Exhaled breath condensate nitrite--methodological problems of sample collection

Area of Science:

• Pulmonary Medicine
• Biomarker Discovery
• Analytical Chemistry

Background:

• Exhaled breath condensate (EBC) analysis is a developing method for monitoring airway inflammation.
• Methodological challenges persist, particularly concerning the reliability of nitrite measurements in EBC.

Purpose of the Study:

• To investigate methodological influences on EBC nitrite levels.
• Key factors examined include surface contamination, flow dependency, storage time, and variability.

Main Methods:

• EBC samples were collected from healthy children, healthy adults, and asthmatic children.
• Nitrite was analyzed using the Griess reaction.
• Variability, flow dependency, and storage stability were assessed under controlled conditions.

Main Results:

• Surface contamination significantly impacted nitrite levels.
• High within-day and inter-day variability was observed.
• No flow dependency was detected, and storage stability was generally satisfactory.

Conclusions:

• EBC nitrite levels are influenced by numerous factors and diverse sources.
• Careful consideration of these influencing factors is crucial for accurate interpretation of EBC nitrite as an airway inflammation biomarker.