Phosphoprotein Isotope-Coded Solid-Phase Tag Approach for Enrichment and Quantitative Analysis of Phosphopeptides from Complex Mixtures

2003 ◽  
Vol 75 (20) ◽  
pp. 5441-5450 ◽  
Author(s):  
Wei-Jun Qian ◽  
Michael B. Goshe ◽  
David G. Camp ◽  
Li-Rong Yu ◽  
Keqi Tang ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Solid Phase ◽  
Complex Mixtures

scholarly journals Nitrogen-containing aromatic compounds: quantitative analysis using gas chromatography with nitrogen phosphorus detector

2021 ◽  
Author(s):  
Yuan Rao ◽  
Arno de Klerk
Keyword(s):  
Gas Chromatography ◽  
Quantitative Analysis ◽  
Aromatic Compounds ◽  
Process Development ◽  
Complex Mixtures ◽  
Response Factors ◽  
Cyanide Anion ◽  
Nitrogen Phosphorus Detector ◽  
Assurance Process ◽  
Nitrogen Containing Compounds

AbstractThe nitrogen-containing aromatic compounds found in the petrochemical industry are varied and extend beyond classes such as the anilines, pyrroles and pyridines. Quantification of these nitrogen-containing compounds that may occur in complex mixtures has practical application for quality assurance, process development and the evaluation of conversion processes. Selective detection of nitrogen-containing species in complex mixtures is possible by making use of gas chromatography coupled with a nitrogen phosphorous detector (GC-NPD), which is also called a thermionic detector. Despite the linearity of the NPD response to individual nitrogen-containing compounds, the response factor is different for different compounds and even isomers of the same species. Quantitative analysis using an NPD requires species-specific calibration. The reason for the sensitivity of the NPD to structure is related to the ease of forming the cyano-radical that is ionized to the cyanide anion, which is detected. The operation of the NPD was related to the processes of pyrolysis and subsequent ionization. It was possible to offer plausible explanations for differences in response factors for isomers based on pyrolysis chemistry. Due to this relationship, the NPD response can in the same way be used to provide information of practical relevance beyond its analytical value and a few possible applications were outlined.

Problems and Solutions in Quantitative Analysis of Complex Mixtures by X-Ray Powder Diffraction

1987 ◽  
Vol 31 ◽  
pp. 295-308 ◽  
Author(s):  
David L. Bish ◽  
Steve J. Chipera
Keyword(s):  
Quantitative Analysis ◽  
Amorphous Materials ◽  
Rietveld Method ◽  
Internal Standard ◽  
Preferred Orientation ◽  
Complex Mixtures ◽  
Calibration Data ◽  
Cell Parameters ◽  
Amorphous Phases ◽  
Standard Data

AbstractIn spite of the wide availability of automated diffractometers and advanced data reduction software, numerous traditional problems still exist that make highly precise and accurate quantitative analyses of complex mixtures difficult. The problems include particle statistics, primary extinction, microabsorption, preferred orientation, overlapping and broad reflections, variation in standard data with composition, availability of pure standards, and detection of amorphous and trace phases. Our analyses of rocks use the matrix flushing method on < 5μm particle-size material mixed with a 1.0-μm corundum internal standard to minimize the first four effects. Integrated intensities are used, and we employ several peaks from each phase whenever possible. We overcame overlap problems through iterative calculations using integral, multiple peaks or with profile refinement. Use of observed and calculated diffraction patterns for every phase enables us to predict the effects of composition and preferred orientation on RIRs. This allows us to correct for these effects if reference intensity ratios (RIRs) are known as a function of composition and orientation. Detection of amorphous phases is a significant problem, and standard mixtures reveal that amounts of amorphous components below 30% are difficult to detect. The poor detection limit and the nature of the diffraction band from amorphous phases make internal standard or spiking methods the best approach for analyzing samples containing amorphous materials. The Rietveld method of quantitative analysis has the potential to minimize all of the above problems. This method requires a knowledge of the crystal structures of all component crystalline phases, but no calibration data are necessary, structural and cell parameters can be varied during the refinement process, so that compositional effects can be accommodated and precise cell parameters can be obtained for every phase. Since this method fits the entire diffraction pattern and explicitly uses all reflections from every phase, complex, overlapped patterns can be easily analysed. In addition, this method presents the opportunity to correct for preferred orientation and microabsorption during data analysis.

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