Fig. 5
Guanidine hydrochloride (GuHCl) pretreatment increases cerebrospinal fluid (CSF) amyloid-β (Aβ) recovery and decreases aliquot size differences as measured by 2D ultraperformance LC-MS/MS. a Aliquots (0.1 ml and 0.5 ml) of CSF from patients with Alzheimer’s disease were denatured with GuHCl before the samples were removed from the aliquot tube (GuHCl Before Transfer) or after the samples were removed from the original aliquot tube (GuHCl After Transfer). b GuHCl denaturation before transfer increased Aβ peptide recovery while decreasing aliquot size-associated recovery differences (n = 7). c When CSF was denatured with GuHCl after the sample was transferred to another tube, Aβ peptide recovery was lower, and concentrations obtained from 0.5-ml aliquots were higher than those obtained from 0.1-ml aliquots (n = 7). Aβ1–34 concentrations were below the limit of detection for two and four subjects under each condition (b and c, respectively). Solid line = line of identity, where y = x