A fluorimetric liquid chromatography for highly sensitive analysis of very long chain fatty acids as naphthoxyethyl derivatives

Abstract

SummaryA simple and sensitive liquid chromatographic method is described for the simultaneous determination of biologically important very long chain fatty acids (docosanoic, tetracosanoic and hexacosanoic acids) as fluorogenic derivatives. The method is based on the derivatization of the fatty acids with 2-(2-naphthoxy)ethyl 2-(piperidino)ethanesulfonate (NOEPES) in toluene in the presence of potassium carbonate and 18-crown-6. Several parameters affecting the derivatization were studied, including reaction temperature, reaction time, reaction solvent, base catalyst and the amount of the reagent. The resulting derivatives were analyzed by HPLC with fluorimetric detection (2ex = 235 nm; 2em = 366 nm). The linear range for the determination of docosanoic, tetracosanoic and hexacosanoic acids was 0.028-1.4 ktM with a detection limit of about 5.6 nM (S/N = 3) (56 fmol per 10 #L injection). Application of the method to the analysis the non-esterified (free) very long chain fatty acids spiked in plasma proved feasible.

Simple derivatization method for sensitive determination of fatty acids with fluorescence detection by high-performance liquid chromatography using 9-(2-hydroxyethyl)-carbazole as derivatization reagent

“…Compared with sulfonate-type ester reagents [21][22][23] for the derivatization of fatty acids, the proposed method offers a number of advantages: phase-transfer agent (18-crown-6) is not required; solvents with drastic toxicity such as benzyl or toluene is not required in derivatization procedure; derivatization reaction proceeds rapidly and smoothly in the presence of coupling agent and base catalyst; the reagent and the derivatized fatty acids are fairly stable for at least 1 week for HPLC analysis. The derivatization of HEC with fatty acids is facile, inexpensive, sensitive and reproducible.…”

“…However, the completed derivatization for fatty acids was required for 6 h, which leading to a tediously analytical procedure. Although 2-(2-naphthoxy)ethyl-2-(piperidino)ethanesulfonate (NOEPES) [22], 2-(2,3-naphthalimido)ethyl trifluoromethanesulfonate (NE-OTF) [23] and 2-(2,3-anthracene-dicarboximido) ethyl trifluoromethanesulfonate (AE-OTF) [24] have been developed as another a type of sulfonate ester reagents for the sensitive determination of fatty acids, crown ether and potassium carbonate are usually used in the derivatization procedure with benzyl or toluene as solvents, which derivatization solution is usually required to treat prior to chromatographic analysis. Benzohydrazide-type reagents such as 4-(1-methylphenanthro [9,10 -d]imidazole -2 -yl)benzohydrazide (MPIB-hydrazide) [25] and 4-(5,6-dimethoxy-2-benzimidazoyl)benzohydrazide) (DMBI-hydrazide) [26] are also important fluorescent labeling agents for the detection of carboxylic acids.…”

Simple and sensitive fluorimetric liquid chromatography method for the determination of valproic acid in plasma

“…Sodium valproate (VA sodium) and nonanoic acid (used as an internal standard, IS) (Sigma, St. Louis, MO, USA), 2-(2-naphthoxy)ethyl 2-(piperidino)ethanesulfonate (NOEPES, synthesized at our laboratory) [17], 18-crown-6 ether (18-crown-6) (TCI, Tokyo, Japan), potassium bicarbonate and sulfuric acid (E. Merk, Darmstadt, Germany), and toluene (Tedia, Fairfield, OH, USA) were used without further treatment. Other chemicals were analytical reagent grade.…”

“…Derivatization of VA with 6,7-methylenedioxy-1-methyl-2-oxo-1,2-dihydroquinoxaline-3-yl propionohydrazide [15] leads to the chromatogram of a serum blank with unfavorably high tailing; and N-(7-methoxy-4-methyl-2-oxo-2H-6-chromenyl)-2-bromoacetamide [16] was also used for the derivatization of VA in spiked plasma. In this work, analytical derivatization of VA with 2-(2-naphthoxy)ethyl 2-(piperidino)ethanesulfonate (NOEPES) [17] was performed. NOEPES is a chemically removable and light stable reagent.…”

A Novel Labeling Reagent of 2-(12-Benzo[b]acridin-5-(12H)-yl)-acetohydrazide for Determination of Saturated and Unsaturated Fatty Acids in Traditional Chinese Herbs by HPLC-APCI-MS

“…Therefore, derivatization of these analytes with labeling reagents has been widely adopted by HPLC with UV, especially fluorescence detection. The common reagents are as the following: (1) bromomethanes, such as 4-bromomethyl-7-methoxycoumarin(Br-Mmc) [23] and 4-bromomethyl-7-acetoxycoumarin (Br-Mac) [24]; (2) diazomethanes, such as 9-anthryldiazomethane (ADAM) [25,26] and 1-pyrenyldiazomethane (PDAM) [27]; (3) amines, such as 9-aminophenanthrene (9-AP) [28] and 5-(dimethylamino)-l-naphthalenesulponyl-semipiperazide (dansyl-semipiperazide) [29]; (4) hydrazides, such as 4-(1-methylphenanthro [9,10-d]imidazol-2-y1)benzohydrazide (MPIB-hydrazide) [30] and 4-(5,6-dimethoxy-2-benzimidazoyl)-benzohydrazide) (DMBI-hydrazide) [31]; (5) sulfonate ester reagents, such as 2-(2,3-naphthalimino)ethyl trifluoromethanesulphonate (NE-OTF) [32], 2-(2-naphthoxy)-ethyl-2-(piperidino)-ethanesulfonate (NOEPES) [33] and 2-(2,3-anthracene-dicarboximido) ethyl trifluoromethanesulfonate (AE-OTF) [34]. Nevertheless, Toyo'oka [35] has reported that many of these reagents have limitations in their applications such as low detection sensitivity, short detection wavelengths, poor stability, tedious analytical procedure and serious interferences in the biological sample analyses.…”