Electrospray ionization impurities

For confirmatory assay, liquid chromatography-tandem mass spectrometry (LC-MS/MS) is becoming more frequently used in the analysis of OTC owing to its high sensitivity and ability. Electrospray ionization (ESI) [55-57] and atmospheric pressure chemical ionization (APCI) [41] methods combined with tandem mass spectrometry are favored because of their higher sensitivity and better reproducibility. Hamscher et al. [58] developed a method for the determination of persistent TC residues in soil fertilized with manure by HPLC tandem mass spectrometry, MS-MS, and confirmation by MS-MS-MS. Zhu et al. [59] developed an LC-tandem mass spectrometry for the analysis of common tetracyclines in water. The detection limit for oxytetracycline was 0.21 pg/L. Lykkeberg et al. [60] used LC-MS/MS for determination of oxytetracycline and its impurities EOTC, TC, ETC, ADOTC, oc-AOTC, and /i-AOTC. 

Pluym et al. compared the use of CE to that of HPLC in chemical and pharmaceutical quality control. They stated that CE could be considered as a complementary technique to HPLC because of its large separation capacity, its simplicity, and its economical benefits. Jimidar et al. decided that CE offers high separation efficiency and can be applied as an adjunct in HPLC method validation. Mol et al. evaluated the use of micellar electrokinetic chromatography (MEKC) coupled with electrospray ionization mass spectrometry (ESI—MS) in impurity profiling of drugs, which resulted in efficient separations. 

Vassort, A., Barrett, D. A., Shaw, P. N., Ferguson, P. D., and Szucs, R. (2005). A generic approach to the impurity profiling of drugs using standardized and independent capillary zone electrophoresis methods coupled to electrospray ionization mass spectrometry. Electrophoresis 26, 1712-1723. 

N. J. Haskins, C. Eckers, A. J. Organ, M. F. Dunk and B. E. Winger, The use of electrospray ionization with Fourier transform ion cyclotron resonance mass spectrometry in the analysis of trace impurities in a drag substance. Rapid Communications in Mass Spectrometry, 1995,9(11), 1027-1030. 

Francolic JD, Lehr GJ, Barry TL, Petzinger G. Isolation of a 2 1 hydrochlorothiazide-formaldehyde adduct impurity in hydrochlorothiazide drug substance by preparative chromatography and characterization by electrospray ionization LC-MS. J Pharm Biomed Anal 2001 26 651-663. 

Coupling CE with electrospray ionization mass spectrometry (MS) can potentially be a very powerful tool for detecting and identifying product-related impurities in recombinant pharmaceuticals. Proteins can be detected in the femtomole range with this mode. Conceivably, the bioanalyst could perform a peptide map with CZE-MS and detect, identify, and sequence aberrant peptides derived from degradates. 

Electrospray ionization with the high resolving power of Fourier transform mass spectrometry (FTMS) makes possible the detection of adducts and subpicomole impurities that confuse lower resolution measurements, as shown in Figure 8.30. This method achieves accurate determination of molecular weights (<0.002 %) and permits the verification of 50-100-mer DNA and RNA sequences. [169,170]... 

Mol, R., Kragt, E., Jimidar, I., De Jong, G.J., Somsen, G.W. Micellar electrokinetic chromato-graphy-electrospray ionization mass spectrometry for the identification of drug impurities. J. Chromatogr. B 843, 283-288 (2006)... 

Shin-ichi K, Analysis of impurities in streptomycin and dihydrostreptomycin hy hydrophilic interaction chromatog-raphy/electrospray ionization quadrupole ion trap/time-of-flight mass spectrometry. Rapid Commun. Mass Spectrom. 2009 23(6) 907-914. 

Siegel MW, Fite WL. Terminal ions in weak atmospheric plasmas. Applications of atmospheric pressure ionization to trace impurity analysis in gases. J Phys Chem. 1976 80 2871-81. Sunner J, Ikonomou MG, Kebarle P. Sensitivity enhancements obtained at high temperatures in atmospheric pressure ionization mass spectrometry. Anal Chem. 1988 60 1308-13. Thomson BA. Micro and nano-electrospray ionization techniques. In Gross M, Caprioli R, editors. Encyclopedia of mass spectrometry Vol6. Ionization methods. Oxford Elsevier, 2007. pp. 435 4. 

Furthermore, tiie products wo% characterized by electrospray ionization mass spectrometry (ESI MS). The ESI MS analyses of the organosilicon carbohydrate products (Rgures 2-3) support the selective formation of an ester bond between one hydroxyl group of the o,P-ethyl glucoside molecules and the diacid siloxanes. For clarification in Figure 2, the non-reactive cyano functionality was an impurity in the commercial diacid disiloxane starting... 

Since the development of modern ionization techniques (i.e. matrix assisted laser desorption ionization, MALDI [13-15] and electrospray [16-18]), mass spectrometry (MS) has proven to be one of the foremost tools for the characterization of numerous dendrimers. Gel permeation chromatography (GPC) has been successfully and widely appKed to the characterization of the molecular weight and polydispersity of these dendrimer molecules [19]. Furthermore, a great deal of information about the structural impurities and defects in dendrimers has... 

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