Skip to Content
Merck
  • Quantitation of 5-Methyltetrahydrofolic Acid in Dried Blood Spots and Dried Plasma Spots by Stable Isotope Dilution Assays.

Quantitation of 5-Methyltetrahydrofolic Acid in Dried Blood Spots and Dried Plasma Spots by Stable Isotope Dilution Assays.

PloS one (2015-11-26)
Markus Kopp, Michael Rychlik
ABSTRACT

Because of minimal data available on folate analysis in dried matrix spots (DMSs), we combined the advantages of stable isotope dilution assays followed by LC-MS/MS analysis with DMS sampling to develop a reliable method for the quantitation of plasma 5-methyltetrahydrofolic acid in dried blood spots (DBSs) and dried plasma spots (DPSs) as well as for the quantitation of whole blood 5-methyltetrahydrofolic acid in DBSs. We focused on two diagnostically conclusive parameters exhibited by the plasma and whole blood 5-methyltetrahydrofolic acid levels that reflect both temporary and long-term folate status. The method is performed using the [2H4]-labeled isotopologue of the vitamin as the internal standard, and three steps are required for the extraction procedure. Elution of the punched out matrix spots was performed using stabilization buffer including Triton X-100 in a standardized ultrasonication treatment followed by enzymatic digestion (whole blood only) and solid-phase extraction with SAX cartridges. This method is sensitive enough to quantify 27 nmol/L whole blood 5-methyltetrahydrofolic acid in DBSs and 6.3 and 4.4 nmol/L plasma 5-methyltetrahydrofolic acid in DBSs and DPSs, respectively. The unprecedented accurate quantification of plasma 5-methyltetrahydrofolic acid in DBSs was achieved by thermal treatment prior to ultrasonication, inhibiting plasma conjugase activity. Mass screenings are more feasible and easier to facilitate for this method in terms of sample collection and storage compared with conventional clinical sampling for the assessment of folate status.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Sodium hydroxide, BioXtra, ≥98% (acidimetric), pellets (anhydrous)
Sigma-Aldrich
Sodium hydroxide, puriss., meets analytical specification of Ph. Eur., BP, NF, E524, 98-100.5%, pellets
Sigma-Aldrich
Sodium hydroxide, ultra dry, powder or crystals, 99.99% trace metals basis
Sigma-Aldrich
Sodium hydroxide, pellets, semiconductor grade, 99.99% trace metals basis
Sigma-Aldrich
Sodium hydroxide, ACS reagent, ≥97.0%, pellets
Sigma-Aldrich
Methanol, ACS reagent, ≥99.8%
Sigma-Aldrich
Sodium hydroxide, reagent grade, 97%, flakes
Sigma-Aldrich
Sodium hydroxide, beads, 16-60 mesh, reagent grade, 97%
Sigma-Aldrich
Sodium hydroxide solution, 50% in H2O
Sigma-Aldrich
Methanol, Laboratory Reagent, ≥99.6%
Sigma-Aldrich
Sodium hydroxide solution, 5.0 M
Sigma-Aldrich
Methanol, ACS reagent, ≥99.8%
Sigma-Aldrich
Methanol, ACS spectrophotometric grade, ≥99.9%
Sigma-Aldrich
Methanol, BioReagent, ≥99.93%
Sigma-Aldrich
Sodium hydroxide, reagent grade, 97%, powder
Sigma-Aldrich
Tetrahydrofolic acid, ≥65% (when packaged), powder
Sigma-Aldrich
Sodium chloride solution, 5 M in H2O, BioReagent, for molecular biology, suitable for cell culture
Sigma-Aldrich
Sodium hydroxide solution, 1.0 N, BioReagent, suitable for cell culture
Sigma-Aldrich
Sodium chloride, BioReagent, suitable for cell culture, suitable for insect cell culture, suitable for plant cell culture, ≥99%
Sigma-Aldrich
Sodium chloride, for molecular biology, DNase, RNase, and protease, none detected, ≥99% (titration)
Sigma-Aldrich
Sodium chloride, tablet
Sigma-Aldrich
Sodium chloride, BioXtra, ≥99.5% (AT)
Sigma-Aldrich
Sodium chloride solution, 5 M
Sigma-Aldrich
Sodium hydroxide solution, BioUltra, for molecular biology, 10 M in H2O
Sigma-Aldrich
Sodium hydroxide, BioUltra, for luminescence, ≥98.0% (T), pellets
Sigma-Aldrich
Sodium chloride solution, BioUltra, for molecular biology, ~5 M in H2O
Sigma-Aldrich
3-Ethyl-2,4-pentanedione, mixture of tautomers, 98%
Sigma-Aldrich
Sodium chloride, AnhydroBeads, −10 mesh, 99.999% trace metals basis
Sigma-Aldrich
Sodium chloride, random crystals, optical grade, 99.9% trace metals basis
Sigma-Aldrich
Sodium chloride-35Cl, 99 atom % 35Cl