Analyzable mixture

Several additional approaches for analyzing mixtures have been developed that do not require such a large difference in rate constants.Because both A and B react at the same time, the integrated form of the first-order rate law becomes... 

Hypochlorous acid reacts similarly to CI2O and cannot be distinguished from CI2O by wet analysis. Gaseous mixtures of CI2, CI2O, and HOCl can be analyzed by mass spectrometry (66,67), by in (68), or by uv spectrophotometry (9,66,69). Gas chromatography can be used to analyze mixtures of air, CI2, and CI2O (54). 

Electrophoresis is used primarily to analyze mixtures of peptides and proteins, rather than individual amino acids, but analogous principles apply. Because they incorporate different numbers of amino acids and because their side chains are different, two peptides will have slightly different acid-base properties and slightly different net charges at a particular pH. Thus, their mobilities in an electric field will be different, and electrophoresis can be used to separate them. The medium used to separate peptides and proteins is typically a polyacrylamide gel, leading to the term gel electrophoresis for this technique. 

Up to this point, we have focused on aqueous equilibria involving proton transfer. Now we apply the same principles to the equilibrium that exists between a solid salt and its dissolved ions in a saturated solution. We can use the equilibrium constant for the dissolution of a substance to predict the solubility of a salt and to control precipitate formation. These methods are used in the laboratory to separate and analyze mixtures of salts. They also have important practical applications in municipal wastewater treatment, the extraction of minerals from seawater, the formation and loss of bones and teeth, and the global carbon cycle. 

Fluorescence lifetime measurements can increase the analytical specificity when analyzing mixtures (1-4) and can indicate changes in chemical binding of the fluorophores under various environmental conditions (5). 

This instrument was used to analyze mixtures of intact proteins, including protein standards and a cell lysate of the bacterium Escherichia coli. A UV... 

High-voltage electrophoresis and subsequent paper chromatography of the fractions obtained made possible the isolation from the analyzed mixture of twenty-two components giving colored spots with ninhydrin and isatin. Among these, fourteen were identified as peptides and their amino acid composition established (Table 5). In the case of eight peptides, also N- and C-terminal amino acids were determined (Table 6). 

N. Blechta et al. [63] used LC-NMR experiments with H- Si indirect detection to analyze mixtures of siloxan polymers. Other studies take advantage of the unique ability of NMR to study dynamic processes like isomerization, for example, the interconversion of rotational isomers or enol-keto tautomers [64,65]. 

A similar experiment but with thymidine and adenine exchanging roles was devised by Ozaki and co-workers to analyze mixtures of shorter oligonucleotides with high resolution, supporting the notion that hydrogen bonding can be considered the key factor for separation (45). The pivotal role of Mg+ ions supports that view. As an example, single mutants in poly-... 

Mass spectrometry was also used to analyze mixtures of deuterated and nondeuterated thiophenes and thienothiophenes 1 and 2, as well as to confirm the structure of l,3,5,6-tetraphenylthieno[3,4-c]thiophene (149) (see also Bugge ). 

A number of analytical techniques have recently been reported for analyzing mixtures of various arsenicais (.2-9.). Although the sensitivity of these techniques is excellent, most are unsuitable to use for routine application either because of poor p cision and incomplete recoveries, or because they are too tedious and time consuming. 

Chromatograph An instrument which can separate and analyze mixtures of chemical substances. Chromosomal Aberration An abnormality of chromosome number or structure. 

A special subroutine, incorporating this correction and the tests for when it should be used, was added to SPECTRA. We checked it by irradiating and analyzing mixtures with known amounts of ytterbium, selenium, and mercury. The true values and the values calculated by the computer agreed within 15% for mercury. The method allowed the determination of mercury in the presence of ytterbium and selenium when their concentration ranged up to 10 times greater than mercury. 

Vannier and Stanley (31) employed fluorescence spectrophotometry to analyze mixtures of grapefruit and lemon oils. D Amore and Corigliano (32) used fluorescence to characterize mandarin, lemon and bergamot oils and related the characteristics to detect adulteration of mandarin oil with terpenes. 

The great breakthrough for silylation methods was its great analytical applicability. It could be shown that silyl derivatives258 of alcohols, phenols, carboxylic acids (incl. fatty acids), amino acids, amines and carbohydrates are useful tools for analyzing mixtures of several unknown compounds via GLC by means of their retention time251, 258. ... 

Since buffers control pH best at their pKa, pick one close to your desired pH. The most common buffer used in HPLC is phosphate. It has two usable pKa s, 2.1 and 7.1, and is UV transparent. A 100-mM solution of phosphate precipitates in solution of >50% MeOH or 70% acetonitrile. Other buffers in common use are acetate, pKa 4.8, formate, pKa 3.8, and chloroacetate, pKa 2.9 all absorb in the UV below 225 nM. Sulfonate, pKa 1.8 and 6.9, should be substituted for phosphate when analyzing mixtures of organic phosphates. 

Moisture content in the mixture of a product has an influence on density of the final product. The moisture of the analyzed mixture has been controlled and the density of the final product measured. Experimental values offered ... 

Paper chromatography has been very widely used to analyze mixtures of the simple sugars and their phosphates, and to elucidate polysaccharide structures. The interest in these compounds is great. They have a widespread occurrence in complex natural mixtures which, before the advent of paper chromatography, presented exceedingly difficult, if not unsolv-able, problems in separation and purification. 

Wahbi reported on the use of second-derivative spectroscopy for the determination of canrenone in spironolactone, and found that the method is stability-indicating for spironolactone [21]. First and second-derivative spectroscopy were also utilized for the simultaneous analysis of spironolactone in combination with either hydrochlorothiazide or frusemide [22], The drugs are extracted with ethanol and analyzed through the use of the zero-crossing method. Nowakowska [23] analyzed mixtures of spironolactone and hydrochlorothiazide in tablets by measuring the absorbance of all species at 239 nm, and that of hydrochlorothiazide at 318 nm. The recoveries for spironolactone were found to be 97.9 to 101.8%, with a coefficient of variation of less than 0.1%. 

Fast atom bombardment 20,000 Ability to analyze mixtures MW and limited sequence information for pure small peptides adaptable for LC/MS (NP- and RP-HPLC) widely available Matrix interference below m/z 500 widely variable response peptide-induced suppression effects limited to flow rates 10 /xl/min... 

Matrix-assisted laser desorption >230,000 Highest achieved mass range for proteins and glycoproteins relatively insensitive to salts ability to analyze mixtures simple to operate Very low resolution limits ability to detect structural variants not presently adapted for LC/MS limited structural information... 

Good for analyzing mixtures High tolerance for salts Not compatible with HPLC-CE... 

Tandem mass spectrometry (MS/MS) is a new analytical technique applied to problems in food and flavor analyses. Rapidity of analysis, a high discrimination against chemical noise, and the ability to analyze mixtures for functional groups are attributes of MS/MS that make it attractive for such problems. Sanple collection and pretreatment differ frcm methods used in GC/MS. Correct choice of an ionization method is paramount. Daughter ion MS/MS spectra are used for conpound identification via comparison with those of authentic compounds, and parent and neutral loss spectra are useful in functional group analysis. Applications to direct analysis of volatiles emitted from fruits and to spice analyses are considered. 

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