Common Stock Solution Preparation

EDTA (EthyleneDiamineTetraAcetic acid) is a polyamino carboxylic acid widely used in molecular biology as a chelating agent. It sequesters divalent and trivalent metal ions such as Zn2+, Ca2+, and Fe3+, which are required cofactors for many enzymes, including DNases.

EGTA (Ethylene Glycol Tetraacetic Acid) is a highly selective calcium ion chelator used in biochemical and cell biology experiments to control free Ca2+ concentrations. EGTA binds calcium ions with much higher affinity compared to magnesium, making it useful for buffering and chelation applications where calcium-specific sequestration is needed.

PIPES (Piperazine-N,N′-bis(2-ethanesulfonic acid) and its sodium salt forms are zwitterionic Good’s buffers commonly used in biochemical and cell biology experiments. PIPES operates effectively in the pH range of approximately 6.1–7.5 and has minimal interaction with divalent metal ions, making it suitable for buffering applications where ion neutrality is important.

ATP disodium salt (Adenosine 5′-triphosphate disodium salt) is the biologically active form of ATP commonly used as an energy substrate in enzymatic assays, cell metabolism studies, and molecular biology applications. It participates in phosphorylation reactions and serves as the universal energy currency in cells.

Dithiothreitol (DTT), also known as Cleland’s reagent, is a commonly used reducing agent in protein biochemistry. It reduces disulfide bonds (–S–S–), stabilizes enzymes, and protects functional thiol groups in proteins. Aqueous stock solutions are best prepared fresh due to susceptibility to oxidation.

IPTG (Isopropyl β-D-1-thiogalactopyranoside) is a lactose analog widely used in molecular biology to induce the expression of recombinant proteins in E. coli under the control of lac or tac promoters. IPTG binds to the lac repressor, releasing it from the lac operator and allowing transcription of downstream genes. It is also used for blue/white selection in cloning.

Tris (Tris(hydroxymethyl)aminomethane), also known as Trizma or THAM, is a widely used biological buffer in molecular biology and biochemistry. It has a pKa of ~8.08 at 25 °C and an effective buffering range between ~7.2 and 9.0, making it suitable for physiological pH applications. The solution’s pH is temperature dependent and should be adjusted at the temperature of intended use.

HEPES (4-(2-Hydroxyethyl)piperazine-1-ethanesulfonic acid) is a zwitterionic Good’s buffer widely used in cell biology and biochemical research. It exhibits a pKa around 7.5 at 25 °C and provides effective buffering between pH 6.8 and 8.2, making it suitable for physiological pH applications. HEPES has low metal ion binding and high solubility in water.

Monosodium phosphate (also called Sodium dihydrogen phosphate) can be used to prepare sodium phosphate buffers or other phosphate-based solutions. A 1 M stock solution is frequently used as a component when preparing phosphate buffers of desired pH by mixing with dibasic sodium phosphate.

A 1 M sodium phosphate dibasic stock solution can be prepared from sodium phosphate dibasic dihydrate (Na₂HPO₄·2H₂O). This solution is commonly used as a component in phosphate buffer systems or other biological applications requiring phosphate ions.

Monopotassium phosphate (KH₂PO₄) is a water-soluble inorganic salt commonly used in biological and biochemical laboratories as a component of phosphate buffer systems. It dissolves readily in water and forms a mildly acidic solution, and is often combined with other phosphate salts to adjust pH in buffer preparation.

Dipotassium phosphate (K₂HPO₄) is a water-soluble inorganic salt commonly used in biochemical and molecular biology applications as a buffering component. It dissolves readily in water and provides alkaline phosphate buffering capacity, often used with other phosphate salts to prepare buffers of precise pH.

Calcium chloride is a salt of calcium and chlorine widely used in biological and chemical laboratories as a source of calcium ions and for preparing ionic solutions. Calcium chloride is available in anhydrous and various hydrated forms, all of which can be used to prepare stock solutions, but hydrates such as the dihydrate are easier to handle due to hygroscopicity of the anhydrous form.

Sodium chloride (NaCl) is a simple inorganic salt widely used in biological, biochemical, and chemical laboratories. It functions as an ionic strength adjuster, a key component in buffer formulations, saline solutions, and cell culture media. The molar mass of sodium chloride is 58.44 g/mol, and this value is used to calculate the mass required for a desired molar concentration.

Potassium chloride (KCl) is a simple inorganic salt widely used in biological, biochemical, and chemical laboratories. It dissolves readily in water and is commonly used to adjust ionic strength, prepare saline solutions, and formulate buffer systems. The molar mass of potassium chloride is 74.55 g/mol.

Magnesium chloride (MgCl2) is a highly water-soluble inorganic salt widely used in molecular biology, biochemistry, and cell biology. Mg2+ acts as an essential cofactor for many enzymes, including DNA polymerases, RNA polymerases, and restriction enzymes.

Ammonium chloride (NH₄Cl) is a white crystalline inorganic salt with high solubility in water, commonly used in biochemical and analytical laboratory settings. It dissociates into ammonium (NH₄⁺) and chloride (Cl⁻) ions in aqueous solution.

Rubidium chloride (RbCl) is a white crystalline inorganic salt that dissolves readily in water and dissociates into rubidium (Rb⁺) and chloride (Cl⁻) ions. It is used in analytical chemistry, research, and specialized biochemical applications.

Lithium chloride (LiCl) is an inorganic salt composed of lithium cations (Li+) and chloride anions (Cl−) forming white crystalline solids. It is highly soluble in water and hygroscopic, absorbing moisture from air.

Manganese(II) chloride (MnCl₂) is an inorganic salt that exists in anhydrous, dihydrate, and tetrahydrate forms. The hydrated forms are pink and readily dissolve in water to give solutions of Mn2+ ions.

Sodium fluoride (NaF) is an inorganic salt composed of sodium and fluoride ions. It appears as a white, odorless crystalline powder that dissolves readily in water to form clear solutions. In research and laboratory settings, aqueous solutions of NaF are commonly used as enzyme inhibitors and analytical reagents.

Biotin (vitamin B7) is a water-soluble vitamin that is only slightly soluble in neutral water but dissolves more readily in warm or alkaline solutions. A 1 mM biotin stock solution can be prepared in phosphate-buffered saline (PBS) for use in biochemical assays and cell culture supplements.

MOPS (3-(N-morpholino)propanesulfonic acid) is a zwitterionic biological buffer with a useful pH range of approximately 6.5–7.9. It is soluble in water and commonly used for biochemical assays, cell culture media, and protein purification applications.

L‑Glutamine is an essential amino acid used as a nutrient and nitrogen source in cell culture media. It is soluble in water and saline but unstable in solution, degrading over time into ammonia, which can be toxic to cells. Therefore, concentrated stock solutions should be prepared, sterile‑filtered, aliquoted, and stored frozen until use.

Ammonium sulfate ((NH₄)₂SO₄) is an inorganic salt widely used in biochemical and analytical laboratories. It dissolves readily in water, forming clear solutions frequently employed for salting‑out proteins, preparing ionic strength adjustment solutions, or general reagent stock solutions. Its solubility in water at 20 °C is high (≈76 g per 100 mL), and the solid appears as white crystalline powder.

Magnesium sulfate (MgSO₄) is highly soluble in water. Laboratory stock solutions are commonly prepared from the heptahydrate form (MgSO₄·7H₂O, MW = 246.47 g/mol) because the anhydrous form is very hygroscopic and difficult to weigh accurately. A 1 M stock solution using MgSO₄·7H₂O is a standard reagent for many biochemical and cell culture applications.

Aluminium sulfate is commonly available in hydrated forms such as hexadecahydrate (Al₂(SO₄)₃·16H₂O) and octadecahydrate (Al₂(SO₄)₃·18H₂O) or as the anhydrous salt. In laboratory settings, the octadecahydrate form is often used to prepare defined‑concentration stock solutions because of its stable crystalline state.

Potassium alum (aluminum potassium sulfate dodecahydrate) is a crystalline inorganic salt that dissolves readily in water to form acidic solutions. It is commonly used in analytical chemistry, water treatment, and as a reagent in laboratory protocols. The hydrated form with 12 molecules of water (KAl(SO₄)₂·12H₂O, MW = 474.39 g/mol) is preferred for solution preparation because it is stable and easy to weigh.

Sodium thiosulfate (Na₂S₂O₃) and its hydrated form sodium thiosulfate pentahydrate (Na₂S₂O₃·5H₂O) are commonly used reagents in analytical chemistry and titration work. Standard stock solutions (e.g., 0.1 M) are frequently prepared for quantitative analyses or as intermediate solutions in redox titrations.

Glucose is a carbohydrate widely used in biochemical and cell culture applications as an energy source and to adjust osmolarity. A 1 M glucose stock solution can be prepared by dissolving 18 g of glucose in deionized or distilled water and adjusting the volume to 100 mL. Because glucose is sensitive to thermal degradation, solutions are typically sterilized by filtration rather than autoclaving.

Sodium bicarbonate (NaHCO₃), also known as baking soda, is a white crystalline powder that is highly soluble in water and mildly alkaline. A standard 1 M sodium bicarbonate solution has uses in buffering, titration analysis, and pH control. The molecular weight of NaHCO₃ is approximately 84.01 g/mol, and the solution at 25 °C has a pH around 8.3 when at 1 M concentration.

Sodium carbonate (Na₂CO₃), also known as soda ash or washing soda, is a white, water‑soluble inorganic compound with strong alkaline properties. In laboratory applications, sodium carbonate solutions are commonly used for pH adjustment, buffering alkaline media, titration analysis, and neutralization of acids. A 1 M stock solution provides a convenient reference for dilution and analytical work.

Trisodium citrate (also called sodium citrate) is a white crystalline salt that dissolves readily in water. It serves as a buffering agent, chelating agent, and pH regulator in biochemical applications. A 1 M stock solution is conveniently prepared by dissolving the appropriate mass of trisodium citrate dihydrate in water and adjusting to the desired final volume.

A 10 M sodium hydroxide (NaOH) stock solution is widely used for pH adjustment and alkaline reagent preparation. The molarity equals the normality for NaOH (10 M ≈ 10 N). A 10 M solution is strongly alkaline and requires careful handling due to the exothermic dissolution of NaOH pellets.

Ammonium acetate is a white crystalline salt widely used in buffer preparation, protein precipitation, chromatography mobile phases, and analytical applications. It is highly soluble in water. A 1 M stock solution can be prepared by dissolving the appropriate mass of ammonium acetate in water and adjusting the total volume.

Potassium acetate is the potassium salt of acetic acid and appears as a white deliquescent crystalline powder that dissolves readily in water. It is widely used as a buffering salt, pH regulator, and in analytical applications. To prepare a 1 M stock solution, dissolve the appropriate mass of potassium acetate in water and adjust to the desired final volume.

Sodium acetate is a sodium salt of acetic acid that dissolves readily in water. Both anhydrous and hydrated forms can be used to prepare a high‑concentration buffer. A 3 M sodium acetate buffer (pH 5.2) is commonly used in molecular biology for nucleic acid precipitation and other applications.

Magnesium acetate is a magnesium salt of acetic acid that dissolves readily in water and can be used as a source of magnesium ions or as a buffering agent. In laboratory settings, concentrated stock solutions (e.g., 1 M) are prepared by dissolving the appropriate mass of magnesium acetate in water and adjusting to the final volume. The tetrahydrate form is often chosen for accurate weighing.

Borate typically refers to boric acid (H₃BO₃) solutions or borate buffers used in biochemical and analytical assays. Boric acid dissolves readily in water and can be used as a stock reagent for preparing buffers with defined pH. Typical borate buffers in the pH 8–9 range are prepared by neutralizing boric acid with a base such as sodium hydroxide.

Sodium azide is supplied commercially as a white crystalline powder and is commonly added to reagent solutions to prevent microbial growth. It is also a potent inhibitor of some enzyme activities. It is highly toxic and reacts with metals and acids to form hazardous compounds; therefore, careful handling and safety precautions are essential.

Sodium orthovanadate (Na₃VO₄) is widely used in biochemical experiments as a **phosphatase inhibitor** and is typically prepared as a **200 mM (0.2 M) stock solution**. To maximize inhibitory activity, the solution must be activated (depolymerized) by repeated pH adjustment and boiling so that it remains colorless and stable at pH 10.

Potassium iodide (KI) is a white crystalline salt that dissolves readily in water, dissociating into potassium and iodide ions. It is widely used in analytical chemistry, biological buffers, nutrition studies, and as a reagent in iodometric titrations. To prepare a laboratory stock solution of defined concentration, dissolve measured KI in deionized water and adjust to the desired final volume.

Glycine‑Cl (glycine hydrochloride) is the hydrochloride salt of glycine, a simple amino acid. It is widely used in the preparation of Glycine‑HCl buffer systems, particularly at low pH ranges (commonly pH ≈ 2.2–3.6), suitable for affinity chromatography elution, immunoassays, and other applications requiring acidic buffer conditions.

Glycine is the simplest amino acid and is highly soluble in water. It is widely used in biochemical applications including buffer preparation (e.g., for electrophoresis or cell culture reagents) and as a reagent in various solution systems. A common laboratory storage form is a defined‑concentration stock solution (such as 1 M).