Reagent Calculators

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A reagent is a substance used in a chemical reaction or analytical procedure to detect, measure, or produce another substance. Reagents range from simple inorganic chemicals (sodium hydroxide, hydrochloric acid) to complex biological molecules (antibodies, restriction enzymes, PCR master mixes). Reagent quality (grade) is critical in analytical chemistry — different grades have different purity levels suited to different applications. Proper preparation, storage, labeling, and disposal of reagents are essential for laboratory safety, reproducibility, and compliance with regulatory requirements.

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Reagent Grades

  • ACS grade: Meets American Chemical Society purity specifications; suitable for most analytical procedures
  • HPLC grade: High purity for chromatographic use; low UV absorbance; suitable as mobile phase
  • Analytical grade (AR): High purity; traceable certificate of analysis
  • Ultrapure grade (e.g., SIGMA Molecular Biology grade): Further purified for molecular biology applications; DNase/RNase-free, protease-free
  • Technical/industrial grade: Lowest purity; suitable only for non-analytical applications
  • HPLC-MS grade: Highest purity for mass spectrometry; minimal ion-suppressing contaminants

Common Lab Reagents

  • Buffers: PBS, Tris-HCl, HEPES — maintain pH in biological experiments
  • Reducing agents: DTT, β-mercaptoethanol — reduce disulfide bonds
  • Detergents: SDS (denaturing), Triton X-100 (non-ionic), CHAPS (zwitterionic)
  • Stains: Coomassie blue, ethidium bromide, SYBR Green

Reagent Preparation Best Practices

Label: name, concentration, date prepared, preparer, expiry. Prepare fresh when stability is limited (DTT, some enzyme buffers). Filter-sterilize (0.22 μm) solutions for cell culture. Store as specified: 4°C, −20°C, or RT, light-sensitive reagents in amber bottles.

Safety

Consult the Safety Data Sheet (SDS) before using any new reagent. Use appropriate PPE. Hazardous categories: flammable (ethanol, acetone), corrosive (HCl, NaOH), toxic (ethidium bromide, acrylamide), carcinogenic.

Glossary

Reagent Grade
The purity classification of a chemical: ACS grade (meets ACS specifications); HPLC grade (low UV absorbance); molecular biology grade (nuclease/protease-free); determines suitability for specific applications.
Safety Data Sheet (SDS)
A standardized 16-section document providing hazard, handling, storage, PPE, and emergency information for chemical substances; required by OSHA for all hazardous laboratory chemicals.
DTT (Dithiothreitol)
A common reducing agent (1–10 mM) that reduces disulfide bonds and maintains protein sulfhydryl groups in reduced state; unstable — prepare fresh or store at −20°C.

Frequently Asked Questions

ACS grade (American Chemical Society): meets ACS purity standards; suitable for most analytical chemistry and general laboratory applications; typically 99%+ purity for common chemicals. HPLC grade: high purity with guaranteed low UV absorbance and particle content; used for chromatographic mobile phases and solvents; may not have all the specific impurity limits of ACS grade. Analytical reagent (AR) grade: similar to ACS grade with a traceable certificate of analysis showing actual impurity levels; used in titrimetry and other quantitative analyses. Molecular biology grade (Ultrapure): additionally tested to be free of nucleases, proteases, and pyrogens; required for PCR, cell culture, and molecular biology applications.

Proper labeling must include: chemical name and concentration; date prepared; preparer's initials; expiration date; hazard warnings (flammable, corrosive, biohazard). Storage requirements vary by reagent: 4°C (most protein solutions, antibodies, enzyme stocks); −20°C (enzymes like Taq polymerase, oligonucleotides, restriction enzymes); room temperature (most inorganic salts, buffers at neutral pH); −80°C (long-term storage of labile enzymes, cell lines). Protect light-sensitive reagents (fluorescent dyes, ethidium bromide, methylene blue) in amber bottles or foil. Discard degraded reagents — failed experiments from degraded reagents waste far more time than frequent preparation of fresh stocks.

Dithiothreitol (DTT): maintains free sulfhydryl groups in proteins; prevents oxidation of Cys residues; used in protein purification, enzyme assays, and reducing conditions in gel electrophoresis. Concentration typically 1–10 mM; unstable — make fresh, store at −20°C, and add fresh before use. β-Mercaptoethanol (β-ME): similar function but odorous (avoid in open bench areas); used in SDS-PAGE loading buffer to reduce disulfide bonds and ensure complete protein denaturation. TCEP (tris(2-carboxyethyl)phosphine): non-thiol reducing agent; more stable than DTT; works over wider pH range; compatible with some downstream applications that DTT is not.

A Safety Data Sheet (SDS), formerly called Material Safety Data Sheet (MSDS), is a standardized document (16 sections per GHS/OSHA format) providing comprehensive information about a chemical substance: physical and chemical properties; health hazards and toxicological data; safe handling and storage; PPE requirements; emergency response (spill, fire, first aid procedures); disposal guidelines; regulatory status. OSHA requires SDS availability for all hazardous chemicals in the workplace. Before using any new reagent: read the SDS, verify appropriate PPE, confirm proper ventilation, and understand emergency procedures. SDS documents are available from chemical suppliers (Sigma-Aldrich, Thermo Fisher, Fisher Scientific).