Techniques for Enhancing Structural Information from High-Performance Liquid Chromatography/Mass Spectrometry

Voyksner, Robert D.; Pack, Terry W.; Smith, C.; Swaisgood, Harold E.; Chen, D.

doi:10.1021/bk-1990-0420.ch002

Cited by 20 publications

(5 citation statements)

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“…This will be very valuable since the identification of unknown pesticide metabolites formed during degradation processes can be unequivocally identified. These difficulties have prompted the need of using HPLC in combination with tandem MS which has been applied to the determination of chlorotriazine pesticides (Voyksner, 1987;Voyksner et al, 1990) and organophosphorus (Betowski and Jones, 1988) and carbamate insecticides (Chiu et al, 1989), all of which testify to an increasing use of tandem MS for screening different groups of pesticides in environmental matrices.…”

Section: Introductionmentioning

confidence: 99%

Analysis of chlorotriazines and their degradation products in environmental samples by selecting various operating modes in thermospray HPLC/MS/MS

Abian¹,

Durand²,

Barceló³

1993

J. Agric. Food Chem.

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Section: Introductionmentioning

confidence: 99%

Analysis of chlorotriazines and their degradation products in environmental samples by selecting various operating modes in thermospray HPLC/MS/MS

Abian¹,

Durand²,

Barceló³

1993

J. Agric. Food Chem.

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“…Particle beam (PB) LC−MS instruments were of great interest because of their ability to generate library-searchable EI spectra. The PB interface coupled HPLC directly to a conventional electron ionization source but was most suited to the analysis of moderately labile and semivolatile compounds . Many thermally labile substances (e.g., cephapirin, cloxacillin, penicillin G, glucuronide, and sulfate metabolites) do not yield molecular ions in PB LC−MS but instead reveal low-mass fragments. , API involves a different principle of ionization, one in which much lower volatility molecules are ionized without decomposition, including polypeptides and even proteins…”

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confidence: 99%

Identification of Unknowns in Atmospheric Pressure Ionization Mass Spectrometry Using a Mass to Structure Search Engine

2008

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This study evaluates a new model for identifying unknown compounds in atmospheric pressure ionization mass spectrometry based on a mass-to-structure (MTS) paradigm. In this method, rudimentary ESI spectrum interpretation is required to recognize key spectral features such as MH (+), MNa (+), and MNH 4 (+), which lead to the unknown's monoisotopic mass. The unknown's mass is associated directly with known organic compounds using an Access 2003 database containing records of 19,438 substances assembled from common sources such as the Merck Index, pesticide and pharmaceutical compilations, and chemical catalogues. A user-defined mass tolerance (+/-0.001-0.5 Da) is set according to the instrument mass accuracyunit mass resolution data require a wide mass tolerance ( approximately 0.5 Da) while tolerances for accurate mass data can be as narrow as +/-0.001 Da. Candidate structures retrieved with the MTS Search Engine appear in a report window providing formulas, mass error, and Internet links. This paper provides examples of structure elucidation with 15 organic compounds based on ESI mass spectra from both unit mass resolution (e.g., quadrupole ion trap and triple-stage quadrupole) and accurate mass instruments (e.g., TOF and Q-TOF). Orthogonal information (e.g., isotope ratios and fragmentation data) is complementary and useful for ranking candidates and confirming assignments. The MTS Search Engine identifies unknowns quickly and efficiently, and supplements existing interpretation schemes for unknown identification.

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“…Diagnostic product ions were identified (Table 1) following the comparison of working standards and blank and spiked forage samples. Chemical structures of the diagnostic product ions m/z 68, 94, 104, and 110 ( Figure 4) were derived from previous studies (Lerch et al 1995;Voyksner et al 1990). To maximize the sensitivity of detection for the identified diagnostic ions, the instrument was programmed using the AMD software.…”

Section: Ion Selection and Optimization Of Gc-ms/ms Conditionsmentioning

confidence: 99%

Improved GC‐MS/MS Method for Determination of Atrazine and Its Chlorinated Metabolites in Forage Plants—Laboratory and Field Experiments

Lin

Lerch

Garrett

et al. 2007

Communications in Soil Science and Plant Analysis

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Analytical procedures using gas chromatography -ion trap tandem mass spectrometry (GC-MS/MS) were developed to analyze atrazine (ATR) and its dealkylated metabolites in four forage species (switchgrass, tall fescue, smooth bromegrass, and orchardgrass). Atrazine, deethylatrazine (DEA), and deisopropylatrazine (DIA) were extracted with methanol (CH 3 OH) followed by liquid -liquid extraction and partitioning into chloroform, with additional cleanup by C 18 solid-phase extraction (SPE). Through the optimization of ionization conditions and ion storage voltages, the background noise of product ion spectra (MS/MS) was reduced dramatically, providing sub-mg/kg detection limits. Mean recoveries of ATR, DEA, and DIA were 94.3, 105.6, and 113.1%, respectively. The estimated limit of detection (LOD) was 0.6 mg/kg for ATR, 1.3 mg/kg for DEA, and 0.3 mg/kg for DIA. These LODs were one to two orders of magnitude lower than those reported for other GC-MS, GC-MS/MS, high pressure liquid chromatography (HPLC)-UV, or HPLC-MS/MS 1753 procedures designed for food-safety monitoring purposes. To validate the developed method, a field experiment was carried out utilizing three replications of four forage treatments (orchardgrass, tall fescue, smooth bromegrass, and switchgrass). Forage plants were sampled for analyses 25 days after atrazine application. DEA concentrations in C3 grasses ranged from 47 to 96 mg/kg, about 10-fold higher than in switchgrass, a C4 species. The ATR and DIA concentrations were similar, ranging from 1.5 to 13.2 mg/kg. The developed method provided sufficient sensitivity to determine the fate of ATR and its chlorinated metabolites via plant uptake from soil or dealkylation within living forage grasses. It also represented significant improvements in sensitivity compared to previous GC methods.

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Techniques for Enhancing Structural Information from High-Performance Liquid Chromatography/Mass Spectrometry

Cited by 20 publications

References 0 publications

Analysis of chlorotriazines and their degradation products in environmental samples by selecting various operating modes in thermospray HPLC/MS/MS

Analysis of chlorotriazines and their degradation products in environmental samples by selecting various operating modes in thermospray HPLC/MS/MS

Identification of Unknowns in Atmospheric Pressure Ionization Mass Spectrometry Using a Mass to Structure Search Engine

Improved GC‐MS/MS Method for Determination of Atrazine and Its Chlorinated Metabolites in Forage Plants—Laboratory and Field Experiments

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