Solutions to be Prepared

All the experiments are performed in test tubes of internal diameter equal to 1.5 cm. 

---

No general rule can be given concerning the strength of the solution to be prepared, as this will depend upon the spectrophotometer used for the study. Usually a 0.01-0.001 M solution is sufficiently concentrated for the highest absorbances, and other concentrations are prepared by dilution. The concentrations should be selected such that the absorbance lies between about 0.3 and 1.5. 

Immediately before use, dissolve sulfo-NHS-biotin (Thermo Fisher) in water at a concentration of 20 mg/ml. Alternatively, the compound may be dissolved in organic solvent to prevent hydrolysis prior to a reaction (i.e., dry DMF or DMSO). Adjust the concentration and quantity of this stock solution to be prepared according to the amount of reagent needed to biotinylate the desired amount of protein. If prepared in water, the sulfo-NHS-biotin stock solution must be used immediately, since the NHS ester is subject to hydrolysis in aqueous environments. 

This solution can be prepared by diluting the stock solution 25 times that is, for each ml of the 26.7 mg ml 1 solution to be prepared,... 

We use the dilution equation (Equation (4.2)) for each solution to be prepared. The dilution equation is... 

To develop our calibration data set using an experimental design (see Chapter 2) in order to be, hopefully, reasonably sure that all the experimental domain is represented by the standard solutions to be prepared. 

The water quality necessary will depend on the solutions to be prepared and on the biochemical procedures to be investigated. Water that is purified only by ion exchange will be low in metal ion concentration, but may contain certain organics that are washed from the ion-exchange resin. These contaminants will increase the ultraviolet absorbance properties of water. If sensitive ultraviolet absorbance measurements are to be made, distilled water is better than deionized. 

The normalization method is the easiest and most straightforward to use and requires no reference standards or calibration solutions to be prepared. Unfortunately, to be applicable, the detector must have the same response to all the components of the sample. Thus, it will depend on the detector that is employed and the sample being... 

This is a quantitative experiment, therefore requiring an analytical solution to be prepared. 

With respect to sample extraction, it should be emphasized that homogenization using a probe is an intrusive technique. Compatibility is required between the sample probe and extraction vessel and the sample solvent, drug, excipients, and related substances. For this verification, it is frequently desirable to also prepare the development samples manually and to compare chromatographic profiles. Furthermore, the probe must be cleaned between extractions. A cleaning procedure should allow for the most concentrated sample solution to be prepared without carryover above a specified limit. This may be measured by running an analysis blank immediately after the sample. 

Administration Subcutaneous, bolus injection dosing solutions to be prepared daily duplicate aliquots of each formulation level collected predose and postdose for the first, seventh, and thirteenth dose to be analyzed (using a validated analytical chemistry method to be transferred to the service provider) for test article concentration... 

This experiment supports the classroom discussion of solution preparation and required calculations (including molar solutions by dilution or by weighing a pure solid, and percent solutions) as well as the concepts of solution conductivity and oxidation and reduction processes at electrode surfaces. There are 11 solutions to be prepared. Rather than have... 

Viscosity measurement methods for polymers under high-pressure CO2 may be divided into four classes pressure driven, falling body, rotational devices, and vibrating wire. Accurate viscosity measurements require a homogeneous solution to be prepared, thus ensuring that phase separation does not occur [19, 76]. 

Chloramine-T diluted solution (to be prepared freshly each day from the stock solution the stock solution itself can be kept for approximately... 

A continuous nitrate/fluoride process has been proposed to take advantage of the ready solubility of columbite ore in a mixture of nitric and hydrofluoric acids, and thus allow the feed solution to be prepared in a cheap and simple manner. The feed contains 45 g/1. of niobium, about 25 g/1. of tantalum and is 8N in hydrofluoric acid and 3N in nitric acid. It is extracted in six stages with three volumes of solvent, together with an additional stage for acid equilibration . A half volume aqueous strip solution is also 8N in hydrofluoric acid and 3N in nitric acid. About 99 per cent of the niobium is extracted into the solvent and is then backwashed in a second extractor with three volumes of 0-5N hydrofluoric acid. The solvent finally passes to a single-stage backwash extractor for removal of tantalum by sodium carbonate solution. 

The original Mn-Mejtacn complex contains PF6 - as a counter ion, which simplifies purification and handling and improves storage stability, but reduces the solubility of the catalyst. Recent developments in using Mn-Mejtacn derivatives for raw cotton bleaching, the pulp and paper industry, and industrial cleaning are based on more soluble counter ions such as chloride, sulfate, or acetate. Such catalysts are more cost-effective to produce, and allow stable weak acidic solutions to be prepared [39]. 

Benzalkcmium chloride is available as Benzalkonium Chloride Solution (Ph. Eur.) which contains a mixture of alkylbenzyldimethylammonium chlorides in water at a concentration of 500 g/L (50 % w/v). If the final concentration of benzalkonium chloride in a product has to be 0.01 % (either w/v or w/w), for 1,000 mL of the preparation 100 mg of benzalkonium chloride is required. Volume measuring would require 0.2 mL of the Benzalkonium Chloride Solution (50 % w/v) to be taken which cannot be performed with adequate accuracy because of its high viscosity. For weighing instead, the density of the solution has to be known. Density may be taken from the product certificate issued by the manufacturer or it has to be measured. If the density would be 0.9805 g/mL (as measured) one should weigh 196 mg of the 50 % Benzalkonium Chloride Solution for 1,000 mL of the solution to be prepared. 

An alternative approach is to use equation (4.5). The known factors include the volume of solution to be prepared, (Vf = 250.0 mL) and the concentrations of the final (0.0100 M) and initial (0.250 M) solutions. We must solve for the initial volume, V. Note that although in deriving equation (4.5) volumes were expressed in liters, in applying the equation any volume unit can be used as long as we use the same unit for both Vj and Vf (milliliters in the present case). The term needed to convert volumes to liters would appear on both sides of the equation and cancel out. 

---