Spot Plate Research Articles

Voltaic Cell Measurements on a Spot Plate with a Cotton Swab Salt Bridge

Microscale voltaic cell measurements using very small solution volumes are carried out on a porcelain spot plate. A suitable salt bridge is constructed by filling the hollow plastic tube of a double-tipped cotton swab with an electrolyte gel mixture. Good results are obtained for a variety of half-cell combinations when the technique is used by students in the general chemistry laboratory.

Comparison of Four Methods for Forage Nitrate Analysis

Twenty forage samples were collected and selected for variation in nitrate content. Each forage samples was analyzed 4 times by 4 different methods: diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic. Five feed extracts were spiked with 2 different amounts of nitrate and analyzed by each method. The spectrophotometric and nitrate-selective electrode had similar percent recoveries, which were close to 100%. The nitrate-selective electrode method had the least variation of the 4 methods. The diphenylamine spot plate method had the poorest average recovery, greatest variation, and was the least accurate. The average coefficients of variation for all samples within a method were 15%, 12%, 6.4%, and 16 for the diphenylamine spot plate, spectrophotometric, nitrate-selective electrode, and high-performance liquid chromatographic methods, respectively. The variation in the nitrate-selective electrode method was lower (P < 0.05) than the other methods. The results from this study suggest that the nitrate-selective electrode method is more accurate and precise than the other methods of analysis tested.

Screening for sediment toxicity in the Rio Santiago basin: A baseline study

AbstractToxicity testing of sediment samples from the Rio Santiago and its main tributaries was performed using a battery of tests that included the ECHA dipstick biocide monitor, the MetPad test, the lettuce seed germination and the root elongation test, the nematode test, spot plate test, and the SOS Chromotest. Assessment was carried out on organic extracts, pore water, and direct sediment. Results of bioassays showed toxicity sources from tributaries and canals flowing into the river and areas being degraded by insults from industrial spills. © by John Wiley &amp; Sons, Inc.

Differential growth of Euplotes vannus fed fragmented versus unfragmented chains of Skeletonema costatum

Differential growth of Euplotes vannus fed fragmented versus unfragmented chains of Skeletonema costatum

A free plastic spot plate for overhead demonstration

The nearest hospital or clinical laboratory is a potential source for many disposable items that can be useful to chemistry teachers.

Mutagenic potential of some chemical components of dental materials.

Abstract Chemical compounds that are used in dental materials or related structurally to compounds that are found in dental materials were tested for bacterial mutagenicity by means of the Ames Test. The results of spot tests and plate incorporation tests indicated that 8 of the compounds were not mutagenic. These same procedures showed that one of the chemicals, p-aminophenylacetic acid, is weakly mutagenic. The data also indicated that the addition of liver extracts containing microsomal enzymes enhanced the mutagenic activity of p-aminophenylacetic acid.

Field Estimation of Phosphate Retention by Andepts

AbstractIn an attempt to develop a field method for soil surveyors and field agronomists to rapidly evaluate whether or not a particular site would retain a large amount of applied phosphate, 59 samples of Andepts from Costa Rica and Guatemala were incubated with rates of P, then analyzed. Phosphate retention ranged from 25 to 99% and correlated quite well with ammonium oxalate extractable Al concentration (R2 = 0.56) in a linear model. In samples with &lt;2.4% ammonium oxalate extractable Al, the amount of applied phosphate retained was related even better to this measurement, while at &gt; 2.4% oxalate extractable Al, retention was not influenced appreciably by oxalate extractable Al concentration. Phosphate retention was also correlated with pH in NaF. By the methods used, &gt;90% phosphate retention was predicted by an oxalate extractable Al concentration of &gt;2.4% or a NaF pH of &gt;10.7. A quick test was devised to assess soils with extremely high phosphate retention. The method consisted of adding a few drops of 0.1 mol NaF L−1 to approximately one gram of soil in a spot plate and, after 10 min, checking the pH with two drops of 0.04% thymolphythalein indicator. This technique was found to correctly identify 79% of the samples as having either ≷90% phosphate retention.

A color reaction of 1,2-diphenols based on colored complex formation with phenylfluorone and iron(III) and its application to the assay of catecholamines in pharmaceutical preparations.

A color reaction of 1, 2-diphenols, such as catecholamines (CA), caffeic acid and gocypol, utilizing colored complex formation among a 1, 2-diphenol, an organic reagent and a metal ion was studied, and suitable conditions for the spectrophotometric determination of 1, 2-diphenols [as norepinephrine (NE), a CA] with phenylfluorone and iron (III) were established. The optimum pH range for the formation of colored complexes in the presence of polyoxyethylene monolauryl ether was pH 8.9-9.9. In the case of NE, the method could be used to determine up to ca. 10μg/10ml, and the apparent molar absorptivity at 630nm was 1.7×105dm3mol-1cm-1. This method was applied to the assay of CA in commercial pharmaceutical preparations. A detection test for CA on a spot plate was also examined.

Color reaction between pyrogallol red-molybdenum(VI) complex and protein.

A color reaction between pyrogallol red(PR) -molybdenum(VI) complex and protein was investigated. A spectrophotometric method using the PR-molybdenum(VI) complex could be used in the concentration range of 0 - 400 μg/10 ml of albumin, where the Sandell sensitivity was calculated to be 0.0048 μg/cm2 for albumin at 600 nm. A detection test of protein on a spot plate was also studied. The proposed method was applied to the determination of urinary protein; analytical results were satisfactory.

イオン交換樹脂粒を使用するウラン（ＩＶ）およびウラン（ＶＩ）の微量検出法 アルセナゾＩＩＩによる検出

“Resin Spot Test” method was applied to the-detection of a minute amount of U(IV) and U(VI). A few particles of the anion-exchange resin (Dowex 1-X 1 [Cl]) impregnated with arsenazo III were put into a drop of sample solution on a spot plate and a drop of acetic acid solution was added to adjust the pH of the solution to 1∼5. After a while, pale-blue green to dull green color appeared on the surface of the resin particles, while blank test was palepurple color. The colors for U(IV) and U(VI) were similar. The limits of identification for both ions were 0.03 μg, and the dilution limits were 1: 106. The time required for this test was remarkably shortened by heating the system with an infrared lamp.

Absence of arsenite mutagenicity in E coli and Chinese hamster cells.

Because exposure to compounds of arsenic has been implicated as a cause of cancer, an investigation of the mutagenicity of sodium aresenite in E coli and in Chinese hamster cells was performed. In the E coli system, Trp + revertants were not induced by arsenite in a variety of experimental protocols including spot tests, treat and plate protocols, and fluctuation tests. The mutator effect of a tif-1 strain was partially blocked by arsenite. Arsenite did not cause the induction of lambda prophage. In Chinese hamster cells, arsenite did not induce ouabain-resistant mutants or thioguanine-resistant mutants. We conclude that arsenite is not mutagenic to E coli or to Chinese hamster cells. When added to the plating medium, arsenite can act as an anti-mutagen by inhibition of induction of the error-prone SOS repair system in E coli.

Spot plate chemistry. General chemistry experiments in a depression

Examples of spot plate chemistry involving the chemical composition of insoluble salts, colorimetric analysis, and kinetics.

RAPID METHOD FOR DETERMINING IN VITRO BLOCKING OF ANTIGEN-ANTIBODY REACTION.

Selected cephalosporins, including cefamandole, cephaloridine, cephaloglycin, and cefoxitin, were examined for their ability to inhibit the enzymatic activity of and act as substrates for beta-lactamases produced by Enterobacter cloacae and Staphylococcus aureus. Enzyme inhibition was determined by Michaelis-Menten kinetic measurements and by a spot plate assay using a chromogenic substrate (Glaxo compound 87/312). These two methods provide comparable estimates of kinetic parameters. Inhibition of beta-lactamase, as measured by these two methods, was generally found to correlate with resistance to hydrolysis and is proposed as a preliminary method of assessing susceptibility of cephalosporins to beta-lactamase hydrolysis. Four 7-alphaOCH(3), 7-alphaH cephalosporin analogue pairs were also examined. The presence of the 7-alphaOCH(3) substituent invariably resulted in reduced susceptibility to enzymatic hydrolysis, regardless of the other C7 substituent. The 7-alphaOCH(3) compounds were also better inhibitors than were their 7-alphaH analogues, with the exception that 7-alphaOCH(3) compounds having C7 adipic acid substituents were less inhibitory to the S. aureus enzyme than were the corresponding 7-alphaH analogues. Response of these two enzymes to 7-alphaOCH(3) and 7-alphaH cephalosporins suggests that beta-lactamase hydrolysis of these compounds involves attack at the alpha side of the betalactam ring.

イオン交換樹脂粒を使用するクロム（ＶＩ）の微量検出法

“Resin Spot Test” method has been applied to the detection of a minute amount of chromium (VI). A few particl es of the anion-exchange resin (Dowex 1-X1 [SO4]) were mixed with a drop of the sample solution on a white spot plate. After chromium (VI) was concentrated on the resin particles, the solution around the particles was removed by a piece of filter paper. On addition of a drop of O.2 N H2SO4 and a drop of 0.02% 1, 5-diphenylcarbonohydrazide, red purple color appears on the resin particles. The limit of identification is 0.0003 μg, and the dilution limit is 1: 108. Sn (II), Fe (II), Mo (VI) and W(VI) ions interfere with this test.

New spot-test for silver(I) based on double iodide formation with bismuth(III)

The formation of an intense brownish-maroon or maroon-red product by the interaction of silver(I) and bismuth(III) solution in the presence of iodide forms the basis of a new and specific spot-test procedure for silver. The test is conducted on a spot plate with 2 or 3 drops of 2% potassium iodide solution, 1 drop of 1% bismuth(III) nitrate solution, and 1 drop of test solution. Limit of detection is 0·01 μg; limit of dilution is 1:5 × 10 6. Most cations and anions do not interfere. Only Tl(I), Cs, S 2O 2− 3, EDTA, pyridine, excess of thiourea, oxidizing ions (NO − 2, IO − 3, IO − 4, MnO − 4, BrO − 3, and S 2O 2− 8) and ions such as Cl −, Br −, I −, SCN −, and N − 3 which cause precipitation of silver, interfere. The product formed is most probably Ag 2BiI 5.

Detection of iodine, bromine, arsenic(III), tin(II), mercury(II), silver, thiosulphate, and sulphite using setoglaucine O and setocyanine supra

Setoglaucine O and Setocyanine Supra can be employed for the detection of iodine, bromine, arsenic(III), tin(II), mercury(II), silver(I), thiosulphate and sulphite. The method for iodine or bromine consists of treating 0.05 ml of 0.01 % solution of Setoglaucine O or Setocyanine Supra on the spot plate, with 0.05 ml of iodine or bromine solution, and diluting the mixture to 0.5 ml. Colour changes are blue to yellow green for iodine and blue to pale yellow for bromine. The tests for arsenic(III), tin(II), mercury(II), silver(I), thiosulphate and sulphite consist of treating 0.1 ml of 0.01 % Setoglaucine O or Setocyanine Supra with 0.05 ml of iodine in potassium iodide and 0.05 ml of the test solution, and diluting to 1 ml. The solution assumes the original blue colour of the dye in the presence of these ions.

Detection of hexacyanoferrate(II) and hexacyanoferrate(III) using Setoglaucine 0 and Setocyanine Supra

Setoglaucine 0 and Setocyanine Supra can be used as reagents for the detection of hexacyanoferrate(II) and hexacyanoferrate(III). The method consists of treating 0.1ml of 3% solution of Setoglaucine 0 or Setocyanine Supra, on the spot plate with one drop (0.05 ml) of the hexacyanoferrate(II) or hexacyanoferrate(III) and diluting the mixture to 0.5 ml. A blue precipitate is obtained with hexacyanoferrate(II), whereas a green precipitate is obtained with hexacyanoferrate(III). The interferences have been investigated.

CHEMICAL ANALYSIS OF PAINT SAMPLES USING THE WEISZ RING OVEN TECHNIQUE

The Weisz ring oven technique is a rapid and sensitive yet simple method for the qualitative analysis of pigments and other inorganic materials of interest in conservation. Ions can be both separated and concentrated prior to spot-testing. The method possesses several advantages over the conventional spot plate tests.

A new spot test for cerium(IV)

A new colour reaction for the detection of cerram(IV) which can be carried out both in a test tube and on a spot plate has been described. The test solution is treated with methylene blue in nitric acid solution (1∶1) to form a rose-red colour. This simple procedure has an advantage over the existing tests in that it is applicable in the presence of oxidising agents like chromium(VI), vanadium(V), nitrate, perchlorate and of coloured ions like copper(II), cobalt(II), nickel(II), chromium(III), iron(III), vanadium(IV), uranium(VI).

Inexpensive spot plate

Inexpensive spot plate