Embossed Paper Platform for Whole Blood Collection, Room Temperature Storage, and Direct Analysis by Pinhole Paper Spray Mass Spectrometry

Abstract

Dry-state microsampling techniques are convenient and advantageous for sample collection in resource-limited settings, including healthcare systems designed for the underserved population. In this work, a microsampling platform based on an embossed hydrophobic paper substrate is introduced together with three-dimensional (3D) printed cartridges that offer opportunities for rapid (<30 min) drying of the collected samples while also preserving sample integrity when the embossed paper chip is shipped at room temperature. More importantly, a new pinhole paper spray ionization method was developed that facilitates direct mass spectrometry (MS) analysis of the dried blood samples without prior sample preparation. We compared the direct pinhole paper spray MS method with a liquid chromatographic (LC) MS approach that relied upon electrospray ionization (ESI) after analytes present in the blood sample were extracted through liquid–liquid extraction. Limits of detection as low as 0.12 and 0.49 ng/mL were calculated for cocaine and its metabolite benzoylecgonine, respectively, when using the direct pinhole paper spray MS method. Analytical merits such as precision and accuracy, recovery, carryover effects, and analyte stability were all quantified for this new paper spray method and compared to the traditional LC-ESI-MS. Although LC-ESI-MS was observed to be 10× more sensitive, the linear dynamic range for both methods was determined to be the same, in the range of 1–500 ng/mL for both cocaine and benzoylecgonine analytes. When fully developed, the current microsampling strategy could offer an easy-to-use kit that can enable a more effective MS analysis of 20 μL dried blood samples delivered by mail. Both sensitivity (10×) and sample stability are found to be more superior for blood prepared in the embossed hydrophobic paper compared to samples prepared in the planar hydrophilic paper.

On-Demand Portable Paper-Based Electrospray Ionization Mass Spectrometry for High-Sensitivity Analysis of Complex Samples

“…As the PSI-MS was employed, therapeutic drugs tended to be degraded after exposing in the air for a period. 41 For the developed PPESI-MS, no noticeable degradation behavior of target compounds in the blood (e.g., risperidone) was observed even after exposing to the air for 30 days (Figure 3d), the RSD between them was only 3%, similar to the microsampling platform based on an embossed hydrophobic paper substrate reported by Frey et al 42 To our knowledge, this case could be related to the dark yellow and the compactness of ZnO-packed micropipette tips, which, to a certain degree, prevented both the illustration of sunlight and the quick interaction with air.…”

Capillary-in-Capillary Electrospray Ionization (CC-ESI) Source Enabling Convenient Sampling and Quantitative Analysis for Point-of-Care Testing

“…Among them, spray-based ionization sources such as DESI are the most widely used MS methods for clinical analyses up to now. For example, a paper spray ionization source enables the direct separation of matrices from a raw sample and has been applied to analyze drugs and biomarkers in biofluids. − Slug-flow microextraction (SFME) nano-electrospray ionization (SFME-nano-ESI) was developed for the direct analysis of therapeutic and illicit drugs in blood or urine samples by combining liquid–liquid extraction and electrospray ionization . A needle biopsy spray or tissue spray was reported to distinguish cancerous and normal tissues. , …”

The Effect of the Physical Morphology of Dried Biofluids on the Chemical Stability of Analytes Stored in Paper and Direct Analysis by Mass Spectrometry

“…The use of hydrophobic paper not only provides an efficient means to prepare 3D biofluid scaffolds to preserve analyte integrity in the dry state but also as a sensitive method for the direct MS analysis of the stored samples without significant dilution. 12 Further development of this field-amenable paper-based platform will combine the fundamental insights from this study with our recently described embossment strategy 26 to expand applications to clinical samples. For example, ongoing studies involve the analysis of collected samples for the detection of malaria metabolites.…”