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Table 1 Analytical assay characteristics

From: Comparison of ELISA- and SIMOA-based quantification of plasma Aβ ratios for early detection of cerebral amyloidosis

  Platform ELISA colorimetric SIMOA
Analyte 1–42 1–40 t-tau 1–42 1–40
Assay Provider EUROIMMUN EUROIMMUN ADx ADx ADx
Catalogue number EQ 6521-9601 EQ 6511-9601 NA NA NA
Biofluid EDTA plasma EDTA plasma EDTA plasma EDTA plasma EDTA plasma
Status Commercial Commercial Prototype Prototype Prototype
Specificity 1–42 1–40 6 tau isoforms 1–42 1–40
Dilution Pre-dilution factora 4 4 4 4 20
Final sample dilutionb 5 5 5 5.8 29
Calibrator Type Recombinant Recombinant Recombinant Recombinant Recombinant
No. of calibrator points 7 7 7 7 7
Range, pg/mL 1–40 1–75 1–100 1–64 1–64
Patient samples Number 199 199 199 199 199
Range, pg/mL 8.1–57.1 22.4–311.8 15.0–102.1 7.9–44.0 60.7–160.0
Within cal. range, % 100% 100% 100% 100% 100%
CV% Intra-assay conc 1.63 1.67 2.15 4.33 2.24
Inter-assay conc 4.82 2.58 13.55 8.59 5.95
Analytical sensitivity LoD, pg/mL 2.4 5.7 Not determined 0.46 0.77
LoQ, pg/mL 3.5 12.5 Not determined 1.21 1.57
S/N ratio 7.60 65.4 Not determined 11.0 240
Antibodies [26, 27] Name capture ADx102 (21F12) ADx103 (2G3) ADx203 ADx102 (21F12) ADx103 (2G3)
Epitope capture (AA) 34–42 33–40 Tau194–204 34–42 33–40
Name detector 2G3 2G3 ADx204 2G3 2G3
Epitope detector (AA) 1–5 1–5 TauN-terminus 1–5 1–5
Assay protocol Incubation times, h 3–0.5–0.5 3–0.5–0.5 3–0.5–0.5 2–0.08 2–0.08
Incubation T, °C 18–25 18–25 18–25 18–25 18–25
Curve fit 4PL 4PL 4PL 4PL 4PL
QC panel, pg/mL QC1: high 30.5 189.2 22.3 13.7 83.2
QC2: intermediate 26.6 149.1 18.9 19.7 75.9
QC3: intermediate 22.0 116.8 21.7 13.4 69.7
QC4: low 20.7 107.3 23.7 10.5 33.3
QC5: low spiked 14.4 0.0 NA 21.6 21.8
QC6: high spiked 117.9 125.6 NA 173.7 181.2
C1: low kit control 23.3 114.6 NA NA NA
C2: high kit control 45.1 186.9 NA NA NA
  1. AA amino acid, β-amyloid, CV coefficient of variation, LoD limit of detection, LoQ limit of quantification, S/N ratio signal to noise ratio, QC quality control, T temperature, t-tau total tau
  2. aSample pre-dilution was performed using assay diluent in polypropylene low-binding 96-well microplates
  3. bFinal sample dilution during sample incubation step in assay protocol