Reagent-grade chemicals

Examples of typical packaging labels from reagent grade chemicals. Label (a) provides the actual lot assay for the reagent as determined by the manufacturer. Note that potassium has been flagged with an asterisk ( ) because its assay exceeds the maximum limit established by the American Chemical Society (ACS). Label (b) does not provide assayed values, but indicates that the reagent meets the specifications of the ACS for the listed impurities. An assay for the reagent also is provided. 

Reagent-Grade Chemicals. Potassium dichromate is an important analytical standard, and other chromium chemicals, in reagent grades, find considerable laboratory use (90,91). This use, though small, is most important in wet analyses. 

SBF is a solution that has inorganic ion concentrations similar to those of human blood plasma but does not contain any cells or protein. A brief summary of SBF, introduced by Cho et al. [17], follows. The ion concentrations of SBF are given in Table 11.1 [17]. The pH of SBF is typically adjusted to 7.25 or 7.40 at 36.5 °C. This fluid is a metastable solution containing calcium and phosphate ions supersaturated with respect to hydroxyapatite. SBF is prepared by successively dissolving the reagent-grade chemicals in ultra-pure water in the order given in Table 11.2 [17]. Each new chemical is added after the previous one has completely dissolved. The temperature... 

Experiments were made in a nitrogen atmosphere using reagent grade chemicals and triply distilled carbon dioxide-free water. Standard solutions of... 

Bio-Rad AG50W resins (sulfonated PSDVB), 50-100 mesh, were treated with NaOH and distilled water washes. The weighing state was obtained after 12 hours of drying in air at 75-80 C. Reagent grade chemicals were used throughout. 

Materials. Aldicarb standards were obtained from the United States Environmental Protection Agency (USEPA), Quality Assurance Section and from Union Carbide Corporation. Crystalline samples of carbofuran and 3-hydroxycarbofuran were supplied by the Agricultural Chemical Group of FMC Corporation. Reference standards of methomyl (99% pure) and oxamyl (99% pure) were obtained from USEPA. HPLC grade methanol was purchased from Burdick and Jackson, Inc. Methylene chloride used for bulk extractions of the carbamate pesticides in solution was recovered, distilled and reused. Analytical reagent grade chemicals and solvents were used in all experiments. Doubly distilled deionized water was used for solution rate studies. Deionized distilled water (DDW) was used for dilutions in reactive ion exchange experim ts., , ... 

Reagent grade chemicals, such as conforming to the ACS Specifications shall be used and water conforming to the Specifications for Reagent Water, ASTM Desigoation D1193... 

Tests. Water, in accordance with ASTM D1193-66, and reagent grade chemicals shall be used for testing. Blanks shall be run and corrections applied when significant... 

The work described here was performed in a laboratory which had been specially modified and equipped to handle chemical carcinogens (10). Strict care was taken to avoid worker exposure to hazardous chemicals during the course of these studies. Reagent grade chemicals used for this work were 1,2-dichloroethane (Alfa Products, Danvers, MA) 1,1,1-trichloroethane (Matheson, Coleman Bell, Norwood, OH) 1,1,2-trichloroethane (J.T. Baker Chemical Co., Phillipsburg, NJ) n-heptane and n-hexane (Burdick Si Jackson Laboratories, Inc., Muskegon, MI). Also,used was a polychlorinated biphenyl whose chemical composition as determined... 

What is the difference between a reagent-grade chemical and a... 

Dibutylamine, piperidine, N-ethylcyclohexylamine, N-ethyldicyclohexylamine, and the ketones were reagent grade chemicals. The 5% palladium on carbon, 5% platinum on carbon, sulfided 5% platinum on carbon and sulfided 5% rhodium on carbon catalysts were obtained from Engelhard Industries. The 20% molybdenum sulfide on alumina (Girdler T-318) was obtained from the Chemetron Corp. Palladium chloride was obtained from Matheson, Coleman and Bell. Ruthenium trichloride was obtained from Ventron. 

Pretreatments of the electrode were carried out by soaking first in HC1 for 10 s and then in H,P0a for 5 min, followed by washing with de-ionized water. The RRDE was then set in a RRDE measuring system (Nikko Keisoku, model DPGS-1). The rotation rate of the electrode was usually 1000 rpm except where specially noted. Electrolytes were of reagent grade chemicals and twice distilled water. A 500 W super high pressure mercury arc lamp (Ushio... 

Synthetic culture medium that enables the survival or growth of test organisms during exposure to the test substance. It is prepared with deionized or glass-distilled water (e.g., ASTM type-1 water) to which reagent-grade chemicals have been added. The resultant synthetic test medium is free from contaminants. The test substance will normally be mixed with, or dissolved in, the test medium. Volume 1(7). 

They did not start from reagent grade chemicals. The experiments involved the in-vitro bleaching of native rhodopsin in solution. They proposed that they caused the disassociation of rhodopsin into a protein and retinaldehyde in accordance with the conventional wisdom of the time. This wisdom conflicted somewhat with the earlier ideas of Kuhne but became the basis of the current conventional wisdom. They claimed to have removed the native retinene, and then recombined colorless rhodopsin-protein, free of all native retinene, with synthetic retinene, in high concentration. This was accomplished by letting the mixture set in the dark. The pH of these solutions was not described as a function of time. They demonstrated that the material after setting in the dark for 60 minutes exhibited a rise in extinction coefficient of 2 1 over a similar sample without the added retinene,. Both samples exhibited a peak absorption near 500 nm following the experiments. It is not clear why the reference sample showed any absorption at 500 nm if it was truly free of all native retinene,. 

Chemicals. Reagent grade chemicals were used in the study of grafting. Acetone, ethyl alcohol and benzene were redistilled before use. Monomer, methyl methacrylate (MMA), was used fresh after purification and distillation. It was purified following the method adopted by Gupta and Nandy (15). CAS was used after standardization by an usual method (16). All CAS solutions used for the study was acidified with 1% H2SO4. 

Note For this assay, use reagent-grade chemicals with the lowest practicable Sb, As, Bi, Cd, Cu, Pb, Hg, Ag, and Sn levels, and use only high-purity water and gases. Rinse all glass- and plasticware twice with 10% nitric acid and twice with 10% hydrochloric acid, and then rinse thoroughly with High-Purity Water. 

Commercially available aqueous standard stock solutions or solutions prepared from analytical reagent grade chemicals may be used. Dilute these to give calibration standards approximately in the range given in Section IV.A.l. 

Only established analytical reagent grade chemicals should be employed for the preparation of standards and reagent solutions and the treatment of samples. 

Acetone and n-propanol were Merck reagent-grade chemicals. SDS and sodium dodecylsulfate (SDOS) (Merck 99% pure) were used without purification, the limiting conductance at 298.15 K in water being the purity criterion (6) nDTMABr (Eastman Kodak) was recrystallized three times from pure acetone and dried 24 hr at 323 K before use. 

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