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Gaida M, Franchina FA, Stefanuto PH, Focant JF. Modeling approaches for temperature-programmed gas chromatographic retention times under vacuum outlet conditions. J Chromatogr A 2021; 1651:462300. [PMID: 34134077 DOI: 10.1016/j.chroma.2021.462300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/19/2021] [Accepted: 05/22/2021] [Indexed: 12/15/2022]
Abstract
This contribution evaluates the performance of two predictive approaches in calculating temperature-programmed gas chromatographic retention times under vacuum outlet conditions. In the first approach, the predictions are performed according to a thermodynamic-based model, while in the second approach the predictions are conducted by using the temperature-programmed retention time equation. These modeling approaches were evaluated on 47 test compounds belonging to different chemical classes, under different experimental conditions, namely, two modes of gas flow regulation (i.e., constant inlet pressure and constant flow rate), and different temperature programs (i.e., 7 °C/min, 5 °C/min, and 3 °C/min). Both modeling approaches gave satisfactory results and were able to accurately predict the elution profiles of the studied test compounds. The thermodynamic-based model provided more satisfying results under constant flow rate mode, with average modeling errors of 0.43%, 0.33%, and 0.15% across all the studied temperature programs. Nevertheless, under constant inlet pressure mode, lower modeling errors were achieved when using the temperature-programmed retention time equation, with average modeling errors of 0.18%, 0.18%, and 0.31% across the used temperature programs.
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Affiliation(s)
- Meriem Gaida
- University of Liège, Molecular Systems, Organic & Biological Analytical Chemistry Group, 11 Allée du Six Août, 4000 Liège, Belgium
| | - Flavio A Franchina
- University of Liège, Molecular Systems, Organic & Biological Analytical Chemistry Group, 11 Allée du Six Août, 4000 Liège, Belgium; University of Ferrara, Department of Chemistry, Pharmaceutical, and Agricultural Sciences, via L. Borsari 46, 44121 Ferrara, Italy.
| | - Pierre-Hugues Stefanuto
- University of Liège, Molecular Systems, Organic & Biological Analytical Chemistry Group, 11 Allée du Six Août, 4000 Liège, Belgium
| | - Jean-François Focant
- University of Liège, Molecular Systems, Organic & Biological Analytical Chemistry Group, 11 Allée du Six Août, 4000 Liège, Belgium
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2
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Wilson MB, Barnes BB, Boswell PG. What experimental factors influence the accuracy of retention projections in gas chromatography-mass spectrometry? J Chromatogr A 2014; 1373:179-89. [PMID: 25482038 DOI: 10.1016/j.chroma.2014.11.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Revised: 08/30/2014] [Accepted: 11/11/2014] [Indexed: 11/29/2022]
Abstract
Programmed-temperature gas chromatographic (GC) retention information is difficult to share because it depends on so many experimental factors that vary among laboratories. Though linear retention indexing cannot properly account for experimental differences, retention times can be accurately calculated, or "projected", from shared isothermal retention vs. temperature (T) relationships, but only if the temperature program and hold-up time vs. T profile produced by a GC is known with great precision. The effort required to measure these profiles were previously impractical, but we recently showed that they can be easily back-calculated from the programmed-temperature retention times of a set of 25 n-alkanes using open-source software at www.retentionprediction.org/gc. In a multi-lab study, the approach was shown to account for both intentional and unintentional differences in the temperature programs, flow rates, and inlet pressures produced by the GCs. Here, we tested 16 other experimental factors and found that only 5 could reduce accuracy in retention projections: injection history, exposure to very high levels of oxygen at high temperature, a very low transfer line temperature, an overloaded column, and a very short column (≤15m). We find that the retention projection methodology acts as a hybrid of conventional retention projection and retention indexing, drawing on the advantages of both; it properly accounts for a wide range of experimental conditions while accommodating the effects of experimental factors not properly taken into account in the calculations. Finally, we developed a four-step protocol to efficiently troubleshoot a GC system after it is found to be yielding inaccurate retention projections.
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Affiliation(s)
- Michael B Wilson
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, MN 55108, USA.
| | - Brian B Barnes
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, MN 55455, USA.
| | - Paul G Boswell
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, MN 55108, USA.
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3
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Peng B, Kuo MY, Yang P, Hewitt JT, Boswell PG. A practical methodology to measure unbiased gas chromatographic retention factor vs. temperature relationships. J Chromatogr A 2014; 1374:207-215. [PMID: 25496658 DOI: 10.1016/j.chroma.2014.11.018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2014] [Revised: 11/07/2014] [Accepted: 11/10/2014] [Indexed: 11/25/2022]
Abstract
Compound identification continues to be a major challenge. Gas chromatography-mass spectrometry (GC-MS) is a primary tool used for this purpose, but the GC retention information it provides is underutilized because existing retention databases are experimentally restrictive and unreliable. A methodology called "retention projection" has the potential to overcome these limitations, but it requires the retention factor (k) vs. T relationship of a compound to calculate its retention time. Direct methods of measuring k vs. T relationships from a series of isothermal runs are tedious and time-consuming. Instead, a series of temperature programs can be used to quickly measure the k vs. T relationships, but they are generally not as accurate when measured this way because they are strongly biased by non-ideal behavior of the GC system in each of the runs. In this work, we overcome that problem by using the retention times of 25 n-alkanes to back-calculate the effective temperature profile and hold-up time vs. T profiles produced in each of the six temperature programs. When the profiles were measured this way and taken into account, the k vs. T relationships measured from each of two different GC-MS instruments were nearly as accurate as the ones measured isothermally, showing less than two-fold more error. Furthermore, temperature-programmed retention times calculated in five other laboratories from the new k vs. T relationships had the same distribution of error as when they were calculated from k vs. T relationships measured isothermally. Free software was developed to make the methodology easy to use. The new methodology potentially provides a relatively fast and easy way to measure unbiased k vs. T relationships.
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Affiliation(s)
- Baijie Peng
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota 55108, USA.
| | - Mei-Yi Kuo
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota 55108, USA.
| | - Panhia Yang
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota 55108, USA.
| | - Joshua T Hewitt
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota 55108, USA.
| | - Paul G Boswell
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota 55108, USA.
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Ramos Alvarenga RF, Wan B, Inui T, Franzblau SG, Pauli GF, Jaki BU. Airborne antituberculosis activity of Eucalyptus citriodora essential oil. JOURNAL OF NATURAL PRODUCTS 2014; 77:603-10. [PMID: 24641242 DOI: 10.1021/np400872m] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
The rapid emergence of multi- and extensively drug-resistant tuberculosis (MDR/XDR-TB) has created a pressing public health problem, which mostly affects regions with HIV/AIDS prevalence and represents a new constraint in the already challenging disease management of tuberculosis (TB). The present work responds to the need to reduce the number of contagious MDR/XRD-TB patients, protect their immediate environment, and interrupt the rapid spread by laying the groundwork for an inhalation therapy based on anti-TB-active constituents of the essential oil (EO) of Eucalyptus citriodora. In order to address the metabolomic complexity of EO constituents and active principles in botanicals, this study applied biochemometrics, a 3-D analytical approach that involves high-resolution CCC fractionation, GC-MS analysis, bioactivity measurements, and chemometric analysis. Thus, 32 airborne anti-TB-active compounds were identified in E. citriodora EO: the monoterpenes citronellol (1), linalool (3), isopulegol (5), and α-terpineol (7) and the sesquiterpenoids spathulenol (11), β-eudesmol (23), and τ-cadinol (25). The impact of the interaction of multiple components in EOs was studied using various artificial mixtures (AMxs) of the active monoterpenes 1, 2, and 5 and the inactive eucalyptol (33). Both neat 1 and the AMx containing 1, 2, and 33 showed airborne TB inhibition of >90%, while the major E. citriodora EO component, 2, was only weakly active, at 18% inhibition.
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Affiliation(s)
- René F Ramos Alvarenga
- Institute for Tuberculosis Research and ‡Department of Medicinal Chemistry and Pharmacognosy, College of Pharmacy, University of Illinois at Chicago , 833 South Wood Street, Chicago, Illinois 60612, United States
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Barnes BB, Wilson MB, Carr PW, Vitha MF, Broeckling CD, Heuberger AL, Prenni J, Janis GC, Corcoran H, Snow NH, Chopra S, Dhandapani R, Tawfall A, Sumner LW, Boswell PG. "Retention projection" enables reliable use of shared gas chromatographic retention data across laboratories, instruments, and methods. Anal Chem 2013; 85:11650-7. [PMID: 24205931 PMCID: PMC3962126 DOI: 10.1021/ac4033615] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Gas chromatography/mass spectrometry (GC/MS) is a primary tool used to identify compounds in complex samples. Both mass spectra and GC retention times are matched to those of standards; however, it is often impractical to have standards on hand for every compound of interest, so we must rely on shared databases of MS data and GC retention information. Unfortunately, retention databases (e.g., linear retention index libraries) are experimentally restrictive, notoriously unreliable, and strongly instrument dependent, relegating GC retention information to a minor, often negligible role in compound identification despite its potential power. A new methodology called "retention projection" has great potential to overcome the limitations of shared chromatographic databases. In this work, we tested the reliability of the methodology in five independent laboratories. We found that, even when each lab ran nominally the same method, the methodology was 3-fold more accurate than retention indexing because it properly accounted for unintentional differences between the GC/MS systems. When the laboratories used different methods of their own choosing, retention projections were 4- to 165-fold more accurate. More importantly, the distribution of error in the retention projections was predictable across different methods and laboratories, thus enabling automatic calculation of retention time tolerance windows. Tolerance windows at 99% confidence were generally narrower than those widely used even when physical standards are on hand to measure their retention. With its high accuracy and reliability, the new retention projection methodology makes GC retention a reliable, precise tool for compound identification, even when standards are not available to the user.
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Affiliation(s)
- Brian B. Barnes
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Ave., St. Paul, MN 55108
| | - Michael B. Wilson
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Ave., St. Paul, MN 55108
| | - Peter W. Carr
- Department of Chemistry, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455
| | - Mark F. Vitha
- Department of Chemistry, Drake University, Des Moines, IA 50311
| | - Corey D. Broeckling
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO 80523
| | - Adam L. Heuberger
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO 80523
| | - Jessica Prenni
- Proteomics and Metabolomics Facility, Colorado State University, Fort Collins, CO 80523
| | - Gregory C. Janis
- MedTox Laboratories, Laboratory Corporation of America®, Holdings, St. Paul, MN 55112
| | - Henry Corcoran
- MedTox Laboratories, Laboratory Corporation of America®, Holdings, St. Paul, MN 55112
| | - Nicholas H. Snow
- Department of Chemistry and Biochemistry, Center for Academic Industry Partnership, Seton Hall University, 400 South Orange Ave., South Orange, NJ 07079
| | - Shilpi Chopra
- Department of Chemistry and Biochemistry, Center for Academic Industry Partnership, Seton Hall University, 400 South Orange Ave., South Orange, NJ 07079
| | - Ramkumar Dhandapani
- Department of Chemistry and Biochemistry, Center for Academic Industry Partnership, Seton Hall University, 400 South Orange Ave., South Orange, NJ 07079
| | | | | | - Paul G. Boswell
- Department of Horticultural Science, University of Minnesota, 1970 Folwell Ave., St. Paul, MN 55108
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Boswell PG, Carr PW, Cohen JD, Hegeman AD. Easy and accurate calculation of programmed temperature gas chromatographic retention times by back-calculation of temperature and hold-up time profiles. J Chromatogr A 2012; 1263:179-88. [PMID: 23040964 PMCID: PMC3478941 DOI: 10.1016/j.chroma.2012.09.048] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Revised: 09/12/2012] [Accepted: 09/16/2012] [Indexed: 11/16/2022]
Abstract
Linear retention indices are commonly used to identify compounds in programmed-temperature gas chromatography (GC), but they are unreliable unless the original experimental conditions used to measure them are stringently reproduced. However, differences in many experimental conditions may be properly taken into account by calculating programmed-temperature retention times of compounds from their measured isothermal retention vs. temperature relationships. We call this approach "retention projection". Until now, retention projection has been impractical because it required very precise, meticulous measurement of the temperature vs. time and hold-up time vs. temperature profiles actually produced by a specific GC instrument to be accurate. Here we present a new, easy-to-use methodology to precisely measure those profiles: we spike a sample with 25 n-alkanes and use their measured, programmed-temperature retention times to precisely back-calculate what the instrument profiles must have been. Then, when we use those back-calculated profiles to project retention times of 63 chemically diverse compounds, we found that the projections are extremely accurate (e.g. to ±0.9 s in a 40 min ramp). They remained accurate with different temperature programs, GC instruments, inlet pressures, flow rates, and with columns taken from different batches of stationary phase while the accuracy of retention indices became worse the more the experimental conditions were changed from the original ones used to measure them. We also developed new, open-source software (http://www.retentionprediction.org/gc) to demonstrate the system.
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Affiliation(s)
- Paul G. Boswell
- Department of Horticultural Science and the Microbial and Plant Genomics Institute, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota, 55108
| | - Peter W. Carr
- Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455
| | - Jerry D. Cohen
- Department of Horticultural Science and the Microbial and Plant Genomics Institute, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota, 55108
| | - Adrian D. Hegeman
- Department of Horticultural Science and the Microbial and Plant Genomics Institute, University of Minnesota, 1970 Folwell Avenue, St. Paul, Minnesota, 55108
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7
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Comparing columns for gas chromatography with the two-parameter model for retention prediction. J Chromatogr A 2011; 1218:5305-10. [DOI: 10.1016/j.chroma.2011.05.082] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Revised: 05/20/2011] [Accepted: 05/23/2011] [Indexed: 11/30/2022]
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8
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Thewalim Y, Bruno O, Colmsjö A. Study of the gas chromatographic behavior of selected alcohols and amines. Anal Bioanal Chem 2010; 399:1335-45. [DOI: 10.1007/s00216-010-4418-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Revised: 11/01/2010] [Accepted: 11/02/2010] [Indexed: 11/24/2022]
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9
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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: 41] [Impact Index Per Article: 2.7] [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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10
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Aldaeus F, Thewalim Y, Colmsjö A. Prediction of retention times and peak widths in temperature-programmed gas chromatography using the finite element method. J Chromatogr A 2009; 1216:134-9. [DOI: 10.1016/j.chroma.2008.11.038] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 11/07/2008] [Accepted: 11/13/2008] [Indexed: 10/21/2022]
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11
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Retention time prediction of compounds in Grob standard mixture for apolar capillary columns in temperature-programmed gas chromatography. Anal Bioanal Chem 2008; 393:327-34. [DOI: 10.1007/s00216-008-2295-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2008] [Revised: 06/25/2008] [Accepted: 07/10/2008] [Indexed: 10/21/2022]
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12
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Santiuste JM, Tarján G, Ullrich E, Takács JM. Contribution to linearly programmed temperature gas chromatography. J Chromatogr A 2008; 1181:103-15. [DOI: 10.1016/j.chroma.2007.12.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2007] [Revised: 12/12/2007] [Accepted: 12/12/2007] [Indexed: 11/30/2022]
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13
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Aldaeus F, Thewalim Y, Colmsjö A. Prediction of retention times of polycyclic aromatic hydrocarbons and n-alkanes in temperature-programmed gas chromatography. Anal Bioanal Chem 2007; 389:941-50. [PMID: 17851653 DOI: 10.1007/s00216-007-1528-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2007] [Revised: 07/22/2007] [Accepted: 07/26/2007] [Indexed: 10/22/2022]
Abstract
We have developed an iterative procedure for predicting the retention times of polycyclic aromatic hydrocarbons (PAHs) and n-alkanes during separations by temperature-programmed gas chromatography. The procedure is based on estimates of two thermodynamic properties for each analyte (the differences in enthalpy and entropy associated with movements between the stationary and mobile phases) derived from data acquired experimentally in separations under isothermal conditions at temperatures spanning the range covered by the temperature programs in ten-degree increments. The columns used for this purpose were capillary columns containing polydimethylsiloxane-based stationary phases with three degrees of phenyl substitution (0%, 5%, and 50%). Predicted values were mostly within 1% of experimentally determined values, implying that the method is stable and precise.
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Affiliation(s)
- Fredrik Aldaeus
- Department of Analytical Chemistry, Stockholm University, 106 91 Stockholm, Sweden
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14
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Nawas MI, Poole CF. Evaluation of a structure-driven retention model for temperature-programmed gas chromatography. J Chromatogr A 2004; 1023:113-21. [PMID: 14760855 DOI: 10.1016/j.chroma.2003.10.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The solvation parameter model is suitable for describing the retention properties of compounds of varied structure in temperature-programmed gas chromatography. An empirical second-order model provides a good account of the change in system constants as a function of program rate. These relationships codify the reduction in retention time at higher program rates and changes in elution order (selectivity) with program rate. The prediction of retention times from structure, while quite good, is probably adversely affected by descriptor quality and the possibility of a mixed retention mechanism on polar stationary phases. Plots of experimental against predicted temperature-programmed retention times for varied compounds are linear but generally contain a small bias from an ideal model (slope of one and an intercept of zero). The average absolute deviation in temperature-programmed retention times on three columns (DB-210, DB-1701 and EC-Wax) varied from 0.15 to 0.89 min with the best results obtained at higher program rates on the columns of lower polarity.
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Affiliation(s)
- Mohamed I Nawas
- Department of Chemistry, Wayne State University, Rm. 180, Detroit, MI 48202, USA
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15
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Prediction of GC retention values under various column temperature conditions from temperature programmed data. Chromatographia 2001. [DOI: 10.1007/bf02491619] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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16
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Van Deursen M, Janssen HG, Beens J, Rutten G, Cramers C. Design considerations for rapid-heating columns applied in fast capillary gas chromatography. ACTA ACUST UNITED AC 2001. [DOI: 10.1002/mcs.10016] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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18
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Chen J, Zhang L, Tian Y, Wang L. Novel approach for the prediction of retention times in operating parameter programmed gas–liquid chromatography with capillary columns. J Chromatogr A 1998. [DOI: 10.1016/s0021-9673(97)00932-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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19
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Hevesi T, Krupcík J. Flow of the carrier gas in open-tubular capillary columns in temperature-programmed gas chromatography. ACTA ACUST UNITED AC 1997. [DOI: 10.1002/jhrc.1240200809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Vezzani S, Moretti P, Castello G. Automatic prediction of retention times in multi-linear programmed temperature analyses. J Chromatogr A 1997. [DOI: 10.1016/s0021-9673(96)01043-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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21
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Theoretical and practical aspects of flow control in programmed-temperature gas chromatography. J Chromatogr A 1997. [DOI: 10.1016/s0021-9673(96)00659-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
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22
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Comparison of the behaviour of gas-liquid and gas-liquid-solid capillary columns through the determination of thermodynamic characteristics. J Chromatogr A 1996. [DOI: 10.1016/0021-9673(96)00253-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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Snijders H, Janssen HG, Cramers C. Optimization of temperature-programmed gas chromatographic separations I. Prediction of retention times and peak widths from retention indices. J Chromatogr A 1995. [DOI: 10.1016/0021-9673(95)00692-3] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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24
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25
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Prediction of programmed temperature retention indices on capillary columns of different polarities. J Chromatogr A 1995. [DOI: 10.1016/0021-9673(95)00024-h] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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26
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Gerbino TC, Costello G. Prediction of programmed temperature retention times on linked capillary columns of different polarity. ACTA ACUST UNITED AC 1994. [DOI: 10.1002/jhrc.1240170807] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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27
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Vezzani S, Moretti P, Castello G. Fast and accurate method for the automatic prediction of programmed-temperature retention times. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)80161-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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28
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Castello G, Vezzani S, Moretti P. Theoretical calculation of gas hold-up time in capillary gas chromatography Influence of column, instrument parameters and analysis conditions and comp. J Chromatogr A 1994. [DOI: 10.1016/0021-9673(94)80549-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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29
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Castello G, Vezzani S, Moretti P. The selectivity and polarity of carbon layer open tubular capillary columns modified with a polar liquid phase. ACTA ACUST UNITED AC 1994. [DOI: 10.1002/jhrc.1240170108] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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30
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Castello G, Gerbino TC. Analysis of polycyclic aromatic hydrocarbons with an ion-trap mass detector and comparison with other gas chromatographic and high- performance liquid chromatographic techniques. J Chromatogr A 1993. [DOI: 10.1016/0021-9673(93)80098-s] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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