Qualitative analysis spectrometry

Multidimensional gas chromatography has also been used in the qualitative analysis of contaminated environmental extracts by using spectral detection techniques Such as infrared (IR) spectroscopy and mass spectrometry (MS) (20). These techniques produce the most reliable identification only when they are dealing with pure substances this means that the chromatographic process should avoid overlapping of the peaks. 

Dear, G.J., Fraser, I.J., Patel, D.K., Long, J., and Pleasance, S., Use of liquid chromatography-tandem mass spectrometry for the quantitative and qualitative analysis of an antipsychotic agent and its metabolites in human plasma and urine, /. Chromatogr. A, 794, 27, 1998. 

Mass spectrometry involves the study of ions in the vapour phase. Mass spectrometers are analytical instruments that convert neutral molecules into gaseous ions and separate those ions according to the ratio of their mass-to-charge (m/z) The location of the mass lines provides a qualitative analysis, and their intensity, mostly measured relative to that of the matrix element or a suitable internal standard, gives a quantitative analysis. 

Polyatomic Organic Molecules. Metal Complexes. Qualitative Analysis - The Identification of Structural Features. Quantitative Analysis - Absorptiometry. Choice of Colorimetric and Spectrophotometric Procedures. Fluorimetry. Applications of UV/Visible Spectrometry and Fluorimetry. 

The basic instrumentation used for spectrometric measurements has already been described in the previous chapter (p. 277). Methods of excitation, monochromators and detectors used in atomic emission and absorption techniques are included in Table 8.1. Sources of radiation physically separated from the sample are required for atomic absorption, atomic fluorescence and X-ray fluorescence spectrometry (cf. molecular absorption spectrometry), whereas in flame photometry, arc/spark and plasma emission techniques, the sample is excited directly by thermal means. Diffraction gratings or prism monochromators are used for dispersion in all the techniques including X-ray fluorescence where a single crystal of appropriate lattice dimensions acts as a grating. Atomic fluorescence spectra are sufficiently simple to allow the use of an interference filter in many instances. Photomultiplier detectors are used in every technique except X-ray fluorescence where proportional counting or scintillation devices are employed. Photographic recording of a complete spectrum facilitates qualitative analysis by optical emission spectrometry, but is now rarely used. 

Only arc/spark, plasma emission, plasma mass spectrometry and X-ray emission spectrometry are suitable techniques for qualitative analysis as in each case the relevant spectral ranges can be scanned and studied simply and quickly. Quantitative methods based on the emission of electromagnetic radiation rely on the direct proportionality between emitted intensity and the concentration of the analyte. The exact nature of the relation is complex and varies with the technique it will be discussed more fully in the appropriate sections. Quantitative measurements by atomic absorption spectrometry depend upon a relation which closely resembles the Beer-Lambert law relating to molecular absorption in solution (p. 357 etal.). 

Emission of ionizing radiations in radioactive decay, nuclear particle and y-ray spectrometry. Quantitative and qualitative analysis by intensity and spectrometric measurements respectively. 

J.H. Beynon, Qualitative analysis of organic compounds by mass spectrometry, Nature, 174 (1954) 735-737. 

Mass spectrometry offers a special advantage over other detection schemes for instrumental chromatography because the mass spectra of the mixture components are acquired, providing a very powerful qualitative analysis tool for these components. 

We discussed the fundamentals of mass spectrometry in Chapter 10 and infrared spectrometry in Chapter 8. The quadrupole mass spectrometer and the Fourier transform infrared spectrometer have been adapted to and used with GC equipment as detectors with great success. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-infrared spectrometry (GC-IR) are very powerful tools for qualitative analysis in GC because not only do they give retention time information, but, due to their inherent speed, they are also able to measure and record the mass spectrum or infrared (IR) spectrum of the individual sample components as they elute from the GC column. It is like taking a photograph of each component as it elutes. See Figure 12.14. Coupled with the computer banks of mass and IR spectra, a component s identity is an easy chore for such a detector. It seems the only real... 

Beynon, J.H. Qualitative Analysis of Organic Compounds by Mass Spectrometry. Nature 1954,174. 735-737. 

Mohn T, Cutting B, Ernst B, Hamburger M (2007) Extraction and analysis of intact glucosinolates-a validated pressurized liquid extraction/liquid chromatography-mass spectrometry protocol for Isatis tinctoria, and qualitative analysis of other cruciferous plants. J Chromatogr 1166 142-151... 

An unknown substance, X, was isolated from rabbit muscle. Its structure was determined from the following observations and experiments. Qualitative analysis showed that X was composed entirely of C, H, and 0. A weighed sample of X was completely oxidized, and the H20 and C02 produced were measured this quantitative analysis revealed that X contained 40.00% C, 6.71% H, and 53.29% O by weight. The molecular mass of X, determined by mass spectrometry, was 90.00 u (atomic mass units see Box 1-1). Infrared spectroscopy showed that X contained one double bond. X dissolved readily in water to give an acidic solution the solution demonstrated optical activity when tested in a polarimeter. 

Inorganic pigments and lakes (organic dyes bonded to an inorganic support) can be recognized by the ratio of elements in their composition, making elemental analysis an important tool in their identification. EDS may facilitate an initial qualitative analysis, but quantitative analysis and the detection of trace elements are needed to identify the inorganic colorant components. Due to sample size restrictions, the methods that can be employed are limited. The techniques of inductively-coupled plasma mass spectrometry (ICP-MS), ICP-optical emission spectroscopy (ICP-OES), and laser ablation ICP-MS are described in the literature (56). 

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