Dried matrix spots and clinical elemental analysis. Current status, difficulties, and opportunities

This article examines the increasing importance of dried matrix spots (DMS), such as dried blood spots, dried urine spots, etc., in biomedical research, the challenges associated with their analysis when quantitative elemental information is aimed at, as well as the benefits deriving from the further usage of these types of samples. The article briefly reviews the historical evolution of this sampling approach in elemental clinical analysis, stressing prospective areas of applications (e.g., newborns or prosthesis control), the methodologies most recently developed to produce DMS of known volume, as well as novel strategies proposed to analyze them, often related to direct solid sampling techniques or fast lixiviation methods. Finally, the article discusses the type of information that could be obtained after isotopic analysis of DMS when targeting non-traditional stable isotopes (e.g., Cu, Fe or Zn), which can significantly help in the early diagnosis of some medical conditions (e.g. Wilson's disease).