic interference in previous analytical methods.

Main Methods:

• A modified end-point enzymatic assay was developed for stool water ammonia determination.
• A key step involved protein precipitation to inactivate urease and other fecal enzymes.
• The method's linearity, precision, and accuracy were evaluated.

Main Results:

• The modified method demonstrated reliability with acceptable precision and accuracy.
• The assay showed linearity up to a concentration of 1.5 mmol/l for stool water ammonia.
• The protein precipitation step effectively prevented interference from urease and NADH-oxidizing enzymes.

Conclusions:

• The modified end-point enzymatic method provides a reliable and accurate means for measuring ammonia in stool water.
• This technique is suitable for clinical and research applications requiring precise ammonia quantification.
• The inclusion of a protein precipitation step enhances the robustness of the enzymatic assay.