Polycarboxylic acids(PACs)are important metabolic products in almost all living bodies,yet current analytical methods for detection of PACs in tea beverages are still unsatisfactory due to the complex matrix and physi...Polycarboxylic acids(PACs)are important metabolic products in almost all living bodies,yet current analytical methods for detection of PACs in tea beverages are still unsatisfactory due to the complex matrix and physicochemical properties of PACs.In this work,a rapid method was developed for the simultaneous determination of 7 PACs,including tartaric acid,α-ketoglutaric acid,malic acid,malonic acid,cis-aconitic acid,succinic acid,and fumaric acid,in beverages,based on selective removal of the matrix in combination with liquid chromatography–mass spectrometry(LC-MS)analysis.By stirring with activated carbon and the Na2CO3 solution,the matrix in beverages was selectively removed,and PACs were almost retained in the supernatant of diluted Na2CO3 solution.Under optimized parameters,the limit of quantitation for the PACs was in the range of 1–50 ng/mL,and the content of the PACs in 8 beverages was determined with the recovery range of 72.2%–122.5%.The contents of malic acid,malonic acid,and succinic acid in tea beverages were found to be greater than those in non-tea beverages.Moreover,the concentration of these PACs in beverages was found to be multiplied many times in their deterioration period,especially for fumaric acid andα-ketoglutaric acid.These results indicated that PACs can be selected as a criterion to differentiate qualified tea beverages from spoiled beverages.展开更多
The reaction of AgNO3 , 4,4′-bipyridine （bpy） and 2,2′-bipyridine-3,3′-dicarboxylic acid （H2bpdc）/2,2′-biquinoline-4,4′-dicarboxylic acid （H2bqdc）/1,3-benzenedicarboxylic acid （H2bdc） gave rise to block-l...The reaction of AgNO3 , 4,4′-bipyridine （bpy） and 2,2′-bipyridine-3,3′-dicarboxylic acid （H2bpdc）/2,2′-biquinoline-4,4′-dicarboxylic acid （H2bqdc）/1,3-benzenedicarboxylic acid （H2bdc） gave rise to block-like crystals of [Ag4（bpy）2（bpdc）2]·13H2O（1）, [Ag2（bpy）（bqdc）（H2O）]·4.5H2O（2） and [Ag2（bpy）2（H2O）2]（bdc）·3H2O（3） by slow evaporation. All the three complexes contain sandwich-like crystal structures, in which anionic sheets built up from different anions （bpdc2- , bqdc2- and bdc2- ） and lattice water molecules via rich hydrogen-bonding interactions are inserted between the cationic silver complex layers, and the abundant Ag···Ag, Ag···N and π-π stacking interactions further strengthen the 3D frameworks. The lattice water molecules are situated among the framework of crystal structure and stabilized by rich hydrogen-bonding interactions, and lattice water molecules may play a role in the orientation of organic anions in the crystal packing. Additionally, the thermal properties of 1, 2 and 3 were also discussed in detail.展开更多
The pyrolysis treatment of lignites could remove thermal-unstable aliphatic structures but enrich aromatic structures in resulting pyrolysis residues,which would facilitate producing benzene polycarboxylic acids(BPCAs...The pyrolysis treatment of lignites could remove thermal-unstable aliphatic structures but enrich aromatic structures in resulting pyrolysis residues,which would facilitate producing benzene polycarboxylic acids(BPCAs).Herein,the demineralized Zhaotong lignite(DZL)was pyrolyzed at 250-550℃ to afford the corresponding pyrolysis residues.Subsequently,DZL and its pyrolysis residues were subjected to oxidation with aqueous sodium hypochlorite.By XRD,FTIR,and element analyses,it was found that the content and polycondensation degree of aromatic structures simultaneously increased with increasing pyrolysis temperature.Furthermore,the yield and selectivity of BPCAs both increased along with raising pyrolysis temperature in resulting products from fully oxidation of DZL and its pyrolysis residues.Based on the distribution of BPCAs,peri-condensed aromatic structures were dominant in DZL and its DPRs,and obviously increased with increasing pyrolysis temperature.More interestingly,good correlation was found between the yield of BPCAs and aromaticity parameters.Meanwhile,the yield of benzenepentacrboxylic acid was well associated with polycondensation degree parameters.展开更多
基金the Analysis and Detection Foundation of Science and Technology Department in Zhejiang Province,China(No.LGC21B050009)the Hangzhou Normal University Innovation Practice and Service Local Plan‘Diligent,Careful Research and Innovation'Scientific Research Project,China(No.YJS2022055).
文摘Polycarboxylic acids(PACs)are important metabolic products in almost all living bodies,yet current analytical methods for detection of PACs in tea beverages are still unsatisfactory due to the complex matrix and physicochemical properties of PACs.In this work,a rapid method was developed for the simultaneous determination of 7 PACs,including tartaric acid,α-ketoglutaric acid,malic acid,malonic acid,cis-aconitic acid,succinic acid,and fumaric acid,in beverages,based on selective removal of the matrix in combination with liquid chromatography–mass spectrometry(LC-MS)analysis.By stirring with activated carbon and the Na2CO3 solution,the matrix in beverages was selectively removed,and PACs were almost retained in the supernatant of diluted Na2CO3 solution.Under optimized parameters,the limit of quantitation for the PACs was in the range of 1–50 ng/mL,and the content of the PACs in 8 beverages was determined with the recovery range of 72.2%–122.5%.The contents of malic acid,malonic acid,and succinic acid in tea beverages were found to be greater than those in non-tea beverages.Moreover,the concentration of these PACs in beverages was found to be multiplied many times in their deterioration period,especially for fumaric acid andα-ketoglutaric acid.These results indicated that PACs can be selected as a criterion to differentiate qualified tea beverages from spoiled beverages.
基金Supported by Funding Project forAcademic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality (No.PHR201008372 and PHR201106124)Open Research Fund Program of Key Laboratory of Urban Stormwater System and Water Environment (Ministry of Education),Beijing University of Civil Engineering and Architecture (No.YH201101003)
文摘The reaction of AgNO3 , 4,4′-bipyridine （bpy） and 2,2′-bipyridine-3,3′-dicarboxylic acid （H2bpdc）/2,2′-biquinoline-4,4′-dicarboxylic acid （H2bqdc）/1,3-benzenedicarboxylic acid （H2bdc） gave rise to block-like crystals of [Ag4（bpy）2（bpdc）2]·13H2O（1）, [Ag2（bpy）（bqdc）（H2O）]·4.5H2O（2） and [Ag2（bpy）2（H2O）2]（bdc）·3H2O（3） by slow evaporation. All the three complexes contain sandwich-like crystal structures, in which anionic sheets built up from different anions （bpdc2- , bqdc2- and bdc2- ） and lattice water molecules via rich hydrogen-bonding interactions are inserted between the cationic silver complex layers, and the abundant Ag···Ag, Ag···N and π-π stacking interactions further strengthen the 3D frameworks. The lattice water molecules are situated among the framework of crystal structure and stabilized by rich hydrogen-bonding interactions, and lattice water molecules may play a role in the orientation of organic anions in the crystal packing. Additionally, the thermal properties of 1, 2 and 3 were also discussed in detail.
基金supported by the National Natural Science Foundation of China(Grant No.21706172)NSFC-Shanxi joint fund for coal-based low carbon(Grant No.U1610223 and U1710102)+1 种基金Key Research and Development(R&D)Projects of Shanxi Province(201903D321061)State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering(Grant No.2021-K79).
文摘The pyrolysis treatment of lignites could remove thermal-unstable aliphatic structures but enrich aromatic structures in resulting pyrolysis residues,which would facilitate producing benzene polycarboxylic acids(BPCAs).Herein,the demineralized Zhaotong lignite(DZL)was pyrolyzed at 250-550℃ to afford the corresponding pyrolysis residues.Subsequently,DZL and its pyrolysis residues were subjected to oxidation with aqueous sodium hypochlorite.By XRD,FTIR,and element analyses,it was found that the content and polycondensation degree of aromatic structures simultaneously increased with increasing pyrolysis temperature.Furthermore,the yield and selectivity of BPCAs both increased along with raising pyrolysis temperature in resulting products from fully oxidation of DZL and its pyrolysis residues.Based on the distribution of BPCAs,peri-condensed aromatic structures were dominant in DZL and its DPRs,and obviously increased with increasing pyrolysis temperature.More interestingly,good correlation was found between the yield of BPCAs and aromaticity parameters.Meanwhile,the yield of benzenepentacrboxylic acid was well associated with polycondensation degree parameters.
