| Collection Tubes |
Sample collection containers are frequently overlooked variables in laboratory settings [110] The same sample might have different protein profiles when collected in two different types of tube [111,112,113] Blood tube components may adsorb some analytes, particularly proteins, leading to their detection loss [114] Release of plasticisers from tubes into samples may adversely affect high-resolution mass spectrometric examinations [62]
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| Anti-Coagulant |
For metabolomics profiling, sodium fluoride (NaF) and EDTA salts caused less interference than sodium citrate or lithium-heparin [115] Heparin [116,117] or EDTA plasma [115,118,119] is recommended for mass spectrometry-based lipidomic and metabolomic analyses; EDTA plasma is unsuitable for NMR-based approaches as it leads to interferences in the spectra [120] EDTA anti-coagulant is preferable for proteomics [111,121]
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| Hemolysis |
One of the most common pre-analytical errors [122] Destruction of red blood cells Release of proteins, metabolites, and lipids into serum or plasma [115,123] May obstruct correct profile interpretation [115,122] MS-based assessments may be affected [124]
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| Incubation Time |
Many chemical and enzymatic reactions will continue and eventually metabolise the lipids [125,126] Blood cells constantly release, uptake, and metabolise compounds [69,119,127] Metabolites are more sensitive to prolonged incubation at room temperature than at 0–4 °C [124] Peptides and degraded proteins can be released from blood cells [128]
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| Centrifugation Force |
Minor differences in centrifugation could lead to variations in metabolomic patterns [129] Higher centrifugation (between 2300 and 4000× g for 5–10 min) is recommended for lipidomic and metabolomic studies [69] Centrifugation at 1300–2000× g for 15 min was recommended for proteomic studies [130]
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| Storage Conditions |
Several analytes can be affected by storage temperature and time [131] Serum proteins change more at room temperature compared with −20 °C and −80 °C [132] Storage at lower temperatures, such as −80 °C, is recommended [133,134]
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| Freeze–Thaw Cycles |
Repeated freeze–thaw of samples can result in profile alterations [135,136] One freeze–thaw cycle leads to dramatic alterations in several urinary proteins [132]
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