Weight/volume solutions

A typical batch procedure involves direct addition of one part Chelex to four parts buffer solution (weight/ volume) with subsequent filtration to remove the resin. This treatment will readily remove iron, copper, zinc, calcium, and magnesium ions. Optimal chelation for iron and calcium ions occurs at pH 5-6.4 for copper, zinc, and magnesium ions, the optimal pH range is 7.4-8.0. 

The best deposits of all six insecticides studied—dieldrin, lindane, endrin, dinitrocresol, heptachlor, and DDT—produced 50% mortality with exposure periods of less than 2 minutes (LT50). All mortality estimates were based on a 72-hour post treatment holding period at about 70 °F. and 60% relative humidity. Lindane and dieldrin were the most toxic. One percent solutions produced 50% mortality with less than 2-seconds exposure (Table I). [1% solutions weight/volume lOmg./ml. = 1% this applies to all further references to concentration.] This left little doubt that surface deposits could be made toxic enough by contact to kill bark beetles in nature even though they may be in contact with the bark surface of their host trees for as little as 1 minute or less. 

Names such as hydrobromic acid refer to an aqueous solution, and percentages such as 48% HBr denote the weight/volume of hydrogen bromide in the solution. 

Small particle size resins provide higher resolution, as demonstrated in Fig. 4.41. Low molecular weight polystyrene standards are better separated on a GIOOOHxl column packed with 5 /u,m resin than a GlOOOHg column packed with 10 /Ltm resin when compared in the same analysis time. Therefore, smaller particle size resins generally attain a better required resolution in a shorter time. In this context, SuperH columns are best, and Hhr and Hxl columns are second best. Most analyses have been carried out on these three series of H type columns. However, the performance of columns packed with smaller particle size resins is susceptible to some experimental conditions such as the sample concentration of solution, injection volume, and detector cell volume. They must be kept as low as possible to obtain the maximum resolution. Chain scissions of polymer molecules are also easier to occur in columns packed with smaller particle size resins. The flow rate should be kept low in order to prevent this problem, particularly in the analyses of high molecular weight polymers. 

Ethanol formulations of salicylic acid (20 and 30%) are used for combination peeling (see salicylic acid section). Trichloroacetic acid is prepared as an aqueous solution, since ethanol solutions do not penetrate the skin. It is prepared by mixing the appropriate concentration of crystals with up to 100 cc of distilled water. Ten and fifteen percent TCA is prepared by mixing 10 or 15 g of crystals in up to 100 cc of total volume, respectively. Aqueous solutions of TCA remain stable for up to 6 months unless contaminated. Other methods have been used to formulate TCA peeling solutions however, the weight/volume methods appear to be the most reliable formulation [5]. Premixed TCA solutions are available from a variety of medical... 

The viscosities of products in solution (0.5 Weight %/volume) were measured by dilute solution viscometry using a Cannon Ubellohde viscometer at 35 °C. 

It is also possible to prepare a standard solution of calcium carbonate accurately using an analytical balance and a volumetric flask, as was suggested previously for EDTA, and pipetting an aliquot (a portion of a larger volume) of this solution into the reaction flask in preparation for the standardization of the EDTA solution. In this case, the concentration of the calcium carbonate solution is first calculated from the weight-volume preparation data (refer back to Example 4.2) and then the molarity of the EDTA solution is determined using Equation (5.54). 

Mass fluxes of alkali elements transported across the solid-solution interfaces were calculated from measured decreases in solution and from known surface areas and mineral-to-solution weight-to-volume ratios. Relative rates of Cs uptake by feldspar and obsidian in the batch experiments are illustrated in Figure 1. After initial uptake due to surface sorption, little additional Cs is removed from solution in contact with the feldspars. In contrast, parabolic uptake of Cs by obsidian continues throughout the reaction period indicating a lack of sorption equilibrium and the possibility of Cs penetration into the glass surface. 

A potent enzyme inhibitor (abbreviated DEP) that acts by ethoxyformylation of proteins, usually at histidine residues. DEP is an irreversible inhibitor of ribonuclease, and rinsing glassware with a 0.1% (weight/volume) DEP solution is recommended to render glassware nuclease-free. Aqueous solutions must be freshly prepared for maximal effectiveness, because DEP will hydrolyze in 6-12 hours at neutral pH. 

Buffer solutions that are isosmotic with respect to some standard, typically chosen such that suspended cells will neither shrink nor expand. Sodium chloride solutions (0.90% weight/volume or 0.155 M) at 37°C is often used to represent physiological conditions. These buffer systems are also important in studies of intact cells and membranal organelles likewise, many pharmaceutical formulations must be prepared as isotonic solutions. Most enzyme-catalyzed reactions are affected by ionic... 

Enrique Moles, 1883-1953. Distinguished Spanish chemist and pharmacist. Professor of Inorganic and Physical Chemistry in the Faculty of Chemical Sciences at Madrid. His papers on non-aqueous solutions, molecular volumes and additivity, inorganic complexes, and atomifc weight determinations were published in the leading journals of Spain, England, France, Italy, and the Netherlands. See... 

Note The counterpoise approximates the weight, volume, and exterior surface area of a solution tube containing 10 steel balls and 50ml of dibutylphthalate. It should be kept standing near the balance, covered with a cloth to protect it from dust. Do not wipe tbe counterpoise wiping will disturb its equilibrium with the prevailing temperature, pressure, and humidity... 

J Jt any mathematical problems involve units of length, weight, volume, F lor money. You incorporate the units into your computations and then report them in the answers so the solution makes sense and is useful. Sometimes you re confronted with problems that have two or more different units — such as feet and inches or pounds and ounces — and you have to make a decision as to which unit to use. 

Weight per volume w/v Grams of solute per volume of solvent g/cm3... 

Multi-element analysis by ETV-ICP-MS using ultrasonic slurry sampling of silicon based minerals such as talc or quartz is described by Rodriguez et al.33 The calibration was performed in the standard addition mode, where slurries were spiked with different weights (volumes) of a multi-element standard solution of the analytes of interest.33... 

Interfacial tension may be measured by a number of techniques, including determining how far a solution rises in a capillary, by measuring the weight, volume or shape of a drop of solution formed at a capillary tip, measuring the force required to pull a flat plate or ring from the surface or the maximum pressure required to form a bubble at a nozzle immersed in the solution. Ring or plate techniques are most commonly used to determine y of milk. 

Calculation of Processing Capacities. The processing capacity of a membrane (V,/Sf) is defined as the volume of charge (feed solutions) that 1 m2 of film surface can handle per day in a batch concentration process to increase the solute weight fraction from z, to Zf at a given operating pressure. The following relationship has been derived by Sourirajan and Kimura (12) ... 

Consistent notation is adopted throughout this book. Diblock copolymers are written poly(monomer A) poly (monomer B) or PA-PB, where examples of PA and PB are illustrated in Fig. 1.2. Similarly, triblock copolymers are written poly(monomer A)-poly(monomer B)-poly(monomer C) or PA-PB PC. Deuterated blocks are denoted dpoly(monomer A) or dPA. The molar mass of a copolymer is denoted by M, or Af corresponding to the weight- or number-average respectively, and the composition is specified by the volume fraction of one component,/. In solution, the volume fraction of a copolymer is denoted [Pg.3]

This column describes the composition of the supporting electrolyte. Concentrations are given In moles per liter wherever possible the entry "KOH 0.1" denotes 0.1 F potassium hydroxide. BrItton-RobInson, Mcllvaine, and other buffers, both mixed and simple, are identified by means of abbreviations. The entry "buffer" means that the solution was said to be buffered at the pH quoted in Column 9 but that no Information was given about the composition of the buffer employed. Maximum suppressors are identified In this column and their concentrations are given in weight/volume per cent. 

The water transport number (tw) accounts for water transport associated to ion electromigration and thus controls the maximum solute weight concentration theoretically achievable in the concentrate. By dividing the instantaneous solute mass transferred into the C compartment by the actual volume accumulated into tank C for 6 tending to infinite, the following can be obtained ... 

To a cold solution of lip,17a-dihydroxyandrost-4-en-3-one-17p-carboxylic acid (5% weight/volume 1 mol) and triethylamine (4 mol) in dichloromethane is added a 50% (weight/volume) solution of ethyl chloroformate (3.9 mol) in dichloromethane. The reaction mixture is allowed to warm to room temperature over a 2 hour period. The triethylamine hydrochloride precipitate which forms is removed by filtration and the filtration is washed successively with 3% sodium bicarbonate, 1% hydrochloric acid and water. The organic layer is separated, dried with magnesium sulfate, and filtered. The filtrate is concentrated in vacuo to a foam. 

The precipitate is filtered, washed and suspended moist in 4 parts of water, concentrated ammonia is added to pH about 7 and the ammonium salt solution is isomerized at 90°C to 100°C for about one-half hour whereafter additional ammonia is added to pH about 9 followed by solid ammonium chloride (about 10% weight/volume) and the solution stirred overnight and the excess of 3,5-diacetamide-2,4,6-triiodobenzoic acid recovered as ammonium salt on the filter. The filtrate is precipitated by means of hydrochloric acid (1 1 ) at pH about 0.5 and the N-methyl-3,5-diacetamido-2,4,6-triiodobenzoic acid collected on a filter, washed and dried. 

Interfacing the TEA to both a gas and a HPLC has been shown to be selective to nitro-based explosives (NG, PETN, EGDN, 2,4-DNT, TNT, RDX and HMX) determined in real world samples, such as pieces of explosives, post-blast debris, post-blast air samples, hand swabs and human blood, at picogram level sensitivity [14], The minimum detectable amount for most explosives reported was 4-5 pg injected into column. A pyrolyser temperature of 550°C for HPLC-TEA and 900°C for GC/TEA was selected. As the authors pointed out, GC uses differences in vapour pressure and solubility in the liquid phase of the column to separate compounds, whereas in HPLC polarity, physical size and shape characteristics determine the chromatographic selectivity. So, the authors reported that the use of parallel HPLC-TEA and GC-TEA techniques provides a novel self-confirmatory capability, and because of the selectivity of the technique, there was no need for sample clean-up before analysis. The detector proved to be linear over six orders of magnitude. In the determination of explosives dissolved in acetone and diluted in methanol to obtain a 10-ppm (weight/volume) solution, the authors reported that no extraneous peaks were observed even when the samples were not previously cleaned up. Neither were they observed in the analysis of post-blast debris. Controlled experiments with handswabs spiked with known amounts of explosives indicated a lower detection limit of about 10 pg injected into column. 

For the most part, the label on consumer products does not indicate which of these percent formulas is used. Typically, a volume/volume calculation is used for solutions made from two liquids. Each manufacturer chooses the method of calculating percent that is most suitable for a particular product. An urban legend of yesteryear claimed that the beer in one state had more alcohol than the beer in an adjacent state. The truth was that one state used a weight/volume percent calculation, whereas the other used a volume/volume approach, and the beers were essentially identical in alcohol content. 

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