Vitamin B12 (Cyanocobalamin) Test

Method description

This is a microbiological method employing the organism Lactobacillus leichmannii to determine vitamin B12 present in food and vitamin concentrates. Vitamin B12 is extracted from a ground, homogenized sample into a solution of sodium phosphate dibasic, citric acid and sodium bisulfite by autoclaving for 10 minutes at 121 – 123 °C. The pH of the solution is adjusted to 6.0 and the diluted extract is added to a basal medium containing all required growth nutrients for L. leichmannii except vitamin B12. The mixture is inoculated with the microorganism and then incubated for 22 hours at 37°C. The growth response of the microorganism is compared quantitatively to that of known standard solutions of cyanocobalamin (vitamin b12). This method is semi-automated utilizing an automated pipettor system and an automated plate reader system.

Acceptable matrices

This method is applicable to cereals, fruit juices, nutritional supplements and meal replacement beverages containing naturally occurring and/or added vitamin B12.

Unacceptable matrices

This method is not recommended for use on milk-based infant formulas and is not designed for use on vitamin concentrates.

Limit of quantitation

0.2 µg/100g to 800,000 µg/100g

Equipment

Automated pipettor system
Automated plate reader system

Method reference

AOAC 952.20 and 986.23

Reportable unit

µg/100g

Sample size requirements

10 grams

Information required by submitter

Please supply an estimate with your sample.

Additional information

This test is ISO/IEC 17025 accredited through A2LA, Certificate # 2769.01.

This method is not designed for use on vitamin concentrates.