| 摘要 |
<p>Vitamin B12 in liquid samples, such as human serum or human plasma, is assayed by a competitive binding technique using intrinsic factor and certain labelled vitamin B12 derivatives. The labelled derivatives are formed from the (d)-monocarboxylic acid isomer of vitamin B12, which isomer is free from other monocarboxylic acid isomers (and derivatives thereof) of vitamin B12, by binding to the (d)-isomer, via the carboxylic group, a compound which is itself a label (e.g. an enzyme) or which comprises a label (e.g. a fluorophore), or to which a label is attached (e.g. a histidine ester to which 125I is attached). The labelled derivatives of the (d)-monocarboxylic acid of vitamin B12, free from other isomeric monocarboxylic acids and derivatives, are novel and constitute one aspect of the invention.</p> |
