Solutions stock solution

Isoflavones Weight (mg) in 50 ml stock solution Stock solution (mg/ml) Working solutions (pg/ml)... 

Component Volume of Stock Solution Stock Solution... 

So-called stock solutions are solutions typically 10, 100 or 1000 times more concentrated than that ultimately required in the final solution. Stock solutions are particularly useful when the same ingredients are required in multiple test solutions, when various concentrations of these ingredients are required or simply for storage purposes. A useful example is fruit-flavoured drink concentrates (syrups or cordials) that are mixed/diluted with water to taste if these drinks were pre-diluted they would typically fill hundreds of bottles. The same principle applies to the preparation and storage of chemical concentrates for preparation of laboratory reagents, solutions and buffers. 

Amino Acids Stock Solutions. Stock solutions of Img/mL of /-alanine, /-histidine, /-isoleucine, /-leucine, /-ornithine, /-phenylalanine, /-proline, /-serine, and /-threonine were prepared in MUIi-Q water (Sartorius, Germany) and filtered with a syringe filter with a pore size of 0.25 pm. The stock solutions were stored in amber glass bottles and refrigerated at 2-4 °C and diluted weekly for derivatization with fluorescein isothiocyanate (FITC). 

FITC Stock Solution. Stock solutions of FITC isomer I -90% at a 10 mM concentration was prepared in AR grade acetone and stored in amber glass bottles wrapped in aluminium foil at -18°C. 

Blocking solution Stock solution Dissolve 10 g bovine serum albumin (BSA) (type IV) in PBS, final volume 100 mL. Store as 1-mL aliquots at-20°C Working solution (4%) Add 1.5 mL PBS to 1 mL of the stock solution... 

A concentrated solution (higher molarity) is converted to a dilute solution (lower molarity) by adding solvent, which means the solution volume increases but the amount (mol) of solute stays the same. As a result, the dilute solution contains fewer solute particles per unit volume and, thus, has a lower concentration than the concentrated solution (Figure 3.10). If you need several different dilute solutions, prepare a concentrated solution (stock solution) and store it and dilute it as needed. 

The stock solution of quinoline-sulphur poison is prepared by refluxing I g. of sulphur with 6 g. of quinoline for 5 hours and diluting the resulting brown liquid to 70 nJ. with xylene which has been purified by distilling over anhydrous aluminium chloride. The addition of the quinoline - sulphur poison ensures that the reduction does not proceed beyond the aldehyde stage it merely slows up the reaction and has no harmful effects. 

Kinetic measurements were performed employii UV-vis spectroscopy (Perkin Elmer "K2, X5 or 12 spectrophotometer) using quartz cuvettes of 1 cm pathlength at 25 0.1 C. Second-order rate constants of the reaction of methyl vinyl ketone (4.8) with cyclopentadiene (4.6) were determined from the pseudo-first-order rate constants obtained by followirg the absorption of 4.6 at 253-260 nm in the presence of an excess of 4.8. Typical concentrations were [4.8] = 18 mM and [4.6] = 0.1 mM. In order to ensure rapid dissolution of 4.6, this compound was added from a stock solution of 5.0 )j1 in 2.00 g of 1-propanol. In order to prevent evaporation of the extremely volatile 4.6, the cuvettes were filled almost completely and sealed carefully. The water used for the experiments with MeReOj was degassed by purging with argon for 0.5 hours prior to the measurements. All rate constants were reproducible to within 3%. 

For the past year Strike had been in consultation with contract labs over the making of phenylisopropyl alcohols using sulfuric acid and allylbenzenes (don t ask). The lab owners would listen patiently as Strike primitively described how and why an OH should go on the beta carbon. And without exception, the lab owners would point out to Strike that the best way to get an OH on the beta carbon would be to put a Br there first. But Strike don t wanna put a Br there first Strike would say, Strike wants the OH put on directly using sulfuric acid " The lab guys had to do what Strike said because Strike was holding all the money (...a fool and her money etc.). But out of curiosity Strike asked how they would get that Br on the beta carbon. Every one of them said it was simply a matter of using the 48% HBr in acetic acid. They even showed Strike their stock solutions (usually from Aldrich or Fisher). 

X mL of 0.2M NaOH Added to 100 mL of Stock Solution (0.04M Acetic Acid, 0.04M H3PO4, and 0.04M Boric Acid)... 

Ethyl bis-(2,4-dinitrophenyl) acetate (indicator) the stock solution is prepared by saturating a solution containing equal volumes of alcohol and acetone with the indicator pH range colorless 7.4-9.1 deep blue. This compound is available commercially. The preparation of this compound is described by Fehnel and Amstutz, Ind. Eng. Chem., Anal. Ed. 16 53 (1944), and by von Richter, Ber. 21 2470 (1888), who recommended it for the titration of orange- and red-colored solutions or dark oils in which the endpoint of phenol-phthalein is not easily visible. The indicator is an orange solid which after crystallization from benzene gives pale yellow crystals melting at 150-153.5°C, uncorrected. 

A stock solution is prepared by weighing out an appropriate portion of a pure solid or by measuring out an appropriate volume of a pure liquid and diluting to a known volume. Exactly how this is done depends on the required concentration units. For example, to prepare a solution with a desired molarity you would weigh out an appropriate mass of the reagent, dissolve it in a portion of solvent, and bring to the desired volume. To prepare a solution where the solute s concentration is given as a volume percent, you would measure out an appropriate volume of solute and add sufficient solvent to obtain the desired total volume. 

Solutions with small concentrations are often prepared by diluting a more concentrated stock solution. A known volume of the stock solution is transferred to a new container and brought to a new volume. Since the total amount of solute is the same before and after dilution, we know that... 

A laboratory procedure calls for 250 mb of an approximately 0.10 M solution of NH3. Describe how you would prepare this solution using a stock solution of concentrated NH3 (14.8 M). 

Balances, volumetric flasks, pipets, and ovens are standard pieces of laboratory instrumentation and equipment that are routinely used in almost all analytical work. You should be familiar with the proper use of this equipment. You also should be familiar with how to prepare a stock solution of known concentration, and how to prepare a dilute solution from a stock solution. 

M stock solution provides the smallest overall uncertainty ... 

I. 000 X 10- 1.000 X 10-k 1.000 X 10-k and 1.000 X 10- M from a 0.1000 M stock solution. Calculate the uncertainty for each solution using a propagation of uncertainty, and compare to the uncertainty if each solution was prepared by a single dilution of the stock solution. Tolerances for different types of volumetric glassware and digital pipets are found in Tables 4.2 and 4.4. Assume that the uncertainty in the molarity of the stock solution is 0.0002. 

The majority of titrations involving basic analytes, whether conducted in aqueous or nonaqueous solvents, use HCl, HCIO4, or H2SO4 as the titrant. Solutions of these titrants are usually prepared by diluting a commercially available concentrated stock solution and are stable for extended periods of time. Since the concentrations of concentrated acids are known only approximately,the titrant s concentration is determined by standardizing against one of the primary standard weak bases listed in Table 9.7. 

Procedure. Prepare a set of external standards containing 0.5 g/L to 3.0 g/L creatinine (in 5 mM H2SO4) using a stock solution of 10.00 g/L creatinine in 5 mM H2SO4. In addition, prepare a solution of 1.00 x 10 M sodium picrate. Pipet 25.00 mL of 0.20 M NaOH, adjusted to an ionic strength of 1.00 M using Na2S04, into a thermostated reaction cell at 25 °C. Add 0.500 mL of the 1.00 x 10 M picrate solution to the reaction cell. Suspend a picrate ion-selective electrode in the solution, and monitor the potential until it stabilizes. When the potential is stable, add 2.00 mL of a... 

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