维生素B12、血清叶酸和holoTC（国际标准）
| 【编号】：NIBSC03/178 【产品名称】：维生素B12、血清叶酸和holoTC（国际标准） 【规格】：个 【价格】：2600元   维生素B12、血清叶酸和holoTC（国际标准）
编号：NIBSC03/178
英文：Vitamin B12, Serum Folate and holoTC (International standard)
标准类型：国际标准品
规格：1个
描述：
1. INTENDED USE
The assay of blood levels of the vitamins B12 and folate is the current
routine procedure for determining deficiency of these vitamins. Deficiency
can result in a number of clinical conditions including megaloblastic and
pernicious anaemia.
The International Standard (IS) for serum B12 and serum folate, 03/178,
was assayed using a wide range of methods in 24 laboratories in 7
countries. Methods included a range of commercial analysers and, for
serum folate, candidate reference methods of isotope-dilution tandem
mass spectrometry coupled to liquid chromatography (LC/MS/MS). The
inclusion of three serum samples in the study, with different B12 and folate
levels, demonstrated a considerable reduction in inter-laboratory variability
when the B12 and folate levels in the samples were determined relative to
the IS with assigned B12 and folate values rather than to the analysers’
calibration.
Since the IS was first established, commercial assays for
holotranscobalamin (holoTC), the active portion of B12, have become
available. There is evidence that holoTC is a better marker of early B12
deficiency than total B12. This prompted another international
collaborative study to assign a holoTC value to the IS for B12 and serum
folate, 03/178. Twelve laboratories in 8 countries participated.
2. CAUTION
This preparation is not for administration to humans or animals in
the human food chain.
The preparation contains material of human origin, and either the final
product or the source materials, from which it is derived, have been
tested and found negative for HBsAg, anti-HIV and HCV RNA. As with
all materials of biological origin, this preparation should be regarded as
potentially hazardous to health. It should be used and discarded
according to your own laboratory's safety procedures. Such safety
procedures should include the wearing of protective gloves and
avoiding the generation of aerosols. Care should be exercised in
opening ampoules or vials, to avoid cuts.
3. UNITAGE
The IS for serum B12 and serum folate, 03/178, has an assigned value of
12.1 nmol/L total folate, made up of 9.75 nmol/L 5MeTHF (5-
methyltetrahydrofolate; coefficient of variation (CV) 5.5%), 1.59 nmol/L
5FoTHF (5-formyltetrahydrofolate; CV 4.2%) and 0.74 nmol/L FA (folic
acid; CV 31.6%), when reconstituted with 1.0 mL distilled/deionised water,
as determined using LC/MS/MS. The total folate content of 12.1 nmol/L is
equivalent to 5.33 ng/mL, using a conventional conversion factor of 2.266.
The IS for serum B12 and serum folate, 03/178, has an assigned
consensus value of 480 pg vitamin B12 (480 pg/mL when reconstituted
with 1.0 mL distilled/deionised water). The preparation will be reevaluated
when a reference measurement procedure has been
established.
The IS 03/178 has an assigned consensus holoTC value of 107 pmol/L
when reconstituted with 1.0 mL (0.107 pmol/ampoule).
The variance in the ampoule contents was determined to be 0.08%.
4. CONTENTS
Country of origin of biological material: United Kingdom.
Each ampoule contains the lyophilized residue of ~1 mL human
serum.
5. STORAGE
Unopened ampoules should be stored at -20°C or below.
Please note: because of the inherent stability of lyophilized material,
NIBSC may ship these materials at ambient temperature.
6. DIRECTIONS FOR OPENING
DIN ampoules have an 'easy-open' coloured stress point, where the
narrow ampoule stem joins the wider ampoule body. Various types of
ampoule breaker are available commercially. To open the ampoule, tap
the ampoule gently to collect material at the bottom (labelled) end and
follow manufactures instructions provided with the ampoule breaker.
7. USE OF MATERIAL
No attempt should be made to weigh out any portion of the freeze-dried
material prior to reconstitution
Reconstitute the contents with 1.0 mL distilled/deionised water on the day of
assay.
8. STABILITY
It is the policy of WHO not to assign an expiry date to their international
reference materials. They remain valid with the assigned potency and
status until withdrawn or amended.
Reference materials are held at NIBSC within assured, temperaturecontrolled
storage facilities. Reference Materials should be stored on
receipt as indicated on the label. For information specific to a particular
biological standard, contact the Technical Information Officer or, where
known, the appropriate NIBSC scientist.
NIBSC follows the policy of WHO with respect to its reference materials.
Accelerated degradation studies on 03/178 indicate that the lyophilized
material will be adequately stable at -20°C with respect to B12, holoTC
and folate content. Once reconstituted, users should determine the
stability of the material according to their own conditions of storage and
use.
Users who have data supporting any deterioration in the characteristics of
any reference preparation are encouraged to contact NIBSC.
9. REFERENCES
SJ Thorpe, A Heath, S Blackmore, A Lee, M Hamilton, S O’Broin, BC Nelson
and C Pfeiffer. An international standard for serum vitamin B12 and serum
folate: international collaborative study to evaluate a batch of lyophilized
serum for B12 and folate content. Clin Chem Lab Med 45, 380-386 (2007).
10. ACKNOWLEDGEMENTS
We thank the participants of the collaborative studies.
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