A high-throughput detection platform for dried blood spots constructed with DESI-MS/MS

Dried blood spot (DBS) technology, as a method of blood collection and preservation, has the advantages of small blood collection, convenient transportation and avoiding the degradation of metabolites. In particular, it has broad clinical application prospects in newborn screening and therapeutic drug monitoring. Desorption electrospray mass spectrometry (DESI-MS) is a simple, rapid and in situ spatial metabolomics detection technique, but its throughput, accuracy and coverage for DBS remain to be investigated compared with traditional methods.

In the UPLC-MS/MS platform, the optimal extraction solvent, extraction solvent volume and extraction method were ACN: H₂O (v:v/3:1), 300 μL and ultrasonic extraction, respectively. Based on the DESI-MS/MS platform, the best spray solvent was MeOH: H₂O (v:v/3:1), the spray velocity was set at 2 μL/min, the spray needle angle was set at 55°, and the capillary voltage was set at 4.5 kv (DESI⁺), respectively. The approach delivered consistent data assurance, broad metabolite coverage, and acceptable reproducibility. Finally, these methods were applied to detect the metabolic profiles of subjects before and after drinking sugar-sweetened soy milk, and the metabolic map was well isolated, and the difference metabolites were successfully found.

Two protocols of metabolic profiles for DBS were constructed and optimized. The good performance of DESI-MS/MS was obtained when comparing to the UPLC-MS/MS. The application of sweetened soy milk showed that the two protocols developed have the practicability of detecting differential changes in metabolic profiles of DBS.