Simultaneous Analysis Of Amino Acids Research Articles

A new green approach to L-histidine and β-alanine analysis in dietary supplements using rapid and simple contactless conductivity detection integrated with high-resolution glass-microchip electrophoresis.

The analysis of dietary supplements is far less regulated than pharmaceuticals, leading to potential quality issues. Considering their positive effect, many athletes consume supplements containing L-histidine and β-alanine. A new microfluidic method for the determination of L-histidine and β-alanine in dietary supplement formulations has been developed. For the first time, capacitively coupled contactless conductivity detection was employed for the microchip electrophoresis of amino acids in real samples. A linear relationship between detector response and concentration was observed in the range of 10-100µmol L-1 for L-histidine (R2 = 0.9968) and β-alanine (R2 = 0.9954), while achieved limits of detection (3 × S/N ratio) were 4.2µmol L-1 and 5.2µmol L-1, respectively. The accuracy of the method was confirmed using recovery experiments as well as CE-UV-VIS and HPLC-UV-VIS techniques. The developed method allows unambiguous identification of amino acids in native form without chemical derivatization and with the possibility of simultaneous analysis of amino acids with metal cations.

Mass spectrometry for screening of metabolic disorders

Background/aim Inborn errors of metabolism (IEM) are a group of congenital disorders that result from deficiency of enzymes or transporters involved in different metabolic pathways in the human body. The most severe form of these disorders appears early in the neonatal period; however, most types of IEMs are responsive to treatment if started early enough before the appearance of serious complications. The introduction of mass spectrometric techniques for analysis of metabolites accumulated in IEM facilitates the early diagnosis through enabling analysis of a large number of samples in a short period of time using small sample sizes suitable for patients in the neonatal period. The aim of this study was to find out the prevalence of amino acids, fatty acids, and organic acids disorders, using mass spectrometry among Egyptian children with metabolic disorders who were referred to the Biochemical Genetics Lab, Human Genetics, and Genome Research Institute, National Research Centre, Cairo, Egypt, over a period of 9 years. Patients and methods The present study enrolled 9245 children who visited Biochemical Genetics Department, Human Genetics, and Genome Research Institute, National Research Centre Cairo, Egypt, during the period from 2013 to 2021. All children were subjected to quantitative analysis of amino acids and acylcarnitine profiles in blood, using liquid chromatography/tandem mass spectrometry, whereas qualitative analysis of organic acids was done in urine by gas chromatography/mass spectrometry. Results Of 9245 suspected patients, 552 (5.97%) patients were diagnosed with 13 different types of IEM. A total of 383 (4.1%) patients were diagnosed with aminoacidopathies, 167 (1.8%) patients were diagnosed with organic acidurias, and two (0.02%) patients were diagnosed with fatty acid oxidation disorders. Phenylketonuria is the most prevalent IEM of this study (2%) followed by maple syrup urine disease (0.98%). Conclusion The simultaneous analysis of amino acids and acylcarnitines in dried blood spots with analysis of organic acids in urine using mass spectrometry provides an integrated panel for the early detection of IEMs in early years of life, facilitating prompt provision of treatment and avoiding serious complications that can be fatal.

Simultaneous analysis of amino acids based on discriminative 19F NMR spectroscopy

The simultaneous analysis of amino acids (AAs) is crucial for human health, diagnosis and treatment of disease, and nutritional quality evaluation in foodstuffs. Here, we establish an easy and rapid method for the simultaneous analysis of AAs using a single reagent 2-(trifluoromethyl)benzaldehyde (oTFMBA) based on spectral-separation-enabled 19F NMR spectroscopy. oTFMBA, a highly sensitive chemosensor, is capable of analyzing 19 proteinogenic AAs or non-amino acid amines (non-AAs) in a complex mixture by adjusting the pH in a toilless way. The 19F signals of oTFMBA-labeled AAs are distributed over a wide range of ∼ 0.7 ppm, demonstrating oTFMBA with higher resolution for simultaneous analysis of AAs compared to the o-phthaldialdehyde (OPA) method (<0.6 ppm). Additionally, 12 AAs were unambiguously identified in human urine, including Asp, Ser, Gly, Thr, Glu, Arg, Ala, Val, Ile, Tyr, His, and Phe. Furthermore, our method’s detection limit for AAs is 5.83 μM, illustrating sensitivity with an ∼100-fold improvement over the OPA method. This work represents an approach to the analysis of AAs or non-AAs in a complicated mixture (even biofluid) using a 19F NMR probe with high sensitivity, which is of great significance for the simultaneous analysis of multiple analytes.

New Advances in Amino Acid Profiling in Biological Samples by Capillary Electrophoresis-Mass Spectrometry.

Capillary electrophoresis-mass spectrometry (CE-MS) offers a high efficiency microseparation platform for amino acid profiling when analyzing volume-restricted biological samples, such as a dried blood spot punch. Direct analysis of amino acids and their analogs is routinely achieved using strongly acidic buffer conditions under positive-ion mode detection with a coaxial sheath liquid interface for electrospray ionization (ESI). New advances in online sample preconcentration, pre-column chemical derivatization, and/or low flow/sheathless CE-MS interface designs can further improve sensitivity while allowing for resolution of amino acid stereoisomers and labile aminothiols with low nanomolar detection limits. Additionally, multiplexed separations in CE-MS based on serial injection of seven or more samples within a single run greatly boosts sample throughput (<2-3min/sample) without added infrastructure costs while allowing for stringent quality control and signal batch correction. Accurate prediction of the electromigration behavior of amino acids and their analogs offers a convenient approach for structural elucidation that is complementary to high-resolution MS and MS/MS. Simultaneous analysis of amino acids together with other classes of ionic metabolites by CE-MS allows for comprehensive metabolomic screening as required for new advances in clinical medicine, nutritional sciences, and population health.

Simultaneous Analysis of Amino Acids and Carboxylic Acids by Capillary Electrophoresis−Mass Spectrometry Using an Acidic Electrolyte and Uncoated Fused-Silica Capillary

A simple, low-cost capillary electrophoresis-mass spectrometry (CE-MS) method is demonstrated for the simultaneous analysis of amino acids and small carboxylic acids (glycerate, lactate, fumarate, succinate, malate, tartrate, citrate, iso-citrate, cis-aconitate, and shikimate). All CE-MS experiments were performed using a single uncoated fused-silica capillary and with a single separation electrolyte, formic acid. For CE polarity, the CE inlet was set as the anode, and the MS side was set as the cathode. By using high-speed sheath gas flow, the apparent mobilities of all compounds were sped up; thus, the migration times of the carboxylic acids were reduced. In positive ion mode ESI-MS detection, small carboxylic acids were detected faintly as m/z = [M + 18](+) or [M + 23](+), after protonated molecule detection (m/z = [M + 1](+)) of the amino acids. In negative ion mode, all of these small carboxylic acids were detected clearly as deprotonated molecules (m/z = [M - 1](-)), after detection of the amino acids. By changing the polarity of the MS during CE separation, both amino acids and small carboxylic acids were detectable in a single electrophoresis analysis run. With this method, the diurnal metabolic changes of pineapple leaves were observed as reflecting Crassulacean acid metabolism.

Multiparametric analysis of amino acids and organic acids in rat brain tissues using GC/MS

Using design of experiment (DOE) theory coupled with multivariate statistical analysis, we have developed a simple and reliable GC/MS-based analytical assay for simultaneous analysis of amino acids and organic acids in rat brain tissue samples. The process of water extraction (pH 10.0) was extensively evaluated using brain tissue samples and a set of 21 reference standards. Acceptable calibration curves were obtained over a wide concentration range, 0.2-35.0 microg/mL for standards and 15.0-2.4 mL/g (tissue) for brain tissue samples. The precision was mostly better than 10% for both the mixed standards and the brain tissue samples. The brain tissue samples exhibited good stability within 48 h with RSD generally less than 15%. Furthermore, the developed analytical method was successfully applied in distinguishing the subtle variation among different parts of the brain tissues, such as cerebral cortex, hippocampus, and thalamus.

Simultaneous analysis of amino acids and amines as their o-phthalaldehyde-ethanethiol-9-fluorenylmethyl chloroformate derivatives in cheese by high-performance liquid chromatography

A high-performance liquid chromatographic method (HPLC) with combined diode array and fluorescence detection of amino acids and amines in various cheese samples is described. The proposal is based on acidic deproteinization, derivatization and gradient optimization studies, resulting in the identification and quantification of 21 amino acids and 9 amines from a single solution, by one injection. The optimized, simple protocol consists of deproteinization (1 M perchloric acid), centrifugation, filtration and the subsequent derivatization with the o-phthalaldehyde-ethanethiol-9-fluorenylmethyl chloroformate (OPA-ET-FMOC) reagent. The method can be characterized with a linearity of wide concentration range (6.25–1000 pM/injection), a good chromatographic reproducibility (average: 2.69% RSD) and an excellent recovery (average: 100.2%; average 3.84% RSD). The developed method was successfully applied in the determination of the amino acid and amine contents of port salut cheese, blue cheese and smoked cheese samples.

Liquid chromatography method for simultaneous analysis of amino acids and biogenic amines in biological fluids with simultaneous gradient of pH and acetonitrile

A liquid chromatography method for simultaneous analysis of amino acids, polyamines, catecholeamines and metanephrines in human body fluids after derivatization with 9-fluorenylmethyloxycarbonyl chloride was developed. The chromatographic behavior of analytes at different pH of mobile phase was studied. Successful baseline resolution of all analyzed compounds was achieved using simultaneous gradient of pH and organic modifier in reverse phase mode of HPLC within 36 min. The repeatability of the proposed procedure in respect of retention time and peak area, expressed as RSD, ranges from 0.06 to 1.64% and 0.4 to 7.6%, respectively. The method linearity in the range of 1–200 μM for amino acids and in the range of 0.1–20 μM for polyamines, catecholeamines and metanephrines was found to be with correlation coefficients higher than 0.994. The limit of quantification (LOQ) was assessed to be in the range of 2.6–10 pmol for amino acids and 2–4 pmol for polyamines, catecholeamines and metanephrines.

Pre‐Capillary Derivatisation and Capillary Zone Electrophoresis for Amino Acids Analysis in Beverages

A simple and rapid method for the simultaneous analysis of amino acids has been developed. Amino acids were derivatised based on pre-capillary derivatisation with 1,2-naphthoquinone-4-sulfonate (NQS) in basic medium (pH 10.0) and developed reaction at 70 degrees C. Their derivatives were analysed by capillary zone electrophoresis (CZE). The parameters affecting CZE separation were investigated including buffer (pH, type and concentration), organic modifier and separation voltage. The optimum condition was 70 mmol L(-1) borate (pH 10.0) containing 10% acetonitrile, separation voltage of 12 kV, and sample injection (0.5 psi, 5s) and on-capillary detection at 240 nm. The separation of seven amino acids was achieved within 17 min. The detection limit was 1.0 mg L(-1) for all studied amino acids. The calibration curves were linear in the concentration range of 1.0-100.0 mg L(-1). The repeatability, intra-day and inter-day analysis were < or = 1.0% and < or = 2.0% for migration time and < or = 5.0% and 6.0% for peak area. The proposed method has been applied to several beverage samples with only a simple dilution and filtration treatment of sample before derivatisation and analysed by CZE.

METABOLIC PROFILING USING GC-MS TO STUDY BIOCHEMICAL CHANGES DURING LONG-TERM STORAGE OF PEARS

Even though the storage disorder core breakdown in 'Conference' pears can be controlled quite well nowadays, its biochemical background remains unclear. In order to induce biochemical changes in pear fruit tissue, (1) late-harvested 'Conference' pears were stored at -1°C under browning-inducing conditions (1% O 2 , 10% CO 2 ) and (2) optimally picked pears were stored at -1°C under following CA conditions: 2.5% O 2 , 0.7% CO 2 ; 15% O 2 , 0.7% CO 2 ; 2.5% O 2 , 5% CO 2 ; 2.5% O 2 , 5% CO 2 . A simultaneous analysis of amino acids, organic acids and sugars was carried out using GC-MS. Multivariate statistics were used to reduce the complexity of the profiling data. All storage conditions were clearly separated. It was found that malic acid, succinic acid and fumaric acid were the most crucial metabolites, explaining most of the variance. Brown tissue is characterised by fumaric acid accumulation and malic and succinic acid depletion. High CO 2 conditions were characterised by enhanced levels of succinic acid whereas malic acid depletes. Depending on their degradation pathway and biosynthetic group, the concentration of certain amino acids increased while that of others decreased. An attempt was made to combine the biochemical observation with the known biochemistry of the Krebs cycle and its related pathways. Although core breakdown is considered as a CO 2 -injury, the biochemical profiles of brown pears were not equal to those of sound pears in high CO 2 conditions.

Simultaneous analysis of amino acid and biogenic polyamines by high-performance liquid chromatography after pre-column derivatization with N-(9-fluorenylmethoxycarbonyloxy)succinimide

A high-performance liquid chromatography method for the simultaneous analysis of amino acids and biogenic polyamines, using a new procedure for pre-column derivatization of amino groups with N-(9-fluorenylmethoxycarbonyloxy)succinimide is described. The separation of 20 amino acids and 4 biogenic polyamines was achieved within 32 min on a sequence of three short (50 mm) reversed-phase C 18, 5 μm columns by elution buffers based on dibutylamine phosphate. The method linearity, calculated for each amino acid and polyamine, has a correlation coefficient higher than 0.991, in concentrations ranging from 0.2 to 50 μM, except for spermine and methionine, where the correlation coefficients were r=0.984 and r=0.979, respectively. The stability of derivatives in acidified samples at 4 °C and room temperature was demonstrated. The limit of quantitation was estimated to be around 50 pM in 50 μl sample injection. The repeatability of the method, expressed as R.S.D., ranged from 1.1 to 6.7%. The presented method was applied for the quantitation of amino acid and polyamine contents in beer, wine, and cell culture samples, using 2-aminoheptanoic acid or 1,7-diaminoheptane as internal standard.

New aspects of the simultaneous analysis of amino acids and amines as their o-phthaldialdehyde derivatives by high-performance liquid chromatography : Analysis of wine, beer and vinegar

A new high-performance liquid chromatography method is described for the simultaneous quantitation of amino acids and amines for 37 compounds (20 amino acids+17 amines), as their o-phthaldialdehyde (OPA)−3-mercaptopropionic acid derivatives, within 53 min. Based on previously documented stoichiometric and reaction mechanism studies, derivatizations have been carried out with the OPA–SH-group=1:50 containing reagents. Reliability and reproducibility of analyses have been considerably improved. Average reproducibility data in a wide concentration range of derivatives had RSD≤3.4%.

Simultaneous Analysis of Enantiomeric Amino Acids Based on Derivatization with (S)(+)-2-t-Butyl-2-methyl-l,3-benzodioxole-4-carboxylic Acid and High-Performance Liquid Chromatography

The fluorescent chiral derivatizing agent in the title, (5)-TBMB carboxylic acid, was applied for highly sensitive HPLC analysis of enantiomeric amino acids. Enantiomeric amino acids derivatized with the agent could be separated as the diastereomers on ODS (C-18) column and determined in less than 0.05 picomole amounts owing to the strong fluorescent chromophore of the reagent (Ex=310 nm, Em=380 nm). Three types of HPLC conditions with different pH values were proposed for the group analysis of amino acids: pH=5.7 for the simultaneous analysis of all amino acids, pH=4.6 for the selective analysis of polar amino acid derivatives and pH=6.0 for that of less polar ones.

Liquid chromatographic separation and detection of n-methylamino acids using mobile phases containing copper(II) ions

The chromatographic separation of N-methylamino acids can be accomplished using a reversed-phase column with an aqueous mobile phase containing copper ions. The N-methylamino acid—Cu complex absorbs UV radiation with λ max around 235 nm. Thus copperions ifluence the retention times and allows the detection of the above solutes. Unsubstituted amino acids also absorb radiation at 235 nm. The molar absorptivities of the two types of solutes seem to be of the same order of magnitude and the detection limits are therefore also close. The method can be utilized in the simultaneous analysis of amino acids and their N-methyl derivatives. Although the method cannot compete with the sensitivity of amino acid analysers, its simplicity and its detection limits make it useful in such research fields as peptide synthesis.

Effects of dietary amino acids on brain amino acids and transmitter amines in rats with a portacaval shunt.

The etiologic relationship between disturbances in metabolism of amino acids and amines and hepatic coma was investigated by examining the effects of diets containing various mixtures of amino acids on brain amine metabolism in rats with a portacaval shunt, using a method for simultaneous analysis of amino acids and amines. Rats with a portacaval shunt were fed on four different amino acid compositions with increased amounts of various amino acids suspected to be etiologically related to hepatic coma, such as methionine, phenylalanine, tyrosine, and tryptophan. The animals were killed 4 weeks after operation. During the experimental period, these animals did not become comatose, but exhibited various behavioral abnormalities. Marked increase in the plasma and brain levels of the augmented amino acids, especially methionine and tyrosine, were observed in rats with a portacaval shunt. Brain noradrenaline, dopamine, and serotonin levels were significantly decreased when the brain tyrosine level was increased. These results indicate that in rats with a portacaval shunt the dietary levels of amino acids greatly influence the brain levels of both amino acids and transmitter amines.

252 - Effects of dietary amino acids on brain amino acids and transmitter amines in rats with a portacaval shunt

: The etiologic relationship between disturbances in metabolism of amino acids and amines and hepatic coma was investigated by examining the effects of diets containing various mixtures of amino acids on brain amine metabolism in rats with a portacaval shunt, using a method for simultaneous analysis of amino acids and amines. Rats with a portacaval shunt were fed on four different amino acid compositions with increased amounts of various amino acids suspected to be etiologically related to hepatic coma, such as methionine, phenylalanine, tyrosine, and tryptophan. The animals were killed 4 weeks after operation. During the experimental period, these animals did not become comatose, but exhibited various behavioral abnormalities. Marked increase in the plasma and brain levels of the augmented amino acids, especially methionine and tyrosine, were observed in rats with a portacaval shunt. Brain noradrenaline, dopamine, and serotonin levels were significantly decreased when the brain tyrosine level was increased. These results indicate that in rats with a portacaval shunt the dietary levels of amino acids greatly influence the brain levels of both amino acids and transmitter amines.