Analysis of avermectin and moxidectin residues in milk by liquid chromatography–tandem mass spectrometry using an atmospheric pressure chemical ionization/atmospheric pressure photoionization source

Turnipseed, Sherri B; Roybal, José E; Andersen, Wendy C.; Kuck, Laura R.

doi:10.1016/j.aca.2004.07.061

Cited by 67 publications

(35 citation statements)

References 16 publications

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“…In addition to the ionization mechanisms described above, some ions (e.g., MNa þ in the positive-ionization mode) can be delivered by thermospray ionization, a process by which ions already present in solution are released into the gas-phase by thermal vaporization (Delobel et al, 2003;Turnipseed et al, 2005). The contribution of this mechanism to the overall ionization process can be estimated through the remaining ions by turning off the UV lamp.…”

Section: Appi Formation Of Ionsmentioning

confidence: 99%

APCI/APPI for synthetic polymer analysis

Terrier

Desmazières

Tortajada

et al. 2011

Mass Spectrometry Reviews

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Modern mass spectrometry of synthetic polymers involves soft ionization techniques. Whereas matrix-assisted laser desorption/ionization (MALDI) and electrospray (ESI) are employed routinely, atmospheric pressure chemical ionization (APCI) and more recently atmospheric pressure photoionization (APPI) are used to a lesser extent. However, these latter ionization methods coupled to liquid-phase separation techniques create new opportunities for the characterization of polymers, especially for low molecular weight compounds or for the polymers that are poorly ionizable by the usual methods. After a part devoted to the description of classical MS methods employed for polymer analysis (MALDI, ESI, and their use with chromatography), APCI and APPI techniques will be described, discussed, and selected examples will present the interest of these ionization sources (or interfaces for LC/MS) in the field of polymer analysis.

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Section: Appi Formation Of Ionsmentioning

confidence: 99%

APCI/APPI for synthetic polymer analysis

Terrier

Desmazières

Tortajada

et al. 2011

Mass Spectrometry Reviews

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“…These photoelectrons in the weakly ionized region can be used as seed electrons to produce new electron avalanche, which called secondary electron emission avalanche (SEEA). 8,9 Theory of photoionization is also important in many fields, such as cooling rates in astrophysical 10 and anesthetic method, 11 liquid chromatography-tandem mass spectrometry 12,13 in medical applications. Therefore, more attention should be paid to discover the effect of photoionization which has been well developed in positive corona 5,6,14 while the effect of photoionization in negative corona has seldom studied up to now.…”

Section: Introductionmentioning

confidence: 99%

The role of photoionization in negative corona discharge

Sun

2016

AIP Advances

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The effect of photoionization on the negative corona discharge was simulated based on the needle to plane air gaps. The Trichel pulse, pulse train, electron density and the distribution of electric field will be discussed in this manuscript. Effect of photoionization on the magnitude and interval of the first pulse will be discussed for different applied voltages. It is demonstrated that the peak of the first pulse current could be weakened by photoionization and a critical voltage of the first pulse interval influenced by photoionization was given.

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“…Since there is no individual MOX formulation monograph or DP reference standard available, the major DPs observed during investigation require isolation, purification and characterization using HPLC, high-resolution mass spectrometry (MS) and nuclear magnetic resonance (NMR) spectroscopy techniques. Nevertheless, several MS methods for the confirmation of MOX and related compounds in API, biological and environmental samples have been published [11,[14][15][16]. MOX and several related compounds/homologs were identified and characterized by MS, and their fragmentation pathways were established by high resolution as well as electron impact mass spectra [17].…”

Section: Introductionmentioning

confidence: 99%

Isolation and characterization of degradation products of moxidectin using LC, LTQ FT-MS, H/D exchange and NMR

et al. 2012

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This study aimed to evaluate the degradation profile and pathways, and identify unknown impurities of moxidectin under stress conditions. During the experiments, moxidectin samples were stressed using acid, alkali, heat and oxidation, and chromatographic profiles were compared with known impurities given in European Pharmacopeia (EP) monograph. Moxidectin has shown good stability under heat, while reaction with alkali produced 2-epi and ∆2,3 isomers (impurities D and E in EP) by characteristic reactions of the oxahydrindene (hexahydrobenzofuran) portion of the macrocyclic lactone. Two new, previously unreported, unknown degradation products, i.e. impurity 1 and impurity 2, detected after acid hydrolysis of moxidectin (impurity 2 was also observed to a lesser extent after oxidation), were isolated from sample matrices and identified using liquid chromatography, NMR, high-resolution FT-ICR MS, and hydrogen/deuterium exchange studies. FTMS analysis showed accurate mass of molecular ion peaks for moxidectin at m/z 640.38412, impurity 1 at m/z 656.37952 and impurity 2 at m/z 611.35684, giving rise to daughter ions traceable up to the seventh levels of MS(n) experiments and supporting the proposed structures. Both unknown impurities along with moxidectin were fully characterized by (1)H, (13)C, 1D HMBC and 2D (NOESY, COSY and HSQC) NMR experiments. The interpretation of experimental data positively identified impurity 1 as 3,4-epoxy-moxidectin and impurity 2 as 23-keto-nemadectin. The identification of new impurities and correlation of their chromatographic profiles with the EP method is very useful to establish the stability profile of moxidectin and its preparations, as well as add value to the forthcoming moxidectin finished product European Pharmacopeia monographs.

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Analysis of avermectin and moxidectin residues in milk by liquid chromatography–tandem mass spectrometry using an atmospheric pressure chemical ionization/atmospheric pressure photoionization source

Cited by 67 publications

References 16 publications

APCI/APPI for synthetic polymer analysis

APCI/APPI for synthetic polymer analysis

The role of photoionization in negative corona discharge

Isolation and characterization of degradation products of moxidectin using LC, LTQ FT-MS, H/D exchange and NMR

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