Analytical performance evaluation of the Waters AAAC RUO kit for the measurement of biological metabolites in dried blood spots, by FIA-MSMS

Significance of the topic

The quantitative analysis of metabolites in dried blood spots (DBS) is critical for newborn screening, clinical research and quality control in metabolic disorders.
This approach offers minimal invasiveness, efficient sample handling and the ability to monitor a broad panel of biomarkers from a single micro-volume blood spot.

Objectives and Overview of the Study

This study evaluates the analytical performance of the Waters AA/AC RUO Kit for flow injection analysis tandem mass spectrometry (FIA-MS/MS) of biological metabolites in DBS samples.
Key goals included:

• Assessing precision and accuracy against kit quality control materials.
• Determining linearity across clinically relevant concentration ranges.
• Evaluating recovery relative to kit certificate of analysis and external enrichment materials.
• Monitoring instrument response stability (analytical drift) over extended runs.

Methodology and Sample Preparation

A two-step protocol was employed for extraction and derivatization from 3.2 mm DBS punches:

1. Analytes were eluted through a filtration plate and collected into a receiver plate.
2. SUAC derivatization reagent was added to the punch; extracted and incubated before combining with the initial eluate.

Prepared samples were analyzed by positive electrospray ionization FIA-MS/MS using multiple reaction monitoring.
Data processing and quality assessment were performed with Analyse-It software and Microsoft Excel.

Used Instrumentation

• Waters ACQUITY UPLC I-Class PLUS System
• Xevo TQD IVD Mass Spectrometer
• Analyse-It Software
• Microsoft Excel

Main Results and Discussion

Precision and accuracy:

• Total imprecision was below 20 % CV for all analytes except argininosuccinic acid at low concentration (33.9 % CV).
• Mean recoveries against kit certificate of analysis fell within ±3 SD for both low and high QC levels.

Recovery relative to external enrichment:

• Most analytes showed 65–123 % recovery versus external QC material.
• Succinylacetone exhibited lower recovery (32 %) requiring further optimization.

Linearity and range:

• Analyte calibration curves spanned 9–11 concentration points
• All analytes achieved R² values > 0.97, confirming linear response across the intended analytical ranges.

Analytical drift:

• Internal standard intensities demonstrated less than 10.5 % deviation over a continuous 17-hour run.
• No significant signal degradation was observed for key metabolites (e.g., guanidinoacetate, creatine).

Benefits and Practical Applications of the Method

• Streamlined workflow enabling extraction, derivatization and analysis from a single DBS punch.
• Broad analyte coverage including amino acids, acylcarnitines, nucleosides, ketones and lysophospholipids.
• High throughput capability for large-scale clinical or epidemiological studies.
• Robust performance suitable for research use and potential screening applications.

Future Trends and Potential Applications

Continued expansion of DBS-based metabolite panels to include emerging biomarkers and lipids.
Integration of automated sample handling and robotics for increased throughput and reproducibility.
Application of machine learning and advanced data analytics to improve diagnostic accuracy and pattern recognition.
Potential adaptation of the workflow for newborn screening programs and decentralized testing platforms.

Conclusion

The Waters AA/AC RUO Kit exhibits robust analytical characteristics—including precision, accuracy, linearity and stability—across a diverse range of metabolites in DBS samples.
Its streamlined FIA-MS/MS workflow supports reliable quantitation and positions it as a valuable tool for clinical research and metabolomic studies.

Reference

• Rossiter P., Stafford N., McBrinn R., Brown H. Analytical performance evaluation of the Waters AA/AC RUO Kit for the measurement of biological metabolites in dried blood spots by FIA-MS/MS. Waters Technology, 2025.