Sample matrix is critical in the evaluation of a dry-slide bromocresol green method for human albumin.
BACKGROUND
A dry-slide bromocresol green method for serum albumin consistently demonstrated negative bias in a proficiency testing scheme, particularly at low albumin concentrations.


RESULTS
Albumin was measured using both a dry-slide method and an immunonephelometric method in patient serum samples and external quality assessment samples. Results obtained using the dry-slide method were lower than those obtained using immunonephelometry (mean bias--1.0 g/L, P=0.0039), but this difference was exaggerated in the quality assessment samples. In three other albumin preparations with assigned concentrations, recovery with the dry-slide method decreased upon dilution of the matrix.


CONCLUSIONS
Our results suggest that apparent under-recovery of albumin using this technology is probably due to the diffusive properties of the quality assessment sample matrix.
Payn
Michelle M
MM
Department of Clinical Biochemistry, East Kent Hospitals NHS Trust, Kent and Canterbury Hospital, UK.
Lawrence
David
D
Willis
Roger
R
Lamb
Edmund J
EJ
D015982:Bias; D001800:Blood Specimen Collection; D001961:Bromcresol Green; D004058:Diffusion; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D011786:Quality Control; D012709:Serum Albumin / Q000032:analysis*
D012709:Serum Albumin; D001961:Bromcresol Green