Determination Of Γ-aminobutyric Acid Research Articles

Determination of γ-aminobutyric acid in fermented soybean products by HPLC coupled with pre-column derivatization

This study reports a pre-column derivatization HPLC stragety to determine the content of GABA in fermented soybean products. 9-Fluorenylmethyloxycarbonyl chloride (Fmoc-Cl) is employed as the derivative reagent with chromophore linked to GABA, which lacks of chromophore for UV/DAD analysis in its pristine structure. After the detection wavelength was confirmed, the derivatization and analysis conditions were also optimized, including pH and amount of boric acid buffer, amount of derivative reagent, the mobile phases and their gradient. Methodological investigation showed that the derivatized GABA (Fmoc-GABA) has good linearity in the range of 1–100 µg/mL, low limit of quantification (LOQ, at 1 µg/mL) and limit of detection (LOD, at 0.3 µg/mL), and good recoveries of three spiked levels (between 83.8% and 100.8% with RSDs less than 5%). Furthermore, thirty-two commercial fermented soy products in four matrices (soy sauce, soy paste, bean curd, lobster sauce) were analyzed by the proposed method for validation. As a consequence, the concentrations of GABA in these soy products were in the range of 48.4–381 mg/kg.

Determination of Γ-Aminobutyric Acid in Fermented Soybean Products by Hplc Coupled with Pre-Column Derivatization

Determination of Γ-Aminobutyric Acid in Fermented Soybean Products by Hplc Coupled with Pre-Column Derivatization

Determination of γ-aminobutyric acid in aerial part of Panax notoginseng by HPLC

Determination of γ-aminobutyric acid in aerial part of Panax notoginseng by HPLC

Determination of γ-aminobutyric acid in leaf, stem and root bark of mulberry by high-performance anion exchange chromatography-integrated pulsed amperometric detection

Summary A simple high-performance anion-exchange chromatography-integrated pulsed amperometric detection method was developed to determine the gammaaminobutyric acid (GABA) content in mulberry. GABA was separated in anion-exchange column under isocratic condition of 20 mM sodium hydroxide solution and detected at integrated pulsed amperometric detection at pico-gram levels. The contents of GABA in the leaf, stem, and root bark of mulberry were calculated without any derivatization or sample purification process using this method. This method showed good linearity, precision, and accuracy for GABA analysis.

Determination of γ-Aminobutyric Acid and Free Amino Acid Contents in Barley Seeds and Amounts Produced by Water Soaking Treatment

Determination of γ-Aminobutyric Acid and Free Amino Acid Contents in Barley Seeds and Amounts Produced by Water Soaking Treatment

A Validated HPLC Method for the Determination of GABA by Pre-Column Derivatization with 2,4-Dinitrofluorodinitrobenzene and Its Application to Plant GAD Activity Study

A validated, selective, and sensitive chromatographic method for determination of γ-aminobutyric acid (GABA) has been developed by precolumn derivative of the sample with 2,4-dinitrofluorodinitrobenzene (FDNB). The derivatives were separated with RP-HPLC on a C18 column and UV detection (360 nm). The calibration curve was linear over a range of 0.2–5.0 mg/mL GABA with a correlation coefficient of 0.9954. The precision of this method is high (RSD = 0.061%). This method also possessed high recovery rate (>99%) and good stability over a period of four weeks. The method was successfully used to determine the glutamate decarboxylase (GAD) activity in several plant tissues.

A high performance liquid chromatography method with electrochemical detection of gamma-aminobutyric acid, glutamate and glutamine in rat brain homogenates

Determination of γ-aminobutyric acid (GABA), glutamate (Glu) and glutamine (Gln) in animal models has been important to understand the normal function and clinical aspects of some neurological diseases. Quantification of these amino acid transmitters has conventionally been performed by using a high performance liquid chromatography (HPLC) system. This paper describes an improved HPLC method with electrochemical detection for glutamate, glutamine and GABA determination in brain homogenates. The protocol is based on a precolumn derivatization of amino acids with o-phthalaldehyde and sodium sulfite, a separation through a C18, 5μm particle size column and an isocratic elution. Several modifications of previous works on methanol percentage, pH, temperature, flow rate and derivatization solution concentration were done to obtain a suitable protocol for amino acid quantification in brain homogenate samples. Total elution time is 35min approximately. Technical requirements and laboratory expenses of this new protocol are minimal. This technique showed high linearity, repeatability and accuracy.

On-line coupling of sequential injection with liquid chromatography for the automated derivatization and determination of γ-aminobutyric acid in human biological fluids

The principle of sequential injection analysis (SIA) was exploited to develop a rapid fully automated and efficient pre-column derivatization procedure coupled on-line to liquid chromatography (HPLC). Using the SIA-HPLC derivatization protocol γ-aminobutyric acid (GABA) was determined fluorimetrically in human biological fluids with o-phthaldialdehyde (OPA) as derivatization reagent and minimum sample pretreatment. A lab-built SIA system was used to handle samples, standard solutions and OPA reagent. Appropriate volumes of the reagents were introduced in the holding coil of the SIA system and were mixed on propulsion to the HPLC loop through a suitable reaction coil. The chemical (pH, c(OPA), c(mercaptoethanol)) and instrumental variables (volumes of sample and reagent, reaction time) of the reaction were studied and optimized in terms of maximum sensitivity. The chromatographic variables (gradient composition of the eluent and flow rate) were studied for optimum selectivity and peak characteristics. The developed experimental configuration facilitated fully-automated operation thus minimizing errors in handling. Additionally the method as a whole provided very satisfactory sensitivity, precision and accuracy. Direct determination of GABA in human urine and cerebrospinal fluid (CSF) at μg L −1 (ppb) levels was accomplished, with minimum sample pretreatment.

Simultaneous determination of γ-aminobutyric acid and polyamines by O-phthalaldehyde—β-mercaptoethanol precolumn derivatization and gradient elution liquid chromatography with electrochemical detection

Simultaneous determination of γ-aminobutyric acid and polyamines by O-phthalaldehyde—β-mercaptoethanol precolumn derivatization and gradient elution liquid chromatography with electrochemical detection

Determination of γ-aminobutyric acid in human cerebrospinal fluid by isocratic high-performance liquid chromatography

Determination of γ-aminobutyric acid in human cerebrospinal fluid by isocratic high-performance liquid chromatography

Determination of γ-Aminobutyric Acid in the Mouse Hypothalamus and Hippocampus Using Liquid Chromatography/Electrochemistry

Abstract A method is described for the rapid detection and measurement of γ-aminobutyric acid (GABA) in crude extracts of mouse brain. This study includes optimisation of the pre-column derivatization of GABA by o-phthalaldehyde in the presence of ethylmercaptan as well as of the chromatographic and electrochemical conditions. The GABA levels have been measured in the hypothalamus and hippocampus of control mice and mice treated with three compounds known for their activity on brain GABA levels.

A specific and sensitive determination of gamma aminobutyric acid in CSF and brain tissue by gas chromatography-mass spectrometry

The determination of γ-aminobutyric acid (GABA) in cerebrospinal fluid and brain extracts is described. Its heptafluorobutyryl-isobutanol derivative was measured both by electron impact and chemical ionization mass fragmentography using GABA-d 6 as internal standard. The derivatization product is stable for several days. The method is sensitive (1 ng absolute in cerebrospinal fluid and 30 pg in standard GABA solutions) and specific, when chemical ionization mode is applied. Normal values of GABA are in rat brain extracts (1.40±0.32 μmol/g fresh weight) and human CSF (18.3±10.0 ng/ml).

Determination of γ-aminobutyric acid in physiological samples by a simple, rapid high-performance liquid chromatographic method

Determination of γ-aminobutyric acid in physiological samples by a simple, rapid high-performance liquid chromatographic method

Determination of γ-aminobutyric acid in brain areas by high-performance liquid chromatography of dansyl derivatives with ultraviolet detection

Determination of γ-aminobutyric acid in brain areas by high-performance liquid chromatography of dansyl derivatives with ultraviolet detection

A fluorimetric method for determination of GABA in tissues following cation exchange chromatography and condensation witho-phthalaldehyde

A spectrofluorimetric method for determination ofγ-aminobutyric acid (GABA) in tissues is described. The GABA was extracted with perchloric acid, purified on a strong cation exchange column and converted to a fluorophor witho-phthalaldehyde andβ-mercaptoethanol at a high pH. Data on recovery, reproducibility, specificity and sensitivity are reported. The concentration of GABA in different parts of the normal rat brain is presented.

Determination of γ-aminobutyric acid by reversed-phase high-performance liquid chromatography and pre-column labeling for fluorescence detection

Determination of γ-aminobutyric acid by reversed-phase high-performance liquid chromatography and pre-column labeling for fluorescence detection

Determination of γ-aminobutyric acid by liquid chromatography with electrochemical detection

γ-Aminobutyric acid (GABA) has been determined in rat brain by derivatization with 2,4,6-trinitrobenzenesulfonic acid. The derivative and an internal standard, 2,4,6-trinitrophenyl-δ-aminovaleric acid, are extracted into toluene and separated by reversed-phase chromatography. Electrochemical reduction of these derivatives permits picomole measurements of GABA in microgram amounts of brain tissue.

A dansylation microassay for some amino acids in brain

A method is described for the determination of γ-amino butyric acid, glycine, glutamine, glutamate, asparate, and taurine in small samples of brain tissue. This is an extension of a method based on the formation of derivatives with [ 3H]dansyl chloride (15) with the addition of 14C-labeled amino acids as internal standards to allow correction for incomplete and variable degrees of dansylation. An improved chromatographic separation of dansyl-taurine is employed. Estimates of the contents of these amino acids in rat cortical tissue are reported and compared with those obtained on an autoanalyser, and with those in the literature using autoanalytical and other methods.

Rapid Determination of γ-Aminobutyric Acid and Arginine in Orange Juice: Application to Detecting Adulteration

Abstract A rapid, semiautomated liquid chromatographic method has been developed for the determination of γ-aminobutyric acid and arginine in orange juice. Data have been gathered on these amino acids, total amino acids, titratable acidity, total phenolics, and soluble solids for several seasons of commercial California, Florida, Arizona, and foreign orange juice concentrates. Possible applications of the data for detecting adulterations were suggested but, for statistical significance, data from at least one additional season should be gathered.