Capillary dropper

Boil 2 g. of the ester with 30 ml. of 10 per cent, sodium or potassium hydroxide solution under reflux for at least 1 hour. If the alcohol formed is water (or alkali) soluble, the completion of the hydrolysis will be indicated by the disappearance of the ester layer. Distil ofiF the liquid through the same condenser and collect the first 3-5 ml. of distillate. If a distinct la3 er separates on standing (or upon saturation of half the distillate with potassium carbonate), remove this layer with a capillary dropper, dry it with a little anhydrous potassium carbonate or anhydrous calcium sulphate, and determine the b.p. by the SiwoloboflF method... 

Application of samples. An aliquot (about one to ten yl) of solution of the sample is spotted on the plate with a capillary dropper or micropipette 1.5 cm. from one end of the plate. Care must be taken to avoid diffusion of the spot moreover, the area of the spot should be restricted to a two- or three millimeter-diameter. To ensure this, the solution should be applied in stages and dried in a stream of warm air. The layer on the plate should not be penetrated during spotting. Multiple spots should be applied on the plate at least one centimeter apart. 

To remove the supernatant liquid, a capillary dropper is generally used. The centrifuge tube is held at an angle in the left hand, the rubber teat or nipple of the... 

Dilute hydrochloric acid Place 2 drops of the test solution in a 3 ml centrifuge tube, and add 2-3 drops of dilute HC1. Note the colour and characteristics of the precipitate. Centrifuge the mixture, balancing the tube with another similar tube containing an approximately equal volume of water. Remove the supernatant liquid, termed the centrifugate, by means of a capillary dropper to... 

Largely SrS04. Wash with a little water. Stir the ppt. with 3-4 drops of water, transfer the suspension by means of a capillary dropper to 1 cm2 of quantitative filter paper contained in a 5 ml crucible. 

Weigh 178 mg of N-bromosuccinimide, put it into a 13 x lOO-mm test tube, and add 0.5 mL of dioxane and 1 millimole (80 mg) of cyclohexene. In another tube chill 0.2 mL of water and add to it 1 millimole of concentrated sulfuric acid. Transfer the cold dilute solution to the first tube with the capillary dropper. Note the result and the nature of the product that separates on dilution with water. 

The infrared cell is filled by inclining it slightly and placing about three drops of the solution in the lower hypodermic port with a capillary dropper. The liquid can be seen rising between the salt plates through the window. In the most common sealed cell, the salt plates are spaced 0.1 mm apart. Make sure that the cell is filled past the window and that no air bubbles are present. Then place the Teflon stopper lightly but firmly in the hypodermic port. Be particularly careful not to spill any of the sample on the outside of the cell windows. 

A reaction vessel is constructed of a 30-ml. Pyrex test tube fitted with a 2-mm. stopcock and a male 10/30 standard-taper ground joint. About 110 mg. (0.001 mol) of reagent-grade tetramethylammonium chloride is dissolved in 5 ml. of distilled water and the solution is transferred via a capillary medicine dropper into the reaction vessel through the opened stopcock. Two drops (about 0.1 ml.) of chlorine-36 stock solution are diluted with 1 ml. of distilled water and sufficient 6 M sodium hydroxide (about one drop) to give a basic solution, and this solution is introduced into the reaction vessel with the capillary dropper. 

To remove the supernatant liquid, a capillary dropper is generally used. The centrifuge tube is held at an angle in the left hand, the rubber teat or nipple of the capillary dropper, held in the right hand, is compressed to expel the air and the capillary end is lowered into the tube until it is just below the liquid (Fig. 2.18). As the pressure is very slowly released the liquid rises in the dropper and the latter is lowered further into the liquid... 

Precipitations are usually carried out in micro centrifuge tubes. After centrifuging, the precipitate collects in the bottom of the tube. The supernatant liquid may be removed either by a capillary dropper (Fig. 2.13) or by means of a transfer capillary pipette. The latter consists of a thin glass tube (internal diameter about 2 mm this can be prepared from wider tubing) 20 to 25 cm in length with one end drawn out in a micro flame to a tip with a fine opening. The correct method of transferring the liquid to the... 

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