Method of high-precision microsample blood and plasma mass densitometry

Area of Science:

• Biomedical Engineering
• Clinical Chemistry

Background:

• Accurate density measurements of blood and plasma are crucial for clinical diagnostics.
• Small sample volumes and potential storage issues present challenges in biological fluid analysis.

Purpose of the Study:

• To quantify the reliability of the mechanical oscillator technique (MOT) for blood and plasma mass density measurements.
• To identify and assess sources of error in density determinations.

Main Methods:

• Utilized the mechanical oscillator technique (MOT) for density measurements.
• Analyzed small sample volumes (<0.1 ml) of blood and plasma.
• Investigated effects of sample storage and temperature equilibration on density readings.
• Evaluated rheological influences using different densitometer sizes.

Main Results:

• Achieved reproducibility of density readings within 10⁻² g/l.
• Demonstrated minimal significant changes in plasma density after storage at +4°C (1 week) or -20°C (2 months).
• Found increased variability in plasma density with longer storage, particularly at -20°C.
• Established significant linear correlations between density and key physiological parameters (protein concentration, hemoglobin concentration).

Conclusions:

• The MOT is a reliable method for rapid density measurements of small biological fluid volumes.
• The technique demonstrates high precision (10⁻² g/l reliability) suitable for clinical applications.
• Understanding error sources like storage and temperature is key for accurate density determination.