Description

HEPES Ultrapure Grade is a refined version of the standard HEPES buffer, designed for high-sensitivity biological and molecular workflows. It delivers the same reliable buffering performance as Biochemical Grade, but with significantly reduced UV-absorbing impurities — minimizing interference in optical and enzyme-based assays.

Both Biofargo's Biochemical and Ultrapure grades are supplied at ≥99.5% assay purity. The difference is refinement: Ultrapure Grade is further processed to achieve lower absorbance at A260 and A280, indicating reduced organic contaminants. This makes a measurable difference in applications where background signal, enzyme stability, or cell viability is critical — such as PCR, fluorescence imaging, and sensitive cell-based assays.

The product forms a clear, colorless solution and maintains stable buffering capacity near physiological pH (pKa 7.6 at 20°C), with tight control of sulfate, residue, and UV absorbance.

For routine cell culture, general protein work, and standard buffer preparation where UV background is not a concern, our HEPES Biochemical Grade is the more cost-effective option.

Specifications

CAS No.	7365-45-9	7365-45-9
Molecular Formula	C₈H₁₈N₂O₄S	C₈H₁₈N₂O₄S
Molecular Weight	238.31	238.31
Purity	≥99.5%	≥99.5%
Grade	Biochemical Grade	Ultrapure Grade
Solubility (1M in H₂O)	Colorless, clear	Colorless, clear
Appearance	White powder	White powder
pKa (20°C)	7.4 – 7.7	7.4 – 7.7
Sulfate	≤0.05%	≤0.05%
Loss on Drying	≤0.5%	≤0.3%
Residue on Ignition	—	≤0.1%
Heavy Metals (Pb)	≤5 ppm	—
Heavy Metals (Fe)	≤3 ppm	—
UV Absorbance (250 nm, 1M)	≤0.10	≤0.10
UV Absorbance (260 nm, 1M)	≤0.05	≤0.05
UV Absorbance (280 nm, 1M)	≤0.04	≤0.04
Recommended Application	General buffers	Cell culture / PCR / sensitive assays

Features

Low UV Absorbance for High Sensitivity Applications — Reduced A260/A280 values indicate lower levels of organic impurities, minimizing interference in fluorescence, PCR, and imaging workflows.
High Chemical Purity (≥99.5%) — Ensures consistent buffering performance across experimental batches while meeting standard reagent-grade requirements.
Optimized for Optical and Enzyme-Based Systems — Lower background signal improves assay accuracy in fluorescence detection, enzyme kinetics, and molecular biology experiments.
Stable Physiological Buffering Capacity — Maintains pH stability around physiological conditions (pKa ~7.6), ideal for biological systems.
Controlled Inorganic Residues — Tight limits on sulfate content and residue on ignition contribute to improved solution clarity and reproducibility.
Excellent Solubility and Clarity — Forms a clear, colorless solution suitable for optical and analytical applications.

Applications

Cell Culture Systems — Suitable for sensitive cell-based assays where reduced impurity levels help maintain cell viability and consistency.
PCR / qPCR / Molecular Biology — Lower UV absorbance minimizes interference with nucleic acid detection and amplification reactions.
Fluorescence Imaging & Optical Assays — Reduced background signal improves sensitivity in fluorescence-based detection systems.
Enzyme Reactions — Ideal for kinase assays, polymerase reactions, and other enzyme-sensitive applications.
Electrophysiology & Neuroscience Research — Suitable for applications sensitive to oxidative or impurity-related interference.
Advanced Research & Process Development — Applicable in workflows requiring higher purity buffering systems and reproducibility.

Safety Disclaimer

This product is intended for laboratory research use only. Not for drug, human, or veterinary use. Review the SDS provided by Biofargo for detailed handling, storage, hazard, and disposal information. Use appropriate PPE when handling. Dispose of waste in accordance with local, state, and federal regulations.

FAQ

When should I use Ultrapure Grade HEPES instead of Biochemical Grade?
Choose Ultrapure Grade when UV-absorbing impurities could interfere with your results — for example in PCR and qPCR, fluorescence imaging, optical and absorbance-based assays, sensitive enzyme kinetics, or cell culture work where cell viability is critical. For routine buffer preparation, general cell culture, and standard protein work, Biochemical Grade is a more cost-effective choice that delivers the same ≥99.5% assay purity. (See our HEPES Biochemical Grade page.)

Does Ultrapure Grade HEPES have higher purity than Biochemical Grade?
Both grades are supplied at ≥99.5% assay purity. The distinction is in refinement: Ultrapure Grade has lower UV absorbance (A250/A260/A280), reflecting reduced organic impurities, plus tighter control of residue. So the difference is less about the headline purity number and more about the impurity profile relevant to sensitive optical and enzymatic applications.

Why does low UV absorbance matter?
UV-absorbing impurities in a buffer add background signal to any measurement made by absorbance or fluorescence. In PCR, nucleic acid quantification, and fluorescence imaging, that background can reduce sensitivity and affect data quality. A buffer with low UV absorbance keeps the buffer itself from interfering with the measurement.

Is Ultrapure Grade HEPES suitable for cell culture?
Yes. Ultrapure Grade is well suited to sensitive cell-based assays, where reduced impurity levels help support cell viability and experimental consistency. For routine cell culture where impurity sensitivity is not a concern, Biochemical Grade also works well and costs less.

Publications

Recent research using HEPES buffer (source: PubMed)

Corazolla, E.M., et al. 2026. HEPES in Cell Culture Alters the Multi-Omics Profile Exhibited by Gaucher Disease Fibroblasts. J Cell Biochem 127(1), e70080. DOI — Study examining how HEPES in culture media influences cellular metabolism and diagnostic outcomes; relevant context for choosing buffer grade in sensitive cell work.
Merli, M., et al. 2022. Pectin-based bioinks for 3D models of neural tissue produced by a pH-controlled kinetics. Front Bioeng Biotechnol 10, 1032542. DOI — HEPES buffer used as a component in optimizing pH-controlled bioink formulations for 3D-bioprinted neural cell models.
Yeung, S.Y., et al. 2022. Reversible Self-Assembled Monolayers with Tunable Surface Dynamics for Controlling Cell Adhesion Behavior. ACS Appl Mater Interfaces 14(37), 41790–41799. DOI — HEPES buffer solution (pH 8) used as the medium for preparing reversible self-assembled monolayers for cell adhesion studies.

HEPES Ultrapure Grade, ≥99.5% — Low UV Absorbance