Collaborative study: Quantification of total folate in food using an efficient single-enzyme extraction combined with LC-MS/MS.

Quantification of the specific folate vitamers to estimate total folate in foods is not standardized. A collaborative study, including eight European laboratories, was conducted in order to determine the repeatability and reproducibility of the method for folate quantification in foods using the plant-origin γ-glutamyl hydrolase as part of the extraction procedure. The seven food samples analyzed represent the food groups; fruits, vegetables, dairy products, legumes, offal, fish, and fortified infant formula. The homogenization step was included, and six folate vitamers were analyzed using LC-MS/MS. Total folate content, expressed as folic acid equivalent, was 17-490 µg/100 g in all samples. Horwitz ratio values were within the acceptable range (0.60-1.94), except for fish. The results for fortified infant formula, a certified reference material (NIST 1869), confirmed the trueness of the method. The collaborative study is part of a standardization project within the Nordic Committee on Food Analysis (NMKL).

Quantitative analysis of tetrahydrofolate metabolites from clostridium autoethanogenum.

INTRODUCTION: Quantification of tetrahydrofolates (THFs), important metabolites in the Wood-Ljungdahl pathway (WLP) of acetogens, is challenging given their sensitivity to oxygen. OBJECTIVE: To develop a simple anaerobic protocol to enable reliable THFs quantification from bioreactors. METHODS: Anaerobic cultures were mixed with anaerobic acetonitrile for extraction. Targeted LC-MS/MS was used for quantification. RESULTS: Tetrahydrofolates can only be quantified if sampled anaerobically. THF levels showed a strong correlation to acetyl-CoA, the end product of the WLP. CONCLUSION: Our method is useful for relative quantification of THFs across different growth conditions. Absolute quantification of THFs requires the use of labelled standards.