Quantification Of Methionine Research Articles

Facile preparation of a sensitive electrochemical sensor with good performance for determination of methionine

In this work, a novel voltammetric sensor for detection of methionine was designed and prepared by using carbon paste electrode (CPE) modified with ZnO hollow quasi-spheres (ZnO hollow QSs) and 1-Butyl-3-methylimidazolium hexafluorophosphate (BMIM.PF6). The results by cyclic voltammetry (CV) showed that the prepared electrode (ZnO-BMIM.PF6/CPE) effectively increased the oxidation peak current and reduced the oxidation peak potential of methionine, and had a suitable electrocatalytic activity for oxidation of methionine. Notably, the ZnO-BMIM.PF6/CPE exhibited high detection capability towards the quantification of methionine in 0.1 M PBS (pH = 7.0) over a concentration range from 0.04 µM to 330.0 µM with a limit of detection (LOD) of 0.02 μM. More importantly, the effectiveness of the ZnO-BMIM.PF6/CPE seneor was also confirmed in real sample (urine detection with acceptable recoveries (98.0-102.7%) and RSDs values ≤ 3.3%.

Quantification of methionine and selenomethionine in biological samples using multiple reaction monitoring high performance liquid chromatography tandem mass spectrometry (MRM-HPLC-MS/MS)

Quantification of selenated amino-acids currently relies on methods employing inductively coupled plasma mass spectrometry (ICP-MS). Although very accurate, these methods do not allow the simultaneous determination of standard amino-acids, hampering the comparison of the content of selenated versus non-selenated species such as methionine (Met) and selenomethionine (SeMet). This paper reports two approaches for the simultaneous quantification of Met and SeMet. In the first approach, standard enzymatic hydrolysis employing Protease XIV was applied for the preparation of samples. The second approach utilized methanesulfonic acid (MA) for the hydrolysis of samples, either in a reflux system or in a microwave oven, followed by derivatization with diethyl ethoxymethylenemalonate. The prepared samples were then analyzed by multiple reaction monitoring high performance liquid chromatography tandem mass spectrometry (MRM-HPLC-MS/MS). Both approaches provided platforms for the accurate determination of selenium/sulfur substitution rate in Met. Moreover the second approach also provided accurate simultaneous quantification of Met and SeMet with a low limit of detection, low limit of quantification and wide linearity range, comparable to the commonly used gas chromatography mass spectrometry (GC–MS) method or ICP-MS. The novel method was validated using certified reference material in conjunction with the GC-MS reference method.

Direct oxidation of methionine at screen printed graphite macroelectrodes: Towards rapid sensing platforms

The direct electrochemical oxidation of methionine has been achieved at bare carbon based electrodes and for the first time at screen printed graphite electrodes in aqueous solutions. Due to scales of economy and intended use as a potential point-of-care sensor, the quantification of methionine was explored at screen printed electrodes, allowing linear ranges over the range 0.05–5.0 mM with a detection limit of 95 × 10 −6 mol L −1 possible in model solutions. Application of this sensor was used for the determination of methionine in a pharmaceutical product containing a complex mixture of vitamins, amino acids, chelated minerals and additional factors with the results agreeing with manufacturers’ specification suggesting that this sensing platform holds promise as a rapid, sensitive and disposable sensor for methionine determination.