I.C instrumentation

H Flaschka and A J Barnard, Jr, Tetraphenylboron (TPB) as an analytical reagent. In Advances in Analytical Chemistry and Instrumentation, Vol I, C N Reilley (Ed), Interscience Publishers, New York, 1960... 

The spectral characteristics of the source, photocells, and the three filters are such that approximate I.C.I. tristimulus values may be calculated (5) and from these a specification in terms of luminous reflectance, dominant wave length, and purity can be obtained. Hardy has cautioned (3), however, that the usefulness of such an instrument as a tristimulus colorimeter depends upon the standardization and constancy of the spectral characteristics of the light source, cell, and filters. 

Conversion tables and charts now available make it possible to express I.C.I. data in forms in which a specified color and the significance of measured color differences can be more easily visualized. For example, I.C.I. values calculated from objective instrumental readings can be converted into the Munsell notation which evaluates the three psychological color attributes—hue, lightness (Munsell value), saturation (Munsell chroma)—on scales of approximately equal visual steps. In addition, the Munsell color charts offer one of the most convenient sources of material standards for direct color comparisons. 

It is significant that in the absence of O2 (solid points in Figure 4) almost no radicals were formed the amount reported is close to the detection limit of the instrument. In one sense, this observation provides an explanation for the positive effect that O, has on the rate of reaction between NO and CH4 [3,4] i.c., O2 enhances CH,- radical formation. However, the results also indicate that NO itself is not very effective in generating active sites which are responsible for CH,- radical production. This means that the reaction of NO with CH4, in the absence of added O, may occur via a nonradical pathway. 

A quantified value for stray light within a turbidimeter is difficult to determine. One method uses a standard addition to a formazin suspension of a known low turbidity. But some instruments have a build-in system to determine the stray light and to correct the turbidity reading accordingly (i.e. Instrument C). 

For VCD measurement, the actual differential signal, at constant CD of the sample, will vary with the light level transmitted at a given wavelength. Denoting the signal at the modulator frequency as I c(i ), and the overall transmission of the instrument and sample as IDC(i/), it can be shown from an analysis of the radiant energy at the detector that... 

McCrone, W.C. and Johnson, R.I., "Techniques, Instruments and Accessories for Microanalysts" a users manual, (1974), Price list, May 1, 1978, pp 25 - McCrone Accessories and Components, 2820 South Michigan Ave., Chicago, IL, 60616,... 

The way in which the changes have affected a well equipped R D laboratory situated in the Plastics Division of I.C.I. is shown in Fig. 1. This demonstrates the impact of instrumentation on sample throughput. It is interesting to note however that the growth has not been linear. The period of rapid improvement in efficiency coincided with the time when mechanical forms of semi-automation, which were easy to develop, install, operate and maintain were in vogue. With the introduction of more sophisticated instrumentation, the per capita output has levelled off, but the complexity of the analysis has increased For example, with 13C NMR as well as XH NMR it is possible to make structural assignments to polymer chains routinely. 

Optical Measuring Instruments. Their Construction, Theory, and Use. By L. C. Martin, F.R.A.S., D.Sc., A.R.C.S., D.I.C., Lecturer in the Optical Engineering Department, Imperial College of Science and Technology, South Kensington. With 172 figures. 17s. 6d. net. 

R. J. Hill and I. C. Madsen, Sample preparation, instrument selection and data, in Stmcture determination from powder diffraction data. lUCr monographs on Crystallography 13, W.I.F. David, K. Shankland, L.B. McCusker, and Ch. Baerlocher, Eds., Oxford University Press, Oxford, New York (2002). 

Carachteristographers are d.c. instruments made up by a current (voltage) power supply and a voltage (current) meter. They give a two quadrant V-I relation for the resistive device. The information supplied by such instruments is more exhaustive than that supplied by a.c. bridges, but the measurement is time consuming, and an inversion of polarity is necessary to detect the possible presence of partially rectifying contacts. In Fig. 9.8, an example of a V-I relation in the first quadrant for a Ge-NTD 12 resistor (see Section 15.2.1.1) is shown. Note that the power used in the measurements can be as low as 10-14W. 

Nelson A, Hui H K, Bennett M, Hahn S and Bankert C S 1993 US Patent 5 204 265 Wolfbeis O S 1991 Oxygen sensors Fiber Optic Chemical Sensors and Biosensors vol 2, ed O S Wolfbeis (Boca Raton, FL Chemical Rubber Company) pp 19-53 Hauenstein B L, Picemo R, Brittain H J and Nestor J A 1993 US Patent 5 190729 Modlin D N and Milanovitch F P 1991 Instrumentation for fiber optic chemical sensors Fiber Optic Chemical Sensors and Biosensors vol 1, ed O S Wolfbeis (Boca Raton, FL Chemical Rubber Company) pp 237-302 Wolthuis R, McCrae D and Hartl I C et al 1992 Development of a medical fiber optic oxygen sensor based on optical absorption change Trans. IEEE Eng. Biol. Med. EBM-39 185-93... 

Automation of analytical instrumentation. I. Spect r omet r i c techniques... 

For some complex mixtures the combination of GC or LC and MS does not provide enough resoluiitin. In recent years, ii has become feasible to couple chromatographic methods with tandem mass spectrometers lo form GC / MS / MS and I. C / MS / MS systems.- There have also been reports of LC/MS" instruments. 

SFC, in which the mobile phase is a supercritical fluid, is a hybrid of gas chromatography (GC) and liquid chromalography (I.C) that combines some of the best features of each. For certain applications, it is superior to both GC and UPLC. In 1985 several instrument manufacturers began to offer equipment spccilically designed for SI C. and the use of such equipment is expanding at a rapid pace. The SFC technique has become an important tool in many industrial, regulatory, and academic laboratories. 

The authors wish to thank Dr. T. Early of GE-NMR Instruments Company, Inc. for obtaining the solid-state i c-NMR spectra and Mr. C. Woitkovich for acquiring the Raman spectra. V. M. Gentile sincerely appreciates fellowship support from The Institute of Paper Chemistry during this work. 

The advantages of these instruments are that for feed zone properties they can operate at typical extruder velocities and normal loads. A further advantage is that the surface can be rubbed in," i.c., be contaminated by polymer as has been found to be the real situation [9]. 

---