Cup-plate method

Thus, the cup-plate method is useful to test several preparations or varying formulations of the same preparation against one organism under identical conditions, and the ditch-plate method enables one preparation to be tested against several organisms... 

Qualitative tests for the presence of pectinesterase, based on a color change of such indicators as Bromothymol Blue or Bromocresol Green, after de-esterification of pectin, are simple and very useful these tests are used as drop tests when checking chromatographic columns85,97 100 or for a qualitative assay of pectinesterase in culture filtrates, using the cup-plate method.113... 

In addition to the aforementioned quantitative methods, the activity of pectic depolymerases is often identified by the cup-plate method.113 Cups are cut out from solidified agar containing the substrate, and are filled with the enzyme solution. After elapse of a cer-... 

Ten iridoids were isolated by Yuan et al. from a Chinese plant, Pedicularis kansuensis, which has been used in folk medicine as cardiac tonic for treatment of collapse, exhaustion, and senility. Among the isolated iridoids, ixoroside (26), boschnaloside (117), 8-ep/-loganic acid (29), and aucubin (15) at a concentration of 20 pg/disk exhibited strong antibacterial activity against E. coli and S. aureus by cup-plate method, having growth inhibition zone of 13-20 mm in diameter [140]. 

The cup plate method of assay (51) is similar to the widely used method of antibiotic assay except that a vitamin Bts deficient medium is employed and zones of stimulation rather than zones of inhibition are measured. The method described in this section is that of Harrison, Lees, and Wood (15). 

For routine assessment of test formulations during development work the cup-plate and ditch-plate methods are adequate. 

There are two modifications to the Wilhelmy plate method. In the first modification, the cup carrying the liquid is mobile and is lowered until the previously immersed plate becomes detached from the liquid surface, and the maximum vertical pull, / max on the balance is noted, similarly to the ring method. Then the capillary force, for the zero contact angle, can be given as... 

The standard bead LC/MS method proved useful in optimizing the cleavage and recovery conditions for HTP biology screening. For example, Fmoc-Lysine and Cbz-Lysine standard beads were selected to examine how compounds with different cLogPs behave at different cleavage conditions. Two different 864-well setups, 864-bead cup plate and 864 master plate, were tested in the experiment. Methanol or tris buffer solution was used to recover the cleaved compounds. The results are summarized in Figure 9.26. 

The flash pt for IPN using the Abel closed cup method is 53°F while the Cleveland open cup method gives a value of 72°F. Min spont ign temp range in air on a heated brass, Al stainless steel or mild steel plate is 245—60° The following data from Ref 6 present, in tabular form, the limits of flammability of IPN vapor/air mixts over a press and temp range ... 

One of the problems which must be solved for quantitative measurements by emission is the need for a blackbody source at the temperature of measurement. And a variety of blackbody references have been used including a V-shaped cavity of graphite 164), a metal plate covered with a flat black paint1S6 160) and a cone of black paper l53). However, none of these methods of producing a blackbody reference spectrum are adequate. In most cases the efficiency of the reference has not been established. The most recent recommendation 1S0) is an aluminium cup painted with an Epley-Parsons solar black lacquer which has an emittance of greater than 98% over the infrared spectral range. 

The quantitation of substances separated by TLC may be carried out in several ways. The most common method is to remove the spot from the plate, elute the compound from the adsorbent and measure the concentration of the compound in solution by spectrophotometry, fluorimetry, etc. The elution process has been significantly improved and facilitated with the Eluchrom instrument developed by Sandoz and marketed by Camag (see Fig.3.6). This instrument permits direct elution from the plates via small PTFE cups in a continuous flow-through mode without the necessity of removal of the adsorbent and with the minimum requirement of solvent (usually less than 1 ml). The measuring instruments used are those available for classical solution analysis. A discussion of these instruments is beyond the scope of this book. 

Olsen and Jatlow (02) modified the Delves procedure to permit the direct use of aqueous standards rather than the method of standard addition. They accomplished this by adding a small drop (ca. 2 jul) of a 150 mg/liter albumin solution to just coat the bottom of the cup. The albumin was dried on a hot plate. In the presence of albumin, aqueous standards gave essentially the same response as blood samples. A small nonspecific molecular absorption (equal to about 3 /mg of lead per 100 ml) due to blood salts was corrected for by adding 50 mM sodium chloride to standards. EDTA had no effect on the analysis. The authors also improved precision by stabilizing the burner mount. Again, the 2833 A line was preferred over the 2170 A line because of greater stability and linearity. These authors employed a similar procedure for the determination of lead in 10 /A of urine. 

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