Derivatization of thiols under flow conditions using two commercially available propiolate esters

Tzanavaras, Paraskevas D.; Tsiomlektsis, A.; Zacharis, Constantinos K.

doi:10.1016/j.jpba.2010.06.002

Cited by 13 publications

(8 citation statements)

References 9 publications

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“…The study of the PCD conditions involved both chemical (pH and amount concentration of MP) and instrumental variables (flow rate of the PCD reagents and length of the RC). It should be noted that the temperature was not examined, since according to our previous findings, it has negligible effect on the reactions . The experimental results are depicted in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The aim of the present study was to develop a new method for the determination of two major thiols such as GSH and CYS by coupling HILIC to automated PCD. The recently introduced thiol‐selective reagent methyl propiolate (MP) was selected for this purpose due to its advantages and useful analytical features . As stated above, all methods reported so far for the analysis of thiols by HILIC are based on MS detection .…”

Section: Introductionmentioning

confidence: 99%

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Determination of glutathione and cysteine in yeasts by hydrophilic interaction liquid chromatography followed by on‐line postcolumn derivatization

Karakosta

Tzanavaras

Themelis

2013

J of Separation Science

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In the present study, we report a new method for the determination of two primary thiols, cysteine (CYS) and glutathione (GSH), by hydrophilic interaction LC. The polar analytes are separated isocratically using a mobile phase consisting of 65% acetonitrile/35% ammonium acetate (15 mmol/L, pH 2.0) and are detected at 285 nm following on-line postcolumn derivatization by the thiol-selective reagent methyl propiolate. The main figures of merit included linearity in the range of 5-200 μmol/L and an LOD 0.6 μmol/L for both compounds. The absence of matrix effect allowed the determination of CYS and GSH in various yeast samples. GSH was present in most of the samples at levels ranging between 0.9 and 3.1 mg/g, whereas CYS was determined in only one sample at a significantly lower concentration. In terms of accuracy, the percent recoveries ranged between 91.2 and 105.6% for GSH, and 91.6 and 106.9% for CYS.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of glutathione and cysteine in yeasts by hydrophilic interaction liquid chromatography followed by on‐line postcolumn derivatization

Karakosta

Tzanavaras

Themelis

2013

J of Separation Science

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“…Online derivatization of the thiols was carried out in the SI setup of Fig. 1, employing a three-zone chemistry, in a reagent/buffer/sample sequence [14,15]. The injection volumes were set at V(EP) 5 V(buffer) 5 50 mL and V(sample) 5 100 mL using an aspiration flow rate of 0.6 mL/min throughout this study.…”

Section: Study Of the Automated Pre-column Derivatizationmentioning

confidence: 99%

“…The amount concentration of the selected thiols was c(CYS) 5 c(GSH) 5 c(NAC) 5 100 mmol/L and of the derivatization reagent c(EP) 5 10 mmol/L. All experiments were carried out at an alkaline pH (pH 5 10.0, 0.1 mol/L Tris) that is necessary for the development of the derivatization reactions [15]. As mentioned in Section 2.1, SI was connected to the HPLC by a 100-cm-long PTFE tube (0.5 mm id) that also favored adequate mixing/overlapping of the zones prior to entering the loop of the high pressure HPLC injection valve.…”

Section: Study Of the Automated Pre-column Derivatizationmentioning

confidence: 99%

“…In our previous studies we explored the potential analytical applications of the reaction of thiols with propiolate esters [14,15]. Our findings demonstrated the feasibility and advantages of this novel class of analytical derivatization reagents: (i) the reactions are simple and proceed in aqueous medium; (ii) propiolate esters react rapidly and selectively with thiols under mild conditions; (iii) they offer adequate sensitivity using simple UV instrumentation; (iv) they are commercially available at a low cost compared with many derivatizing reagents for thiols; (v) the reaction can be readily carried out under flow conditions.…”

Section: Introductionmentioning

confidence: 99%

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Automated pre‐column derivatization of thiolic fruit‐antibrowning agents by sequential injection coupled to high‐performance liquid chromatography using a monolithic stationary phase and an in‐loop stopped‐flow approach

Karakosta

Tzanavaras

Themelis

2011

J of Separation Science

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The present study reports the very first application of ethyl propiolate (EP) as an advantageous pre-column derivatization reagent for the determination of thiols by liquid chromatography (LC). Cysteine (CYS), glutathione (GSH) and N-acetylcysteine (NAC) were derivatized online under stopped-flow conditions in a sequential injection (SI) system coupled to HPLC. The formed derivatives were separated isocratically with a monolithic stationary phase (100×4.6 mm id) and UV detected at 285 nm. Critical parameters that affected the online pre-column derivatization reaction (e.g. the reaction time and the amount concentration of EP) and the separation (e.g. pH and the composition of the mobile phase) were investigated. The developed analytical scheme offers a total analysis time of less than 10 min, limits of detection in the range of 0.24-0.35 μmol/L and satisfactory linearity up to 200 μmol/L for all analytes. The proposed method was applied to the analysis of the selected thiols--that are often employed as antibrowning agents--in fresh fruit samples.

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Post-column labeling techniques in amino acid analysis by liquid chromatography

Rigas

2013

Anal Bioanal Chem

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Amino acid analysis (AAA) has always presented an analytical challenge in terms of sample preparation, separation, and detection. Because of the vast number of amino acids, various separation methods have been applied taking into consideration the large differences in their chemical structures, which span from nonpolar to highly polar side chains. Numerous separation methods have been developed in the past 60 years, and impressive achievements have been made in the fields of separation, derivatization, and detection of amino acids (AAs). Among the separation methods, liquid chromatography (LC) prevailed in the AAA field using either pre-column or post-column labeling techniques in order to improve either separation of AAs or selectivity and sensitivity of AAA. Of the two approaches, the post-column technique is a more rugged and reproducible method and provides excellent AAs separation relatively free from interferences. This review considers current separations combined with post-column labeling techniques for AAA, comparison with the pre-column methods, and the strategies used to develop effective post-column methodology. The focus of the article is on LC methods coupled with post-column labeling techniques and studying the reactions to achieve optimum post-column derivatization (PCD) conditions in order to increase sensitivity and selectivity using various types of detectors (UV-Vis, fluorescence, electrochemical etc.) and illustrating the versatility of the PCD methods for practical analysis.

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Derivatization of thiols under flow conditions using two commercially available propiolate esters

Cited by 13 publications

References 9 publications

Determination of glutathione and cysteine in yeasts by hydrophilic interaction liquid chromatography followed by on‐line postcolumn derivatization

Determination of glutathione and cysteine in yeasts by hydrophilic interaction liquid chromatography followed by on‐line postcolumn derivatization

Automated pre‐column derivatization of thiolic fruit‐antibrowning agents by sequential injection coupled to high‐performance liquid chromatography using a monolithic stationary phase and an in‐loop stopped‐flow approach

Post-column labeling techniques in amino acid analysis by liquid chromatography

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