Analyzers colorimeters

In addition to fiber length, strength, and fineness, two other properties that have significant bearing on fiber and yam properties are color and trash measurements, which have been accompHshed by instmmentation such as the Colorimeter and the Shirley Non-Tint Analyzer. 

Colored and fluorescent dyes have the advantage of being relatively cheap and easy to use. Standard procedures are available for detection of the dyes using colorimeters and fluorimeters. Some of these instruments can be used in the field to analyze samples as they are collected following exposure to the dyes. Fluorescein has been widely used for studying spray deposition within and outside canopies. ... 

A typical colorimetric analyzer is illustrated schematically in Figure 6-8. Sample air is drawn at a metered rate into a contact column, where the air is scrubbed with a metered flow of potassium iodide buffered at a pH of 6.8. The reaction of oxidants with the potassium iodide solution produces the yellow triiodide ion (I, ). The colored solution flows to a colorimeter cell, where the absorbance of the triiodide ion is measured... 

A colorimeter (Figure 4) has been designed specifically for analyzing >2/ ) passive samplers. It is lightweight, portable and simple to use. Features incorporated into the unit include a ten-minute timer with audible alarm to ensure complete color development of the samples before analysis, a cuvette slot which... 

The colorimeter is designed to convert % transmittance (% T) to absorbance (Abs) (Figure 5). It is also programmed with the slope from the standard curve of absorbance vs. nanomole NO2 and thus derives a nanomole NO2 value for each sampler analyzed. Additionally, the factor of 2.3 nanomoles per ppm hour exposure is incorporated so that the colorimeter can calculate and display a ppm hour value for each sampler by performing the following functions ... 

The sensitivity range for the colorimeter, following the method above, is 0-20 ppm hours NO2. If a sampler exceeds 20 ppm hours, it can be diluted with an additional, known aliquot of azo dye reagent and analyzed again. This value is multiplied by the dilution factor to arrive at the accurate ppm hour value. By performing a one fold dilution (dilution factor 2), the sensitivity range of the colorimeter can be extended to 40 ppm hours NO2. A dilution flask is supplied in case of the need for further dilutions. 

As the colorimeter described here has been designated specifically for NO2 and NO evaluation, so could a colorimeter be dedicated to analyzing other contaminants, given a reliable colorimetric wet analysis for determination of exposed sampler contents. 

Colorimeter. An instrument for routine chemical analysis. Compounds or ions which absorb light in the visible part of the spectrum (400 to 800 nanometers) or which are convertible by specific reagents to such compounds can be analyzed with a colorimeter. The instrument typically incorporates an incandescent light bulb as light source, filters to separate the spectral region, a cuvette to contain the sample solution, and a photometer. See also Colorimetry,... 

Meat discoloration studies typically involve a maximum of 5 days, with discoloration analy-sis being performed every day or on alternate days. The actual experimental time involved in the objective assessment of discoloration is not extensive and depends on the number of samples being analyzed. Colorimetric measurements with hand-held colorimeters are very rapid (three measurements per meat surface in < 1 min). Spectral scans of meat surfaces require 1 to 2 min. Extraction and analysis of ground meat products has the added step of homogenization and filtration prior to spectrophotometry, but relative to many laboratory procedures, this is relatively quick. Isolation and purification of preparative amounts of myoglobin requires only 2 to 3 days once appropriate preparations are made. Finally, metmyoglobin can be reduced to oxymyoglobin in 15 to 20 min. 

Commercial colorimeters that measure color by analyzing light reflected from the sample surface are readily available (e.g., Konica Minolta, 2005). 

If a water sample contains both soluble and insoluble manganese (Mn) compounds and ions, and it is filtered to separate the dissolved and insoluble fractions, and the filtrate and insoluble residue are analyzed separately, the results can be expressed as total dissolved Mn and total suspended or insoluble Mn. Phosphorus (P) can be determined colorimet-rically as the ortho-phosphate ion, P043, in aqueous samples after a reaction that forms an intensely blue-colored derivative. However polyphosphate ions and other ions and compounds containing P do not form this derivative. Total P in a sample can be determined with the same colorimetric procedure after acid hydrolysis and oxidation of all ions and compounds containing P to P04 3. In some elemental analyses the sample is treated with reagents designed to make available for measurement some fraction of an element or elements but not the total amount. For example, a soil sample may be treated with water at pH 3 to simulate the leaching process of acid rain. A total elemental analysis of the filtrate provides information about just those elements solubilized by the mild acid treatment. This can be called the determination of total mild acid leachable elements. 

All the systems discussed here use conventional strip chart recorders for recording the photometer or colorimeter output, and the resulting record is a conventional histogram in which the absorbance of the eluate or eluate-reagent reaction mixture is recorded as a function of time. In addition, some prototype systems of the UV- and carbohydrate analyzers use on-line computers for data storage and processing (Cl, S7). 

Dried samples were analyzed for total carbon (TO using a Carlo Erba 1500 C-N-S-Analyser. The carbonate carbon (CC) was measured after acidification with perchloric acid by a carbon dioxide colorimeter (Colourimetrics, Inc., Golden, CO). The organic carbon (OC) was calcnlated as the difference between TC... 

The instruments which analyze a substance by virtue of the electron shells of the atoms in the visible area of the spectra are called colorimeters. These instruments measure the difference in the color intensity of a reference solution with a defined concentration of the component analyzed and the color intensity of the sample solution. 

Colorimeters are constructed based on the principle of continuous ray. That means the light ray passes continuously from the light source to the detector. The main elements of every colorimeter are a light source, two cuvettes, a detector and a monitoring device. One cuvette is used for the reference solution and has the same thickness of the sample room. Usually, the thickness of the sample room and consequently the thickness of the analyzing sample can be varied in the analyzing cuvette. The principle scheme of the colorimeter is shown in Figure 2.50. 

For reference, a spectrophotometer/colorimeter with direct concentration readout costs on the order of 2000 a digital Na/K flame photometer with an automatic sample-diluter, about 4000 a flexible, computer-controlled, single-channel analyzer under 25,000 a computer-based parallel-fast analyzer, about 50,000 and a multi-channel analyzer from about 80,000 to well over 200,000. 

Recommended Analytical Methods To analyze electrolyzer feed brine after the ion-exchanger, it is advisable to acidify the sample before testing. This will dissolve any magnesium hydroxide precipitates and make it detectable by colorimeter analysis. Such analysis will reveal any magnesium breakthrough because of upsets in the primary treatment. 

The melting and polymerization temperatures of the monomers were analyzed by differential scanning colorimeter (DSC) under nitrogen atmosphere and the results are summarized in Table 1. Monomer IC with 3 wt % of diamine (ODA) curing agent shows that the onset and completion temperatures of polymerization reaction are 256 and 300°C, respectively (1260-315°C and the reaction time of 32-36 hr) The same... 

The Duboscq Colorimeter is an instrument used to analyze samples by differences in color intensity. Explain how an accuracy of 2% is achieved. 

Isolation of tocopherois is accompanied by losses due to oxidation. Therefore, the edible oil is dissolved in acetone at 20-25 °C in the presence of ascorbyl palmitate as an antioxidant. The major portion of triacylglycerols is separated by crystallization at — 80 °C. Tocopherois remaining in solution are then analyzed by thin layer or gas chromatography (after silylation of the phenolic HO-group) or by HPLC (cf. Fig. 3.46). UV spectrophotometry is also possible. However, the fluorometric method based on an older colorimet-... 

Huge numbers of analyses must often be performed to get meaningful results and for reasons of economics. This has resulted in the development of a number of automated procedures in which traditional wet chemical methods of analysis have been adopted to automate procedures. With such procedures, the samples are introduced through a sampler and the analyses performed and results posted without manual manipulation of reagents and apparatus. Such procedures have been developed and instruments marketed for the determination of a number of analytes. In water, automated analyses have been developed from wet chemical procedures for alkalinity, sulfate, ammonia, nitrate/nitrite, and metals. The somewhat cumbersome West-Gaeke determination of sulfur dioxide in air has been adapted to automated analyzers. Colorimetric (absorption spectrophotometric) procedures are popular for such automated analytical instruments, using simple, rugged colorimeters for absorbance measurements. 

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