Acetic acid diluting stock solution

P 67] A stock standard solution of benzophenone in 2-propanol (0.5 M) with a drop of glacial acetic acid was diluted to give further standard solutions of 0.1-0.4 M [72, 74]. These solutions were stored at room temperature, protected from exposure to light and were employed for a device having an optical path of 50 pm. When using a second generation device with a 500 pm path, the stock solution concentration was reduced to 0.05 M. 

A stock solution of lumefantrine was prepared in methanol-acetic acid (99.8 0.2 v/v). Standard working solutions were prepared by diluting the stock solution with acidic methanol. Calibration standards in plasma were prepared by spiking blank plasma (4900 fxL) with 100 jxL of working solution. 

Your instructor has prepared a 50 ppm riboflavin stock solution in 5% (by volume) acetic acid. Prepare a series of calibration standard solutions that are 0.2, 0.4, 0.6, 0.8, and 1.0 ppm from the 50 ppm stock solution and again use 5% acetic acid for the dilution. Use 25-mL volumetric flasks for these standards and shake well. 

Dilute collagen stock solution to 50 pg/mL in 0.02 N acetic acid. 

Eluent A 0.01 M sodium acetate+ 9.1% methanol, pH 5.75 is prepared by diluting 100 ml of the stock sodium acetate to 11 and adding 100 ml of methanol the pH is adjusted to 5.75 with acetic acid. This solution is stable at room temperature under helium for 2 weeks. 

Sodium acetate buffer 0.1 M, pH 5.0 Dilute 1 M sodium acetate stock solution (81.04 g/1) with H20 and adjust to pH 5.0 with acetic acid. Make up to ten times the original volume with H20. 

Prepare stock 10 mM galacturonic acid solution by dissolving 0.2122 g D-galac-turonic acid monohydrate in 100 ml of 20 mM sodium acetate buffer, pH 5.0 (appendix 2A). Dilute this stock solution 10-fold with buffer. Store up to 1 week at 4°C. 

Dissolve 4.84 g of Tris base in 700 ml of distilled water. Add 1.14 ml of glacial acetic acid and 2 ml of 0.5 M EDTA, pH 8.0. Bring the final volume of the solution to 1 liter with distilled water. NOTE A 50x concentrated stock can be prepared and stored at room temperature for long term by multiplying all of the masses and volumes of the Tris base, glacial acetic acid, and EDTA components by 50. This 50x concentrated stock will be diluted 1 50 with distilled water to give a 1 x working solution. 

The enzyme assay was prepared by mixing 500 yL of 0.100 M phosphate buffer (pH 7.20), 50 yL of ethylhomocholine, 25 yL of 500 mM acetylcholine, and 25 fiL of serum diluted 1 4 with isotonic saline. Stock solutions of the substrate and internal standard were prepared in 10 mM acetate buffer (pH 4.5). The assay proceeded for 10 minutes ambient temperature (22°C) before being stopped by the addition of 25 yL of 2.50 M perchloric acid. This amount of perchloric acid did not stop the reaction instantaneously, but a correction can be made by running a zero-time control. The samples were filtered through 0.45 /urn filters before injection of 20 yL aliquots into the HPLC. 

Test for Sulfide Ion. Add 2-3 drops of lead acetate to 2 ml of the stock solution which has been acidified with dilute acetic acid. A brown or black precipitate denotes the presence of sulfide ion. Add 1-2 drops of sodium nitroprusside solution (0.1 per cent) to 2 ml of the stock solution. A deep red color indicates the presence of. sulfide ion. 

Stock solution. Measure 1 ml. of phenylhydrazine by pipet into a 10-ml. volumetric flask, add 3 ml. of acetic acid and swirl under the tap to cool to room temperature, and dilute with water to 10 ml. The solution contains 1 mmole of phenylhydrazine acetate per milliliter. If a substance to be tested for the presence of a carbonyl function is soluble in water to the extent of 8-10 microdrops in 1 ml. of water, dissolve 1 mmole of sample in 1 ml. of water and add 1 ml. of the stock solution. Separation of an oil or solid indicates the presence of a carbonyl function. If the sample is soluble to the extent of only about 4 microdrops in 1 ml. of water (diethyl ketone), treat 1 mmole of material with 1 ml. of water and add a few drops of methanol until solution is complete then add 1 mole of stock solution. A sample insoluble in water can be dissolved in methanol, ethanol, or dioxaiie and treated with 1 ml. of stock solution. 

A free flowing monomer, ethylene glycol dimethacrylate (EGD) stabilised with 0.1% hydroquinone is thickened with 0.0, 2.0, 4.0, 6.0, 8.0, 10.0, 12.0, 14.0 and 16.0% of methyacrylate butadiene styrene (MBS). Two further samples of the same monomer are thickened with similar increasing concentrations of cellulose nitrate (CN) and silicone dioxide (SiCh) for comparison. An accurate weight of 10.0 g of each thickened monomer is dissolved in 25% n-propanol and 75% glacial acetic acid. Then 0.25 ml of 1000 ppm Zn metal stock standard solution is added to each mixture. These solutions are also spiked with 0.5 ml of 1000 ppm indium (In) metal as internal standard. All mixtures are diluted to mark with the 25% n-propanol/glacial acetic acid. The mixtures contain 2.5 ppm Zn and 5.0ppm In per ml. 

The peptides were dissolved in DMSO and then diluted with O.IM ammonium acetate buffer (AAB) at pH6.5 to obtain lOmM stock solutions in AAB (10% DMSO) the peptides were stored at -126°C. Prior to labelling, the peptides were thawed and diluted to ImM in AAB containing 10% gentisic acid. Typically, 2-5 gL of "LuCl, (11-229 MBq, 0.3-6.2 mCi) was added to 5-10 gL of the peptide P3, P4 or octreotide, followed by addition of 80-188 gL of O.IM AAB with 10 mg/mL gentisic acid. The pH was measured and adjusted within a range of 4.0-5.5 with AAB the solution was subsequently incubated at 70°C for 30 min. The effect of temperature (40-70°C) and incubation time (10-60 min) was studied for Lu-P3. 

Solution 1 0.10 M acetic acid. You are to dilute a stock solution that is 1.0 M. 

The number of moles of solute present in the more dilute solution equals the number of moles of solute that must be present in the more concentrated (stock) solution, because this is the only source of acetic acid. 

Preparation of di-t-buh/lsilylene (DTBS) derivatives The diol, hydroxy acid or amino acid (100 /rg) was dissolved in acetonitrile (30 fA). N-Methylmorpholine (20 1), 1-hydroxybenzotriazole (9 yg) (dried in vacuo at 40 °C prior to preparing the stock solution 3 mg dissolved in 1 ml of acetonitrile and di-t-butylchloro-silane (3.5 fi ) were added sequentially, and the mixture was heated in a Reacti-Vial at 80 °C for 1 h (phenolic substrates and anthranilic acid) or 15 h (other substrates). The resulting solution was diluted to 100/il with ethyl acetate and used for GC and GC-MS analysis. For the derivatization of sterically... 

Serially dilute the stock solution down to standard working solutions at the desired concentrations with 50% methanol containing 20 mM ammonium acetate and 0.1% formic acid. 

Reagents Solution I Basic bismuth nitrate (850 mg) is dissolved in 10 ml of acetic acid and 40 ml of water. Solution II Potassium iodide (8 g) is dissolved in 20 ml of water. The two solutions are mixed and can be kept in brown bottles for several months. Before use 10 ml of this stock solution is diluted with 20 ml of acetic acid and 100 ml of water. 

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