Buffers and chemicals

Transcription

1 Buffers and chemicals A. Commonly Used Buffers Buffer Synonyms pk Molecular weight Phosphate (pk 1 ) , free acid Glycine-HCl Citrate (pk 1 ) , free acid Formate , Na salt Carbonate (pk 1 ) Succinate (pk 1 ) , free acid Acetate , Na salt Citrate (pk 2 ) , Na salt Succinate (pk 2 ) , dina salt MES , hydrate Carbonate (pk 2 ) Bicarbonate , bicarbonate Citrate (pk 3 ) , trina salt, dihydrate PIPES ACES MOPS HEPES Phosphate (pk 2 ) , Na salt, monobasic TES Barbital Barbitone , barbituric acid Veronal Triethanolamine TRICINE TRIS BICINE Glycylglycine Borate , Na tetraborate CHES Ethanolamine Glycine-NaOH , Na salt hydrate CAPS Triethylamine Phosphate (pk 3 ) , Na salt, dibasic 90

2 B. Concentrations of Commercial Liquids ph of dilute solutions Molecular Compound weight Molarity 1 M 0.1 M 0.01 M Acetic acid, glacial Formic acid Hydrochloric acid, 38% Nitric acid, 70% Phosphoric acid Sulfuric acid Ammonium hydroxide Ethanolamine, 99% Triethanolamine Formaldehyde, 37% Hydrogen peroxide, 30% Mercaptoethanol C. Standard Buffer Solutions mm Borate buffer solutions, ph at 25 C Dissolve g of borate (Na 2 B 4 O 7 10H 2 O) in 70 ml of distilled water and add x ml of 0.1 N HCl according to the ph required. Then Make up to 100 ml mm Borate buffer solutions, ph at 25 C Dissolve g of Borate (Na 2 B 4 O 7 10H 2 O) in 70 ml of distilled water and add x ml of 0.1 N NaOH according to the ph required. Then 91

3 dilute to 100 ml mm Glycine-HCl buffer solutions, ph at 25 C * Glycine, C 2 H 5 NO 2, M.W Dissolve g of glycine in 70 ml of distilled water and add x ml of 0.2 N HCl according to the ph required. Then QS to 100 ml mm Glycine-NaOH buffer solutions, ph at 25 C * Glycine, C 2 H 5 NO 2, M.W Dissolve g of glycine in 70 ml of distilled water and add x ml of 0.2 N NaOH according to the ph required. Then QS to 100 ml

4 M Sodium carbonate-sodium bicarbonate buffer solutions, ph at 20 C * Na 2 CO 3 10H 2 O, M.W * NaHCO 3, M.W Dissolve x g of Na 2 CO 3 10H 2 O and y g of NaHCO 3 in distilled water according to the ph required and bring the total volume to 100 ml. ph x g y g ph x g y g mm Carbonate buffer solutions, ph at 25 C * NaHCO 3, M.W Dissolve 0.21 g of NaHCO 3 in 70 ml of distilled water and add x ml of 0.1 M NaOH according to the ph required. Then dilute to 100 ml mm Succinic acid-naoh buffer solutions, ph at 25 C * Succinic acid, C 4 H 6 O 4, M.W Dissolve g of succinic acid in 50 ml of distilled water and add x ml of 0.2 N NaOH according to the ph required. Then QS to 100 ml. 93

5 Citric acid-na 2 HPO 4 (McIlvaine) buffer solutions, ph approx * Citric acid monohydrate, C 6 H 8 O 7 H 2 O, M.W * Na 2 HPO 4 anhydrous, M.W * Na 2 HPO 4 2H 2 O, M.W Mix x ml of 0.1 M citric acid (21.01 g/l) and y ml of 0.2 M Na 2 HPO 4 (Na 2 HPO 4 anhydrous 28.4 g/l or Na 2 HPO 4 2H 2 O g/l) according to the ph required. ph x ml y ml ph x ml y ml M Citric acid-sodium citrate buffer solutions, ph * Citric acid monohydrate, C 6 H 8 O 7 H 2 O, M.W * Trisodium citrate dihydrate, C 6 H 5 O 7 Na 3 2H 2 O, M.W Dissolve x g of citric acid and y g of trisodium citratein in distilled water according to the ph required and make up to 100 ml. 94

6 ph x g y g ph x g y g M Sodium acetate-acetic acid buffer solutions, ph approx * Sodium acetate trihydrate, CH 3 COONa 3H 2 O, M.W * Acetic acid glacial, CH 3 COOH, M.W Mix x g of sodium acetate and y ml of glacial acetic acid according to the required ph and make up to 100 ml. ph x g y ml ph x g y ml M Na 2 HPO 4 -NaH 2 PO 4 buffer solutions, ph at 25 C * Na 2 HPO 4 anhydrous, M.W ; 0.2 M solution contains g/l * Na 2 HPO 4 2H 2 O, M.W ; 0.2 M solution contains g/l * Na 2 HPO 4 12H 2 O, M.W ; 0.2 M solution contains g/l * NaH 2 PO 4 H 2 O, M.W ; 0.2 M solution contains g/l * NaH 2 PO 4 2H 2 O, M.W ; 0.2 M solution contains g/l Mix x ml of 0.2 M Na 2 HPO 4 and y ml of 0.2 M NaH 2 PO 4 and dilute to 100 ml with distilled water. 95

7 ph x ml y ml ph x ml y ml mm Triethanolamine hydrochroride-naoh buffer solutions, ph at 20 C * Triethanolamine hydrochloride, C 6 H 15 NO 3 HCl,M.W The hydrochloride is prepared by dissolving pure triethanolamine in 1 volume of ethanol, neutralising with conc. HCl, and cooling to 0 C. Dissolve g of triethanolamine hydrochloride in 50 ml of distilled water and add x ml of 0.1 N NaOH according to the ph required. Then Make up to 100 ml with distilled water mm Tris (hydroxymethyl) aminomethane-hcl buffer solutions, ph at 25 C * Tris, C 4 H 11 NO 3, M.W Dissolve g of tris in 50 ml of distilled water and add x ml of 0.1 M HCl according to the required ph. Dilute to 100 ml with H 2 O. 96

8 NOTE: Tris solutions absorb CO 2 from the air. # 0.1 N HCl Dilute conc. HCl (commercial, 38%) 116 times with distilled water (8.621 ml/l). # 0.1 N NaOH Dissolve 4 g of NaOH in 1 litre of distilled water. PBS (10X) Na 2 HPO 4 anhydrous g (Na 2 HPO 4 2H g) (Na 2 HPO 4 12H g) KH 2 PO g KCl... 2 g NaCl g Distilled Water... 1 litre 97