Quantitative in situ analysis

The temperature range is between 170 and 210 °C and the pressure may vary between 15 and 25 MPa. Altering these conditions will considerably change the composition of the reaction mixture. The authors were able to show that Raman. spectroscopy is a very suitable method for quantitative in situ analysis of the synthesis of this substance. 

While our Raman spectroscopic method is useful for the identification of the solid reaction products and the analysis of surface products, it is not suitable for direct, total quantitative in situ analysis of solids. 

Hausner M, Wuertz S. High rates of conjugation in bacterial biofilms as determined by quantitative in situ analysis. Appl Environ Microbiol August 1999 65(8) 3710-3. 

Three methods for quantitative analysis of niclosamide at concentrations of 0.5-2.0 ppm were given. For in situ analysis, safranine dye solution was added to the sample and the extraction solution added which formed the upper phase. The niclosamide content was determined by the color intensity of the upper phase. The colors were compared with blanks of known concentration. When an accurate determination was required, niclosamide was extracted from the water sample with amylacetate, a methanol solution of sodium hydroxide was added to the extraction, and the resulting yellow color was measured at 385 mft in a spectrophotometer. Third method made use of a calibration curve [60],... 

Optical fiber detectors (OFD) are devices that measure electromagnetic radiation transmitted through optical fibers to produce a quantitative signal in response to the chemical or biochemical recognition of a specific analyte. Ideally, an OFD should produce a specific and accurate measurement, continuously and reversibly, of the presence of a particular molecular species in a given sample medium. Additionally, OFD should pro vide maximum sensitivity and minimal interferences fromsuperfluous ions or molecules to obtain low detection limits. Other attractive features include the miniaturization of the fiber s tip to accommodate single-cell analysis and portable instrumentation to allow in situ analysis. 

Ambesi-Impiombato A, D Urso G, Muscettola G, de Bartolomeis A. 2003. Method for quantitative in situ hybridization histochemistry and image analysis applied for Homer la gene expression in rat brain. Brain Res Prot 11 189-196. 

The alkaloid contents in a single alkaloid cell from M. cordata roots of three different thicknesses (age 1-2 years) were determined as follows. The liquid from various numbers of alkaloid cells (Table II) was removed uniformly and collected in the microtrap. The liquid in the capillary and connection tubes was washed into the microtrap to make a certain definite volume for analysis. Quantitative analysis of each alkaloid was carried by preparing a calibration graph (4). Figure 3 shows the HPLC chromatogram of alkaloids from the alkaloid cells. The content of each alkaloid per single alkaloid cell in tissues from three different thickness of roots and its ratio are shown in Table II. The liquid in colorless cells contained only a minute amount of protopine and allocryptopine (Fig. 3). The thicker the roots, the more alkaloids were contained in a single alkaloid cell. In any thickness of root, the content of protopine-type alkaloids exceeded that of benzo[c]phenanthridine-type alkaloids. The ratio of the former to the latter was almost steady over 5 mm of root thickness (86-87%). The ratio of alkaloids in methanol extracts of the same fresh samples (thickness 5 mm) was determined by HPLC (Table III). The ratio of protopine-type alkaloids in the methanol extracts ( 80%) was less than that in the liquid from the alkaloid cells ( 87%). This was because the liquid in alkaloid cells near the cambium were picked up more than that in center cells (pith). Thus, intracellular components scattered in different places are analyzed qualitatively and quantitatively in situ by HC. 

Kong, J., and Ringer, D. P. (1995) Quantitative in situ image analysis of apoptosis in well and poorly differentiated tumor from rat liver. Am. J. Pathol. 147(6), 1626-1632. 

Quantitative fluorimetric analysis on real samples usually requires a separation of the fluorescent analyte from its matrix because of the wide occurrence of fluorescent and quenching impurities. Occasionally, simple solvent extraction will do the trick. More often, chromatographic separation is necessary, and the fluo-rimeter becomes merely a detector for the chromatographic eluates. Recently, however, the application of immunochemistry to analytical chemistry has permitted in-situ analysis on a scale never before possible. Although the earliest immunochemical analyses utilized radioisotopes, the most popular ones used today employ fluorescent probes or labels. 

Raeburn SP, llton ES, Veblen DR (1997b) (Quantitative determination of the oxidation state of iron in biotite using X-ray photoelectron spectroscopy 11. In situ analysis. Geochim Cosmochim Acta 61 4531-4537... 

TLC is useful both as an analytical and a preparative technique, and substances tentatively identified by TLC may be further characterized by various analytical techniques such as nuclear magnetic resonance spectrometry, mass spectrometry, or gas liquid chromatography. Moreover, many specific chemical detection tests are available to help identify substances separated by TLC. TLC is a microanalytical procedure and provides for separations and at least tentative identification of substances in the milligram (mg), microgram (/ig), and nanogram (ng) range. TLC can provide the biochemist with a method of eluting separated substances from plates for quantitative analyses. Recent studies indicate that elution techniques may not be the best alternative for quantitative analyses of many substances separated by TLC and that the preferred method may involve quantitative in situ densitometric analysis [1,2]. 

In most equilibrium-based analytical methods, the success or failure of a determination is not affected by the reaction mechanism, provided that the reaction is either quantitative or the measured parameter at equilibrium is linearly proportional to the initial concentration of the species of interest. This is not the case in reaction-rate methods. Any development of a kinetic method should include, if possible, a complete study of the reaction mechanisms involved in the procedure. (Unfortunately, some reactions, such as catalytic reactions, are so complicated that complete elucidation of the mechanism is impossible.) It should also include a detailed study of the effects of typical sample-matrix components, which can act as catalysts, induce side-reactions, alter the activity of the reactants, and so on. The rates and rate constants for chemical reactions are very sensitive to low concentrations of such spectator species hence, samples containing the same true initial composition of the species of interest but coming from different sources can very often give quite different apparent concentrations. Unless the experimenter is aware of the total reaction mechanism and of all possible factors that can affect either the activation energy or the reaction path, erroneous analytical results can be obtained. A detailed investigation of the simultaneous, in situ, analysis of binary amine mixtures illustrates this point. (Most systems, by the way, are less error-prone than this one.) The rate constants for the reaction of many individual organic amines with methyl iodide in acetone solvent... 

In addition due to inadequate methods for in situ analysis at ambient concentrations analysis of airborne particles in their various forms has been limited. Even if the aerosols are analysed in detail changes have been found to occur in aerosol composition when collected by filters as they tend to react with the filter material itself. Therefore not only is improved identification of sulphate and nitrate speciation reaction mechanisms required but also improved techniques for in situ analysis to facilitate greater understanding of the quantitative aspects of the atmosphere which play a fundamental role in the long range transport of these pollutants. 

One of the most commonly used direct methods for additive analysis in polymers is based on infrared spectroscopy [4]. With the advent of Fourier transform infrared spectrometers (FTTR) and the development of sophisticated quantitative software programs, direct in-situ analysis of antioxidants is a well established technique. 

X-ray fluorescence and photothermal spectrometry are also employed for in situ analysis. It is possible as well to determine elements reliably and quantitatively, after removal from a plate. Laser pyrolysis scanning (LPS) may also be used as a quantification method for TLC [102]. No spray reagent is required for TLC-LPS-FID/ECD. Low ng detection for LPS-FID and pg detection for LPS-ECD is possible. The technique combines the advantage of the separation power of TLC and GC detection modes. 

Ease of Detection and Stability. Numerous compounds are thermally produced in foods, but not all are suitable as chemical markers of sterility. Some of the compoimds that need to be ruled out include volatiles and unstable intermediates that rapidly undergo subsequent reactions. Preferably, the marker compound should be easily extracted wi an aqueous solvent and easily determined without many additional operations. The marker should also be stable during analysis. In situ analysis would be ideal however, accurate quantitation by simple in situ methods, such as surface fluorescence or near infrared measurements, is questionable. 

The isotope dilution analysis method provides a definitive technique that does not depend on the comparison to one or more external calibration standards for quantitation. The method is similar to the standard addition technique in that a known quantity of analyte material is added to the sample to be analyzed, thereby performing the quantitation in situ. This approach ehminates matrix interference problems. The method is also similar to the internal standardization procedure, with the exception that a form of the analyte itself serves as the internal standard. AU of these factors combine to provide analysis characteristics comparable to the most basic gravimetric methods. 

Vander Putten.E., Dehairs, E, Andre, L., and Baeyens,W. (1999). Quantitative in situ micro-analysis of minor and trace elements in biogenic calcite using infrared laser ablation— inductively coupled plasma mass spectrometry—3 critical evaluation. Anal. Chim. Acta 378(1), 263. 

Since 1975 there has been a movement toward the in situ analysis of specific species in complex mixtures without initial application of separation science to simplify the problem. The possible applications of such chemically selective devices, particularly those designed to quantitatively monitor organic compounds, cover a wide range of situations, including on-line monitoring and control of... 

The interfacial properties of IL/electrode interfaces are different from other media (i.e., aqueous or traditional nonaqueous media) because of the unique properties of ILs, especially the electrochanical properties. To understand the electrode/electrolyte interface chanistry for sensor research, the mechanisms of the electrochemical reactions, and the essential performance-limiting factors, both in the bulk and at the surface of the electrode materials need to be investigated, preferably in situ. In situ analysis is much desired due to the fact that ex situ measurements are usually not able to follow the fast kinetics at electrode interfaces. The past decades have been characterized by a spectacular development of in sim techniques for studying interfacial processes at metal electrodes. Radioactive tracer [31, 32], pulse potentiody-namic [33, 34], and galvanostatic methods [35] have been applied quantitatively to study the adsorption of organic compounds at solid metals. In the study of complex... 

Formation of acetaldehyde and metallic Pd by passing ethylene into an aqueous solution of PdCl2 was reported by Phillips in 1894 15] and used for the quantitative analysis of Pd(II)[16], The reaction was highlighted after the industrial process for acetaldehyde production from ethylene based on this reaetion had been developed[l,17,18]. The Wacker process (or reaction) involves the three unit reactions shown. The unique feature in the Wacker process is the invention of the in situ redox system of PdCl2-CuCl2. 

Quantitative analytical methods using FIA have been developed for cationic, anionic, and molecular pollutants in wastewater, fresh waters, groundwaters, and marine waters, several examples of which were described in the previous section. Table 13.2 provides a partial listing of other analytes that have been determined using FIA, many of which are modifications of conventional standard spectropho-tometric and potentiometric methods. An additional advantage of FIA for environmental analysis is its ability to provide for the continuous, in situ monitoring of pollutants in the field. ... 

In situ quantitation The fluorimetric analysis was made in UV light (2e,c = 313 nm, /-n > 460 nm FI 46 filter). The signal-noise ratio was better above 2 = 460 nm than when a FI 39 filter is employed. 

In situ quantitation The in situ fluorimetric analysis was made under long-wavelength UV light (2eic = 365 nm, An > 560 nm) and is illustrated in Figure 1. The detection limits for maltose, glucose and fructose were ca. 10 ng substance per chromatogram zone. 

In situ quantitation The reagent was not suitable for a sensitive, direct, photometric analysis. 

In situ quantitation Quantitative analysis (Figs. 2 and 3) could be performed both absorption-photometrically with long-wavelength UV light (2 = 365 nm) or fluorimetrically (2eic = 436 nm Afi = 546 nm [monochromation filter M 546] or 2fi > 560 nm). 

In situ quantitation Fluorimetric analysis was made with long-wavelength UV light (2exc = 365 nm, X(, > 430 nm). The detection limit on HPTLC plates that were analyzed in a moist state was 25 ng cholesterol per chromatogram zone (Fig. 1). 

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