Routine quantitative analysis

Dynamic headspace GC-MS involves heating a small amount of the solid polymer sample contained in a fused silica tube in a stream of inert gas. The volatile components evolved on heating the sample are swept away from the sample bulk and condensed, or focused on a cryogenic trap before being introduced onto the chromatographic column via rapid heating of the trap. The technique can be used qualitatively or quantitatively DHS-GC-MS is considered to be well suited towards routine quantitative analysis. 

Whilst these methods are informative for the characterisation of synthetic mixtures, the information gained and the nature of these techniques precludes their use in routine quantitative analysis of environmental samples, which requires methods amenable to the direct introduction of aqueous samples and in particular selective and sensitive detection. Conventionally, online separation techniques coupled to mass spectrometric detection are used for this, namely gas (GC) and liquid chromatography (LC). As a technique for agrochemical and environmental analyses, high performance liquid chromatography (HPLC) coupled to atmospheric pressure ionisation-mass spectrometry (API-MS) is extremely attractive, with the ability to analyse relatively polar compounds and provide detection to very low levels. 

Mass Spectrometric Interfaces for Routine Quantitative Analysis.162... 

Routine quantitative analysis, enzyme analysis and kinetics. More sensitive at lower concentrations than visible and UV absorption. 

Partial Least Squares Regression is a valuable tool in FTIR-spectroscopy, not only for (routine) quantitative analysis of mixtures, but also as a research application. Due to its ability to expose correlations in complex, multivariate data sets, PLS is gaining importance rapidly in spectroscopy-assisted-research. 

For routine quantitative analysis, pulse polarography and voltammetry are perhaps the most useful of the modern variants on the classic method. Unlike d.c. 

Selected-ion monitoring (SIM), where the ion abundances of preselected ions are acquired. Selected-ion monitoring is applied in routine quantitative analysis. In quadrupole and magnetic sector instruments, acquisition in SIM mode provides a substantial gain in signal-to-noise ratio (S/N). 

This study was conducted for the purpose of evaluating atomic absorption and flame emission spectroscopy for the routine quantitative analysis of large numbers of water samples for elements present in quantities ranging from large to trace amounts. 

Method of Nobuhara et al. (1980). A simple and rapid method for the routine quantitative analysis of the six major alkaloids in gum opium by direct isocratic HPLC on a reversed phase partition mode column without using ion-pair reagents was successfully used by Nobuhara et al. (1980) under the following conditions ... 

In addition to these qualitative studies, quantitative bioanalysis, e.g., in preclinical and clinical studies to provide pharmacokinetic and pharmacodynamic data, is an essential part of drug development. Quantitative bioanalysis is the most important application area of LC-MS, in terms of number of instruments applied and the number of analyses performed. Fast, high-throughput, and routine quantitative analysis by LC-MS also demands fast and automated sample pretreatment strategies and advanced data-processing software. 

After the first demonstration of multiply charged gas-phase proteins ions, all major instrument manufacturers developed atmospheric-pressure ion sources, equipped with electrospray interfaces for both protein characterization and LC-MS applications. Within 5 years, electrospray interfacing became the method of choice in LC-MS coupling. It led to a large increase in the use of MS for the characterization and identification of labile and polar analytes as well as to routine quantitative analysis. The advent of electrospray ionization for peptide and protein analysis stimulated further development and analytical application of existing and new mass analysis approaches, such as quadrupole ion traps, Fourier-transform ion-cyclotron resonance MS, and quadru-pole-time-of-flight hybrid instruments. It opened new application areas, such proteomics. LC-MS... 

Polymer specimens are particularly difficult to analyze in the AEM. Generally, there are small amounts of heavy elements in a polymer. These low levels are difficult to detect in a material that changes readily in the electron beam. These difficulties preclude routine quantitative analysis of polymers in either the SEM or AEM although microanalysis techniques can be applied. The major consideration for the polymer microscopist is that changes occur in the polymer during study. 

The suitability of an analytical method has to be proven by showing its accuracy. This may be achieved by determining the coefficients of variation (a criterion for assessing precision) and by determining the recovery rates (a criterion for assessing the accuracy of the mean or bias). A routine quantitative analysis must produce correct results even in the presence of significant variations in the measurement environment. 

Modern quantitative software packages can easily handle up to 20 components and 500 spectra can be included in one calibration set. The success of absorption spectroscopy for routine quantitative analysis owes much to the use of double-beam systems to achieve the required measurement robustness. 

For the analytical spectroscopist working in a quality assurance laboratory or a research technical-support group, the need to provide cost-effective, robust, reproducible and simply operated quantitative methods of compositional and microstructure analysis can be a prime task and important challenge. Vibrational spectroscopy techniques have proved themselves among the most powerful for the routine quantitative analysis of polymers, with the wide variety of sampling procedures usually offering a method (at least semi-quantitative) for even the most intractable of materials. 

Two general modes of data acquisition are available in MS full-scan acquisition and selective ion monitoring (SIM). In full-scan analysis, a continuous series of mass spectra is acquired during the chromatographic run. For high-efficiency open capillary GC columns, sufficiently fast scanning is required in order to acquire a sufficient number of data points (typically 10 to 20) to adequately describe the chromatographic peak profile. However, in routine quantitative analysis of a limited number of components, better results in terms of lower detection limits are achieved by the use of SIM, in which the intensity of a (number of) ion(s) is monitored. The choice between full-scan and SIM acquisition in a particular application depends on the required detection limit and information content. 

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