Sampling pastes

Based on these results, several different commercial and experimental protease samples were obtained from enzyme companies and were tested for starch yield using the enzymatic corn wet milling process (Figure 3). Two commercial protease enzymes (enzymes A and C) gave starch yields comparable to the conventionally wet milled sample. Pasting properties, residual protein in starch, and surface characteristics of starch samples obtained from... 

The need for unattended and precise sample injection for HPLC has lead to development of a wide variety of automated sample injection devices. Autosamplers function in essentially the same way as manual injectors, except that the sample is introduced automatically from a sample vial held in a carousel or an X-Y grid (Fig. 3.15). The carousel format provides a reliable and rapid means of moving samples past an injection station, whereas the XY grid format allows a convenient random access configuration. 

For small stresses the modulus is a constant and the material behaves elastically. It returns to its original condition when the stress is removed. For larger stresses, the elastic limit may be exceeded, and the sample undergoes a permanent, or plasic, deformation. Important stresses are compressional stresses, in which the force acts in one dimension only hydrostatic, in which the force acts equally in all directions and shearing, in which forces act to move parallel planes of the sample past each other. 

Kepner, R. J., Pratt, J. 1994. Use of fluorochromes for direct enumeration of total bacteria in environmental samples past and present. Microbiol. Rev. 58 603-615. 

Samples can be introduced manually into the valve with a syringe to fill the sample loop. Automated sampling valves are routinely used today in which samples are taken from an autosampler for unattended operation. The major limitation of valve injectors is that the sample size is fixed, and the loop must be changed in order to vary the injected sample size. There are automated motor-driven adjustable syringes that provide enough pressure to inject the sample past a check valve that prevents backflow. 

Tint Tint is a ratio of the reflectance of a reference paste to that of a sample paste consisting of a mixture of zinc oxide, plastidzer, and carbon black. 

The first heat and isothermal temperature is used to examine the as-reeeived eondition of the sample and to erase the previous unknown heat history. This is done by heating the sample past its melting point and holding it at that temperature isothermally for several minutes to ensure temperature equilibration. 

It is very good practice, and one which should be mandatory in all laboratories, to label the container correctly before the sample is put into it. The label should carry the full name of the contents (not a set of initials) and sufficient additional information to identify the sample uniquely. This may be a batch number, an experiment number, a date, or anything else unique to that individual sample, i.e. information which distinguishes it from all other samples, past, present or future, of the same material. Any analyst receiving a sample not so identified is fully justified in throwing it away without further inquiry, and if he does so there will be no second offenders. Replicate samples should be called A, B, C, etc., to distinguish them from one another. 

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