scholarly journals 4-t-Butylbenzylation of carboxylic acid for GC–MS analysis

2020 ◽  
Vol 2 (5) ◽  
Author(s):  
Shinji Tsunoi ◽  
Nao Yamamoto ◽  
Tomohiro Yasuhisa ◽  
Riko Akehi ◽  
Itaru Suzuki ◽  
...  
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Water Samples ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Good Sensitivity ◽  
Good Reproducibility ◽  
Methyl Radical ◽  
Microwave Reactor

Abstract We report a 4-t-butylbenzyl derivatization for the analysis of carboxylic acids by GC–MS (EI). Carboxylic acids were analyzed as a 4-t-butylbenzyl ester after the derivatization with 4-t-butylbenzyl bromide. On the mass spectra of 4-t-butylbenzyl ester, [M-15]+ ions were observed with high intensity. These ions were tertiary benzyl cations generated by the elimination of a methyl radical from molecular ions. After optimization of the 4-t-butylbenzyl derivatization conditions using microwave reactor, we established a method for the determination of the carboxylic acids in water samples. The method showed good sensitivity and good reproducibility, and was successfully applied to the analysis of rain water samples.

scholarly journals Comparison of Three Solid Phase Materials for the Extraction of Carboxylic Acids from River Water Followed by 2D GC × GC-TOFMS Determination

2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
G. O. Bosire ◽  
J. C. Ngila ◽  
H. Parshotam
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Natural Organic Matter ◽  
Solid Phase ◽  
Cooling Water ◽  
Raw Water ◽  
Aliphatic Carboxylic Acid ◽  
Hydrophobic Nature ◽  
Relationship Of

The extraction and determination of aliphatic and aromatic carboxylic acids as well as their influence on the aromaticity and molecularity relationship of natural organic matter (NOM) in water are reported in this study. Three solid phase extraction (SPE) sorbents were used and their extraction efficiencies evaluated after chromatographic determinations (using gas chromatography with a time of flight mass spectrometer (GC × GC-TOFMS) and liquid chromatography with organic carbon detector (LC-OCD)). More than 42 carboxylic acids were identified in raw water from the Vaal River, which feeds the Lethabo Power Generation Station, South Africa, with cooling water. The aromatic carboxylic acid efficiency (28%) was achieved by using Strata™X SPE while the highest aliphatic carboxylic acid efficiency (92.08%) was achieved by silica SPE. The hydrophobic nature of NOM in water depends on the nature of organic compounds in water, whether aromatic or aliphatic. The LC-OCD was used to assess the hydrophobicity levels of NOM as a function of these carboxylic acids in cooling water. The LC-OCD results showed that the aromatic nature of NOM in SPE filtered water followed the order Silica>Strata X>C-18. From the results, the hydrophobicity degree of the samples depended on the type and number of carboxylic acids that were removed by the SPE cartridges.

Rearrangement processes and stability of molecular ions in the mass spectra of 3-aryl-5-methylisoxazole-4-carboxylic acids

1972 ◽  
Vol 8 (7) ◽  
pp. 806-809
Author(s):  
K. K. Zhigulev ◽  
R. A. Khmel 'nitskii ◽  
M. A. Panina ◽  
I. I. Grandberg ◽  
B. M. Zolotarev
Keyword(s):  
Carboxylic Acids ◽  
Mass Spectra ◽  
Molecular Ions ◽  
Rearrangement Processes

scholarly journals Cost-Effective Detection of Perfluoroalkyl Carboxylic Acids with Gas Chromatography: Optimization of Derivatization Approaches and Method Validation

2019 ◽  
Vol 17 (1) ◽  
pp. 100 ◽  
Author(s):  
Zhen Li ◽  
Hongwei Sun
Keyword(s):  
Gas Chromatography ◽  
Surface Water ◽  
Solid Phase Extraction ◽  
Carboxylic Acids ◽  
Water Samples ◽  
Solid Phase ◽  
Cost Effective ◽  
Phase Extraction ◽  
Surface Water Samples

The reliable quantification of perfluoroalkyl carboxylic acids (PFCAs) in environmental samples like surface water by using gas chromatography (GC) remains challenging because the polar PFCAs call for derivatization before injection and problems involving the integration of sample pretreatment and derivatization procedures. Here we proposed a cost-effective method for the GC based determination of C4–C12 PFCAs in surface water samples by integrating solid phase extraction and PFCAs anilide derivatization. First, we assessed the performance of different PFCAs derivatization methods, namely esterification and amidation. Esterification was unable to derivatize C4–C6 PFCAs. On the contrary, amidation procedures by using 2,4-difluoroaniline (DFA) and N,N′-dicyclohexylcarbodiimide (DCC) could successfully transform all the PFCA analogs to produce anilide derivatives, which could be easily detected by GC. Then the reaction conditions in the amidation approach were further optimized by using orthogonal design experiments. After optimizing the instrumental parameters of GC, the limits of detection (LOD) of this derivatization method were determined to be 1.14–6.32 μg L−1. Finally, in order to establish an intact method for the quantification of PFCAs in surface water samples, solid phase extraction (SPE) was used for extraction and cleanup, which was further integrated with the subsequent amidation process. The SPE-amidation-GC method was validated for application, with good accuracy and precision reflected by the PFCAs recoveries and derivatization of triplicates. The method reported here could provide a promising and cost-effective alternative for the simultaneous determination of C4–C12 PFCAs in environmental water samples.

Pteridines CI Synthesis and Properties of Lumazine-6- and -7-carboxylic Acids

Pteridines ◽  
1993 ◽  
Vol 4 (4) ◽  
pp. 178-186 ◽  
Author(s):  
Roland Eisele ◽  
Keiichi Aritomo ◽  
Wolfgang Pfleiderer
Keyword(s):  
Carboxylic Acid ◽  
Carboxylic Acids ◽  
Resonance Effect ◽  
Uv Spectra ◽  
High Yield ◽  
Methyl Group ◽  
Methyl Derivatives ◽  
Pyrimidine Moiety

Summary Lumazine-6-(8) and 7-carboxylic acid (23) and their N-methyl derivatives (12, 13, 21, 26, 28, 29) have been synthesized and characterized by the determination of their pK values and the UV spectra of the neutral, mono and dianion species. It was noticed that the acidities of the two N-H protons of the pyrimidine moiety are almost the same indicating that the dianions of 8 and 23, respectively, are I: 1 mixtures of the corresponding N-l and N-3 deprotonated forms. The lumazine-7-carboxylic acids (23, 26, 28, 29, 31, 33) are in comparison to their 6-carboxyJic acid counterparts (8, 12, 13, 21, 39) stronger acids by about I pK unit due to the resonance effect of the 4-oxo function on C-7 but not C-6. Alkaline KMn04 oxidation of 6.7-dimethyl-Iumazine (30) forms expectedly 6-methyl-Iumazine-7-carboxylic acid (31) in high yield according to the activation of the 7-methyl group by the electron-attracting 4-carbonyl residue.

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