In the article by Carter and Jones in the January 2009 issue of the
Annals (Ann Clin Biochem
2009;46:79–81), the following two sentences appeared in
the second paragraph of the Discussion (page 80): ‘Unfortunately, the MACs (molar
absorption coefficients) used to calculate the concentration of 25-OH-D3 and 25-OH-D2
solutions are still the subject of uncertainty. We have been unable to find the
definitive reference to this but, in a personal communication, Dr Hector DeLuca,
Steenbock Research Professor, Department of Biochemistry, University of
Wisconsin-Madison, a leading authority on vitamin D, indicated that 18200 is used in his
laboratory for both 25-OH-D3 and 25-OH-D2’.
Since the article was published, Dr DeLuca has contacted the authors with the
following:
In your 2009 article in the Annals of Clinical Biochemistry
(46:79–81), I was quoted on page 80 in regard to the extinction
coefficient of 25-hydroxyvitamin D2 and 25-hydroxyvitamin D3 as being 18,200. I may have
misled you because we use 19,400 for 25-hydroxyvitamin D2 and 18,200 for
25-hydroxyvitamin D3. Vitamin D2 and vitamin D3 also differ as documented by C.E. Bills
in Sebrell and Harris, ‘The Vitamins’ (vol. II, pages 195 and 202, 1954). Although they
both have the same chromophore, D2 has a double bond at 22–23 that provides a small
increase in U.V. absorption at 265 nm.
The authors apologize for any confusion caused by the information given in the original
article that was passed on in good faith.
