The investigation, development and application of non-targeted metabolomic methods applying dried blood spot collection

Palmer, Elliott ORCID: 0000-0001-6495-3677 (2020). The investigation, development and application of non-targeted metabolomic methods applying dried blood spot collection. University of Birmingham. Ph.D.

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Abstract

The use of dried blood spots (DBS) as an alternative sampling method to venous blood draws is a well established technique within clinical and pharmaceutical research set- tings, with routine assays applied to quantify a small number of analytes applying targeted analytical assays. However the use of DBS within non-targeted metabolomics research is limited. Concerns about DBS have limited its use for non-targeted work and therefore its applicability in large scale studies where DBS is a very attractive alterna- tive. With lower costs associated with collecting, storing and transporting samples, DBS offer a great alternative to whole biofluid samples.

This thesis aims at assessing the applicability of DBS collection in non-targeted metabolomics scenarios. Initially, the stability of DBS was studied over the course of 12 months, at various temperatures and guidelines surrounding the best practices of storing DBS identified with suitable stability at room temperature in the short term however for longer term storage of samples should be at -20◦C or -80◦C.

Secondly a surface analysis method was developed with the aim of increasing the throughput of DBS data collection. The method developed applied a simple 5 second extraction from the surface of a DBS with parameters optimised to be able to extract multiple thousands of features and similar analytical performance to a comparable direct infusion mass spectrometry method.

Additionally, a new method for normalisation of whole blood volume spotted onto the DBS card was developed for non-targeted analysis with the goal of reducing non-biological variation within the sample. Results demonstrated applying the Brad- ford assay to the measurement of total protein content with a DBS reduced the non- biological variation present within the sample.

Finally, a surrogate of DBS in dried serum and plasma spots were applied in a medium scale biological study in developing countries, proving that whether or not you are using the whole biofluid or whether it is dried, a comparable biological con- clusion is reached with similar lipid classes significantly changing in relation to hyper- vitaminosis A in both plasma or serum and their associated dried biofluid spots.

The research presented within this thesis has demonstrated the applicability of DBS for non-targeted metabolomics in mammalian research. With new methods to nor- malise data, to reduce technical variation and analyse DBS using a surface analysis technique. Further assessment in real world biological research applications are re- quired to expand the application of DBS.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):