Bromine thymol blue indicator - 0.02%(w/v)in isopropyl alcohol , CAS No.B196457

CAS: B196457 Cat. No.: B196457

GRADE & PURITY 0.02%(w/v)in isopropyl alcohol

Storage

Room temperature

Shipped In

Normal

Specifications

사양 및 순도

0.02%(w/v)in isopropyl alcohol

보관 조건

Room temperature

배송

Normal

Application Protocols

Item-specific, validated protocols for SKU B196457 — Not specified for this item; refer to CoA/Spec Sheet. General/literature protocols for bromothymol blue as a pH indicator:

• Titration indicator (visual):
  1. Prepare a 0.04% w/v stock in 50% ethanol/water (or dissolve in minimal NaOH, then dilute with water).
  2. Add 2–4 drops per 100 mL of analyte solution before titration.
  3. Titrate to a stable green endpoint for neutrality (yellow→green→blue). Verify with a pH meter for critical assays.
• Spectrophotometric pH determination (ratiometric):
  1. Prepare buffer standards pH 6.0–8.0 and add a constant dye concentration (e.g., 5–20 µM).
  2. Record absorbance at λmax of acidic and basic forms (literature values depend on solvent); compute Ablue/Ayellow ratio vs pH to obtain calibration.
  3. Measure unknowns under identical conditions and interpolate pH from the calibration plot.
• Culture media coloration (research use): filter-sterilize a dilute aqueous stock and add to sterile media at low mg/L levels; validate that the indicator does not interfere with downstream readouts. Notes:
• Use amber vials and prepare fresh solutions routinely to maintain color fidelity.
• Dispose of dye-containing wastes per institutional guidelines.

Biological Roles

This product is a laboratory indicator dye and does not serve a physiological role. No biological activity or metabolic function is claimed for the material supplied. Literature/general context:

• Reporter of extracellular pH: Bromothymol blue is frequently incorporated at low concentrations in microbial culture media and certain cell-based assays as a visual readout of acidification/alkalinization due to metabolic activity (e.g., carbohydrate fermentation studies). It does not participate in metabolism but responds to proton activity.
• Spectroscopic pH probe: The dye’s acid/base forms have distinct absorbance bands, which can be calibrated for noninvasive monitoring of pH in buffered aqueous systems. This is a physical indicator function rather than a biochemical interaction.
• Adsorption/interaction considerations: Like many anionic dyes, the deprotonated form may weakly interact with proteins or polymeric cationic surfaces via electrostatic or hydrophobic contacts; such interactions can shift apparent pKa or λmax in complex matrices (literature observation). Validate calibrations in the exact matrix of use.
• Cytotoxicity/biocompatibility: Not specified for this item; if using in biological contexts, determine acceptable working concentrations empirically and consult open literature/SDS. Typical media concentrations are on the order of a few mg/L. Research use only: Not for diagnostic or therapeutic use.

Buffer Applications

As a colorimetric pH indicator, this dye is used to visualize pH in buffers rather than to form a buffer itself. Practical usage (literature/general):

• pH range: optimal visual transition around 6.0–7.6, suitable for phosphate (pH ~6–8), HEPES (pH 6.8–8.2), MOPS (pH 6.5–7.9), or carbonate/bicarbonate systems near neutrality.
• Typical indicator solution preparation:
  • 0.04–0.10% w/v indicator stock in 50–95% ethanol/water, or
  • 0.04% w/v in water adjusted with minimal NaOH/KOH to dissolve (yields blue stock); dilute into buffer/sample to avoid significant pH shift.
• Working concentration: add minimally (e.g., 1–3 drops of 0.04–0.1% solution per 50–100 mL) to avoid perturbing buffer capacity or ionic strength.
• Spectrophotometric calibration:
  • Prepare buffer standards at known pH (e.g., 6.0 to 8.0 in 0.2 pH steps), add constant dye concentration, and record Ablue/Ayellow ratio to construct a calibration curve in your matrix.
• Interferences and matrix effects:
  • Strongly colored or turbid samples obscure visual endpoints; use potentiometric pH measurement or UV–Vis ratiometry.
  • High ionic strength or cationic polymers can shift apparent pKa; validate in situ. Item-specific composition, purity, and recommended preparation for SKU B196457 — Not specified for this item; refer to CoA/Spec Sheet.

Green Alternatives

Considering the application is visual pH indication in water-rich systems, “greenness” relates to solvent use and dye handling rather than replacement of the chromophore itself. Options and trade-offs (literature/general):

• Solvent minimization:
  • Prefer purely aqueous stocks formed by slight neutralization with NaOH/KOH to dissolve the dye, avoiding ethanol or isopropanol. Trade-off: basic stock introduces alkalinity; control addition volumes carefully.
• Alternative indicators around neutral pH:
  • Phenol red (pH ~6.8–8.4): widely used in cell culture; lower bromine content but narrower neutrality coverage on the acidic side; color yellow→red.
  • Thymol blue (first transition ~1.2–2.8; second ~8.0–9.6): not optimal for neutral endpoints; less suitable in many neutral titrations, potentially requiring more organic co-solvent.
  • Methyl red (pH ~4.4–6.2): greener for acidic endpoints; not appropriate near pH 7.
• Operational improvements:
  • Use minimal indicator concentration consistent with a sharp endpoint (typically a few drops of 0.04–0.1% solution per 50–100 mL titration).
  • Employ amber glassware and make small, fresh batches to reduce waste from photobleaching.
• Comparative snapshot (literature):
  • Bromothymol blue vs phenol red: BTB centers around 7.0 (yellow→blue via green), offering symmetrical sensitivity about neutrality; phenol red shifts alkaline and may be preferable for biological media where pH >7.2. Note: Item-specific environmental profile, metal content, and impurity thresholds — Not specified for this item; consult SDS/CoA for accurate sustainability metrics.

Pharmaceutical Uses

• This product is supplied for research use only.
• Item-specific pharmacopeial status, residual solvent limits, or excipient qualifications — Not specified for this item; refer to CoA/Spec Sheet. General/literature context (non-clinical, formulation/manufacturing):
• Process indicator: dyes like bromothymol blue can serve as in-process visual markers for pH adjustment during development-scale buffer/media preparation, cleaning validation colorants, or visualization aids in training materials.
• Diagnostic kit components (research-use only): occasionally included as a visible pH reporter in research assay kits or culture media formulations to provide a quick readout of reaction progress or contamination (no diagnostic claims here).
• Extractables/leachables considerations: When formulating development prototypes that include indicator dyes, assess dye–polymer interactions and potential migration/adsorption to process materials; document as part of method development.
• Regulatory note: Transitioning any indicator-containing process to GMP or clinical manufacturing would require sourcing a compendial-grade material or otherwise establishing quality attributes (identity, purity, residual metals/solvents, microbiological limits) and safety assessments—outside the scope of this research-only catalog item.

Physical Properties

Item-specific physical constants for SKU B196457 — Not specified for this item; refer to CoA/Spec Sheet. Literature/general properties for bromothymol blue (indicator dye, free acid unless noted):

• Appearance: orange to red-brown crystalline powder (literature).
• pH transition range: approximately 6.0–7.6 (literature), with color change from yellow (acid) → green (near neutral) → blue (alkaline).
• Color forms (qualitative, literature):
  • Acidic (H2In): yellow, lactone-rich form.
  • Basic (In2−/In−): blue, extended phenolate resonance form.
• Solubility (literature): sparingly soluble in water as free acid; readily soluble in ethanol and in aqueous alkaline solutions (forms soluble salt/anion); indicator solutions often prepared at 0.02–0.1% w/v in ethanol/water or alkaline water.
• Melting/decomposition: dyes of this class typically darken and decompose on strong heating; exact MP/dec — Not specified for this item; refer to CoA/Spec Sheet.
• Partition/logP, pKa, refractive index, density — Not specified for this item; consult literature as needed and verify against your specification. Notes:
• Physical behavior depends strongly on counterion and hydration (free acid vs sodium salt). Verify the exact form supplied for precise constants.

Quality and Grades

• Item-specific grade/purity for SKU B196457 — Not specified for this item; refer to CoA/Spec Sheet.
• Interpreting grades for indicator dyes (general guidance):
  • Indicator grade: assessed for sharp, reproducible color transition within the stated pH range; limited interfering impurities that shift hue or broaden the transition.
  • Analytical reagent (AR) grade: high purity suitable for analytical titrations; low inorganic residue/ash content; minimal UV–Vis background at working wavelengths.
  • Dye content vs. total assay: some suppliers report “dye content” (chromophore %) rather than total assay; salts/hydrates affect apparent purity by weight. Confirm the exact chemical form (free acid, sodium salt, or mixed indicators) on the CoA.
• Stabilizers: Not typically required for solid indicator dyes. If present (e.g., desiccant in packaging), it serves to maintain dryness and prevent caking; none specified for this item.
• Recommended verification (practical):
  • Record absorbance spectra of working solutions at acidic and basic pH to verify expected λmax positions and isosbestic behavior (literature practice).
  • Perform a standard buffer titration (pH ~5.8→7.8) to confirm transition range sharpness and absence of trailing color.
• Documentation: For regulated work or method validation, rely on the lot-specific CoA for acceptance criteria.

Reaction and Applications

Primary use is as a visible pH indicator for analytical chemistry and process monitoring rather than as a reactant. Analytical and laboratory applications (literature/general):

• Aqueous acid–base titrations around neutrality: transition range ~pH 6.0–7.6, with a distinct yellow (acidic) to blue (basic) change via green at the endpoint—useful for carbonate system titrations, weak acid/weak base titrations, and environmental alkalinity assessments.
• Buffer verification and method qualification: quick screening of buffer make-up near physiological pH; observe color against prepared standards.
• Microbiology/cell culture media: added at low concentrations as a visual pH reporter in media formulations; supports rapid identification of metabolic acidification/alkalinization (non-sterile to sterile filtration required for culture use).
• Spectrophotometric pH assays: two-color forms with well-defined absorbance maxima enable ratiometric pH estimation and calibration curves in the near-visible region (verify λmax for the form and solvent used).
• Educational and demonstrative experiments: CO2 dissolution (carbonic acid formation) and respiratory gas exchange studies; acid rain and buffering capacity demonstrations. Practical tips:
• Prepare fresh dilute solutions for highest color fidelity; photobleaching and slow oxidative changes can occur upon storage in light/air.
• For endpoint clarity, titrate with vigorous mixing and avoid highly colored or turbid matrices that mask the transition; consider potentiometric backup for critical assays.

Reaction Conditions

There are no canonical “reaction conditions” for this item as it is used as a pH indicator rather than a reactant. General usage conditions (literature/good practice):

• Concentration: indicator stocks typically 0.04–0.1% w/v; add minimally to analytical mixtures (a few drops per 50–100 mL) to avoid perturbing equilibria.
• pH window: most informative in the 6.0–7.6 range; outside this range the color is predominantly one form (yellow in acid, blue in base) and provides less sensitivity.
• Temperature: ambient laboratory conditions; extreme temperatures may alter the apparent transition range slightly due to pKa temperature dependence (≈ −0.002 to −0.01 pH units/°C typical for indicators; verify empirically).
• Light/oxygen exposure: minimize prolonged exposure when preparing standards for spectrophotometric calibration; use amber glass and nitrogen blanket if long-term optical stability is required.
• Matrix: ionic strength and solvent composition (ethanol content) can shift the transition characteristics; keep conditions consistent between calibration and measurement. Item-specific validated conditions, λmax, extinction coefficients — Not specified for this item; consult literature and verify experimentally for your application.

Safety and Handling

Item-specific hazard classification for SKU B196457 — Not specified for this item; refer to the SDS for authoritative information. General safety considerations for sulfonphthalein indicators (literature/good practice):

• Likely hazards: non-volatile organic dye; dust may cause mechanical irritation to eyes/respiratory tract; may stain skin, clothing, and porous surfaces. Classification varies by supplier and form (free acid vs salt); consult SDS.
• PPE: lab coat, safety glasses, disposable nitrile gloves. Use a dust mask or operate in a fume hood if handling powders that can aerosolize.
• Handling: avoid creating dust clouds. Prepare indicator solutions with appropriate ventilation. Prevent contamination of analytical glassware used for UV/Vis work (dyes can adsorb to glass/plastic).
• Incompatibilities (general): strong oxidizers (may bleach/oxidize the chromophore); strong acids/bases can shift color (intended) but concentrated reagents may promote degradation; avoid prolonged exposure to UV light (photofading possible in solution).
• First aid (overview, non-exhaustive):
  • Eyes: rinse cautiously with water for several minutes; remove contact lenses if present and easy to do; seek medical attention if irritation persists.
  • Skin: wash with soap and water; remove contaminated clothing.
  • Ingestion/Inhalation: move to fresh air, rinse mouth; seek medical advice if unwell.
• Spill/cleanup: avoid dry sweeping; gently dampen to suppress dust, collect with inert absorbent. Dispose according to institutional and local regulations. Always defer to the product-specific SDS for B196457.

Solvent Selection

As a solid acid–base indicator dye, solvent choice pertains to preparing stock and working indicator solutions rather than using it as a reaction solvent.

• Polarity/miscibility (literature):
  • Sparingly soluble in neutral water as the free acid; readily soluble in ethanol and in aqueous alkaline solutions (sodium/potassium salts greatly increase solubility).
  • Common vehicles: ethanol/water (e.g., 50–95% ethanol), aqueous 0.01–0.05 M NaOH, or buffer solutions in the basic range to form the blue anionic species.
• Practical selection:
  • For general pH titrations: 0.04–0.1% w/v in ethanol/water affords rapid wetting and homogeneous color development on mixing with aqueous analytes.
  • For purely aqueous systems where organic solvents are undesirable: prepare a dilute alkaline stock (e.g., slight molar excess NaOH) and dilute into sample/buffer; minimize base carryover to avoid pH bias.
  • For spectrophotometry: choose solvent consistent with your assay pH; filter stock through 0.2 µm PTFE to remove particulates that can scatter light.
• Compatibility notes:
  • Avoid strong oxidants (chromophore bleaching) and concentrated acids/bases (dye degradation) in stock solutions.
  • In non-aqueous titrations, BTB is generally not preferred; choose indicators appropriate for non-aqueous media (e.g., crystal violet, thymol blue) depending on acid/base strength.
• Item-specific solubility data — Not specified for this item; verify empirically and/or consult CoA.

Storage and Reconstitution

• Storage conditions (item-specific): Room temperature (per Product Data). Protect from light and moisture for best stability. Shipped under normal conditions.
• Shelf life: Not specified for this item; refer to CoA/Spec Sheet.
• Reconstitution/preparation (general/literature):
  • For a 0.04% w/v indicator solution: dissolve 0.040 g dye in 100 mL of 50% ethanol/water. Alternatively, wet with a few drops of 0.1 M NaOH to initiate dissolution, then bring to volume with water or buffer. Mix until homogeneous; filter if clarity is required for spectrophotometry.
  • For aqueous-only stocks: dissolve the dye in a minimal volume of dilute base (e.g., 0.01–0.05 M NaOH), then dilute with water; standardize addition volumes to avoid altering sample pH.
• Handling of solutions: Store solutions in amber glass at room temperature or refrigerated if compatible with your workflow; minimize light exposure. Prepare fresh at regular intervals (e.g., weekly to monthly) depending on sensitivity of your application.
• Freeze–thaw guidance: Not typically applicable to dry dye. Avoid freezing/thawing aqueous indicator solutions repeatedly; prepare in small aliquots if long-term use is anticipated.
• Compatibility: Avoid strong oxidizers and prolonged UV exposure; both can bleach the chromophore over time. Research Use Only: For laboratory use; not for human or animal administration.

Structure and Identity

• Item-specific identifiers: CAS, SMILES, InChIKey, Molecular Formula, and exact Molecular Weight — Not specified for this item; refer to CoA/Spec Sheet.
• Common identity (literature): This product name closely corresponds to the sulfonphthalein pH indicator bromothymol blue (often abbreviated BTB), a dibrominated thymol blue analogue widely used around neutral pH. If your workflow requires exact identifiers for regulatory or analytical documentation, confirm against the CoA/SDS for this specific SKU (B196457).
• Structural class (literature):
  • Sulfonphthalein dye scaffold featuring a sulfonate-bearing isobenzofuranone core (phthalein) spiro-fused to a substituted phenolic system.
  • Two bromine substituents on the aryl rings (source of “bromo-”), and tert-alkyl (isopropyl) groups derived from the thymol motif.
  • Acid–base responsive phenolic groups that interconvert between lactone/quinone-like and phenolate forms, generating distinct visible colors.
• 2D structure description (literature): central spiro junction connects a sulfonated isobenzofuranone to a phenolic triarylmethane-like framework; bromine atoms on two of the outer rings; tert-alkyl substituents ortho/para to phenols; conjugation extends across rings and is perturbed by protonation state.
• Synonyms (literature): bromothymol blue; BTB; bromthymol blue; 3′,3″-dibromothymolsulfonephthalein.
• Note: Provide your analytical team with the exact specification sheet for definitive identifiers of this catalog lot.

Synthetic Utility

This product functions primarily as an analytical indicator rather than a synthetic reagent or building block. Literature/general considerations:

• Acid–base monitoring: Incorporation into reaction aliquots to provide rapid visual feedback during neutralizations, work-up pH adjustments, or buffer preparations around neutrality (e.g., enzyme-compatible work-ups where pH 6.5–7.5 is targeted).
• Spectator dye: In some educational or method-development settings, used to visualize mixing fronts or quench progress in aqueous work-ups without participating in the reaction chemistry.
• Not typically employed in stoichiometric or catalytic transformations, cross-couplings, or protecting-group chemistry. For such needs, consider appropriate functional dyes or indicators tailored to non-aqueous media (e.g., crystal violet for strong acid titrations in glacial acetic acid). Caveats:
• The dye’s strong color can complicate colorimetric or chromogenic reaction monitoring if present; remove or avoid when UV–Vis detection of analytes is required.
• In biphasic systems, the indicator may partition unevenly depending on pH and solvent polarity, leading to ambiguous color reads—rely on pH meter for critical decisions.

Target Specificity

Not applicable — this product is a small-molecule pH indicator dye, not a biological targeting reagent, antibody, or affinity probe. It does not possess antigen/epitope specificity. If your workflow requires molecular recognition (e.g., immunodetection, receptor binding), select an appropriate targeted reagent from relevant catalog categories.