Dilution stock solution preparation

Dilute stock solutions Prepare 1, 5, 10 and 100 ng/mL cadmium standard stock solutions by making appropriate serial dilutions of 1,000 xg/mL cadmium standard stock solution with the diluting solution described in Section 3.5.6. 

Stock solution. Prepare a 200- ug mL stock solution in ACN Fortification solutions. Prepare 0.04 and 0.2 lagmL fortification solutions by dilution of the stock solution in acetonitrile (trinexapac-ethyl). Prepare 0.05 and 0.25 j.gmL fortification solutions by dilution of the stock solution in water (trinexapac). 

The major problem with the intravenous route in children is dosing errors. Because of the unavailability of stock solutions prepared for pediatric doses, errors in dilution of an adult stock solution have resulted in 10- to 20-fold errors in administered doses [87,88], A secondary problem is the maintenance of patent intravenous lines in infants and nonsedated children. 

Stock solutions of anthracyclines (1 mg/mL) were prepared in double distilled water and stored at 4°C in the dark. Standard working solutions were prepared by diluting stock solutions with double distilled water or 0.1 M phosphoric acid. Aliquots of blank human plasma (0.5 mL) were spiked with working solutions of anthracyclines, mixed with 0.5 mL of 0.2M dibasic sodium phosphate buffer (pH 8.4), extracted with 4 mL of chloroform 1-heptane (9 1 v/v) by shaking for 15 min and centrifuged at 4000 rpm for 10 min. The lower organic layer was re-extracted with 0.25 mL of 0.1M phosphoric acid. The upper aqueous layer was collected and assayed. The injection volume was 50 fiL. Retention times for daunorubicinol, daunorubicin, idarubicinol, idarubicin, doxorubicinol, doxorubicin, epirubicinol, and epirubicin were 6,7, 9.1, 8.0, 11.3, 5.1,6.4, 5.5, and 7.0 min, respectively. 

Stock solutions of epirubicin and the IS (1 mg/mL) were prepared in methanol/water (1 1 v/v) and stored at 4°C. Standard working solutions were prepared by diluting stock solutions with 20mM... 

Prepare five identical dilutions of the stock solution prepared in step 1 by diluting 10 mL of the solution to 100 mL. Use a clean 10-mL volumetric pipet and a clean 100-mL volumetric flask, and make the measurement and transfer as carefully as possible (see Table 4.1). Label each as 2/1, 2/2, etc., to indicate that they are solutions 1 to 5 prepared in step 2. 

Prepare four calibration standards with concentrations of 0.0435,0.0870,0.174, and 0.261 g/L in the alkane solvent by diluting the stock solution prepared in step 1. Use the 25-mL volumetric flasks prepared in step 1. 

In recent years, a great diversity of structurally well-defined functionalized fullerenes has been designed and synthesized for that purpose. Some of them exhibit pronounced solubility in water (vide infra). But even for compounds being virtually insoluble in water, stable aqueous phases can be obtained in plenty of cases by diluting stock solutions of the compounds in polar organic solvents with various amounts of water. Notably, dimethyl sulfoxide (DMSO) and tetrahydro-furan (THF) have turned out to be excellent surfactants for preparing stable aqueous fullerene solutions (Angelini et al., 2005 Cassell et al., 1999 Da Ros et al., 1996 Gun kin et al., 2006 Illescas et al., 2003). Also cosolvents such as dimethylforma-mide (DMF) and methanol can be used to promote water solubility. After subsequent dilution of a saturated solution of C60 in benzene with THF, acetone and finally water, actually stable aqueous suspensions of pristine fullerene can be obtained (Scrivens et al., 1994). 

Since certified reference materials for seawater nutrient analysis are currently unavailable, individual laboratories must prepare their own standard solutions for instrument calibration. Standard stock solutions are prepared at high concentrations (mM) so that they can be used for months without significant alterations in concentration. Working low-concentration standard solutions are unstable and need to be prepared daily by diluting stock solutions with distilled water or low-nutrient seawater. In this case, the accuracy of nutrient analysis at a given laboratory is highly dependent upon the accuracy of the daily preparation of the calibration solutions. 

A calibration curve was prepared by transferring, in each case, 5 ml of diluted sample solution plus varying amounts of diluted stock solution to a 100 ml volumetric flask as indicated in Table 6.2 and then making up to 100 ml with de-ionised water. 

Dilute 10 mL of stock solution prepared above to 1L. The strength of this secondary standard is 10 mg NH3-N/L or 1 mL = 10 pg NH3-N = 12.2 pg NH3. Prepare a series of Nessler tube standards as follows ... 

A solution of 125ug/LAs(V) in deionized water was prepared by serial dilution of a 1,000 mg/L As(V) stock solution prepared from As205. This solution and the synthetic Grande Ronde groundwater were air-saturated. 

System Suitability Preparation - Pipet 5 ml of the stock solution, prepared as directed under Standard preparation, into a 25-ml volumetric flask, dilute with isooctane to volume, and mix. Heat this solution at reflux for 2 hours, cool, and irradiate for 1 hour under long-wavelength and short-wavelength ultraviolet light. This solution contains cholecalciferol, pre-cholecalciferol, and tachysterol. 

The concentration was further corrected for radiochemical purity according to the manufacturer s specifications because liquid scintillation counting measures the total sample activity and does not account for the presence of radiolabeled impurities. Stock solutions were stored at -15°C or -20° C in order to minimize sample loss due to hydrolysis. Injected sample solutions were prepared in 0.25 mL plastic vials by diluting stock solutions with buffer or deionized water and were also stored at -15° C or -20° C. 

Standard Preparations Dissolve 338.5 mg of mercuric chloride, in about 200 mL of water in a 250-mL volumetric flask, add 14 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Pipet 10.0 mL of this solution into a 1000-mL volumetric flask containing about 800 mL of water and 56 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Pipet 10.0 mL of the second solution into a second 1000-mL volumetric flask containing 800 mL of water and 56 mL of 1 2 sulfuric acid, dilute to volume with water, and mix. Each milliliter of this diluted stock solution contains 0.1 pig of mercury. Pipet 1.25, 2.50, 5.00, 7.50, and 10.00 mL of the last solution (equivalent to 0.125, 0.250, 0.500, 0.750, and 1.00 ptg of mercury, respectively) into five separate 150-mL beakers. Add 25 mL of aqua regia to each beaker, cover with watch glasses, heat just to boiling, simmer for about 5 min, and cool to room temperature. Transfer the solutions into separate 250-mL volumetric flasks, dilute to volume with water, and mix. Transfer a 50.0-mL aliquot from each solution into five separate 150-mL beakers, and add 1.0 mL of 1 5 sulfuric acid and 1.0 mL of a filtered solution of 1 25 potassium permanganate solution to each. Heat the solutions just to boiling, simmer for about 5 min, and cool. 

Modifier Stock Solution Weigh 20 g of ultrapure magnesium nitrate hexahydrate and dilute to 100 mL. Just before use, prepare a Modifier Working Solution by diluting stock solution 1 10. A volume of 5 p,L will provide 0.06 mg of magnesium nitrate. 

Dissolve 5.7194 g of H3B03 in water and dilute to 11 to yield a 1.000 g Bl-1 stock solution. Prepare a 100/xgBml-1 stock solution by diluting 100 ml of the 1.000 g Bml-1 stock solution to 11 in a volumetric flask. 

GSSG (Sigma) 100 M stock solution Prepare a 0.1 M solution (0.328g GSSG/ 5 mL phosphate buffer) and dilute 1 1000 to 1001aM with phosphate buffer. 

The commercial preparation should be recrystallized from dilute alcohol, and a 0.1% stock solution prepared in 90% alcohol. 

Prepare 2 ppm standard (secondary) from the prepared 50 ppm by proper dilution (20 ml of 50 ppm stock diluted exactly to 500 ml for preparing 2 ppm standard). These more diluted stock solutions do not keep well even with addition of tolune and hence must be made up frequently). 

Diluting Stock Solutions If you want to know the concentration and volume of the solution you want to prepare, you can calculate the volume of stock solution you will need. What volume, in milliliters, of 2.00M calcium chloride (CaC ) stock solution would you use to make 0.50 L of 0.300M calcium chloride solution ... 

Usually solutions prepared this way range in molarity from 3.7 to 3.2 TEACL. Store this solution at room temperature. Prepare a diluted stock solution of 2.4M TEACL, which can be kept in refrigerator. 2.4Af TEACL should have a refractive index of 1.4042. Acceptable readings are from 1.4041 - 1.4043. 

Cyanide and sulfide ions interfere with the test for halides. If such ions are present, they must be removed. To accomplish this, acidify 2 mL of the stock solution prepared above with dilute nitric acid and boil it for about 2 minutes. This will drive off any HCN or H2S that is formed. When the solution cools, add a few drops of a 5% silver nitrate solution. A volumitwus precipitate indicates a halide. A faint turbidity does not mean a positive test. Silver chloride is white. Silver bromide is off-white. Silver iodide is yellow. Silver chloride will readily dissolve in concentrated ammonium hydroxide, whereas silver bromide is only slightly soluble. 

Three sets of spiked MCEF samples were prepared by injecting 15 pL of 5, 10 and 20 pg/mL dilute cadmium stock solutions on 37 mm diameter filters (part no. AAWP 037 00, Millipore Corp., Bedford, MA) with a calibrated micropipet. The dilute stock solutions were prepared by making appropriate serial dilutions of a commercially available certified 1,000 pg/mL cadmium standard stock solution (Fisher Chemical Co., Lot 913438-24) with the diluting solution (4% HNO3, 0.4% FICI). Each set contained six samples and a sample blank. The amount of cadmium in the prepared sets were equivalent to 0.5, 1 and 2 times the Action Level TWA target concentration of 2.5 pg/m for a 60 L air volume. 

Detection limit Detectability Further dilution of lowest concentration of stock solutions prepared from Model A and Model B or C as described under Recovery Lowest concentration o the analyte which can be clearly identified on the chromatogram at the preselected wavelength (3 times noise)... 

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