Postcolumn addition of buffer for thermospray liquid chromatography/mass spectrometry identification of pesticides

Voyksner, Robert D.; Bursey, Joan T.; Pellizzari, Edo D.

doi:10.1021/ac00272a067

Cited by 117 publications

(23 citation statements)

References 22 publications

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“…were observed with abundant sodium and potassium adduct ions with System C. These adduct ions probably were due to impurities in the mobile phase. The presence of these types of ions in TSP has been reported previously [26]. Figure 2 summarizes the solvent-mediated CI mass spectra of aminocarb for Sys- The mass spectra in the solvent-mediated CI mode were in general consistent with those obtained in the filament-assisted buffer ionization mode, although in the solvent-mediated CI mode a somewhat higher fragmentation level is observed [1,6] By increasing the ion source temperature, large increases were not detected in the thermally assisted hydrolysis formation of the methylisocyanate from the carbamate moiety as observed in the filament-assisted buffer ionization mode.…”

Section: Carbamic Acid Esterssupporting

confidence: 62%

“…mobile phase [16,17], require adjustments to obtain the necessary limits of detection and reproducibility, Mass spectrometric investigations of carbamate pesticides via different types of TSP interfaces have been reported widely [1][2][3][4][5][6][7][18][19][20][21][22][23][24][25][26]. These studies, however, indicate that solitary protonated molecules and /or molecular ammonium adduct ions are formed by carbamates that provide no structural information.…”

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confidence: 99%

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Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry

Volmer

Levsen

Honing

et al. 1995

J. Am. Soc. Mass Spectrom.

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Section: Carbamic Acid Esterssupporting

confidence: 62%

mentioning

confidence: 99%

Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry

Volmer

Levsen

Honing

et al. 1995

J. Am. Soc. Mass Spectrom.

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“…were observed with abundant sodium and potassium adduct ions with System C. These adduct ions probably were due to impurities in the mobile phase. The presence of these types of ions in TSP has been reported previously [26]. Figure 2 summarizes the solvent-mediated CI mass spectra of aminocarb for Sys- The mass spectra in the solvent-mediated CI mode were in general consistent with those obtained in the filament-assisted buffer ionization mode, although in the solvent-mediated CI mode a somewhat higher fragmentation level is observed [1,6] due to the lower proton affinity of the organic modifiers (methanol or acetonirril) as compared to ammonia.…”

Section: Amsupporting

confidence: 62%

“…The study proves conclusively that comparable spectra can be obtained under thermosprar with different interfaces and mass spectrometers. {J Am Soc Mass Spectrom 1995, 6, 656-667 C urrently thermospray (TSP) has been used extensively as a liquid chromatography-mass spectrometry (LC-MS) interface for the determination of a wide range of chemical classes; for example, pesticides [1][2][3][4][5][6][7] mobile phase [16,17], require adjustments to obtain the necessary limits of detection and reproducibility, Mass spectrometric investigations of carbamate pesticides via different types of TSP interfaces have been reported widely [1][2][3][4][5][6][7][18][19][20][21][22][23][24][25][26]. These studies, however, indicate that solitary protonated molecules and /or molecular ammonium adduct ions are formed by carbamates that provide no structural information.…”

mentioning

confidence: 99%

Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry

VOLMER¹,

LEVSEN²,

HONING³

et al. 1995

Journal of the American Society for Mass Spectrometry

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Sixteen carbamate pesticides that belong to four chemical classes (oxime-N-methylcarbamates, aryl N-methylcarbamates, N-phenylcarbamates, and methyl esters of substituted carbamic acids) were investigated via three different commercially available thermospray interfaces and ion sources that exh ibit wide differences in source geometry. Comparisons were made between the three interfaces with respect to ion formation and sensitivity of detection. Experimental parameters were standardized to obtain comparable experimental conditions. Very similar mass spectra for most carbamates were obtained that illustrate independence from the geometry of the ion ization and desolvation chambers of the interfaces. These findings are in sharp contrast to several literature reports. However, thermally labile carbamates ga ve unsatisfactory results with regard to spectral compatibility between the interfaces. Such differences were due to thermally assisted hydrolysis reactions that occur in the vaporizer probe prior to ionization and reflect di fferences in the vaporizer designs. The study proves conclusively that comparable spectra can be obtained under thermosprar with different interfaces and mass spectrometers. {J Am Soc Mass Spectrom 1995, 6, 656-667 C urrently thermospray (TSP) has been used extensively as a liquid chromatography-mass spectrometry (LC-MS) interface for the determination of a wide range of chemical classes; for example, pesticides [1][2][3][4][5][6][7] mobile phase [16,17], require adjustments to obtain the necessary limits of detection and reproducibility, Mass spectrometric investigations of carbamate pesticides via different types of TSP interfaces have been reported widely [1][2][3][4][5][6][7][18][19][20][21][22][23][24][25][26]. These studies, however, indicate that solitary protonated molecules and /or molecular ammonium adduct ions are formed by carbamates that provide no structural information. For an unambiguous identification of carbamates in environmental samples, several additional fragment ions are required for proof of presence. Several methods have been reported to increase the number of fragment ions ; for example, use of different ionization modes [1,6], postcolumn addition of adduct reagents [4,19] or increased operating temperatures of the TSP in terface

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“…The sensitivity was always much better in PI mode than in the NI mode of operation (about 30% lower). In contrast, other authors have found greater differences in sensitivities between both ionization modes because filament-off ionization was used (26). In the case of chlorotnazines differences in the base peak when using the two ionizing additives are also noticeable, with the formation of [M + HJ + or [M • 60]"*"* as base peaks when either ammonium formate or ammonium acetate are used.…”

Section: 811) Although the [M + H] + Ion Was The Base Peak For Smentioning

confidence: 93%

Use of Solvent Adduct Ions To Confirm Structure of Selected Herbicides with Thermospray Liquid Chromatography/Mass Spectrometry

Barceló

1990

ACS Symposium Series

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Conventional positive-ion and negative-ion modes (PI and NI ,respectively), the use of ammonium acetate and ammonium formate and the addition of 2% chloroacetonitrile in the liquid chromatographic eluent using filament-on thermospray LC-MS have been applied for the determination of selected herbicides. By using acetonitrile-water and 0.05 M ammonium acetate mixtures, the chlorotriazine herbicides showed [M + (CH 3 CN)H] + and [M -H] -ions as base peaks in PI and NI modes, respectively. When ammonium formate and ammonium acetate were added to methanol-water eluent, the phenylurea herbicides exhibited in PI mode a relevant peak between 50-70% relative intensity corresponding to [M + (CH 3 OH)NH 4 ] + and [M + (CH 3 COOH)NH 4 ]+, respectively, whereas the base peak was [M + NH 4 ] + in both cases. The formation of [M + HCOOHNH 4 ] + was incidently observed in PI when ammonium formate was used. With this ionizing additive and NI the chlorinated phenoxyacid herbicides exhibited [M + HCOO] -as base peak, thus allowing a complementary structural information to [M + CH 3 COO] -, a typical ion obtained whenammonium acetate was added as ionizing additive. The addition of 2% chloroacetonitrile to acetonitrile-water eluent showed in NI mode a [M + Cl] -ion as base peak instead of [M + CH 3 COO] -or [M + HCCO] -ions in combination with other main ions which were assigned to [M -H] -and [M + H] -. Applications are reported for the determination of phenylurea and chlorinated phenoxyacid herbicides in spiked water samples by using PI and NI modes, respectively.

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Postcolumn addition of buffer for thermospray liquid chromatography/mass spectrometry identification of pesticides

Cited by 117 publications

References 22 publications

Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry

Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry

Comparative study of different thermospray interfaces with carbamate pesticides: Influence of the ion source geometry

Use of Solvent Adduct Ions To Confirm Structure of Selected Herbicides with Thermospray Liquid Chromatography/Mass Spectrometry

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