Vitamins D and A can be successfully measured by LC-MS/MS in cord blood diluted plasma.
OBJECTIVE
In widely used protocols for the collection and isolation of cord blood mononuclear cells, investigators are left with substantial volumes of diluted plasma which could be used for other measurements. The aim of this study was to ascertain the validity of umbilical cord blood (UCB) diluted plasma samples for vitamin D, A and E analysis compared to UCB serum samples.


METHODS
Twenty UCB matched samples of diluted plasma and serum were collected. The samples were analysed by two liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods on two separate occasions.


RESULTS
The results of 25(OH)D3 obtained by the two laboratories demonstrated close agreement with a mean difference of 0.14nmol/L [95% confidence interval (95% CI), -6.8 to 7.1]. Both methods demonstrate close agreement for 25(OH)D3 in UCB serum versus diluted UCB plasma; mean difference 2.2nmol/L [95% CI, -9.5 to 13.9] and 4.1nmol/L [95% CI, -14.5 to 6.1] for the results from Lab A and Lab B, respectively. Vitamin A was quantified by Lab A in UCB serum and diluted UCB plasma; mean difference 0.07μmol/L [95% CI, -0.41 to 0.28]. Results of 25(OH)D3 epimer and vitamin E in the diluted UCB plasma were below the limit of quantification, and could not be compared with UCB serum.


CONCLUSIONS
Diluted UCB plasma can be used for the quantification of retinol and 25(OH)D3 by LC-MS/MS. By contrast, quantification of 25(OH)D3 epimer and vitamin E in diluted UCB plasma is not supported by this study due to limitations in analytical sensitivity.
School of Medical Sciences, RMIT University, Victoria, Australia; Security Forces Hospital, Dammam, Saudi Arabia.
Ali A
AA
Albarhani
Deakin University, Victoria, Australia.
Fiona
F
Collier
School of Medical Sciences, RMIT University, Victoria, Australia; Murdoch Children's Research Institute, Melbourne, Australia.
Ronda F
RF
Greaves
Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia.
Anne-Louise
AL
Ponsonby
Murdoch Children's Research Institute, Melbourne, Australia; Department of Paediatrics, University of Melbourne, Victoria, Australia.
Katrina J
KJ
Allen
Deakin University, Victoria, Australia; Child Health Research Unit, Barwon Health, Victoria Australia.
Peter J
PJ
Vuillermin
School of Medical Sciences, RMIT University, Victoria, Australia.
Peter
P
Roche
University of Western Australia, Western Australia, Australia. Electronic address: michael.clarke@uwa.edu.au.
Michael W
MW
Clarke
D002853:Chromatography, Liquid / Q000379:methods; D005312:Fetal Blood / Q000737:chemistry*; D006801:Humans; D010949:Plasma / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods; D014801:Vitamin A / Q000097:blood*; D014807:Vitamin D / Q000097:blood*; D014810:Vitamin E / Q000097:blood
D014801:Vitamin A; D014807:Vitamin D; D014810:Vitamin E
Cholecalciferol; Mass spectrometry; Neonates; Retinol; Umbilical cord blood diluted plasma