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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维生素B12、血清叶酸和holoTC（国际标准）

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