Filter pipette

Room 2 DNA extraction. In this room the DNA is extracted. All working steps should be performed with filter pipette tips. Coats and gloves must be worn to protect both the lab personal and the samples. Air conditioning is recommended. For work with samples with small amounts of DNA, a specific portion of the room... 

Filter pipettes and micro filtration devices are available commercially. Thus, the Whatman syringe filters No. 402/0803/06 (with 4 mm effective diameter) and 402/0805/06 (with 13 mm effective diameter) are suitable for micro- or semimicro-work respectively. 

Filtering pipettes Used with volumes less than about 10 mL to remove solid impurities from a liquid. 8.1C... 

A filtering pipette is a microscale technique most often used to remove solid impurities from a liquid with a volume less than 10 mL. It is important that the mixture being filtered be at or near room temperature because it is difficult to prevent premature crystallization in a hot solution saturated with a solute. 

Depending on the amount of solid being filtered and the size of the particles (small particles are more difficult to remove by filtration), it may be necessary to put the filtrate through a second filtering pipette. This should be done with a new filtering pipette rather than with the one already used. 

Decantation is the easiest method of removing solid impurities and should be considered first. A filtering pipette is used when the volume of liquid to be filtered is less than 10 mL (see Technique 8, Section 8.1, Part C), and you should use gravity... 

Filter the hot solution through a fluted filter, a filtering pipette, or a filter-tip pipette to remove insoluble impurities or charcoal. 

An alternative method of drying a small volume of organic phase is to pass it through a filtering pipette (Technique 8, Section 8.1C) that has been packed with a small amount (about 2 cm) of drying agent. Again, the solvent is removed by evaporation. 

For the tablets weigh an amount of powdered tablets equivalent to about 0 5 g of cyclobarbitone calcium into a 100-ml glass-stoppered cylinder, add 10 ml of 4 per cent sodium hydroxide solution and 40 ml of water and shake mechanically for thirty minutes. Transfer quantitatively to a 100 ml graduated flask with water, dilute to volume with water, mix and filter. Pipette 25 ml of the filtrate into a glass-stoppered... 

Dissolve 0 5 g of lotion containing 0 2 per cent of chlorocresol in sufficient 72 per cent ethanol (prepared from industrial methylated spirit that has been refluxed for four hours over potassium hydroxide and distilled) to make exactly 50 ml. Shake well, chill in ice-water and filter. Pipette 10 ml of the filtrate into a 20-ml graduated flask and dilute to 12 ml with the 72 per cent ethanol. Add 2 ml of a 0 012 per cent solution of 2,6-dichloro-p-benzoquinone-4-chloroimine in 95 per cent ethanol (refluxed and distilled as above) and 2 ml of a 1 5 per cent aqueous borax solution, mixing after each addition. Allow to stand in the dark for one hour and then dilute to volume with the 72 per cent ethanol. Mix and measure the extinction at 650 m/U in a 2-cm cell subtract the value of a reagent blank and read off the amount of chlorocresol from a calibration curve. 

Dimethoxybenzidine reagent. Mix 0 5 g of 3,3 -dimethoxybenzidine and 0 5 g of activated charcoal (50- to 200-mesh) with 100 ml of wopropyl alcohol, shake well and filter. Pipette 40 ml of the filtrate into a 100-ml graduated flask, dilute to volume with N hydrochloric acid and mix. This reagent should be freshly prepared on the day it is to be used. 

---