INDEX instrumentation

The sample size required depends on the viscosity of the sample, the cell size of the density measurement device and the refractive index instrument. The density measurement requires a sample size of about 7-10 ml and the measurement must be made after a stabihzation period with no flow. In contrast, the refractive index measurement is made on a flowing stream. 

The autosampler required a RS232 communication at 9600 baud using ASCII character strings in a question-and-answer manner. The density device (Anton Paar) communicated at 2400 baud and a complete data buffer of information was transmitted. The computer program was designed to select and validate data for each measurement. Finally, the refractive index instrument had to be strobed to provide data using an RS232 interface at 1200 baud. 

A different system has been introduced by Index Instruments [2]. This modular analysis system (MAS) provides the analysis of up to four different parameters refractive index, density, colour and optical rotation. A wide range of viscosities can be handled. The analysis, wash and drying times can be selected by computer control so that crosscontamination can be reduced to undetectable levels. Samples are only in contact with inert materials such as glass, synthetic sapphire, PTFE and 316 stainless steel. 

Fig. 7.5 Schematic layout of the Index Modular Analysis System (MAS). Reproduced with permission of Index Instruments Ltd.

Index Instruments Ltd, Bury Road Industrial Estate, Ramsey, Huntingdon, Cambridgeshire, PE17 INA, UK. 

The major types of off-index instruments that can be employed are discussed below. 

Off index instruments can generate a significant chunk of portfolio alpha and often depends on the skill of the individual portfolio manager. Managers also engage in securities lending in order to earn a steady stream of cash that helps them beat their benchmarks. 

As noted earlier, indexation lags prevent indexed bonds returns from being completely inflation-proof According to Deacon and Derry (1998), this suggests that an indexed bond can be regarded as a combination of a true indexed instrument (with no lag) and an nonindexed bond. Equation (12.13) expresses the price-yield relationship for a bond whose indexation lag is exactly one coupon period. 

One of the most common instruments associated with the polyethylene industry is the Melt Index instrument that is found in research, product and manufacturing facilities around the globe. For commercial applications, polyethylene is sold according to Melt Index values summarized in material specification data sheets, usually by the Melt Index value determined with a 2.16 kg weight (MI ... 

The Melt Index instrument was developed by Imperial Chemical Industries (ICI) scientists [1] in the late 1930s in order to test polyethylene... 

A 3.160 mg/mL solution of PMMA in chloroform was prepared. One sample of 100 oL was injected into a Waters 150CALC GPC with an internal viscometer, Viscotek Model T60A, and an external refractive index instrument. The flow rate of the run was 1.000 mL/min. 

Composition The law of mass aclion is expressed as a rate in terms of chemical compositions of the participants, so ultimately the variation of composition with time must be found. The composition is determined in terms of a property that is measured by some instrument and cahbrated in terms of composition. Among the measures that have been used are titration, pressure, refractive index, density, chromatography, spectrometry, polarimetry, conduclimetry, absorbance, and magnetic resonance. In some cases the composition may vary linearly with the observed property, but in every case a calibration is needed. Before kinetic analysis is undertaken, the data are converted to composition as a function of time (C, t), or to composition and temperature as functions of time (C, T, t). In a steady CSTR the rate is observed as a function of residence time. 

In Raman spectroscopy the intensity of scattered radiation depends not only on the polarizability and concentration of the analyte molecules, but also on the optical properties of the sample and the adjustment of the instrument. Absolute Raman intensities are not, therefore, inherently a very accurate measure of concentration. These intensities are, of course, useful for quantification under well-defined experimental conditions and for well characterized samples otherwise relative intensities should be used instead. Raman bands of the major component, the solvent, or another component of known concentration can be used as internal standards. For isotropic phases, intensity ratios of Raman bands of the analyte and the reference compound depend linearly on the concentration ratio over a wide concentration range and are, therefore, very well-suited for quantification. Changes of temperature and the refractive index of the sample can, however, influence Raman intensities, and the band positions can be shifted by different solvation at higher concentrations or... 

The evaluation methods could be direct, e.g., measuring a containment index, or indirect, e.g., measuring pressure loss or velocity distribution. The direct methods are used to measure the performance of a hood or an inlet during periodic preventive maintenance. Indirect methods are used for verifying or checking on a daily basis (routine checks). How often each method is used depends on the availability of instrumentation and qualified personnel, since direct measurement of a hood s performance can be both expensive and difficult. On the other hand, indirect methods are usually easier to use and can sometimes include inexpensive, continuously monitoring instruments (pressure gauges or velocity indicators). 

In the laboratory, RI is measured using a refractometer. The instrument has two prisms and a light source. The technician spreads a small amount of sample on the faces of both prisms in the refractometer. The light is then directed at the sample and the scale is read. The observed scale is then converted to a refractive index with tables supplied with the instrument and corrected for the sample temperaturi. ... 

Photoelectric-Colorimetric Method. Although the recording spectrophotometer is, for food work at least, a research tool, another instrument, the Hunter multipurpose reflectometer (4), is available and may prove to be applicable to industrial quality control. (The newer Hunter color and color difference meter which eliminates considerable calculation will probably be even more directly applicable. Another make of reflection meter has recently been made available commercially that uses filters similar to those developed by Hunter and can be used to obtain a similar type of data.) This instrument is not a spectrophotometer, for it does not primarily measure the variation of any property of samples with respect to wave length, but certain colorimetric indexes are calculated from separate readings with amber, blue, and green filters, designated A, B, and G, respectively. The most useful indexes in food color work obtainable with this type of instrument have been G, which gives a... 

The international normalized ratio (INR) is a method to standardize repotting of the prothrombin time, using the formula, INR = (PTpatie t/PTcontroi)ISI, where PT indicates the prothrombin times (for the patient and the laboratory control), and ISI indicates the international sensitivity index, a value that varies, depending upon the thromboplastin reagent and laboratory instrument used to initiate and detect clot formation, respectively. 

Compilations of Reference Spectra There are several compilations of reference mass spectra available of which the oldest is the American Petroleum Institute (Ref 82) collection of spectra obtained mostiy on the older type instruments. Recent collections index spectra variously, eg, under reference number (Ref 19). molecular weight (Refs 12 19), molecular formula (Ref 19), fragment ion values (Ref 19), and base peak (Refs 12 19). A quarterly journal, Archives of Mass Spectral Data ... 

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