Identification definitive

Thermoanalytical methods (tga, dta) often enable definite identification of the type of asbestos fibers (Fig. 7). For example, the strong exotherm observed with chrysotile at 830°C can be used as a routine indicator for determining the chrysotile content of talc (4,10). Thermal methods are also usefiil for determining certain mineral contaminants of asbestos fibers, for example bmcite and calcite in chrysotile. 

When the gas chromatograph is attached to a mass spectrometer, a very powerful analytical tool (gas chromatography-mass spectrometry, GC-MS) is produced. Vapour gas chromatography allows the analyses of mixtures but does not allow the definitive identification of unknown substances whereas mass spectrometry is good for the identification of a single compound but is less than ideal for the identification of mixtures of... 

Definitive identification of lysine as the modified active-site residue has come from radioisotope-labeling studies. NaBH4 reduction of the aldolase Schiff base intermediate formed from C-labeled dihydroxyacetone-P yields an enzyme covalently labeled with C. Acid hydrolysis of the inactivated enzyme liberates a novel C-labeled amino acid, N -dihydroxypropyl-L-lysine. This is the product anticipated from reduction of the Schiff base formed between a lysine residue and the C-labeled dihydroxy-acetone-P. (The phosphate group is lost during acid hydrolysis of the inactivated enzyme.) The use of C labeling in a case such as this facilitates the separation and identification of the telltale amino acid. 

It is important to recognize that the following analytical methods essentially determine EO-PO ratio ( H NMR, IR, cleavage methods) or even simply alkylene oxide content (compleximetric methods) of the analyte, and as such are not specific quantitative or qualitative methods for poloxamers, since EO-PO copolymers of a different structure (for instance, random copolymers, or PO-EO-PO block copolymers) may respond to the methods in a way indistinguishable from poloxamers. The principal technique that permits definitive identification of a sample as a poloxamer is C NMR, which allows structural details, such as the distribution of EO and PO units along the polymer chain, to be elucidated [10]. 

Although clinical examination provides important clues to diagnosis of congenital myopathies, ultrastructural and histochemical examination of muscle biopsies provides the key to definitive identification. Most of the congenital myopathies... 

The combination of HPLC with mass spectrometry therefore allows more definitive identification and the quantitative determination of compounds that are not fully resolved chromatographically. 

A more definitive identification may be obtained by combining retention characteristics with more specific information from an appropriate detector. Arguably, the most information-rich HPLC detectors for the general identification problem are the diode-array UV detector, which allows a complete UV spectrum of an analyte to be obtained as it elutes from a column, and the mass spectrometer. The UV spectrum often allows the class of componnd to be determined but the... 

The mass spectrometer provides the most definitive identification of aU of the HPLC detectors. It allows the molecular weight of the analyte to be determined - this is the single most discriminating piece of information that may be obtained - which, together with the structural information that may be generated, often allows an unequivocal identification to be made. 

Chlorambucil - there is no problem with the quantitation ion (at m/z 254), although the second ion proves to be a little difficult. While the ion at m/z 303 is the obvious choice, this is not very intense and therefore for samples containing small amounts of analyte the precision of measurement of this ion will be reduced and it may not be detectable at all levels at which the quantitation ion is observed. We could possibly consider the (M- -2) ion, as the combination o/m/z 254 (high mass, and therefore reasonable specificity), the presence of one chlorine, and the chromatographic retention time could be considered sufficient for definitive identification in those cases in which the intensity o/m/z 303 is insufficient. 

The need for a more definitive identification of HPLC eluates than that provided by retention times alone has been discussed previously, as have the incompatibilities between the operating characteristics of liquid chromatography and mass spectrometry. The combination of the two techniques was originally achieved by the physical isolation of fractions as they eluted from an HPLC column, followed by the removal of the mobile phase, usually by evaporation, and transfer of the analyte(s) into the mass spectrometer by using an appropriate probe. 

The, chain voAiantS are characterized by the presence of two abnormal components, an abnormal Hb-F (02 /2) and an abnormal Hb-A (tt2 32) Of these two, the 02 2 component dominates and the 02 32 component Is often difficult to detect. The methods of choice are starch gel electrophoresis and anion-exchange chromatography using DEAE-Sephadex or DE-52 Cellulose. Chain analyses of these Isolated hemoglobin components will lead to a definitive Identification. 

A definitive identification of the proteins in each peak is not possible, however, the elution times of the peaks at 13-14 min. and 15 min. are close to the times which would be expected for gamma-globulins and albumins, two of the principal classes of serum proteins. These data also indicate the loading capacity of this column with serum. More than 14 mg. of undiluted serum was injected before evidence of overloading in the form of band broadening and peak distortion was observed. 

Summarizing, even a close match of any action and absorption spectra does not allow a definite identification of the photoreceptor. Additional information is required. 

Tandem MS has emerged as a definitive approach for identifying proteins from multiple sources including complex mixtures. In comparison to PMF, MS/MS permits more definitive identification of proteins. Matching of multiple MS/MS spectra to peptide sequences within the same protein... 

The first, definitive identification of KDO as a constituent of the LPS from Escherichia colt 0111-B4 (and from its UDP-galactose-4-epi-merase-less mutant, J-5) was reported by Heath and Ghalambor.29 When analyzing their LPS preparations for 3,6-dideoxy-L-xyZo-hex-... 

Mass spectrometry Both universal and specific. Definitive identification fg-pg-ng... 

Different capillary columns are available for organic acid separation and analysis. In our laboratory, the gas chromatography column in all GC-MS applications is crosslinked 5% phenyl (poly)methyl silicone, 25 m internal diameter 0.20 mm stationary phase film thickness 0.33 pm (Agilent HP-5, DB-5, or equivalent). Several instrument configurations are commercially available, which allow for positive identification of compounds by their mass spectra obtained in the electron impact ionization mode. A commercially available bench-top GC-MS system with autosampler (Agilent 6890/5973, or equivalent) is suitable. Software for data analysis is available and recommended. The use of a computer library of mass spectra for comparison and visualization of the printed spectra is required for definitive identification and interpretation of each patient specimen. 

UDP-apiose (5) is very unstable under a variety of conditions of pH and temperature this instability had previously prevented 7 the isolation of sufficient quantities of UDP-apiose for definitive identification. UDP-[U-l4C]apiose is degraded at pH 8.0 to uridine 5 -phosphate and 3-C-(hydroxymethyl)-a-D-[U-14C] erythrofuranosyl 1,2-phosphate at 80, 25, and 4°. The half-lives of UDP-[U-14C]apiose under these conditions are 31.6 seconds, 97.2 minutes, and 16.5 hours, respectively.7 The half-life of UDP-[U-,4C]apiose at pH 3.0 and 40° is 4.67 minutes. It is degraded7 to uridine 5 -pyrophosphate and D-[U-I4C]apiose. At pH 6.2-6.6 and 4°, degradation (of both the... 

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