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Table 13 Assay characteristics compared to human GFAP assays

From: Development of a novel, sensitive translational immunoassay to detect plasma glial fibrillary acidic protein (GFAP) after murine traumatic brain injury

Supplier Quanterix# Banyan# BioVendor Randox Elecsys Novel MSD assay
Catalog number N4PA BC-2209 RD192072200R Stroke Array   
Volume of sample/well (μL) 152 250 35 N/A 50 12.5
LLOD (pg/mL) Outcome 0.221 N/A 45 N/A *50 †30 9
Protocol 2.5 SD above background signal of blank. 2 reagent lots and 3 instruments, 12 runs total. N/A 3 SD above background signal. N/A *2 SD above lowest standard point.
†N/A
2.5 SD above background signal of 16 blank replicates.
LLOQ (pg/mL) Outcome 0.467 10 N/A 160 N/A < 24.8
Protocol Serial dilutions of calibrator assayed in triplicate. 2 reagent lots and 3 instruments, 12 runs total. Lowest measured concentration of serum pools (n = 7, some spiked) with duplicate CV < 15%. N/A N/A N/A 10 SD above background signal of 16 blank replicates. Lowest measured concentration of plasma specimens (n = 8) with duplicate CV < 20%.
ULOQ (pg/mL) Outcome 4000 320 25,000 100,000 *150,000
†100,000
> 16,534
Protocol N/A Highest measured concentration of serum pools (n = 7, some spiked) with duplicate CV < 15%. N/A N/A N/A Highest measured concentration of plasma specimens (n = 8) with duplicate CV < 20%.
Intra-assay CV (%) Outcome 4.2 3.6 5.1 3–4 *1.1–1.9
†0.8–0.62
5.0
Protocol Within-run CV from 5 days, 2 runs/day, 1 plasma pool/run, 3 replicates/pool. Within-run CV from 5 days, 1 run/day, 5 serum pools/run, 4 replicates/pool. Within-run CV from 8 replicates of 2 serum specimens. N/A *Within-run CV from 1 run, 4 serum specimens, 21 replicates/specimen.
†Within-run CV from 1 run, 5 serum specimens, 21 replicates/specimen.
Within-run CV from 5 days, 1 run/day, 3 plasma pools/run, 5 replicates/pool.
Inter-assay CV (%) Outcome 0.0 0.8 5.7 N/A *2.7–4.2
†1.8–5.9
7.2
Protocol Between-day CV from 5 days, 2 runs/day, 1 plasma pool/run, 3 replicates/pool. Between-day CV from 5 days, 1 run/day, 5 serum pools/run, 4 replicates/pool. Between-run CV from 7 runs, 2 serum specimens/run. N/A *Between-day CV from 10 runs, 4 serum specimens/run, 21 replicates/specimen
†Between-day CV from 10 runs, maximum 2 runs/day, 5 serum specimens/run, 6 replicates/specimen.
Between-day CV from 5 days, 1 run/day, 3 plasma pools/run, 5 replicates/pool
Recovery Outcome 50–120% N/A 83–115% N/A N/A 62–97%A
86–105%B
Protocol Spike 80 and 800 pg/mL into serum (n = 2) and plasma (n = 2). N/A Spike 500, 1000, and 5000 pg/mL into serum (n = 3). N/A N/A Spike 100, 1000, and 10,000 pg/mL into plasma (n = 5).
Dilution Linearity Outcome 102–121% 89–100% 97–121% N/A N/A 93–105%
Protocol Spiked serum diluted 1:4 to 1:128. Combined clinical specimens with a low-concentration serum pool in different proportions (n = 11) Serum (n = 3) diluted 1:2 to 1:8. N/A N/A Plasma (n = 3) diluted 1:2 to 1:16.
Performance data retrieved from: Supplier Supplier Supplier Posti et al 2017 [47] *Tichy et al [15]
†Luger et al [18]
 
References [7, 11,12,13,14, 26, 31, 44] [4, 8, 9, 17, 24, 25, 40] [6, 10, 11] [16, 41, 47] [15, 18]  
  1. #Same antibody pair used between assays. A Recovery data for samples with low endogenous GFAP. B Recovery data for samples with high endogenous GFAP. N/A data not available, LLOD lower limit of detection, LLOQ lower limit of quantification, ULOQ upper limit of quantification, CV coefficient of variation, SD standard deviation