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Lubinska-Szczygeł M, Polkowska Ż, Rutkowska M, Gorinstein S. Chemical, Aroma and Pro-Health Characteristics of Kaffir Lime Juice-The Approach Using Optimized HS-SPME-GC-TOFMS, MP-OES, 3D-FL and Physiochemical Analysis. Int J Mol Sci 2023; 24:12410. [PMID: 37569785 PMCID: PMC10418508 DOI: 10.3390/ijms241512410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 07/31/2023] [Accepted: 08/02/2023] [Indexed: 08/13/2023] Open
Abstract
The study aimed to provide the chemical, aroma and prohealth characteristics of the kaffir lime juice. A procedure using solid-phase microextraction with gas chromatography (SPME-GC-TOFMS) was optimized and validated for the determination of terpenes of kaffir lime. Main physicochemical parameters: pH, vitamin C, citric acid and °Brix were evaluated. Micro- and macro elements were determined using microwave plasma optic emission spectrometry (MP-OES). The binding of kaffir lime terpenes to human serum albumin (HSA) was investigated by fluorescence spectroscopy (3D-FL). β-Pinene and Limonene were selected as the most abundant terpenes with the concentration of 1225 ± 35 and 545 ± 16 µg/g, respectively. The values of citric acid, vitamin C, °Brix and pH were 74.74 ± 0.50 g/kg, 22.31 ± 0.53 mg/100 mL, 10.35 ± 0.70 and 2.406 ± 0.086 for, respectively. Iron, with a concentration of 16.578 ± 0.029 mg/kg, was the most abundant microelement. Among the macroelements, potassium (8121 ± 52 mg/kg) was dominant. Kaffir lime binding to HSA was higher than β-Pinene, which may indicate the therapeutic effect of the juice. Kaffir lime juice is a source of terpenes with good aromatic and bioactive properties. Fluorescence measurements confirmed its therapeutic effect. Kaffir lime juice is also a good source of citric acid with potential industrial application. The high content of minerals compared to other citruses increases its prohealth value.
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Affiliation(s)
- Martyna Lubinska-Szczygeł
- Department of Analytical Chemistry, Faculty of Chemistry, Gdańsk University of Technology, 80-233 Gdansk, Poland;
| | - Żaneta Polkowska
- Department of Analytical Chemistry, Faculty of Chemistry, Gdańsk University of Technology, 80-233 Gdansk, Poland;
| | - Małgorzata Rutkowska
- Department of Analytical Chemistry, Faculty of Chemistry, Gdańsk University of Technology, 80-233 Gdansk, Poland;
| | - Shela Gorinstein
- Institute for Drug Research, School of Pharmacy, Hadassah Medical School, The Hebrew University, Jerusalem 91120, Israel;
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Zhang S, Zhang L, Yu M, Luo D, Chen S, Liu W, Zhang Y, Zhang L, Zhao T. Essential oils of Zingiber officinale: Chemical composition, in vivo alleviation effects on TPA induced ear swelling in mice and in vitro bioactivities. Front Nutr 2022; 9:1043175. [PMID: 36352904 PMCID: PMC9639606 DOI: 10.3389/fnut.2022.1043175] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 10/03/2022] [Indexed: 11/24/2022] Open
Abstract
Zingiber officinale (ZO) is a traditional food condiment. The essential oils of Z. officinale (ZOEOs) are known to have multiple bioactivities. In this study, gas chromatography mass spectrometer (GC-MS) analytical method was used to identify active ingredient present in ZOEOs. A total of 41 compounds were identified in ZOEOs. Major components in ZOEOs were zingiberene (19.71%), (+)-β-cedrene (12.85%), farnesene (12.17%), α-curcumene (10.18%) and β-elemene (3.54%). Experimental results of 12-O-tetradecanoylphorbol-13 acetate (TPA) induced ear swelling validation mice model showed that ZOEOs treatment has better anti-inflammatory effect compared with ibuprofen (positive control) at high concentrations. Histological and immunohistochemical analysis showed that ZOEOs significantly decreased COX-2, IL-6 and NF-κB expression in a dose dependent manner. The mRNA levels of COX-2 and NF-κB were also down regulated by the application of ZOEOs. This indicated that ZOEOs exhibited positive effects in ear skin protection. Antibacterial experimental results showed that EOZOs had anti-bacterial effects on Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus. DPPH radical scavenging, A549 cell line and LNCaP cell line inhibition results indicated that ZOEOs exhibited potential antioxidant and anti-tumor properties. The findings of these study provide scientific basis on therapeutic use of ZO in food, cosmetic and pharmaceutical industries.
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Affiliation(s)
- Silu Zhang
- Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Shenzhen Precision Health Food Technology Co., Ltd., Shenzhen, China
| | - Lijun Zhang
- Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China
| | - Mengjie Yu
- Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- School of Traditional Chinese Medicine, Guangdong Pharmaceutical University, Guangzhou, China
| | - Donghui Luo
- Guangdong Provincial Key Laboratory of Plant Resources Biorefinery, School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China
| | - Shuai Chen
- Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Weifeng Liu
- Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Yehui Zhang
- Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
| | - Lanyue Zhang
- Guangdong Provincial Key Laboratory of Plant Resources Biorefinery, School of Biomedical and Pharmaceutical Sciences, Guangdong University of Technology, Guangzhou, China
- *Correspondence: Lanyue Zhang
| | - Tiantian Zhao
- Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs, Guangdong Key Laboratory of Agricultural Products Processing, Sericulture and Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, China
- Food Science and Engineering Department, Chaozhou Branch of Chemistry and Chemical Engineering Guangdong Laboratory, Chaozhou, China
- Tiantian Zhao
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Pemberton TA, Chen M, Harris GG, Chou WKW, Duan L, Köksal M, Genshaft AS, Cane DE, Christianson DW. Exploring the Influence of Domain Architecture on the Catalytic Function of Diterpene Synthases. Biochemistry 2017; 56:2010-2023. [PMID: 28362483 DOI: 10.1021/acs.biochem.7b00137] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Terpenoid synthases catalyze isoprenoid cyclization reactions underlying the generation of more than 80,000 natural products. Such dramatic chemodiversity belies the fact that these enzymes generally consist of only three domain folds designated as α, β, and γ. Catalysis by class I terpenoid synthases occurs exclusively in the α domain, which is found with α, αα, αβ, and αβγ domain architectures. Here, we explore the influence of domain architecture on catalysis by taxadiene synthase from Taxus brevifolia (TbTS, αβγ), fusicoccadiene synthase from Phomopsis amygdali (PaFS, (αα)6), and ophiobolin F synthase from Aspergillus clavatus (AcOS, αα). We show that the cyclization fidelity and catalytic efficiency of the α domain of TbTS are severely compromised by deletion of the βγ domains; however, retention of the β domain preserves significant cyclization fidelity. In PaFS, we previously demonstrated that one α domain similarly influences catalysis by the other α domain [ Chen , M. , Chou , W. K. W. , Toyomasu , T. , Cane , D. E. , and Christianson , D. W. ( 2016 ) ACS Chem. Biol. 11 , 889 - 899 ]. Here, we show that the hexameric quaternary structure of PaFS enables cluster channeling. We also show that the α domains of PaFS and AcOS can be swapped so as to make functional chimeric αα synthases. Notably, both cyclization fidelity and catalytic efficiency are altered in all chimeric synthases. Twelve newly formed and uncharacterized C20 diterpene products and three C25 sesterterpene products are generated by these chimeras. Thus, engineered αβγ and αα terpenoid cyclases promise to generate chemodiversity in the greater family of terpenoid natural products.
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Affiliation(s)
- Travis A Pemberton
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Mengbin Chen
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Golda G Harris
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Wayne K W Chou
- Department of Chemistry, Brown University , Box H, Providence, Rhode Island 02912, United States
| | - Lian Duan
- Department of Chemistry, Brown University , Box H, Providence, Rhode Island 02912, United States
| | - Mustafa Köksal
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Alex S Genshaft
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - David E Cane
- Department of Chemistry, Brown University , Box H, Providence, Rhode Island 02912, United States
| | - David W Christianson
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
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Li R, Chou WKW, Himmelberger JA, Litwin KM, Harris GG, Cane DE, Christianson DW. Reprogramming the chemodiversity of terpenoid cyclization by remolding the active site contour of epi-isozizaene synthase. Biochemistry 2014; 53:1155-68. [PMID: 24517311 PMCID: PMC3985761 DOI: 10.1021/bi401643u] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The class I terpenoid cyclase epi-isozizaene synthase (EIZS) utilizes the universal achiral isoprenoid substrate, farnesyl diphosphate, to generate epi-isozizaene as the predominant sesquiterpene cyclization product and at least five minor sesquiterpene products, making EIZS an ideal platform for the exploration of fidelity and promiscuity in a terpenoid cyclization reaction. The hydrophobic active site contour of EIZS serves as a template that enforces a single substrate conformation, and chaperones subsequently formed carbocation intermediates through a well-defined mechanistic sequence. Here, we have used the crystal structure of EIZS as a guide to systematically remold the hydrophobic active site contour in a library of 26 site-specific mutants. Remolded cyclization templates reprogram the reaction cascade not only by reproportioning products generated by the wild-type enzyme but also by generating completely new products of diverse structure. Specifically, we have tripled the overall number of characterized products generated by EIZS. Moreover, we have converted EIZS into six different sesquiterpene synthases: F96A EIZS is an (E)-β-farnesene synthase, F96W EIZS is a zizaene synthase, F95H EIZS is a β-curcumene synthase, F95M EIZS is a β-acoradiene synthase, F198L EIZS is a β-cedrene synthase, and F96V EIZS and W203F EIZS are (Z)-γ-bisabolene synthases. Active site aromatic residues appear to be hot spots for reprogramming the cyclization cascade by manipulating the stability and conformation of critical carbocation intermediates. A majority of mutant enzymes exhibit only relatively modest 2-100-fold losses of catalytic activity, suggesting that residues responsible for triggering substrate ionization readily tolerate mutations deeper in the active site cavity.
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Affiliation(s)
- Ruiqiong Li
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania , Philadelphia, Pennsylvania 19104-6323, United States
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Aaron JA, Lin X, Cane DE, Christianson DW. Structure of epi-isozizaene synthase from Streptomyces coelicolor A3(2), a platform for new terpenoid cyclization templates. Biochemistry 2010; 49:1787-97. [PMID: 20131801 PMCID: PMC2840623 DOI: 10.1021/bi902088z] [Citation(s) in RCA: 128] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The X-ray crystal structure of recombinant epi-isozizaene synthase (EIZS), a sesquiterpene cyclase from Streptomyces coelicolor A3(2), has been determined at 1.60 A resolution. Specifically, the structure of wild-type EIZS is that of its closed conformation in complex with three Mg(2+) ions, inorganic pyrophosphate (PP(i)), and the benzyltriethylammonium cation (BTAC). Additionally, the structure of D99N EIZS has been determined in an open, ligand-free conformation at 1.90 A resolution. Comparison of these two structures provides the first view of conformational changes required for substrate binding and catalysis in a bacterial terpenoid cyclase. Moreover, the binding interactions of BTAC may mimic those of a carbocation intermediate in catalysis. Accordingly, the aromatic rings of F95, F96, and F198 appear to be well-oriented to stabilize carbocation intermediates in the cyclization cascade through cation-pi interactions. Mutagenesis of aromatic residues in the enzyme active site results in the production of alternative sesquiterpene product arrays due to altered modes of stabilization of carbocation intermediates as well as altered templates for the cyclization of farnesyl diphosphate. Accordingly, the 1.64 A resolution crystal structure of F198A EIZS in a complex with three Mg(2+) ions, PP(i), and BTAC reveals an alternative binding orientation of BTAC; alternative binding orientations of a carbocation intermediate could lead to the formation of alternative products. Finally, the crystal structure of wild-type EIZS in a complex with four Hg(2+) ions has been determined at 1.90 A resolution, showing that metal binding triggers a significant conformational change of helix G to cap the active site.
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Affiliation(s)
- Julie A. Aaron
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323
| | - Xin Lin
- Department of Chemistry, Box H, Brown University, Providence, RI 02912-9108
| | - David E. Cane
- Department of Chemistry, Box H, Brown University, Providence, RI 02912-9108,To whom correspondence should be addressed. D.W.C.: telephone: (215) 898-5714; fax: (215) 573-2201; . D.E.C.: telephone: (401) 863-3588; fax: (401) 863-9368;
| | - David W. Christianson
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, PA 19104-6323,To whom correspondence should be addressed. D.W.C.: telephone: (215) 898-5714; fax: (215) 573-2201; . D.E.C.: telephone: (401) 863-3588; fax: (401) 863-9368;
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Lucero M, Estell R, Tellez M, Fredrickson E. A retention index calculator simplifies identification of plant volatile organic compounds. PHYTOCHEMICAL ANALYSIS : PCA 2009; 20:378-384. [PMID: 19533596 DOI: 10.1002/pca.1137] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
INTRODUCTION Plant volatiles (PVOCs) are important targets for studies in natural products, chemotaxonomy and biochemical ecology. The complexity of PVOC profiles often limits research to studies targeting only easily identified compounds. With the availability of mass spectral libraries and recent growth of retention index (RI) libraries, PVOC identification can be achieved using only gas chromatography coupled to mass spectrometry (GCMS). However, RI library searching is not typically automated, and until recently, RI libraries were both limited in scope and costly to obtain. OBJECTIVE To automate RI calculation and lookup functions commonly utilised in PVOC analysis. METHODOLOGY Formulae required for calculating retention indices from retention time data were placed in a spreadsheet along with lookup functions and a retention index library. Retention times obtained from GCMS analysis of alkane standards and Koeberlinia spinosa essential oil were entered into the spreadsheet to determine retention indices. Indices were used in combination with mass spectral analysis to identify compounds contained in Koeberlinia spinosa essential oil. RESULTS Eighteen compounds were positively identified. Total oil yield was low, with only 5 ppm in purple berries. The most abundant compounds were octen-3-ol and methyl salicylate. The spreadsheet accurately calculated RIs of the detected compounds. CONCLUSION The downloadable spreadsheet tool developed for this study provides a calculator and RI library that works in conjuction with GCMS or other analytical techniques to identify PVOCs in plant extracts.
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Affiliation(s)
- Mary Lucero
- USDA, ARS, Jornada Experimental Range, Las Cruces, NM 88003, USA.
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Lin X, Cane DE. Biosynthesis of the sesquiterpene antibiotic albaflavenone in Streptomyces coelicolor. Mechanism and stereochemistry of the enzymatic formation of epi-isozizaene. J Am Chem Soc 2009; 131:6332-3. [PMID: 19385616 PMCID: PMC2690639 DOI: 10.1021/ja901313v] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Epi-isozizaene synthase from Streptomyces coelicolor catalyzes the multistep cyclization of farnesyl diphosphate (2, FPP) to the tricyclic sesquiterpene hydrocarbon (+)-epi-isozizaene (3), which is converted in turn to the antibiotic albaflavenone (1) in a two-step, cytochrome P450-catalyzed oxidation. Competitive incubation of deuterated and nondeuterated samples of (3S)-NPP and (3RS)-NPP followed by GC-MS analysis of the degree of deuteration in the resulting labeled epi-isozizaene established that (3R)-NPP is the natural cyclization intermediate. Incubation of (3RS)-(Z)-[1-(2)H]NPP (4b) with epi-isozizaene synthase gave [11(anti)-(2)H]epi-isozizaene (3b), indicating that the S(N)' cyclization of 4 involves the predicted anti stereochemistry, consistent with the inference from earlier experiments with chirally deuterated FPP. Incubation of separate samples of [12,12,12-(2)H(3)]FPP (2d) and [13,13,13-(2)H(3)]FPP (2e) gave epi-isozizaenes 3d and 3e, thereby establishing the stereochemical course of the cyclization of the proposed intermediate acorenyl cation 6, as well as the stereochemistry of the successive 1,2-methyl migration and deprotonation that generate the final product. Further insights into the mechanism and the role of the enzyme came from site-directed mutagenesis of active site residues in two universally conserved Mg(2+)-binding domains and the identification of six minor sesquiterpene products 9-13 and 15 produced by the wild-type and mutant proteins. The aberrant products are believed to result from derailment and premature quenching of the normal intermediates of the cationic cyclization cascade.
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Affiliation(s)
- Xin Lin
- Department of Chemistry, Box H, Brown University, Providence, Rhode Island 02912-9108
| | - David E. Cane
- Department of Chemistry, Box H, Brown University, Providence, Rhode Island 02912-9108
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Castello G, Moretti P, Vezzani S. Retention models for programmed gas chromatography. J Chromatogr A 2009; 1216:1607-23. [DOI: 10.1016/j.chroma.2008.11.049] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2008] [Revised: 11/17/2008] [Accepted: 11/19/2008] [Indexed: 11/29/2022]
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Harangi J. Chromatographic Index–Intensity Fingerprint: Identification of Multicomponent Samples. Chromatographia 2008. [DOI: 10.1365/s10337-008-0678-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Zellner BD, Bicchi C, Dugo P, Rubiolo P, Dugo G, Mondello L. Linear retention indices in gas chromatographic analysis: a review. FLAVOUR FRAG J 2008. [DOI: 10.1002/ffj.1887] [Citation(s) in RCA: 160] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Nakagawa K, Kawana S, Yamaguchi S. Application of Pentafluorobenzyl and Hexafluoroisopropyl Esters for Retention Indexes in GC-Negative Ion Chemical Ionization MS. Chromatographia 2008. [DOI: 10.1365/s10337-008-0593-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Pietrogrande MC, Mercuriali M, Pasti L. Signal processing of GC–MS data of complex environmental samples: Characterization of homologous series. Anal Chim Acta 2007; 594:128-38. [PMID: 17560394 DOI: 10.1016/j.aca.2007.05.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 05/07/2007] [Accepted: 05/13/2007] [Indexed: 10/23/2022]
Abstract
Identification and characterization of homologous series by GC-MS analysis provide very relevant information on organic compounds in complex mixtures. A chemometric approach, based on the study of the autocovariance function, EACVF(tot), is described as a suitable tool for extracting molecular-structural information from the GC signal, in particular for identifying the presence of homologous series and quantifying the number of their terms. A data pre-processing procedure is introduced to transform the time axis in order to display a strictly homogenous retention pattern: n-alkanes are used as external standard to stretch or shrink the original chromatogram in order to build up a linear GC retention scale. This addition can be regarded as a further step in the direction of a signal processing procedure for achieving a systematic characterization of complex mixture from experimental chromatograms. The EACVF(tot) was computed on the linearized chromatogram: if the sample presents terms of homologous series, the EACVF(tot) plot shows well-defined deterministic peaks at repeated constant interdistances. By comparison with standard references, the presence of such peaks is diagnostic for the presence of the ordered series, their position can be related to the chemical structure of the compounds, their height is the basis for estimating the number of terms in the series. The power of the procedure can be magnified by studying SIM chromatograms acquired at specific m/z values characteristic of the compounds of interest: the EACVF(tot) on these selective signals makes it possible to confirm the results obtained from an unknown mixture and check their reliability. The procedure was validated on standard mixtures of known composition and applied to an unknown gas oil sample. In particular, the paper focuses on the study of two specific classes of compounds: n-alkanes and oxygen-containing compounds, since their identification provides information useful for characterizing the chemical composition of many samples of different origin. The robustness of the method was tested in experimental chromatograms obtained under unfavorable conditions: chromatograms acquired in non-optimal temperature program conditions and chromatographic data affected by signal noise.
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Stojanović G, Palić I, Ursić-Janković J. Composition and antimicrobial activity of the essential oil ofMicromeria cristata andMicromeria juliana. FLAVOUR FRAG J 2005. [DOI: 10.1002/ffj.1507] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Western RJ, Marriott PJ. Methods for generating second dimension retention index data in comprehensive two-dimensional gas chromatography. J Chromatogr A 2003; 1019:3-14. [PMID: 14650600 DOI: 10.1016/j.chroma.2003.09.006] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Two methods of generating transportable second dimension retention data are outlined for comprehensive two-dimensional gas chromatography (GC x GC). They are both refinements of a previously outlined procedure, which adapted 'isovolatile' curves to retention prediction maps developed in our laboratory, extended to a more polar homologous series, the linear primary alcohols. The earlier work investigated maps based on alkanes and methyl ketones and methyl esters; here the method of data collection to generate the retention map has also changed, extending the retention base range. The resulting retention map permits a retention basis to be used for GC x GC data, however, a more polar retention set than alkanes is required. The calculation of 'retention indices' is aided by the generation of 'fractional reference compound' curves, by either direct manipulation of data local to the solute, or generation of a discrete curve coincident with the retention co-ordinates of the target compound.
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Affiliation(s)
- Robert J Western
- Australian Centre for Research on Separation Science, RMIT University, GPO Box 2476V, Melbourne 3001, Australia
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