Degradation products identification

Orthogonal extraction, improvements in TOF/MS resolution, and improvements in electronics have created a new application for TOF/MS in accurate mass measurements [70,71]. Accurate mass applications have traditionally been associated with high-resolution magnetic sector and FTMS systems. The ability to provide accurate mass measurements (+5 ppm) with more cost-effective instrumentation has created potential opportunities in the pharmaceutical industry. Such applications can offer improved selectivity for single-stage instrumentation and metabolite or impurity/degradation product identification, particularly when standard compounds are not available, such as in early drug discovery. 

When degradation product identification was required, GC/MSD was enlisted. After 3 min of treatment by AFT under typical operating conditions, 15 mL of anodic solution was taken out and imme ately extracted using 3 mL hexane. The sanq>le was analyzed by an Agilent 6890N Network GC System equipped with an Agilent 5973 Network Mass Selective Detector and Agilent 7683 Series Injector. GC conditions have been reported 21). 

Chrysin (17) was the first flavone to be isolated in a pure form, and its stmcture was elucidated by identification of its alkaline degradation products (72—74). The stmcture was confirmed by synthesis (75,76). The same procedures were used to estabflsh the stmcture of other flavones and in so doing the foundation of flavone chemistry was laid (77). 

For organic toxic chemicals and their degradation products the number of possibilities is very high. The environmental samples composition usually is very complicated. Unambiguous identification needs serial-pai allel strategy of analysis with many-stage crosschecking of data. 

In 1947, L-rhamnose was first recognized by Stacey as a constituent of Pneumococcus Type II specific polysaccharide. This finding was confirmed, in 1952, by Kabat et al. and in 1955 again by Stacey when 2,4- and 2,5-di-O-methyl-L-rhamnose were synthesized and the former was shown to be identical with a di-O-methylrhamnose, obtained by hydrolysis of the methylated polysaccharide. This result indicated a pyranose ring structure for the rhamnose units in the polysaccharide. Announcement of the identification of D-arabinofuranose as a constituent of a polysaccharide from M. tuberculosis aroused considerable interest. The L-enantiomer had been found extensively in polysaccharides, but reports of the natural occurrence of D-arabinose had been comparatively rare. To have available reference compounds for comparison with degradation products of polysaccharides, syntheses of derivatives (particularly methyl ethers) of both d- and L-arabinose were reported in 1947. 

Chopra NM, Campbell BS, Hurley JC. 1978. Systematic studies on the breakdown of endosulfan in tobacco smokes Isolation and identification of the degradation products from the pyrolysis of endosulfan I in a nitrogen atmosphere. J Agric Food Chem 26 255-258. 

Herbach, K.M., Stintzing, E.C., and Carle, R., Identification of heat-induced degradation products from purified betanin, phyUocactin and hylocerenin by high-performance liquid chromatography/electrospray ionization mass spectrometry, Rapid Commun. Mass Spectrom., 19, 2603, 2005 20, 1822, 2006. 

Schwartz, S.J. and Von Elbe, J.H., Identification of betanin degradation products, Ztschr. Lebensm. Enters. Forsch., 176, 448, 1983. 

Hammer E, D Krpowas, A Schafer, M Specht, W Erancke, E Schauer (1998) Isolation and characterization of a dibenzofuran-degrading yeast identification of oxidation and ring clavage products. Appl Environ Microbiol 64 2215-2219. 

Grifoll M, M Casellas, JM Bayona, AM Solanas (1992) Isolation and characterization of a fluorene-degrading bacterium identification of ring oxidation and ring fission products. Appl Environ Microbiol 58 2910-2917. 

Bumpus JA, M Tatarko (1994) Biodegradation of 2,4,6-trinitrotoluene by Phanerochaete chrysosporium identification of initial degradation products and the discovery of a metabolite that inhibits lignin peroxidases. Curr Microbiol 28 185-190. 

Validation of true extraction efficiency normally requires the identification and quantitation of field-applied radiolabeled analyte(s), including resulting metabolites and all other degradation products. The manufacturer of a new pesticide has to perform such experiments and is able to determine the extraction efficiency of aged residues. Without any identification of residue components the calculation of the ratio between extracted radioactivity and total radioactivity inside the sample before extraction gives a first impression of the extraction efficiency of solvents. At best, this ratio is nearly 1 (i.e., a traceability of about 100%) and no further information is required. Such an efficient extraction solvent may serve as a reference solvent for any comparison with other extraction procedures. 

Obviously, use of such databases often fails in case of interaction between additives. As an example we mention additive/antistat interaction in PP, as observed by Dieckmann et al. [166], In this case analysis and performance data demonstrate chemical interaction between glycerol esters and acid neutralisers. This phenomenon is pronounced when the additive is a strong base, like synthetic hydrotalcite, or a metal carboxylate. Similar problems may arise after ageing of a polymer. A common request in a technical support analytical laboratory is to analyse the additives in a sample that has prematurely failed in an exposure test, when at best an unexposed control sample is available. Under some circumstances, heat or light exposure may have transformed the additive into other products. Reaction product identification then usually requires a general library of their spectroscopic or mass spectrometric profiles. For example, Bell et al. [167] have focused attention on the degradation of light stabilisers and antioxidants... 

Applications Rather intractable samples, such as organic polymers, are well suited to FD, which avoids the need for volatilisation of the sample. Since molecular ions are normally the only prominent ions formed in the FD mode of analysis, FD-MS can be a very powerful tool for the characterisation of polymer chemical mixtures. Application areas in which FD-MS has played a role in the characterisation of polymer chemicals in industry include chemical identification (molecular weight and structure determination) direct detection of components in mixtures off-line identification of LC effluents characterisation of polymer blooms and extracts and identification of polymer chemical degradation products. For many of these applications, the samples to be analysed are very complex... 

Capillary HPLC-MS has been reported as a confirmatory tool for the analysis of synthetic dyes [585], but has not been considered as a general means for structural information (degradant identification, structural elucidation or unequivocal confirmation) positive identification of minor components (trace component MW, degradation products and by-products, structural information, thermolabile components) or identification of degradation components (MW even at 0.01 % level, simultaneous mass and retention time data, more specific and much higher resolution than PDA). Successful application of LC-MS for additive verification purposes relies heavily and depends greatly on the quality of a MS library. Meanwhile, MB, DLI, CF-FAB, and TSP interfaces belong to history [440]. 

Various LC-PB-MS and LC-APCI-MS comparisons have been reported on polymer additive extracts [540, 563,629,630]. The complementary character of the El and APCI modes was confirmed. Yu et al. [630] compared LC-PB-MS and RPLC-UV-APCI-MS for detection and identification of unknown additives (in the 252 to 696 Da range) in an acetonitrile extract from PP (containing Irganox 1076, Naugard XL-1 and a degradation product, NC-4, 3-(3,5-di-f-butyl-4-hydroxyphenyl) propanoic acid, 7,9-di-f-butyl-l-oxaspiro [4,5] deca-6,9-diene-2,8-dione and octadecanol-1). Comparison was based on El data (identification of chemical structure), APCI (MW information CID spectrum with limited fragmentation) and PDA (210 nm). The components were identified by El and confirmed by APCI- (with better sensitivity and linearity) MS and PDA showed... 

The conversion in the animal body of at least some of the water-insoluble chlordan to a water-soluble degradation product must facilitate the elimination of the poison through its excretion into the urine by the kidneys. Moreover, the degradation of chlordan as shown in the present experiments may be a mechanism for its detoxification, as in the case of DDT (1). Only the isolation of the degradation product, its identification, and a study of its toxicity can determine this point. 

Certainly, the identification of the degradation products responsible for the cytotoxic effects and their metabolic pathways require a thorough elucidation, and a cultured RPE offers a good model for these investigations. 

The occurrence, behavior, and toxicity of all these emerging contaminants continue to be an intensive area of research, especially investigations about their removal from environmental waters (e.g., through advanced oxidation, photolysis, microbial degradation, etc.). Therefore, the identification of intermediates and degradation products originated as a result of these removal mechanisms is of... 

If there is only interest in determining the elimination or degradation percentages, as in the studies mentioned above, experiments can be performed at low contaminant concentrations, similar to those found in the environment. However, if metabolites identification analysis is wanted to be performed, higher concentrations are needed. That is, because degradation products are usually at much lower concentration than the initial parent compound. 

The instrumental analysis for the identification of UV filters degradation products formed during the fungal treatment process was performed by means of HPLC coupled to tandem mass spectrometry using a hybrid quadrupole-time-of-flight mass spectrometer (HPLC-QqTOF-MS/MS). Chromatographic separation was achieved on a Hibar Purospher STAR HR R-18 ec. (50 mm x 2.0 mm, 5 pm, from Merck). In the optimized method, the mobile phase consisted of a mixture of HPLC grade water and acetonitrile, both with 0.15% formic acid. The injection volume was set to 10 pL and the mobile phase flow-rate to 0.3 mL/min. 

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