A validated method for capillary phosphatidylethanol 16:0/18:1 quantification with two different 10-µl volumetric...

Area of Science:

• Clinical Chemistry
• Toxicology
• Biomarker Analysis

Background:

• Phosphatidylethanol (PEth) is a reliable biomarker for alcohol consumption, traditionally measured in venous whole blood.
• Growing interest exists in quantifying drugs and biomarkers in capillary blood for less invasive sampling.
• Volumetric absorptive microsampling (VAMS) devices offer a promising approach for capillary blood collection.

Purpose of the Study:

• To adapt and validate a laboratory method for quantifying PEth in capillary dried blood spot (DBS) samples.
• To evaluate the performance of two VAMS devices, Capitainer®B Vanadate and Mitra®, for PEth analysis.
• To compare PEth quantification results from capillary DBS samples with established venous blood measurements.

Main Methods:

• Method development and validation for PEth quantification in capillary DBS using two VAMS devices (Capitainer and Mitra).
• Automatic sample extraction was employed, allowing simultaneous analysis of both VAMS types.
• Validation included assessing performance across a defined measuring range and comparing results with a validated venous blood method.

Main Results:

• The Mitra device met all pre-established validation criteria for PEth quantification in the range of 0.03 to 4.0 µM.
• The Capitainer device met most criteria but showed deviations in accuracy for PEth levels ≥ 0.5 µM (-17.1% to -20.5%).
• Correlation analysis indicated an acceptable proportional mean difference (-7.6%) between Capitainer and venous blood results, with no constant bias.

Conclusions:

• Both Capitainer and Mitra VAMS devices are suitable for PEth analysis in capillary blood.
• The Mitra device demonstrated full compliance with validation criteria, making it highly reliable for capillary PEth quantification.
• The Capitainer device showed acceptable performance, though accuracy at higher concentrations warrants consideration for specific applications.