Spot plate

The progress of the photolysis can be followed either by observing the disappearance of the typical nitrite bands between 1600 and 1680cm (6.25 and 5.95 ju) in the infrared spectrum or by disappearance of the diphenyl-amine-sulfuric acid spot plate test. 

An interesting PLC variation of the nrea clathration techniqne has been proposed by Chaffee and Johns [82]. Component mixtnres are applied onto TLC plates (20 cm X 20 cm X 0.5 mm) coated with Kieselgnhr G/nrea (2 1), prepared from a slnrry in urea-saturated methanol (Iml/g powder). Spotted plates are left in methanolic atmosphere overnight to allow clathrate formation. To remove methanol, plates are air dried for 2 to 3 h at room temperatnre and then developed in -heptane. Two bands of acychc (Rf 0.9 to 1.0) and cyclic (Rf 0.0 to 0.1) hydrocarbons are distinguished, and components are recovered qnantitatively by extraction with chloroform. 

Add 2 drops of color reagent. Compare color produced with reference compounds on spot plate or other white porcelain surface. 

Clean the plates with anhydrous acetone or ethanol. NOT WATER If you don t have the tiny agate mortar and pestle, try a Witt spot plate and the rounded end of a thick glass rod. The spot plate is a piece of glazed porcelain with dimples in it. Use one as a tiny mortar the other as a tiny pestle. 

Pour a small volume of one of the solutions into the well of a spot plate. Test the solution using universal pH paper. By comparing the colour of the paper, estimate the pH of the solution. Record your results in you table. 

MesoScale Discovery (MSD) succeeded in introducing product with a similar technology approach based upon ruthenium redox-mediated electrochemical detection (Figure 2.14). MSD is a joint venture of its parent company, MesoScale, and IGEN, a company that pioneered much of fhe work on electrochemical detechon based on the ruthenium redox system. MSD s Multi-Spot plates contain antibodies immobilized on multiple working electrode pads within each well, allowing each spot within the well to serve as an individual assay. Multiplexed cytokine immxmoassays can be performed in 96-well (4,7, or 10 spots per well) patterns with detection limits of 1 to 10 pg/mL and a linear dynamic range up to 3,000 pg/mL. Both 24-and 384-well electrode systems are available. 

Pierce introduced an array-of-arrays microplate product called Search-Light in which antibodies are directly printed into the wells of the microplate. Also, we have reviewed MSD s Multi-Spot plate products having antibodies immobilized onto multiple working electrodes. These products (albeit with some novel approaches to create microarrays and means for detection) utilize the classic immunosorbent sandwich assay but have the advantage of parallel processing using microarrays. 

Many tests are described in Ref 14 and following is the abstract of some tests Qualitative Tests. Pulverize the proplnt to test, extract it. with ether on methylene chloride (as described in MIL-STD-286A, Method 104.1 or in Vol 2 of Encycl, p C131-L) and evaporate the solvent using a stream of dry air. Place ca 1 mg of this residue on a spot plate and add a few drops of the reagent, such as de-... 

Add to 1 mg residue on a spot plate 3 drops of 10% selenious acid soln in coned hydrochloric acid and if the color developed is blue, DPhA and/or its nitroso is present. Dissolution of selenious acid in HCl is fa-... 

Analyst 91(1082), 366-67(1966) CA 65, 3659(1966) (For detection of dinitro- and trinitro- aromatic bodies in industrial blasting expls, a 5—10 mg sample of expl to test is placed on a spot plate, and a drop of Me2CO-EtOH and a drop of 25% aq Me 4NOH. soln are added. The formation of a blue color indicates the presence of 2,4-DNT while 2,4,6-TNT gives a dark red color. A slight yellow color is formed initially with NG. If NG 2,4-DNT are both present, a green color is initially obtd. None of the other common components of blasting expls interfered. It is not indicated in CA which color is produced by m-MNT)... 

The completion of the oxidation should be tested by adding 1 drop of an alcoholic phenolphthalein solution and 3 drops of water to 1 drop of the oxidation mixture on a porcelain spot plate. Amine oxides give no color with phenolphthalein. 

To ca lmg sample placed on a spot plate are added while stirring 3 drops coned H2S04 and... 

To test for RDX, a few crystals of the material for test fixe placed in the indenture of a white spot plate and.l drop of test solution (lmg of DPhA in 10ml of 85% sulfuric acid) is added. A strong blue color in 1 minute indicates RDX. A blue color is obtd with HMX only after 5 mins or longer has elapsed (Ref 1)... 

Place 3-5 mg of the material-to be tested in the indenture of a white spot plate. Add 5 drops of either acetone or dimethylformade (DMeFA). 

Heat a solution of 0.2 g of the reagent and 0.2-0.3 g of the alkene in glacial acetic acid on the steam bath for 15 minutes or until the potassium iodide test shows that the reaction is complete. Cool the mixture in ice. If a solid separates, filter it off if not, pour the reaction mixture on to 5-10 g of crushed ice. Recrystallise the resulting solid or oil from ethanol. Test Add a drop of the reaction solution to a drop of potassium iodide solution on a spot plate the presence of unreacted reagent is revealed by the liberation of iodine ... 

Reagents are added after pretreatment of the sample. The spot test is performed in a porcelain spot plate with 6 to 12 cavities. The test is performed using a few drops of sample, standards, and reagents. The color developed is compared with thiocyanate standards. The test is semiquantitative and is suitable for screening SCN in water. 

If the pH of the solution is above 10, add about 0.2 g Na2C03 and mix. Add a drop of phenophthalein indicator which will turn the solution red (or pink) in alkaline medium. Add 1 N HC1 dropwise till the color disappears. Place 3 drops of the above pretreated sample, 3 drops of distilled water, and 3 drops each of thiocyanate standards (0.05, 0.1, and 0.2 mg SCNYL) in the cavities of porcelain spot plate. Add 1 drop of chloramine-T solution to each cavity and mix with a clean glass rod. This is followed by the addition of 1 drop of pyridine-barbituric acid to each cavity. Again, mix the contents and allow it to stand for a minute. If thiocyanate is present, the sample spot will turn pink to red, depending on the concentration of SCN- in the sample. If deep red coloration is produced, dilute the sample and repeat the test. 

The above test would give SCN- concentration in an estimated range. For greater accuracy, place more standards in the cavities of spot plate for color comparison. Alternatively, once the SCN concentration range in the sample is known from the above screening test, prepare several thiocyanate standards within that range and repeat the spot test for color comparison. 

Wasicky, R. and Frehden, O., Spot-plate tests in the examination of drugs. I. Aldehyde and amine tests for the recognition of ethereal oils, Mikrochim. Acta, 1, 55, 1937 Chem. Abs., 31, 5944, 1937. 

Wear face shield, goggles, laboratory coat, and nitrile rubber gloves. Cover spill with a 1 1 1 mixture by weight of sodium carbonate or calcium carbonate, clay cat litter (bentonite), and sand. Using a plastic shovel, scoop into a pail of water in the fume hood (about 66 mL/g). Cautiously add aqueous 5.5% ceric ammonium nitrate (4 volumes per volume of aqueous solution) and stir for an hour. If the solution remains orange, an excess of ceric ammonium nitrate is present and the azide has been completely destroyed. The solution can be washed into the drain with at least 50 times its volume of water.6,7 The solid residue is treated as normal refuse. A spot test for checking if azide is completely destroyed is as follows Place a drop of the test solution in the depression of a spot plate and treat with 1 or 2 drops of dilute hydrochloric acid. Add a drop of ferric chloride solution and gently heat the spot plate. A red color indicates hydrazoic acid and incomplete decomposition. 

Parkash and Bansal reported the detection and determination of microgram quantities of ethylenediaminetetraacetic acid with molybdophosphoric acid by a spectrophotometric method [25]. For the detection of EDTA, 5 to 10 Amberlite IRA-400 resin beads (hydroxide form) were placed on a white spot-plate and blotted dry. One drop of sample solution was added, followed by one drop of 4% molybdophosphoric acid solution. A blue color develops if EDTA is present. For the determination, the sample solution (2 mL, containing 18.6 to 186 pg of EDTA) and 4% molybdophosphoric acid solution (3 mL) are mixed for 5 minutes and diluted to 10 mL with water or sodium acetate-acetic acid buffer solution of pH 2. The absorbance is measured at room temperature at 690 nm against a reagent blank. 

Ong, T-M. Use of the spot, plate and suspension test systems for the detection of the mutagenicity of environmental agents and chemical carcinogens in Neurospora crassa. Mutat. Res. 53 297-308, 1978. 

Add one drop of 0.1 M HC1 to the first depression of a spot plate. Dip a 2-cm long universal pH paper into the solution. Remove the excess liquid from the paper by touching the plate. Compare the color of the paper to the color chart provided (Fig. 22.1). Record the pH on your Report Sheet (1). 

Repeat the same procedure with 0.1 M acetic acid, 0.1 M sodium acetate, 0.1 M carbonic acid (or club soda or seltzer), 0.1 M sodium bicarbonate, 0.1 M ammonia, and 0.1 M NaOH. For each solution, use a different depression of the spot plate. Record your results on the Report Sheet (1). 

Place 2 mL of 2% starch solution in each of two labeled test tubes. To the first test tube (no. 1), add 2 mL of your own saliva. (Use a 10-mL graduated cylinder to collect your saliva.) To the second test tube (no. 2), add 2 mL of dilute sulfuric acid (3 M H2S04). Place both test tubes in a water bath that has been previously heated to 45°C. Allow the test tubes with their contents to stand in the warm water bath for 30 min. Transfer a few drops of each solution into separate depressions of a spot plate or two separately labeled microtest tubes. (Use two clean, separate medicine droppers for transferring.) To each sample (in microtest tubes or on a spot plate), add 2 drops of iodine solution. Record the color of the solutions on your Report Sheet. 

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