Detection of S‐adenosylhomocysteine and methylation index in blood by capillary electrophoresis

Abstract

This work proposes an approach to the direct analysis of S‐adenosylhomocysteine (SAH) and the methylation index in blood using CE with UV detection (CE‐UV). After application of meglumine postinjection, we achieved SAH in‐capillary preconcentration in the HClO4 extracts of erythrocytes, which improved the detection limit (S/N = 3) of SAH up to 3 fmol or 180 nmol/L at the injection volume of 50 nL, taking into account the sample dilution rate. CE‐UV was carried out in 30 mM glycine and 45 mmol/L HCl (pH ∼1.8) at 17 kV in a capillary 48 cm in length and 50 μm id. Accuracy of the technique was 101% and reproducibility was about 12%.

Capillary electrophoresis and phenylboronic acid solid phase extraction for the determination of S‐adenosylmethionine/S‐adenosylhomocysteine ratio in human urine

“…The sensitivity (LOD) of the method for analysis of SAM and SAH was 0.07 mol/L (S/N = 3), and the LOQ (S/N = 10) was 0.2 mol/L taking into account sample preparation. These results are similar to CE-and HPLC-UV obtained previously [11,15,16,23].…”

“…To determine SAM and SAH concentrations, previously used buffer solutions with low pH and high ionic strength, such as glycine‐HCl (pH 1.8) and phosphate‐Na (pH 2.5) , were used. In preliminary experiments, we tested these BGEs and 50 mM citrate Na (pH 3.0), 20 mM HCl, and 4% v/v acetic acid.…”

“…Here, Na + ions play the role of a leading electrolyte, and SAM, having a slightly lower mobility, is concentrated behind the Na + zone. The concentration of SAH also occurs, but the presence of Na + is not sufficient to prevent broadening of the SAH peak after the transient isotachophoretic concentration stage [23]. Previously, we found that the addition of NMDG, which has intermediate mobility between the SAM and SAH, can solve this problem and prevent peak broadening of SAH; this is illustrated in Fig.…”

“…To address this problem, large‐volume injection method has previously been developed to determine SAM and SAH in tissues; however, their use was problematic for SAH analysis in blood . It was shown that the addition of N‐methyl‐D‐glucamine (meglumine) (NMDG) can solve this problem , but the mechanism of SAM and SAH in‐capillary concentration was not studied in details. However, it was apparent that the chemical composition of the matrix plays an important role and therefore it was clear that the use of this approach for the analysis of urine limited to broad variations in pH, NaCl, urea, and other matrix components that have a significant influence on concentration and separation of analytes.…”

Different detection and stacking techniques in capillary electrophoresis for metabolomics

“…CE with direct UV detection was used to determine this index as well as SAH levels in rat blood plasma. 36 The new method did not require complicated sample preparation i.e. derivatization.…”