Grinding, sample

There are two major problems associated with the x-ray method. The first problem is encountered during sample preparation. At this step, preferred orientation of the particles must be minimized [1], Reduction of particle size is one of the most effective ways of minimizing preferred orientation, and this is usually achieved by grinding the sample. Grinding, however, can also disorder the crystal lattice. Moreover, decreased particle size can cause a broadening of x-ray lines, which in mm affects the values of /c and /a. The relationship between the crystallite size, t, and its x-ray line breadth, /3, (assuming no lattice strain) is given by the Scherrer equation [2] ... 

Acetylsalicylic acid Tablet Drug determination in three different formulations. Intact analysis in transmittance mode and sample grinding in reflectance mode. 148... 

A custom robotic system was developed to meet the design objectives. The peripherals accomplish four major LUOs reagent dehvery, sample grinding, centrifugation and sample pipetting. A schematic drawing of the system layout is shown in Fig. 6.7. 

The same laboratory describes a group of complexes with a unique property among metal complexes, referred to as luminescence tribochromism [39], which is a substantial change in the emission of the solid upon application of pressure. This phenomenon contrasts with the more common triboluminescence, which refers to the transient emission seen upon sample grinding or crushing. In this case, the effect was observed in a set of complexes of formula [Au2( J.-TU)((j,-dppm)]Y and [Au2( i-MeTU)( i-dppm)]Y (TU = 2-thiouracyl MeTU = 6-methyl-2-thiouracyl Y = CF3COOT NCV, CKV, Au(CN)2 ). 

The extraction and isolation of three groups of carotenoids of different polarity are described in Basic Protocol 1. A method for prepurifying carotenoids using crystallization is described in Basic Protocol 2. Carotenoids may be purified further by chromatographic techniques (unit F2.3) and characterized (units F2.2 F2.4). Support Protocols 1 and 2 describe the preparation of the sample before extraction. This process consists mainly of removing water from the sample followed by sample grinding or homogenizing. 

Sampling Grind solid sample Grind solid sample or Grind solid sample or... 

Sample Grinding, mixing, subsampling preparation sample Representative... 

Barthes, B.G., D. Brunet, H. Ferrer, J. Chotte, and C. Feller. 2006. Determination of total carbon and nitrogen content in a range of tropical soils using near infrared spectroscopy Influence of replication and sample grinding and drying. J. Near Infrared Spectrosc. 14 341-348. 

Weigh out 3 g of lauric acid and place it in a 25-mL beaker. Weigh out 0.6 g of benzoic acid. Heat the lauric acid gently on a hot plate until it melts (50°C). Add the benzoic acid to the beaker. Mix it thoroughly until a uniform solution is obtained. Cool the beaker in cold water to obtain a solid sample. Grind the sample to a fine powder in a mortar with a pestle. 

MASS SPEC ATOMIC ABSORPTION ATUO - CHO AND N SAMPLE GRINDING... 

Equipment essential for electrophoresis includes power sources, gel molds, sample grinding trays, electrode buffer trays, reusable ice packs (or a 4° cold room), a gel slicer, staining trays, assorted glassware, variable temperature incubators), hot/stir plates, and a pH meter. Details on equipping a laboratory for electrophoresis are given elsewhere.12,17... 

Malt Samples Grind 30 g of the sample to a fine powder in a Maig-Seck mill. Accurately weigh 25 g of the powder, and transfer it into a 1000-mL Erlenmeyer flask. Add 500 mL of a 0.5% sodium chloride solution, and allow the infusion to stand for 2.5 h at 20° 0.2°, agitating the contents by gently rotating the flask at 20-min intervals. 

For solids sampling, grind the particles in the lot before sampling. Particle size is directly proportional to the sampling variation. Thus, reducing the particle size will reduce the theoretical sampling variation, even when the sample mass is not increased. 

Rapid dissolution of very fine particles produced during sample grinding (Holdren and Berner, 1979 Fung and Sanipelli, 1982 Talman and Nesbitt, 19H8). 

The rapid dissolution of structurally damaged surface sites produced during sample grinding (Petrovich, 1981). 

It is time consuming and precise work to prepare a TEM cross-section sample by the ion milling method as described above. One has to glue the sample, grind the sample down to about 10 pm and then ion mill the sample at a low angle, 15°, to obtain electron transparency. In order to control the final ion milling process, one often has to check whether the sample is ready or not. Here we introduce a new simple and useful preparation method for TEM cross-section sample preparation the so-called ion shadow method [4.27]. 

The somewhat complicated results obtained in this study would, probably, be simplified by sample grinding and subsequent sample handling in an inert atmosphere. 

Sample pretreatment involves modification of the physical form of the sample in such a way that the dioxins can be extracted efficiently. Some environmental matrices such as fly ash require pretreatment involving acid attack, usually with HCl, to destroy the structure of the matrix and to allow better recovery of the dioxins. For certain samples, denatu-rants are added so as to destroy any protein-analyte interactions and disrupt micellular formation, both of which can decrease recoveries of dioxins. For example, formic acid has been used as a denaturant prior to extraction of dioxins in plasma or serum. Sodium or potassium oxalate (20 mg per g milk) is added to milk samples to disrupt fat globules. Depending on the type of sample, grinding, homogenization, and blending of various sample phases... 

However, there are some methods for extraction of cellulose from plants. Han and Rowell s (1996) method describes a procedure for extraction of holocellulose, hemicelluloses, cellulose and lignin [18]. The method consists of four principle steps (1) preparation of sample (grinding of the wood), (2) removal of extractives, (3) preparation of holocellulose (removal of lignin), (4) preparation of a-cellulose (removal of hemicellulose). Several other procedures for a-cellulose extraction from wood samples have already been described during the last decades. Older methods used benzene-methanol instead of toluene-ethanol as organic solvent for the second step. Toluene-ethanol works as well as benzene-methanol mixture, and reduces health risks associated with the use of benzene and methanol. 

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