Fig. 1.

Effect of storage volume on CSF Aβ. Results in CSF show the concentration of Aβ₄₂, Aβ₄₀, and Aβ₃₈ decreased with decreased storage volume (A, C, E). Concentration of Aβ₄₂ decreased proportionally more than Aβ₄₀ (B) and Aβ₃₈ (D) with lower storage volume, resulting in a decrease in the Aβ₄₂:Aβ₄₀ and Aβ₄₂:Aβ₃₈ ratios. (F) Aβ₄₀ showed a nonsignificant tendency to decrease more than Aβ₃₈, (P = .05). Data for sample S8 at 125 μL were excluded due to insufficient volume in the assay well; the line interpolates through this point. Error bars represent standard error of the mean. Abbreviations: CSF, cerebrospinal fluid; Aβ, amyloid β.