Preweighed vials

To sample into preweighed vials, we need the following field supplies and equipment ... 

Collect one sample at a time to prevent switching of preweighed vial caps or magnetic stir bars. 

Collect samples using the previously described procedure for sampling into preweighed vials. One methanol-preserved container is sufficient for each... 

Use all of the practical tips offered for sampling into preweighed vials. 

The system has a modular design. The Automatic Weigh Station allows an operator to place reagents into preweighed vials. The station then automatically records the weight of the reagents and adds solvent to achieve specified molar concentration. The specific amount of solvent is calculated by the software. The Vortex Mixer is used automatically by the system to solubilize dry reagents. The mixer is also used for liquid-liquid extractions. 

To purify your product, recrystallize your collected solid from acetone. To accomplish this, transfer the solid to a 125-mL flask. Add a small amount (20 ruL to start) of acetone and a stir bar. Heat to fully dissolve the solid. Add small amounts of acetone, order 1 ruL at a time, as needed, to aid in the dissolution. When solid is dissolved, remove from heat. Cool with the aid of an ice bath. Crystals should form. If they do not, try scratching the inside of the flask with a glass rod. Or, boil off some solvent and recool. Remove these crystals by suction filtration just as you did to collect your impure product. Wash these crystals with a cold 5 ruL portion of acetone and allow them to dry on the filter paper. Transfer to a preweighed vial. Calculate yield of cholesteryl nonanoate from cholesterol and calculate the conversion of cholesterol to cholesteryl nonanoate. 

The RAM synthesizer (Fig. 34), which has a modular design, is a fully automated workstation designed to execute the entire process of solution- and solid-phase synthesis [88, 89]. The Automatic Weigh Station allows the necessary reagents to be placed into preweighed vials. 

Dissolve each QC compound in the well with 2 ml of acetonitrile, and transfer the solution to a preweighed vial. Then rinse the well with three 0.5-mL aliquots of acetonitrile, and transfer the rinse solutions to the vial. Remove solvent on a rotary evaporator, freeze the vial, and lyophilize for 14 h to remove trace amounts of moisture before weighing. To ensure complete moisture removal, lyophilize the vial for 2 additional hours and weigh until the weight change is < 0.10 mg. 

In preweighed autosampler vials with water, preserved with sodium bisulfate (NaHS04) or with unpreserved water... 

Option 4. Extrude the soil from the airtight coring devices into preweighed, labelled autosampler vials with PTFE-lined septum caps a magnetic stir bar and 5 ml of analyte-free water. Weigh to determine the sample weight. A sample prepared in this manner is also ready for analysis. Store at 2-6°C analyze within 48 hours of collection. 

Sample containers certified precleaned, preweighed, labelled autosampler vials with... 

Clean the outside surface of the barrel with a paper towel. By depressing the plunger quickly, extrude the soil into a preweighed sample vial. Clean the threads of the vials of soil particles with a paper towel and cap the vial with its own PTFE-lined septum cap. 

Sample containers precleaned, preweighed, labelled VOA vials or 2-ounce jars with 10 ml of purge-and-trap grade methanol... 

With a clean Pasteur pipette, carefully puncture through the denatured protein disk and remove the chloroform layer at the bottom of each tube. Transfer the chloroform layer from both tubes to a singlt, preweighed 4-ml glass vial with a Teflon-lined screw cap. Take care not to... 

Blow off residual ether in a slow stream of nitrogen, teasing apart DNA with Pasteur pipets if necessary. Transfer to preweighed clean glass vial and dry to constant weight. 

Draw 20 pL blood immediately (<2 min) after the injection by retro-orbital puncture in heparinized capillary pipets and transfer to preweighed scintillation vials. Reweigh the vials and count for radioactivity (see Notes 25-27). 

Weigh 1 mg of aflatoxin and dissolve it in 100 ml of acetonitrile. Some suppliers provide mycotoxins as preweighed dry films in a vial in that case, dissolve the film in the required volume of acetonitrile to get a solution of lOpgml. With a calibrated spectrophotometer, measme the absorbance. A, at the wavelength of maximal absorption, which depends on the solvent used (355 nm in acetonitrile). Calculate the concentration of the stock solution by using the formula... 

Assemble a distillation apparatus using your smallest round-bottom flask to distill from (Technique 14, Figure 14.10, but insert a water condenser as shown in Experiment 7A). Use a hot plate with an aluminum block to heat. Preweigh (tare) and use a 5-mL conical vial to collect the product. Immerse the collection vial in a beaker of ice to ensure condensation and to reduce odors. Distill your ester and record its boiling-point range in your notebook. 

As distillate condenses in the Hickman head, transfer the liquid from the reservoir to a preweighed 3-mL conical vial. If your Hickman head does not have a side port, it will be necessary to use a 9-inch Pasteur pipette. In the latter case, it is helpful to bend the tip of the pipette slightly by heating it in a flame. The distillate can then be removed without removing the thermometer. Be sure to cap the conical vial used for storage each time after you transfer the distillate. Continue to distill the mixture, and transfer the distillate to the vial until the temperature in the Hickman head increases above 78°C or until the temperature in the Hickman head drops several degrees below 78°C and remains at this lower temperature for 10 minutes or more. You should collect about 0.4 mL of distillate. The distillation should then be interrupted by removing the apparatus from the heat source. 

When the solution is dry, transfer it to a clean, dry, 3-mL vial using a Pasteur pipette and distill it (aluminum block about 140°C) using a clean, dry Hickman still (Technique 14, Figure 14.5). Each time the Hickman head becomes full, transfer the distillate to a preweighed conical vial using a Pasteur pipette. 

Using an automatic pipette or a dispensing pump, place 1.0 mL of f-pentyl alcohol (2-methyl-2-butanol, MW = 88.2) in a preweighed 5-mL conical vial. Reweigh the vial to determine the exact weight of alcohol delivered. 

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