Observation of inconsistent carbon isotope compositions of chlorine-isotopologue pairs of individual organochlorines by gas chromatography-high resolution mass spectrometry

Caiming Tang; Jianhua Tan; Ke Zheng; Qiuxin Huang; Xianzhi Peng; Yujuan Fan

arxiv: 1907.08897 · v1 · pith:SUH4VVKPnew · submitted 2019-07-21 · ⚛️ physics.chem-ph · physics.ins-det

Observation of inconsistent carbon isotope compositions of chlorine-isotopologue pairs of individual organochlorines by gas chromatography-high resolution mass spectrometry

Caiming Tang , Jianhua Tan , Yujuan Fan , Ke Zheng , Qiuxin Huang , Xianzhi Peng This is my paper

Pith reviewed 2026-05-24 18:47 UTC · model grok-4.3

classification ⚛️ physics.chem-ph physics.ins-det

keywords carbon isotope compositionchlorine isotopologuesorganochlorinesGC-HRMSnon-random distributionisotope effectspollutant source identification

0 comments

The pith

Carbon isotope ratios from chlorine-isotopologue pairs of organochlorines are inconsistent, implying non-random isotopologue distributions.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The study measures raw carbon isotope ratios by gas chromatography-high resolution mass spectrometry for chlorine-isotopologue pairs such as 12C35Cl4 versus 12C13C35Cl4 in chloroethylenes, polychlorinated biphenyls, methyl-triclosan, and hexachlorobenzene. Data simulations confirm that differences persist after accounting for background subtraction, dual 13C substitution, deuterium effects, and hydrogen transfer. The inconsistencies lead directly to the conclusion that isotopologues within each organochlorine are not randomly distributed. This observation is interpreted through reaction thermodynamics, kinetics, and mass spectrometry isotope effects, with anticipated uses in tracing pollutant formation and sources.

Core claim

Inconsistent carbon isotope ratios derived from chlorine-isotopologue pairs of individual organochlorines were observed, and the isotopologues of each organochlorine were thus inferred to be non-randomly distributed.

What carries the argument

GC-HRMS measurement of carbon isotope ratios from specific chlorine-isotopologue pairs, validated against simulations for background, dual substitutions, deuterium, and hydrogen-transfer artifacts.

If this is right

The real distributions of carbon and chlorine isotopologues in organochlorines differ from the random expectation used in many models.
Exploration of formation conditions for organochlorine pollutants can incorporate these isotopologue-specific signatures.
Source identification of organochlorine pollutants gains an additional constraint from the observed inconsistencies.
Isotope effects during electron ionization contribute to the measured differences alongside formation processes.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Routine isotope-ratio monitoring of organochlorines may need pair-specific corrections if the non-random pattern holds across more compounds.
Principles from clumped-isotope geochemistry could be tested for applicability to synthetic organic molecules under environmental conditions.
Controlled laboratory synthesis of organochlorines under varying temperatures could map how the inconsistency scales with reaction conditions.

Load-bearing premise

The measured differences in carbon isotope ratios reflect actual non-random distributions of isotopologues rather than residual instrumental or processing artifacts.

What would settle it

Re-measurement of the same compounds with an orthogonal technique such as compound-specific isotope analysis by IRMS that yields identical ratios for both members of each isotopologue pair would falsify the non-random distribution claim.

Figures

Figures reproduced from arXiv: 1907.08897 by Caiming Tang, Jianhua Tan, Ke Zheng, Qiuxin Huang, Xianzhi Peng, Yujuan Fan.

**Figure 1.** Figure 1: Representative chromatograms and high resolution mass spectra of the investigated organochlorines. TCE: trichloroethylene, PCE: tetrachloroethylene, PCB: polychlorinated biphenyl, Me-TCS: methyl-triclosan, HCB: hexachlorobenzene, NL: nominal level, m/z: mass to charge ratio [PITH_FULL_IMAGE:figures/full_fig_p022_1.png] view at source ↗

**Figure 2.** Figure 2: Simulated mass spectrum (molecular ion) of an imaginary organochlorine on electron ionization mass spectrometry and illustration of the definition of chlorine-isotopologue pairs (CIPs). The formula of the compound is postulated to be CmCln with the omission of other elements; Group a (a0-an) corresponds to chlorine isotopologues of which all the carbon atoms are 12C; Group b (b0-bn) corresponds to chlorine… view at source ↗

**Figure 3.** Figure 3: Measured carbon isotope ratios with/without background subtraction, and simulated carbon isotope ratios with/without background subtraction or with background addition. IR: isotope ratio (13C/12C); Mea_with BS: measured carbon isotope ratios with background subtraction; Mea_without BS: measured carbon isotope ratios without background subtraction; Sim_theoretical: theoretically simulated carbon isotope rat… view at source ↗

**Figure 4.** Figure 4: Measured carbon isotope ratios derived from the CIPs of the investigated organochlorines. Error bars represent the standard deviations [PITH_FULL_IMAGE:figures/full_fig_p027_4.png] view at source ↗

read the original abstract

This study investigated the consistency/inconsistency of carbon isotope compositions of chlorine-isotopologue pairs, e.g., 12C235Cl4 vs. 12C13C35Cl4, of individual organochlorines including two chloroethylenes, three polychlorinated biphenyls, methyl-triclosan and hexachlorobenzene. The raw carbon isotope ratios were measured by gas chromatography-high resolution mass spectrometry. Data simulations in terms of background subtraction, background addition, dual 13C-atoms substitution, deuterium substitution and hydrogen-transfer were conducted to confirm the validity of measured carbon isotope ratios and their differences. Inconsistent carbon isotope ratios derived from chlorine-isotopologue pairs of individual organochlorines were observed, and the isotopologues of each organochlorine were thus inferred to be non-randomly distributed. Mechanistic interpretation for these findings was tentatively proposed according to a basic principle in clumped-isotope geochemistry, reaction thermodynamics and kinetics, along with isotope effects occurring on electron ionization mass spectrometry. This study sheds light on the actual carbon isotope compositions of chlorine-isotopologue pairs of organochlorines, and yields new insights into the real distributions of carbon and chlorine isotopologues. The inconsistent carbon isotope compositions of chlorine-isotopologue pairs are anticipated to benefit the exploration of formation conditions and source identification of organochlorine pollutants.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The paper reports inconsistent carbon isotope ratios from chlorine isotopologue pairs in several organochlorines and infers non-random distributions, backed by targeted simulations.

read the letter

The main takeaway is that the authors measured different carbon isotope ratios from chlorine-isotopologue pairs (such as 12C2 35Cl4 vs. 12C13C 35Cl4) across two chloroethylenes, three PCBs, methyl-triclosan, and hexachlorobenzene, then concluded the isotopologues are non-randomly distributed in the molecules. They support this with GC-HRMS data and simulations that check background subtraction, dual 13C substitution, deuterium effects, and hydrogen transfer. Those simulations are a clear positive; they show the authors tried to rule out several straightforward artifacts before drawing the inference. The observation itself appears new for these compounds and ties into existing ideas from clumped-isotope work and ionization effects. The softer spot is whether the simulations cover everything that could produce an apparent ratio difference. HRMS-specific issues such as variable resolving power across m/z, mass-defect shifts in peak centroids, or small differences in ion transmission between isotopologue windows are not obviously addressed, and any of those could mimic the inconsistency without requiring non-random molecular distributions. The abstract does not give raw spectra, exact integration rules, or error budgets, so the link from measured ratios to the distribution claim stays provisional. This work is for environmental chemists who rely on isotope ratios for source tracking of organochlorine pollutants. A reader already working on GC-HRMS isotope methods or pollutant forensics would get concrete data points to think about, even if they end up testing the artifact question themselves. It should go to peer review; the experimental claim is specific enough that referees can check the data tables and instrument settings directly.

Referee Report

2 major / 2 minor

Summary. The manuscript reports GC-HRMS measurements of carbon isotope ratios derived from chlorine-isotopologue pairs (e.g., 12C235Cl4 vs. 12C13C35Cl4) of individual organochlorines including chloroethylenes, PCBs, methyl-triclosan and hexachlorobenzene. After data simulations addressing background subtraction, dual-13C substitution, deuterium substitution and hydrogen-transfer effects, inconsistent carbon isotope ratios are observed and interpreted as evidence for non-random isotopologue distributions, with tentative mechanistic explanations drawn from clumped-isotope principles and EI-MS isotope effects.

Significance. If the inconsistencies are shown to arise from true molecular distributions rather than unaccounted instrumental effects, the result would challenge assumptions underlying compound-specific isotope analysis of organochlorines and offer new constraints for source apportionment and formation-condition studies. The explicit use of targeted simulations to test measurement validity is a methodological strength that strengthens the experimental claim.

major comments (2)

[Data simulations] Data simulations section: the simulations cover background, dual-13C, deuterium and hydrogen-transfer effects but omit HRMS-specific phenomena such as mass-defect-induced centroid shifts, m/z-dependent resolving power variations, or differential ion transmission efficiencies between isotopologue windows; any of these could systematically alter apparent 13C/12C ratios without implying non-random molecular distributions.
[Results] Results and discussion: without tabulated raw peak areas, exact integration windows, full uncertainty budgets, or the complete set of replicate spectra, it is not possible to verify that the reported ratio differences exceed the magnitude of the unmodeled HRMS biases identified above.

minor comments (2)

Provide a table listing all studied compounds with their exact formulas, retention times, and the specific m/z windows used for each isotopologue pair.
Clarify the number of independent injections per compound and the statistical criterion used to declare a ratio difference 'inconsistent'.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the detailed and constructive review. The comments highlight important considerations for strengthening the interpretation of our GC-HRMS measurements. We address each major comment below.

read point-by-point responses

Referee: [Data simulations] Data simulations section: the simulations cover background, dual-13C, deuterium and hydrogen-transfer effects but omit HRMS-specific phenomena such as mass-defect-induced centroid shifts, m/z-dependent resolving power variations, or differential ion transmission efficiencies between isotopologue windows; any of these could systematically alter apparent 13C/12C ratios without implying non-random molecular distributions.

Authors: We agree that the simulations did not explicitly model all HRMS-specific effects. In the revised manuscript we will add a dedicated discussion of mass-defect centroid shifts, m/z-dependent resolving power, and differential ion transmission, including order-of-magnitude estimates of their possible influence on the measured ratios. We maintain that the observed inconsistencies are unlikely to arise solely from these effects because (i) they appear reproducibly across chemically distinct compounds measured under identical instrumental conditions and (ii) the magnitude of the ratio differences exceeds the typical size of such biases reported for the same instrument class. If feasible with available instrument parameters, we will also incorporate a simplified simulation of these effects. revision: partial
Referee: [Results] Results and discussion: without tabulated raw peak areas, exact integration windows, full uncertainty budgets, or the complete set of replicate spectra, it is not possible to verify that the reported ratio differences exceed the magnitude of the unmodeled HRMS biases identified above.

Authors: We accept that greater data transparency is required for independent verification. In the revised submission we will deposit in the supplementary information (i) tabulated raw peak areas for all reported measurements, (ii) the exact m/z integration windows employed, (iii) a complete uncertainty budget that propagates both statistical and systematic contributions, and (iv) representative replicate spectra. The full raw data files will be made available upon request. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental observation with independent simulations

full rationale

The paper reports direct GC-HRMS measurements of carbon isotope ratios from chlorine isotopologue pairs in organochlorines, followed by simulations that test specific artifact hypotheses (background, dual-13C, deuterium, hydrogen-transfer). The central inference of non-random isotopologue distribution follows from the observed ratio inconsistencies after those checks; no equation, fitted parameter, or self-citation is shown to reduce the reported ratios or the inference back to the input data by construction. The work contains no mathematical derivation chain, uniqueness theorem, or ansatz that could trigger any of the enumerated circularity patterns.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The central claim rests on the assumption that GC-HRMS measurements and the listed simulations adequately capture all relevant isotope effects and artifacts; no free parameters or new entities are introduced.

axioms (1)

domain assumption Standard assumptions in high-resolution mass spectrometry for isotope ratio measurements hold after background and substitution simulations.
Invoked to validate that measured differences reflect molecular distributions rather than artifacts.

pith-pipeline@v0.9.0 · 5800 in / 1148 out tokens · 21115 ms · 2026-05-24T18:47:01.065110+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

21 extracted references · 21 canonical work pages

[1]

H., Malik R

Ali U., Syed J. H., Malik R. N., Katsoyiannis A., Li J., Zhang G., Jones K. C., Organochlorine pesticides (OCPs) in South Asian region: a review. Sci. Total Environ. 2014, 476, 705-717

work page 2014
[2]

A., Killham, K

Meharg, A. A., Killham, K. , Environment: A pre -industrial source of dioxins and furans. Nature 2003, 421, 909-910

work page 2003
[3]

F., Natural formation of vinyl chloride in the terrestrial environment

Keppler, F., Borchers, R., Pracht, J., Rheinberger, S., Sch ö ler, H. F., Natural formation of vinyl chloride in the terrestrial environment. Environ. Sci. Technol. 2002, 36, 2479-2483

work page 2002
[4]

R., Triebskorn, R., Wildlife ecotoxicology of pesticides: can we track effects to the population level and beyond? Science 2013, 341, 759-765

Kö hler, H. R., Triebskorn, R., Wildlife ecotoxicology of pesticides: can we track effects to the population level and beyond? Science 2013, 341, 759-765

work page 2013
[5]

Malaria J

Konradsen, F., Manuweera, G., Van den Berg, H., Global trends in the production and use of DDT for control of malaria and other vector-borne diseases. Malaria J. 2017, 16, 401-408

work page 2017
[6]

Chan, J. K. Y., Wong, M. H. , A review of environmental fate, body burdens, and human health risk assessment of PCDD/Fs at two typical electronic waste recycling sites in China. Sci. Total Environ. 2013, 463, 1111-1123

work page 2013
[7]

, Dioxins and PCBs in feed and food —review from European perspective

Malisch, R., Kotz, A. , Dioxins and PCBs in feed and food —review from European perspective. Sci. Total Environ. 2014, 491, 2-10

work page 2014
[8]

B., Su, Y., Bao, L

Mi, X. B., Su, Y., Bao, L. J., Tao, S., Zeng, E. Y. , Significance of cooking oil to bioaccessibility of dichlorodiphenyltrichloroethanes (DDTs) and polybrominated diphenyl ethers (PBDEs) in raw and cooked fish: implications for human health risk. J. Agric. Food Chem. 2017, 65, 3268-3275. Page 20

work page 2017
[9]

J., Ruffolo, R., Helm, P

Pena-Abaurrea, M., Jobst, K. J., Ruffolo, R., Helm, P. A., Reiner, E. J. , Identification of potential novel bioaccumulative and persistent chemicals in sediments from Ontario (Canada) using scripting approaches with GC× GC-ToF MS analysis. Environ. Sci. Technol. 2014, 48, 9591-9599

work page 2014
[10]

, Software LS-MIDA for efficient mass isotopomer distribution analysis in metabolic modelling

Ahmed, Z., Zeeshan, S., Huber, C., Hensel, M., Schomburg, D., Mü nch, R., Eisenreich W., Dandekar, T. , Software LS-MIDA for efficient mass isotopomer distribution analysis in metabolic modelling. BMC Bioinformatics 2013, 14:218, 1-11

work page 2013
[11]

Anderegg, R. J. , Selective reduction of mass spectral data by isotope cluster chromatography. Anal. Chem. 1981, 53, 2169-2171

work page 1981
[12]

T., Gruen, D

Ono, S., Wang, D. T., Gruen, D. S., Lollar, B. S., Zahniser, M. S., McManus, B. J., Nelson, D. D., Measurement of a doubly substituted methane isotopologue, 13CH3D, by tunable infrared laser direct absorption spectroscopy. Anal. Chem. 2014, 86, 6487-6494

work page 2014
[13]

Clumped-isotope

Eiler, J. M. , “Clumped-isotope” geochemistry —the study of naturally -occurring, multiply-substituted isotopologues. Earth Planet. Sci. Lett. 2007, 262, 309-327

work page 2007
[14]

A ., Eiler, J

Wang, Z ., Schauble, E. A ., Eiler, J. M. , Equilibrium thermodynamics of mu ltiply substituted isotopologues of molecular gases. Geochim. Cosmochim. Ac. 2004, 68, 4779-4797

work page 2004
[15]

A., Lawson, M., Davis, C

Stolper, D. A., Lawson, M., Davis, C. L., Ferreira, A. A., Neto, E. S., Ellis, G. S., Lewan, M. D ., Martini, A. M ., Tang, Y ., Schoell, M ., Sessions, A. L ., Eiler, J. M. , Formation temperatures of thermogenic and biogenic methane. Science 2014, 344, 1500-1503

work page 2014
[16]

Y., Ash, J

Yeung, L. Y., Ash, J. L., Young, E. D., Biological signatures in clumped isotopes of O 2. Science 2015, 348, 431-434. Page 21

work page 2015
[17]

Y., Li, S., Kohl, I

Yeung, L. Y., Li, S., Kohl, I. E., Haslun, J. A., Ostrom, N. E., Hu, H., Fischer T. P., Schauble E. A., Young, E. D. , Extreme enrichment in atmospheric 15N15N. Sci. Adv. 2017, 3: eaao6741, 1-9

work page 2017
[18]

Tang, C., Tan, J., Quasi-targeted analysis of halogenated organic pollutants in fly ash, soil, ambient air and flue gas using gas chromatography -high resolution mass spectrometry with isotopologue distribution comparison and predicted retention time alignment. J. Chromatogr. A 2018, 1555, 74-88

work page 2018
[19]

Tang, C., Tan, J., Xiong S., Liu, J., Fan, Y., Peng X., Chlorine and bromine isotope fractionation of halogenated organic pollutants on gas chromatography columns. J. Chromatogr. A 2017, 1514, 103-109

work page 2017
[20]

Tang, C., Tan, J., Simultaneous observation of concurre nt two-dimensional carbon and chlorine/bromine isotope fractionations of halogenated organic compounds on gas chromatography. Anal. Chim. Acta 2018, 1039, 172-182

work page 2018
[21]

J., Isotope effects in fragmentation

Derrick, P. J., Isotope effects in fragmentation. Mass Spectrom. Rev. 1983, 2, 285-298. Page 22 Figure legends Figure 1. Representative chromatograms and high resolution mass spectra of the investigated organochlorines. TCE: trichloroethylene, PCE: tetrachloroethylene, PCB: polychlorinated biphenyl, Me-TCS: methyl-triclosan, HCB: hexachlorobenzene, NL: no...

work page 1983

[1] [1]

H., Malik R

Ali U., Syed J. H., Malik R. N., Katsoyiannis A., Li J., Zhang G., Jones K. C., Organochlorine pesticides (OCPs) in South Asian region: a review. Sci. Total Environ. 2014, 476, 705-717

work page 2014

[2] [2]

A., Killham, K

Meharg, A. A., Killham, K. , Environment: A pre -industrial source of dioxins and furans. Nature 2003, 421, 909-910

work page 2003

[3] [3]

F., Natural formation of vinyl chloride in the terrestrial environment

Keppler, F., Borchers, R., Pracht, J., Rheinberger, S., Sch ö ler, H. F., Natural formation of vinyl chloride in the terrestrial environment. Environ. Sci. Technol. 2002, 36, 2479-2483

work page 2002

[4] [4]

R., Triebskorn, R., Wildlife ecotoxicology of pesticides: can we track effects to the population level and beyond? Science 2013, 341, 759-765

Kö hler, H. R., Triebskorn, R., Wildlife ecotoxicology of pesticides: can we track effects to the population level and beyond? Science 2013, 341, 759-765

work page 2013

[5] [5]

Malaria J

Konradsen, F., Manuweera, G., Van den Berg, H., Global trends in the production and use of DDT for control of malaria and other vector-borne diseases. Malaria J. 2017, 16, 401-408

work page 2017

[6] [6]

Chan, J. K. Y., Wong, M. H. , A review of environmental fate, body burdens, and human health risk assessment of PCDD/Fs at two typical electronic waste recycling sites in China. Sci. Total Environ. 2013, 463, 1111-1123

work page 2013

[7] [7]

, Dioxins and PCBs in feed and food —review from European perspective

Malisch, R., Kotz, A. , Dioxins and PCBs in feed and food —review from European perspective. Sci. Total Environ. 2014, 491, 2-10

work page 2014

[8] [8]

B., Su, Y., Bao, L

Mi, X. B., Su, Y., Bao, L. J., Tao, S., Zeng, E. Y. , Significance of cooking oil to bioaccessibility of dichlorodiphenyltrichloroethanes (DDTs) and polybrominated diphenyl ethers (PBDEs) in raw and cooked fish: implications for human health risk. J. Agric. Food Chem. 2017, 65, 3268-3275. Page 20

work page 2017

[9] [9]

J., Ruffolo, R., Helm, P

Pena-Abaurrea, M., Jobst, K. J., Ruffolo, R., Helm, P. A., Reiner, E. J. , Identification of potential novel bioaccumulative and persistent chemicals in sediments from Ontario (Canada) using scripting approaches with GC× GC-ToF MS analysis. Environ. Sci. Technol. 2014, 48, 9591-9599

work page 2014

[10] [10]

, Software LS-MIDA for efficient mass isotopomer distribution analysis in metabolic modelling

Ahmed, Z., Zeeshan, S., Huber, C., Hensel, M., Schomburg, D., Mü nch, R., Eisenreich W., Dandekar, T. , Software LS-MIDA for efficient mass isotopomer distribution analysis in metabolic modelling. BMC Bioinformatics 2013, 14:218, 1-11

work page 2013

[11] [11]

Anderegg, R. J. , Selective reduction of mass spectral data by isotope cluster chromatography. Anal. Chem. 1981, 53, 2169-2171

work page 1981

[12] [12]

T., Gruen, D

Ono, S., Wang, D. T., Gruen, D. S., Lollar, B. S., Zahniser, M. S., McManus, B. J., Nelson, D. D., Measurement of a doubly substituted methane isotopologue, 13CH3D, by tunable infrared laser direct absorption spectroscopy. Anal. Chem. 2014, 86, 6487-6494

work page 2014

[13] [13]

Clumped-isotope

Eiler, J. M. , “Clumped-isotope” geochemistry —the study of naturally -occurring, multiply-substituted isotopologues. Earth Planet. Sci. Lett. 2007, 262, 309-327

work page 2007

[14] [14]

A ., Eiler, J

Wang, Z ., Schauble, E. A ., Eiler, J. M. , Equilibrium thermodynamics of mu ltiply substituted isotopologues of molecular gases. Geochim. Cosmochim. Ac. 2004, 68, 4779-4797

work page 2004

[15] [15]

A., Lawson, M., Davis, C

Stolper, D. A., Lawson, M., Davis, C. L., Ferreira, A. A., Neto, E. S., Ellis, G. S., Lewan, M. D ., Martini, A. M ., Tang, Y ., Schoell, M ., Sessions, A. L ., Eiler, J. M. , Formation temperatures of thermogenic and biogenic methane. Science 2014, 344, 1500-1503

work page 2014

[16] [16]

Y., Ash, J

Yeung, L. Y., Ash, J. L., Young, E. D., Biological signatures in clumped isotopes of O 2. Science 2015, 348, 431-434. Page 21

work page 2015

[17] [17]

Y., Li, S., Kohl, I

Yeung, L. Y., Li, S., Kohl, I. E., Haslun, J. A., Ostrom, N. E., Hu, H., Fischer T. P., Schauble E. A., Young, E. D. , Extreme enrichment in atmospheric 15N15N. Sci. Adv. 2017, 3: eaao6741, 1-9

work page 2017

[18] [18]

Tang, C., Tan, J., Quasi-targeted analysis of halogenated organic pollutants in fly ash, soil, ambient air and flue gas using gas chromatography -high resolution mass spectrometry with isotopologue distribution comparison and predicted retention time alignment. J. Chromatogr. A 2018, 1555, 74-88

work page 2018

[19] [19]

Tang, C., Tan, J., Xiong S., Liu, J., Fan, Y., Peng X., Chlorine and bromine isotope fractionation of halogenated organic pollutants on gas chromatography columns. J. Chromatogr. A 2017, 1514, 103-109

work page 2017

[20] [20]

Tang, C., Tan, J., Simultaneous observation of concurre nt two-dimensional carbon and chlorine/bromine isotope fractionations of halogenated organic compounds on gas chromatography. Anal. Chim. Acta 2018, 1039, 172-182

work page 2018

[21] [21]

J., Isotope effects in fragmentation

Derrick, P. J., Isotope effects in fragmentation. Mass Spectrom. Rev. 1983, 2, 285-298. Page 22 Figure legends Figure 1. Representative chromatograms and high resolution mass spectra of the investigated organochlorines. TCE: trichloroethylene, PCE: tetrachloroethylene, PCB: polychlorinated biphenyl, Me-TCS: methyl-triclosan, HCB: hexachlorobenzene, NL: no...

work page 1983