Validity period of reagents

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The shelf life of reagents: To be honest, don’t expect any standard or document to specify a shelf life that you can simply follow. No standard or document dares to determine the shelf life of reagents used in laboratories, and this is because the actual shelf life of reagents varies depending on the environmental conditions and usage conditions in each laboratory, as well as the purpose of the experiments being conducted. The criterion for determining whether a reagent is effective is that its use should not affect the test results. Also, never ask others which standard specifies this expiration date; if one is truly determined, they can study statistical methods and calculate the expiration date for the reagents in their own laboratory. 2. Validity period of references
Name, Concentration, Validity Period
Starch indicator: 5 g/L – 5 days; 10 g/L – 5 days
Ammonium chloride-hydrochloric acid buffer solution, pH = 9.6–9.7 – 7 days
Ethanol solutions: 78%, 75%, 72%, 70% – all 7 days
Iodine indicator – 7 days
Magnesium oxide 2% – 7 days
Resorcinol hydrochloride solution – 7 days
Ammonia solution 1:04 – 47 days
Bromocresol purple aqueous solution 1.60% – 7 days
Phenolphthalein indicator: 5 g/L and 10 g/L – both 7 days
Protein removal reagent – 7 days
Saturated picric acid solution – 7 days
Silver nitrate solutions: 9.6 g/L and 50 g/L – both 7 days
Starch solution 1% – 7 days
Rosolic acid 0.5 g/L – 7 days
Working solution (for urea detection) – 7 days
Iodine-potassium iodide solution – 7 days
Hydrochloric acid-N-(1-naphthyl)ethylenediamine 0.10% – 10 days
Naphthylamine hydrochloride 1 g/L – 10 days
Saturated methylene blue solution – 14 days
Color-developing agent (for detecting adulteration in raw milk) – 15 days
Methylene blue indicator: 1 g/L and 10 g/L – both 1 month
Methyl red indicator: 0.1 g/L and 2 g/L – both 1 month; 1 g/L – 1 month
Bromothymol blue indicator 1% – 1 month
Bromocresol green indicator: 1 g/L and 2 g/L – both 1 month
Potassium chromate indicator: 50 g/L and 100 g/L – both 1 month
Ferroin indicator – 1 month
Calcon carboxylate indicator (1:100) – 1 month
Crystal violet aqueous solution 0.20% – 1 month
Fluorescein indicator 0.5 g/100 ml – 1 month
Solid methylthymol blue indicator – 1 month
Ammonia buffer solution, pH = 10.0 – 1 month
pH calibration solution, pH = 9.18 – 1 month
pH calibration solution, pH = 4.003 – 1 month
pH calibration solution, pH = 6.86 – 1 month
Triethanolamine-hydrochloric acid buffer solution 14.92 g/L – 1 month
Bromothymol blue 0.04% – 1 month
Crystal violet staining solution – 1 month
Safranin staining solution – 1 month
Iodine solution – 1 month
Sodium hydroxide solutions: 4%, 40%, 25%, 10% – all 1 month
Potassium hydroxide ethanol solution 28 g/L – 1 month
Aluminum hydroxide suspension – 1 month
Brilliant green solution 0.10% – 1 month
Potassium chloride solutions: 3 mol/L and saturated – both 1 month
Potassium ferrocyanide solution 172 g/L – 1 month
Zinc acetate solution 219 g/L – 1 month
Lead acetate solution 200 g/L – 1 month
Acetic acid solution 1:04 – 1 month
p-Aminobenzenesulfonamide solution 1% – 1 month
Boric acid solution 20 g/L – 1 month
Disulfonic acid phenol reagent – 1 month
Barium chloride solutions: 0.1 mol/L and 100 g/L – both 1 month
Potassium oxalate-sodium hydrogen phosphate solution 0.131018519 – 1 month
Copper citrate solution – 1 month
Lead acetate solution 200 g/L – 1 month
Ammonium oxalate solution 4% – 1 month
Triethanolamine solution 1:02 – 1 month
Potassium nitrate standard solution – 1 month
Nitrate nitrogen standard solution – 1 month
Zinc sulfate 535 g/L – 1 month
Manganese sulfate 380 g/L – 1 month
Copper sulfate solution 20 g/L – 1 month
Ferric chloride hexahydrate 0.25 g/L – 1 month
Alkaline reagents – 1 month
Zinc dichromate 12.285 g/L – 1 month
Potassium dichromate 12.258 g/L – 1 month
Sulfanilamide 5 g/L – 1 month
Magnesium sulfate heptahydrate 22.5 g/L – 1 month
Triethanolamine solution 1:03 – 1 month
Wijs solution 13 g/L – 1 month
Boric acid solution 20 g/L – 1 month
Quimolybdocopper solution – 1 month
Citric acid solution 0.1 mol/L – 1 month
Ammonium chloride-EDTA solution – 1 month
Cadmium sulfate solution – 1 month
Ammonium hydroxide-ammonia buffer solution – 1 month
Iodine stock solution – 1 month
Potassium iodide solutions: 1 mol/L, 10%, 15%, and saturated – all 1 month
Potassium iodate standard solution 10 mmol/L – 1 month
Iodine solution 0.005 mol/L – 1 month
Magnesium chloride 2% – 1 month
Calcium chloride 27.5 g/L – 1 month
Alkaline potassium sodium tartrate – 1 month
Nessler’s reagent – 1 month
Fehling’s reagents A and B 0.5 g – 1 month
Chloroform-glacial acetic acid solution 2:03 – 1 month
Barium chloride solution 25 g/L – 1 month
Ether-ethanol 2:01 – 1 month
Tetramine solution – 1 month
Magnesium sulfate heptahydrate 22.5 g/L – 1 month
Ammonia nitrogen standard solutions: 10.0 µg/ml and 1000 µg/ml – both 1 month
Potassium sodium tartrate 500 g/L – 1 month
Alkaline potassium iodide (for BOD5 determination) – 1 month
Sulfuric acid-silver sulfate solution 100:01:00 – 1 month
Anhydrous manganese(II) sulfate solution 340 g/L – 1 month
Sodium azide reagent – 1 month
Sodium thiosulfate 0.01 mol/L – 1 month
Ammonium iron(II) sulfate 0.1 mol/L – 1 month
Anhydrous calcium chloride solution 27.5 g/L – 1 month
α-Naphthol ethanol solution 1% – 1 month
Periodic acid – 1 month
Sodium thiosulfate 1.0 mol/L – 1 month
Sodium thiosulfate solution 0.35% – 1 month
Hydrogen peroxide 10% – 1 month
Bromocresol purple ethanol solution 1.60% – 1 month
Bromocresol purple aqueous solution 0.04% – 1 month
Silver nitrate 2% – 1 month
Potassium nitrate standard stock solution 1.468 g/L – 1 month
Sodium nitrite standard solution – 1 month
Saturated sodium hydroxide solution – 2 months
Congo red indicator 1 g/100 ml – 2 months
Nitric acid solution 1:01 – 2 months
Potassium permanganate solution 0.1 mol/L – 3 months
Sulfuric acid solutions: 0.1 mol/L, 1.0 mol/L, 0.5 mol/L – all 3 months
Hydrochloric acid solutions: 0.5 mol/L and 2 mol/L – both 3 months
Silver nitrate solution 0.1 mol/L – 3 months
Sulfuric acid solution 1:15 – 3 months
Sulfuric acid 90% – 3 months
Sulfuric acid solution 2 mol/L – 3 months
Hydrochloric acid solution 2 mol/L – 3 months
Diacetyl monoxime 2% – 6 months
Acidic reagents – 6 months
Nitrate nitrogen stock solution 7.218 g/L – 6 months