Manual of basic techniques for a health laboratory - libdoc.who.int

368 Manual of basic techniques for a health laboratoryWillis solution (No. 64)This is a saturated solution of sodium chloride.Sodium chloride (NaCl)125gDistilled water500mlDissolve the sodium chloride by heating the mixture to boiling point. Leave to cooland stand. Check that some of the salt remains undissolved. If it has all dissolvedadd a further 50g. Filter into a corked bottle. Label the bottle “WILLIS SOLU-TION” and write the date.Wintrobe solution (No. 65)Ammonium oxalate (NH 4) 2C 2O 4·H 2O) 1.2gPotassium oxalate (K 2C 2O 4·H 2O) 0.8gDistilled waterq.s. 100mlDissolve the two salts in 50ml of distilled water in a 100-ml volumetric flask.Make up the volume to 100ml with distilled water. Label the volumetric flask“WINTROBE SOLUTION” and write the date.Put 0.5ml of this mixture in each 5-ml bottle used for the collection of blood.Leave the open bottles to dry at room temperature or, preferably, place them in anincubator at 37°C.Zenker fixative (No. 66)Potassium dichromate (K 2Cr 2O 7) 2.5gMercuric chloride (HgCl 2) 5.0gSodium sulfate (Na 2SO 4) 1.0gDistilled waterq.s. 100mlJust before use, add 5ml of glacial acetic acid to the solution.Dissolve the three salts in 50ml of distilled water in a 100-ml volumetric flask.Make up the volume to 100ml with distilled water. Label the volumetric flask“ZENKER FIXATIVE” and write the date.Warning: Glacial acetic acid is highly corrosive and mercuric chloride is highlypoisonous. This fixative should be made up by fully qualified and experiencedtechnicians only.