Study of laser desorption/ionization time-of-flight mass spectrometry for the analysis of pesticides

Benazouz, M.; Hakim, B.; Debrun, J.L.

doi:10.1002/(sici)1097-0231(19980815)12:15<1018::aid-rcm269>3.0.co;2-9

Cited by 8 publications

(3 citation statements)

References 4 publications

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“…Matrix-assisted laser desorption/ionization time-of-flight spectrometry (MALDI-TOFMS) is a powerful analytical technique widely used in the characterization of synthetic organic polymers, [1][2][3][4][5][6][7][8][9] proteins and peptides, [10][11][12][13] metabolites, 14 and other biopolymers. 15,16 Recently, block copolymers 17 have also been characterized by this technique.…”

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confidence: 99%

Detailed structural analysis of diblock copolymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Wilczek-Vera

Waddell³

et al. 1999

Rapid Commun. Mass Spectrom.

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The individual block length distributions of poly(a-methylstyrene)-b-poly(4-vinylpyridine) diblock copolymers have been determined by the MAC MALDI-TOFMS method of analysis of copolymers, which combines matrix assisted laser desorption/ionization time-of-flight mass spectrometry with computational data treatment. The problem of the possibility of multiple assignments of chemical composition to the mass spectral peaks is discussed in detail. A solution based on the pattern of peak clusters is proposed and verified using the statistical random coupling hypothesis test. The progress of the anionic polymerization in a series of polymers prepared by sequential addition of the second monomer to a living chain system is studied and shown in three-dimensional (3-D) plots of experimental individual blocks length distributions. The presence of unreacted homopolymer has been observed as well as bimodal and trimodal distributions for the poly(amethylstyrene) and the poly(4-vinylpyridine) segments. A depolymerization process of the homopoly(amethylstyrene) in the series of poly(a-methyl-styrene)-b-poly(4-vinylpyridine) diblock copolymers was detected following a temperature rise. It was confirmed that it is impossible to place a single unit of 4VP at the end of each PaMS chain. Copyright # 1999 John Wiley & Sons, Ltd. Received 24 December 1998; Revised 22 February 1999; Accepted 24 February 1999 Matrix-assisted laser desorption/ionization time-of-flight spectrometry (MALDI-TOFMS) is a powerful analytical technique widely used in the characterization of synthetic organic polymers, 1-9 proteins and peptides, 10-13 metabolites, 14 and other biopolymers. 15,16 Recently, block copolymers 17 have also been characterized by this technique. Block copolymers have many interesting properties with applications to drug delivery, micellization and brush formation, 18,19 among others. It is known 20,21 that the properties of block copolymers are determined by the chain lengths of the individual segments and their distributions. In one case, it has been demonstrated that the size of the core of block copolymer micelles depends both on the molecular weight and the molecular weight distribution of the core forming block. 21 Therefore, a general method of independent determination of the chain length distributions for both constituent parts of a block copolymer 17 was developed using the MALDI-TOFMS technique. As the proposed method gives the possibility of direct experimental determination of the composition distribution for block copolymers, it was possible to confirm that block copolymers with narrow molecular weight distributions may have complex and even bimodal composition distributions. It was also found that the polydispersity factors observed for the individual parts were higher than those for the whole polymer. The random coupling hypothesis has been confirmed experimentally. 17 The polymers studied were of the type ABA, where A corresponds to a poly (amethylstyrene) chain and B to a polystyrene chain. The error introduced by the ...

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confidence: 99%

Detailed structural analysis of diblock copolymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Wilczek-Vera

Waddell³

et al. 1999

Rapid Commun. Mass Spectrom.

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“…Recently, laser desorption/ionization (LDI) coupled to mass spectrometry has been explored as a means of rapidly identifying contaminant pesticides due to the fact mass spectrometry requires little to no sample preparation and offers a high degree of selectivity and sensitivity. For pure particles, because the analyte must absorb light at the wavelength used for LDI, several pesticides that do not meet this prerequisite have been shown to be difficult to analyze from direct LDI but can be analyzed upon the addition of a matrix compound . Two-step LDI has been shown to be feasible for analysis of a range of pesticides and offers high ion yields and a high degree of selectivity by decoupling the desorption and ionization steps. , Carrying out experiments with a matrix compound and using techniques such as two-step LDI are very powerful techniques in their own regard but have some drawbacks.…”

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confidence: 99%

Detection of Pesticide Residues on Individual Particles

Whiteaker

Prather

2002

Anal. Chem.

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An aerosol time-of-flight mass spectrometer (ATOFMS) is used to analyze the size and composition of individual particles containing pesticides. Pesticide residues are found in the atmosphere as a result of spray drift, volatilization, and suspension of coated soils. The ability of the ATOFMS to identify the presence of these contaminants on individual particles is assessed for particles created from pure solutions of several commonly used pesticides, as well as pesticides mixed with an organic matrix, and coated on soils. The common names of the pesticides studied are 2,4-D, atrazine, chlorpyrifos, malathion, permethrin, and propoxur. Analysis of the mass spectra produced by single- and two-step laser desorption/ionization of pesticide-containing particles allows for identification of peaks that can be used for detection of pesticide residues in the ambient aerosol. The identified marker peaks are used to approximate detection limits for the pesticides applied to soils, which are on the order of a fraction of a monolayer for individual particles. Results suggest that this technique may be useful for studying the real-time partitioning and distribution of pesticides in the atmosphere immediately following application in agricultural regions.

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“…20,21 Many pesticides are possible candidates for detection by REMPI mass spectrometry but have only received marginal attention until now. 22,23 Also, systematic studies applying L2MS to the analysis of these environmentally important compounds have not yet been performed. This paper expands the applications of L2MS described above with respect to both analyte selection and investigated matrixes.…”

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Analysis of Water Contaminants and Natural Water Samples Using Two-Step Laser Mass Spectrometry

et al. 2000

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The applicability of two-step laser mass spectrometry (L2MS) to the analysis of water contaminants and environmental water samples is demonstrated. First, the ionization characteristics of a selection of naphthyl and carbamate pesticides and of phenol were determined. The ion signal of all compounds increased with ionization laser pulse energy, within the investigated range (20-200 microJ). Ion yields relative to an internal standard, benz[alanthracene, reached 30% for naphthyl pesticides ionized at 225 nm and 2-8% at 266 nm. At 266 nm, similar relative ion yields were found for phenol. Carbamate pesticides showed lower relative ion yields at all wavelengths, by a factor of approximately 10-100, but higher relative ion yields, on the order of 1%, were obtained when using short (ps) laser pulses for ionization. These data allow one to estimate the detection limits of these analytes in a variety of matrixes once they are known for one of the compounds. Second, the quantitative analysis of carbaryl, phenol, and polycyclic aromatic hydrocarbons in rainwater is demonstrated. The aqueous samples were frozen to permit direct L2MS analysis of organic pollutants without tedious sample preparation. Detection limits were in the low-microgram per liter concentration range and recoveries of phenol from spiked rainwater samples were above 90%. The specific advantages are exemplified with the investigation of dynamic washout processes of atmospheric organic pollutants with a resolution of 0.01 mm of precipitation.

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Study of laser desorption/ionization time-of-flight mass spectrometry for the analysis of pesticides

Cited by 8 publications

References 4 publications

Detailed structural analysis of diblock copolymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Detailed structural analysis of diblock copolymers by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

Detection of Pesticide Residues on Individual Particles

Analysis of Water Contaminants and Natural Water Samples Using Two-Step Laser Mass Spectrometry

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