Table 1.

Explanation of acronyms used in Figure 5.

Acronym	Method	Comment
SLE	Solid-liquid extraction	Use of aqueous/organic mixtures to preferentially extract target analytes.
FIA	Flow injection analysis	A high throughput analysis method, often coupled to tandem MS for biomarker quantification; useful for screening of diseases. Potential for autosampler carry-over for performing online derivatizations.
MALDI	Matrix-assisted laser desorption ionization	High sample throughput for small pharmaceuticals, and not susceptible to ionization suppression by salts and buffers. Singly-charged species dominate for quantitation of biomolecules.
LDTD	Laser diode thermal desorption	High throughput (~9 s/sample), used for pharmaceutical discovery as alternative to plasma-based sources.
APCI	Atmospheric pressure chemical ionization	Enhanced detection of low-abundance molecules in small volume samples; capable of coupling to LC.
ICP	Inductively coupled plasma	Laser ablation allows ICP to be used for DBS analysis; causes atomization and ionization of gas-phase atoms. Typically used for metal analysis.
LC	Liquid chromatography	Allows highly sensitive detection when coupled to MS by reducing matrix effects. Pre-treatment of complex mixture required.
MS	Mass spectrometry	A versatile approach to chemical detection based on molecular weight measurements and fragmentation patterns.
GC	Gas chromatography	Allows highly sensitive detection of small molecules when coupled to MS. requires extensive sample preparation including but not limited to pre-derivatization and solid-liquid extractions.
SSSP	Sealing surface-sampling probe	Elimination of inhomogeneity by sampling entire DBS. Compatible with LC separations.
LMJ-SSP	Liquid microjunction surface-sampling probe	Better suited for non-porous/hard surfaces; incompatible with LC-separations.
CE	Capillary electrophoresis	Highly sensitive and does not require sample extraction; well suited for genotyping from small microvolumes. Reproducibility may be limited by adsorption of serum components and other matrix components in capillary wall.
ESI	Electrospray ionization	Commonly interfaced with LC for analysis of DBS, after analyte extraction from paper substrate
DESI	Desorption electrospray ionization	Uses ESI droplets to enable direct analysis of DBS without prior extraction or treatment.
DART	Direct analysis in real time	Uses metastable helium gas to enable direct analysis of DBS without prior treatment.
APTDCI	Atmospheric pressure thermal desorption chemical ionization	Enables qualitative and quantitative analysis of lipophilic compounds such as sterols in newborn screening. Works well for ionization of low proton-affinity compounds.
LA-ICP	Laser ablation inductively coupled plasma	Detection of trace metals (e.g., lead) in blood. Limited by matrix effects of sample but requires little to no sample preparation. Analysis of DBS in solid state.