Читать книгу Fundamentals of Analytical Toxicology - Robin Whelpton - Страница 46

DBS are produced by the deposition of either haemolyzed whole blood, or capillary blood onto either filter paper, or dedicated paper cards. As compared with either whole blood or plasma, sample transport and storage are easier because refrigeration is not needed provided that the analyte is stable and can be recovered from the spot quantitatively (Wagner et al., 2016; Freeman et al., 2018). Problems are that (i) capillary blood is not venous blood, and (ii) volumetric blood collection directly from the patient onto the medium on which the blood is to be dried is extremely difficult (Sulochana et al., 2019).

Thus, for qualitative work such as screening for inborn errors of metabolism, or for detection of substance misuse, DBS are acceptable provided that the analyte is stable in the spot, but reliable quantitative work means measuring a known volume of venous blood onto the storage medium before allowing it to dry (Section 20.3.1.1). This being said, in forensic work, measurement of the haemoglobin content of a blood spot found at a scene, for example, may serve to give a surrogate measure of the amount of blood deposited initially.