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

Annex. Reagents and their preparation 365Label the volumetric flask “SODIUM HYDROXIDE 0.01 MOL/L SOLUTION”and write the date.Warning: Sodium hydroxide is corrosive.Sodium metabisulfite, 20g/l (2%) solution (No. 55)Sodium metabisulfite (Na 2S 2O 5) 0.5gDistilled waterq.s. 25mlMake up freshly for use.Label the volumetric flask “SODIUM METABISULFITE 2% SOLUTION” andwrite the date.Stuart transport medium, modified (No. 56)Agar 4.00gDistilled water1000mlHeat until dissolved and add while hot:Sodium chloride (NaCl) 3.00gPotassium chloride (KCl) 0.20gDisodium hydrogen phosphate (Na 2HPO 4),anhydrous 1.15gSodium dihydrogen phosphate (NaH 2PO 4),anhydrous 0.20gSodium thioglycolate 1.00gCalcium chloride (CaCl 2), 10g/l (1%) aqueoussolution (freshly prepared)10mlMagnesium chloride (MgCl 2), 10g/l (1%)aqueous solution10mlFinal pH: 7.31. Stir until dissolved and add 10g of neutral charcoal powder.2. Dispense 5–6ml of medium per 13mm ¥ 10mm screw-capped tube (avoidcrushing).3. Autoclave at 121°C for 20 minutes. Invert the tubes before the medium solidifiesin order to distribute the charcoal uniformly. Label the tubes “STUARTTRANSPORT MEDIUM, MODIFIED” and write the date. Store in the refrigerator.Sulfosalicylic acid, 30g/l (3%) solution (No. 57)Sulfosalicylic acid3 gDistilled waterq.s. 100mlLabel the volumetric flask “SULFOSALICYLIC ACID 3% SOLUTION” and writethe date.TIF (thiomersal–iodine–formaldehyde) fixative (No. 58)1. Prepare a stock solution:Tincture of thiomersal, 1:1000200mlFormaldehyde, 10% solution (No. 28)25mlGlycerol5 mlDistilled waterq.s. 250ml