Scanning measurement, quality control

To ensure quality control material suppliers and developers routinely measure such complex properties as molecular weight and its distribution, crystallinity and crystalline lattice geometry, and detailed fracture characteristics (Chapter 6). They use complex, specialized tests such as gel permeation chromatography (2, 3), wide- and narrow-angle X-ray diffraction, scanning electron microscopy, and high-temperature pressurized solvent reaction tests to develop new polymers and plastics applications. 

Experimental Methods Measurements of specific heat and enthalpies of transition are now usually carried out on quite small samples in a Differential scanning calorimeter (DSC). DSC is applied to two different moles of analysis, of these the one is more closely related to traditional calorimetry and is described here. In DSC an average-temperature circuit measures and controls the temperature of sample and reference holders to conform to a Organisation and Qualities... 

This observation has become an important contributor to the development of rapid, automatic scanning of outer tissues of grains (primarily bran tissues) which contribute both strong color and taste characteristics to grain products such as wheat flour. The ability to measure both the concentration and distribution of such components is paramount to quality control in bakeries, and to definition of raw materials. An example of the systems necessary for routine analysis is included in a following section. 

Quality control, pharmaceutical product identity checks, and quantification are important fields in the broad application of the different spectroscopic methods. There are many spectroscopic aspects, e.g., concerning sample preparation, influences from different accessories, and possibly spectrometer effects, which certainly influences quantitative measurements. The latter problems could be solved using calibration transfer between different spectrometer types, for example, a scanning and an FT-near-IR spectrometer. 

As seen in Section 3 excellent insight into surface quality, defects, and bulk purity can be obtained from scatter measurements. Also, astute analysis can result in simple, inexpensive in-process and final quality control procedures for production of a variety of surfaces, materials, and optics. As can be seen, much can be learned from visual examination of BRDF plots and raster scans. This is often sufficient for pass/fail tests of product quality. The data can also be analyzed in more detail using various formulas and computer programs. In addition, because the data are digital, they can be rapidly analyzed by computer in on-line process control applications. SORIC and leaders in the stray light community have developed a BRDF database (16, 17) for commonly used surfaces and materials employed by scientists and engineers (18,19, 20, 21, 22, 23). 

Purity (/4ssay). There is one test run by almost every quality control lab to answer the following How much of what I want is in the final product The complexity of purity tests runs the gamut from a simple taste/smell test or specific gravity measurement to a gas or liquid chromatograph equipped with a mass spectrometer. In almost every case, an IR or NIR scan can give as much (or more) information as any complex test and may be performed on-line instead of in the lab. 

This equipment can be used for research work to measure the heat output of new compositions, to compare the laboratory result with the theoretical heat output value. In addition, calorimetry can be used for quality-control work in manufacturing. As an example each batch of energetic material that is produced, or perhaps purchased, can be tested in the calorimeter for heat output. The new material should yield the same heat value as the previous sample of the material. If it doesn t, the reason needs to be determined before the new material is put into production. Also, a calibrated differential scanning calorimeter (DSC) can be used to determine the heats of various processes that occur in energetic materials as the sample tempera-tnre is raised. 

Quantitative TLC has been treated in detail from theoretical and practical viewpoints, including descriptions of protocols for sample calibration, for establishing resolution, sensitivity, detectability, and optimum scan rate, and for comparing the performance characteristics of different slit-scanning densitometers [98]. Validation of a measurement process, such as QTLC, involves two related activities. One is quality control (QC), which develops... 

---