Analytical Determination of Vitamin B12 Content in Infant and Toddler Milk Formulas by Liquid Chromatography Tandem Mass Spectrometry (LC-MS/MS)

Identification of vitamin B12 producing bacteria based on the presence of bluB/cobT2 homologues

OBJECTIVES

The objective of the study was to develop a strategy for the identification of new vitamin B₁₂-producing species and to characterize their production capability using a fast and sensitive LC-MS/MS method developed in this study.

RESULTS

Searching for homologues of the bluB/cobT2 fusion gene known to be responsible for the production of the active vitamin B₁₂ form in P. freudenreichii was shown to be a successful strategy for the identification of new vitamin B₁₂-producing strains. The analysis of the identified strains via LC-MS/MS showed the ability of Terrabacter sp. DSM102553, Yimella lutea DSM19828 and Calidifontibacter indicus DSM22967 to produce the active form of vitamin B₁₂. Further analysis of vitamin B₁₂ production capability of Terrabacter sp. DSM102553 in M9 minimal medium and peptone-based media revealed that the highest yield of 2.65 µg of vitamin B₁₂ per g dry cell weight was obtained in M9 medium.

CONCLUSIONS

The proposed strategy enabled identification of Terrabacter sp. DSM102553, whose relatively high yields obtained in the minimal medium open new perspectives for the possible application of the strain for biotechnological vitamin B₁₂ production.

Determination of Vitamin B12 in Milk and Dairy Products by Isotope-Dilution Liquid Chromatography Tandem Mass Spectrometry

An isotope-dilution liquid chromatography tandem mass spectrometry method was established for the determination of vitamin B12 in milk and dairy products. The samples were spiked with stable isotope-labeled vitamin B12 and digested by pepsin and amylase. The various forms of cobalamin were transformed to cyanocobalamin by potassium cyanide after they were released from the enzymatically digested samples. Cyanocobalamin was extracted and purified by an immunoaffinity SPE cartridge and then measured in multiple reaction monitoring mode (MRM). The linear correlation coefficient (R2) of this method was greater than 0.999 in the range of 2–100 ng/mL. The detection limit and the quantification limit were 0.5 μg/kg and 1.0 μg/kg, respectively. The spiked recoveries ranged from 92.0% to 99.4% at the three spiked levels with the relative standard deviation (RSD) between 1.89% and 4.51%. The measured results of NIST SRM1849a and NIST SRM1869a by the current method are all within the reference value range. The Z value was 0.8 during participating in the FAPAS proficiency test using the developed method in 2021. The method is simple, rapid, accurate, and sensitive, and it is suitable for the determination of vitamin B12 in different types of milk and dairy products such as whey powder, whole milk powder, pure milk, fermented milk, infant formula, and prescription food for special medical purposes.

Determination of cobalamin and related compounds in foods

The microbiological assay of total cobalamin (vitamin B₁₂) by Lactobacillus delbrueckii subsp. lactis ATCC7830 is now used worldwide in food analysis because of its high sensitivity, low running cost, and no expensive instruments. It has been recently reported that some foods contain a substantial number of inactive corrinoid compounds, some of which are active in this bacterium. These results indicate that the microbiological method must be replaced with high-performance liquid chromatography or liquid chromatography/electrospray ionization-tandem mass spectrometry as there can specifically determine biologically active cobalamin. Nowadays, powerful tools, such as immunoaffinity columns, purify cobalamin simply and specifically. In this chapter, we summarized the determination methods of cobalamin and related compounds in foods. Various inactive corrinoids found in foods were also characterized.

Development of a simple and sensitive HPLC-DAD method for quantification of vitamin B12 fortified in infant food

To prevent infants from vitamin B12 deficiency, infant food is designed based on cow's milk or cereal with the fortification of vitamin B12. A method for quantitative determination of vitamin B12 in infant food was developed with hydrophilic high performance liquid chromatography (HPLC) coupled with a diode array detector (DAD). The sensitivity of the detector was enhanced by implementing a 60 mm high-sensitivity LightPipe flow cell, and the limit of detection (LOD) and limit of quantification (LOQ) were improved as low as 0.006 μg 100 g^-1 and 0.02 μg 100 g^-1 respectively. The effect of sample extraction and enrichment, chromatography separation parameters on the analyte, were studied in detail and optimized. Under these conditions, the method performed a good linear analytical range of 0.3-50 μg L^-1, and a good repeatability with % RSD below 2.8% and recovery of 90.2-96.5% (n = 6). To the best of our knowledge, for the first time, 60 mm high-sensitivity LightPipe flow cell was included in the HPLC-DAD method for determination of the trace amount of vitamin B12 in infant food. The proposed method was further validated by analysis of FAPAS QC samples (T21120 and T21118), and it was specific and precise for the intended use.

Development of Pretreatment Method for Analysis of Vitamin B12 in Cereal Infant Formula using Immunoaffinity Chromatography and High-Performance Liquid Chromatography

Vitamin B₁₂ deficiency may lead to serious health issues in both infants and adults. A simple analytical method involving sample pretreatment with enzyme, followed by cyanide addition under acidic conditions; separation on an immunoaffinity column; and high-performance liquid chromatography (HPLC) was developed for the rapid detection and quantitation of vitamin B₁₂ in powdered milk. Detection limit and powdered milk recovery were determined by quantitative analysis. The limits of detection and quantitation were 2.71 and 8.21 μg/L, respectively. Relative standard deviations of the intra-day and inter-day precisions varied in the ranges of 0.98%–5.31% and 2.16%–3.90%, respectively. Recovery of the analysis varied in the range of 83.41%–106.57%, suggesting that the values were acceptable. Additionally, vitamin B₁₂ content and recovery in SRM 1849a were 54.10 μg/kg and 112.24%, respectively. Our results suggested that the analytical method, including the sample pretreatment step, was valid. This analytical method can be implemented in many laboratory-scale experiments that seek to save time and labor. Therefore, this study shows that immunoaffinity–HPLC/ultraviolet is an acceptable technique for constructing a reliable database on vitamin B₁₂ in powdered milk containing starch as well as protein and/or fat in high amounts.

Influence of food groups on plasma total homocysteine for specific MTHFR C677T genotypes in Chinese population

Scope

It has been demonstrated that a mutation of MTHFR C677T increases plasma total homocysteine (Hcy) concentration and decreases folate. Natural foods can improve Hcy levels, but the effect of certain foods remains undetermined. The aim of this study was to investigate the association between food groups and Hcy, and to explore the correlations between Hcy and dietary folate/vitamin (Vit) B12 for genotype‐specific population.

Methods and results

A total of 4507 adults were enrolled in this study, all of whom underwent physical examinations and genotyping. A dietary recall questionnaire, which assessed the frequency (F) and quantity (Q) of food consumption, was completed by all. For the male CC group, after adjustment for age and BMI, fish (F) was negatively correlated with Hcy; for the male CT group, fish (F) and eggs (F) were negatively associated with Hcy, whereas cereal/wheat (Q) were positively correlated with Hcy; for the male TT group, fish (F), meat (Q), milk (F), and fruits/vegetables (Q) were negatively associated with Hcy, whereas sugar (Q) and salt (Q) were positively associated with Hcy. For the female CC group, fruits/vegetables (Q), eggs (F) and meat (F) were negatively correlated with Hcy, but soy (F) was positively correlated with Hcy; for the female CT group, eggs (F) and meat (Q) were negatively correlated with Hcy, whereas soy (F), fried foods (F) and salt (Q) were positively correlated with Hcy; for the female TT group, fish(F), eggs (F), and fruits/vegetables (F) were negatively associated with Hcy. Furthermore, we found that Hcy was more closely correlated with folate than with Vit B12 for males (CC, CT and TT) and female TT genotype. However, the correlation between Hcy and Vit B12 was stronger for the female CT/CC groups.

Conclusion

Hcy levels were influenced by food groups to varying degrees, which were based on gender and MTHFR C677T genotypes. Hcy levels were more closely correlated with folate for males (CC, CT and TT) and the female TT group, but it was more closely correlated with Vit B12 for the female CT/CC groups.