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Articles from the Molekula editorial team
Coverage of chemistry, regulatory updates, methods, supply-chain insight, and product spotlights. New articles published daily.
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Method
Lithium chloride in molecular biology: RNA precipitation and beyond
Lithium chloride (LiCl) is a critical reagent in molecular biology, primarily used for RNA precipitation due to its high ionic strength and ability to disrupt hydrogen bonding. It is effective at concentrations of 0.3–1.0 M, with optimal recovery at 0.5 M. LiCl is also used in protein purification and nucleic acid fractionation. Its use is supported by ISO and REACH compliance, and it is available in ACS and FCC grades. Safety data (SDS) and CoA are provided by suppliers.
Jun 19, 2026 · 5 min read -
Method
Sucrose Density-Gradient Centrifugation: Practical Tips for Optimal Results
Sucrose density-gradient centrifugation separates macromolecules by buoyant density. Key factors include gradient preparation accuracy, rotor type, temperature control, and sample loading. Use high-purity sucrose (≥99.5%) and ensure gradient homogeneity to avoid band distortion. Centrifugation times and speeds depend on the target molecule (e.g., 100,000 × g for 2–4 hours for ribosomes). Always validate gradients with marker proteins or nucleic acids.
Jun 16, 2026 · 4 min read -
Method
Sodium Dodecyl Sulfate (SDS) in Protein Gel Electrophoresis: A Technical Overview
SDS is a critical detergent in SDS-PAGE, denaturing proteins and imparting uniform negative charge. It enables separation by molecular weight, with typical concentrations of 0.1–1% (w/v) in running buffers and gels. SDS is used in conjunction with reducing agents like DTT or TCEP to break disulfide bonds. Its compatibility with downstream applications such as Western blotting and mass spectrometry is well established.
Jun 14, 2026 · 4 min read -
Method
Imidazole as a buffer and metal-affinity elution reagent: practical considerations for biochemical applications
Imidazole is widely used in biochemical workflows as a pH buffer and for eluting histidine-tagged proteins from Ni-NTA resins. It is effective between pH 6.5 and 8.5, with a pKa of 6.95 at 25 °C. Typical concentrations range from 100 to 500 mM in elution buffers. Its low toxicity and compatibility with downstream applications make it a standard reagent in protein purification and enzymatic assays.
Jun 12, 2026 · 5 min read -
Method
Filter Sterilisation of Biochemical Buffers: Choosing Pore Size and Material
Filter sterilisation of biochemical buffers requires selecting a pore size of 0.22 µm for standard sterilisation and 0.1 µm for ultrafiltration. Membrane materials such as PVDF, PES, and nylon are commonly used, with PVDF offering superior chemical resistance and low protein binding. Compatibility with buffer pH, solvents, and intended application is critical.
Jun 6, 2026 · 5 min read -
Method
Calibrating pH Meters for Chemistry and Biology Buffers
pH meters must be calibrated using certified buffer solutions (e.g., pH 4.01, 7.00, 10.01) at the temperature of use to ensure accuracy. Calibration should be performed before each use and after electrode storage. Temperature compensation is essential; most meters have automatic temperature compensation (ATC) via a built-in sensor. For biological and chemical applications, calibration with at least two points is standard. Repeated calibration with the same buffer may indicate electrode drift or contamination.
Jun 5, 2026 · 5 min read -
Method
Diluting Concentrated Stocks: C1V1 = C2V2 and Serial Dilutions
To dilute concentrated stocks accurately, use the formula C1V1 = C2V2, where C1 and V1 are the initial concentration and volume, and C2 and V2 are the final concentration and volume. For serial dilutions, apply the formula iteratively across multiple steps, ensuring consistent dilution factors. Precision depends on calibrated equipment and correct technique.
Jun 3, 2026 · 4 min read -
Method
Calculating Molarity: Mass, Molecular Weight, Volume and Common Pitfalls
Molarity (mol/L) is calculated using mass (g), molecular weight (g/mol), and volume (L). The formula is M = (mass / MW) / volume. Common errors include incorrect unit conversion, ignoring solute hydration, and inaccurate volume measurement. Always verify units and use calibrated equipment.
Jun 2, 2026 · 4 min read -
Method
CAS Registry Numbers Explained: How to Find the Right One
CAS registry numbers are unique identifiers for chemical substances, essential for accurate sourcing and regulatory compliance. Each number is assigned by the Chemical Abstracts Service and consists of up to 10 digits separated by hyphens. Use official databases like CAS SciFinder or Reaxys to verify and locate the correct number for a given compound.
May 28, 2026 · 4 min read