Reducing Sugar Content Assay Kit (Fehling, Colorimetric Method)

Cat. No.: P1509420

GRADE & PURITY BioReagent

Visão geral

  Fehling's Reagent (also known as Fehling's solution or Fehling's test) was invented by the German chemist Hermann von Fehling in 1849. Similar to Benedict's Reagent, it is used to detect the presence of reducing sugars. The principle is that soluble reducing sugars (such as glucose, fructose, and maltose) react with the reagent under heating conditions to form a brick-red precipitate of cuprous oxide (Cu₂O).

Assay Principle

  Reducing sugars possess aldehyde or ketone groups. When boiled in an alkaline solution, they can reduce Cu²⁺ in Fehling's Reagent to Cu⁺, causing the blue color of the reagent to fade. The degree of decolorization is proportional to the concentration of reducing sugars in the solution. Absorbance can be measured colorimetrically at 590 nm, and the reducing sugar content in the sample can be calculated by referring to a standard curve. This kit is primarily used for the quantitative detection of reducing sugars in samples such as starch-containing foods, alcoholic beverages, carbonated drinks, meat products, preserved fruits, and plant materials. Total sugar content can also be measured but requires prior hydrolysis. It can also be used for qualitative tests of reducing sugars. This kit is for research use only and is not suitable for clinical diagnosis or other purposes.

Applicable Samples: Starch-containing foods, alcoholic beverages, carbonated drinks, meat products, preserved fruits, plant materials, etc.

Reagents, consumables and Equipments not provided

• Spectrophotometer (capable of measuring absorbance at 590 nm).
• Test tubes or centrifuge tubes, conical flasks, volumetric flasks, glass beads, water bath or alcohol burner, cuvettes.
• Reducing sugar standards (1 mg/mL) such as fructose or invert sugar, hydrochloric acid solution, sodium hydroxide solution, 10% lead acetate solution, saturated sodium sulfate solution, distilled water, iodine solution.

Operating Steps (For Reference Only)

1. Preparation of Fehling's Reagent

Mix equal volumes of Fehling's Reagent A and B immediately before use. Do not store the mixture.

2. Preparation of pH Neutralization Solution (1×)

Dilute the pH Neutralization Solution (10×) with water at a 1:9 ratio.

3. Extraction of Reducing Sugars from Samples

3.1 Solid Samples (e.g., starch-containing foods, plant materials)

Weigh 10–20 g (accurate to 0.01 g) of pulverized or homogenized sample into a 250 mL volumetric flask. When the volume approaches 150 mL, add 1–3 drops of Methyl Red Indicator. If the solution turns red, adjust it to a faint yellow color using the pH Neutralization Solution (1×). For air-dried samples, weigh about 3 g directly into the flask, moisten with a small amount of water, then add water to about 150 mL before adding the indicator and neutralization solution. Place the flask in an 80°C constant temperature water bath for 30 minutes, shaking several times to fully extract reducing sugars.

For samples rich in protein, add lead acetate solution at this stage to precipitate proteins until no more white flocculent precipitate forms. Then add saturated sodium sulfate solution to remove excess lead ions. After 30 minutes, remove, cool, dilute to the mark with water, mix well, and filter. Collect the filtrate for use.

3.2 Alcoholic Beverages

Weigh 100 g (accurate to 0.1 g) of well-mixed sample into an evaporating dish. Add 1–3 drops of Methyl Red Indicator and adjust to a faint yellow color with the pH Neutralization Solution. Evaporate on a water bath to one-quarter of the original volume. Transfer to a 250 mL volumetric flask. Proceed with incubation in an 80°C water bath for 30 minutes (shaking occasionally) as described in 3.1. For protein-rich samples, follow the corresponding steps. Collect the filtrate for use.

3.3 Carbonated Beverages

Weigh 100 g (accurate to 0.1 g) of well-mixed sample into an evaporating dish. Gently stir on a water bath to remove carbon dioxide. Transfer to a 250 mL volumetric flask. Rinse the dish with water and combine the rinses into the flask. Dilute to the mark with water and mix well for use.

3.4 Hydrolysis and Extraction of Total Sugars

Weigh 0.5–3 g of plant sample, cut into pieces, add about 3 mL of distilled water, and homogenize. Transfer to a conical flask. Rinse the homogenizer 2–3 times with 12 mL of distilled water and combine the rinses into the flask. Add 10 mL of 6 M hydrochloric acid solution to the flask, mix, and boil for 30 minutes with occasional stirring. Check for complete hydrolysis by placing 2 drops of the hydrolysate in a small tube and adding 1 drop of iodine solution. No blue color indicates complete hydrolysis. After hydrolysis, cool to room temperature. Add 6 M sodium hydroxide solution dropwise to bring the pH close to neutral. For protein-rich samples, follow the corresponding steps. Filter or centrifuge, dilute the filtrate/supernatant to 100 mL with distilled water, mix well. Take 10 mL of this solution and dilute to 100 mL with distilled water, mix well for use.

4. Preparation of Reducing Sugar Standard Curve

Set up blank tube (No. 0) and gradient standard tubes (Nos. 1–6) according to the table below, adding reagents in order.

Tube No.	0 (Blank)	1	2	3	4	5	6
Glu Standard (1 mg/mL) Volume (mL)	0	0.5	1	1.5	2	2.5	3
Distilled Water Volume (mL)	3	2.5	2	1.5	1	0.5	0
Fehling's Reagent Volume (mL)	2	2	2	2	2	2	2
Theoretical Glucose Content (mg)	0	0.5	1	1.5	2	2.5	3

Mix each tube well. Heat in a boiling water bath for 15 minutes. Cool with cold or tap water. Centrifuge at 2500 rpm for 5–10 minutes. Transfer the supernatant to a 1 cm pathlength cuvette. Zero the spectrophotometer with the blank tube and measure the absorbance of each standard tube at 590 nm. Plot the standard curve using the absorbance of each standard tube as the y-axis and the corresponding glucose content as the x-axis.

5. Measurement of Sample Reducing Sugars

Pipette 3 mL of the prepared reducing sugar extract into a tube, add 2 mL of Fehling's Reagent, and mix well. Perform the same procedures as for the standard curve: heat in a boiling water bath for 15 minutes, cool, centrifuge, transfer the supernatant, and measure absorbance at 590 nm (zeroed with the blank tube). Use the sample's absorbance value in the regression equation to calculate the reducing sugar content in the sample.

6. Result Calculation

Sample Reducing Sugar Content (%) = (m × V_T × N) / (m₀ × V_S × 1000) × 100 

Parameter Explanation: 

m: Reducing sugar content in the sample (mg) obtained from the standard curve. 

V_T: Total volume of the extract (mL). 

N: Dilution factor. m₀: Sample mass (g). 

V_S: Volume of extract used for the assay (mL). 

1000: Unit conversion factor.

Qualitative Test for Reducing Sugars

1. Prepare Fehling's Reagent Working Solution: Immediately before use, mix equal volumes of Fehling's Reagent A and B.

2. Add 1–2 mL of the test sample to a clean test tube.

3. Add 1 mL of the Fehling's Reagent working solution to the tube and mix thoroughly.

4. Place the mixture in a boiling water bath for 1–3 minutes.

5. Observe the color change of the mixture. The color should change in the order: light blue -> brown -> brick red (precipitate).

Interpretation of Results

Reducing Sugar (e.g., ribose, glucose, fructose)	Brick red precipitate
Non-reducing Sugar (e.g., sucrose, starch)	No color change

Precautions

1. If the reducing sugar concentration in the sample extract is too high, dilute appropriately before measurement.

2. If the concentration is too low, increase the sample concentration or the volume of extract used.

3. The volumes of extract and Fehling's Reagent can be reasonably decreased or increased as needed.

4. Fehling's Reagent A and B must be stored separately and mixed as required immediately before use.

5. Fehling's Reagent B is strongly alkaline. Handle with care.

6. Preparation of 6 M HCl: Mix equal volumes of commercially available concentrated hydrochloric acid and distilled/deionized water. This process is exothermic. Handle with care to avoid injury.

7. Preparation of 6 M NaOH: Dissolve 24 g of sodium hydroxide in distilled water and make up to 100 mL. Dissolving NaOH is exothermic. Handle with care to avoid injury.

8. Pigments can interfere with sugar measurement. If the extract is deeply colored, decolorize it before assay. Decolorization methods and amounts of decolorizing agents vary for different samples; please consult relevant literature. For example, 5% activated charcoal can be used for decolorizing red wine.

9. For your safety and health, please wear a lab coat and disposable gloves during operation.

10. Please use reagents as soon as possible after opening to avoid affecting subsequent experimental results.

Specifications

Sinónimos

Reducing Sugar (RS) Assay Kit

Especificações e pureza

BioReagent

Grau

BioReagent

Aplicação

Cell Metabolism

Tipo de amostra

Food, Plant

Método de deteção

Colorimetric Method

Detection instrument

UV-Visible Spectrophotometer

Detection wavelength

590nm

Armazenamento e envio

Condições de armazenamento de armazenamento

Store at 2-8°C,Room temperature

Enviado em

Wet ice

Estabilidade e armazenamento

Each component has a shelf life of 1 year under corresponding storage conditions.

Contents & Storage

P1509420	Component	50T	Storage
P1509420A	Glu Standard (1 mg/mL)	30 mL	2-8℃.
P1509420B	Fehling's Reagent A	50 mL	RT.
P1509420C	Fehling's Reagent B	50 mL	RT.
P1509420D	Methyl Red Indicator	10 mL	RT.
P1509420E	pH Neutralization Solution (10×)	50 mL	RT.

Application Protocols

Item-specific tested applications and step-by-step procedures are not provided in the Product Data. The following is a generalized literature-style protocol for Fehling colorimetric determination; use only if consistent with the kit IFU.

• Materials (general)

  • Fehling Solution A (CuSO4) and Solution B (alkaline tartrate), mixed fresh.
  • Reducing sugar standard (e.g., D-glucose).
  • Deionized water, test tubes or microplate, heating block or boiling water bath, spectrophotometer/plate reader in the visible range.

• Example procedure (general)

  1. Prepare a standard curve covering the expected sample range. Include reagent blank.
  2. Mix Fehling A and B in equal volumes to create working reagent.
  3. In tubes or wells, add sample or standard to working reagent in the volumes specified by the kit (not specified here). Mix thoroughly.
  4. Heat at near-boiling temperature for a fixed time (e.g., 10 minutes). Avoid evaporation; use caps or a covered plate.
  5. Cool rapidly to room temperature in a water bath.
  6. Measure absorbance at the wavelength specified by the kit (commonly within 600–750 nm for blue complex decrease). Subtract blank and interpolate from the standard curve.

• QC recommendations

  • Perform duplicates/triplicates, include spike recoveries, and verify linearity (R²≥0.99) across the working range.

Always prioritize the kit’s instructions for use for volumes, timing, and wavelengths.

Biological Roles

This section contextualizes the analytes (reducing sugars) measured by the kit.

• Reducing sugars in biology (literature/general)

  • Many monosaccharides (e.g., D-glucose, D-galactose) and some disaccharides (e.g., lactose, maltose) exhibit reducing activity due to an open-chain aldehyde or α-hydroxyketone tautomer capable of electron transfer in alkaline conditions.
  • Central roles: Energy metabolism (glycolysis, pentose phosphate pathway), storage and mobilization (glycogen/starch breakdown yields reducing ends), and structural biosynthesis (nucleotide sugars as donors).
  • Chemical behavior in complex matrices: Reducing sugars participate in Maillard reactions with amino groups, producing advanced glycation end-products (AGEs) upon heating—relevant to food chemistry and sample stability.

• Analytical implications (general)

  • Interconversion between cyclic and open-chain forms is pH- and temperature-dependent; assay conditions shift equilibria to forms that reduce Cu(II).
  • Different sugars have different effective reducing potentials and kinetics; method calibration should match the primary analyte when feasible.
  • In biological extracts, endogenous reductants (ascorbate, glutathione) and metal-binding metabolites can bias reducing-sugar assays; appropriate cleanup or alternative enzymatic assays may be preferable.

• Item-specific note

  • The kit is intended for research use only (per Product Data). No medical or clinical diagnostic claims are made or implied.

Buffer Applications

This product is an assay kit rather than a buffering agent. It is not typically used to prepare biological buffers.

• Practical note
  • If the kit supplies any premixed solutions, use them as provided; do not substitute with external buffers unless the kit IFU explicitly permits, as buffering/chelating components can disrupt the Cu(II)–tartrate chemistry.
  • For sample preparation, simple aqueous dilutions are generally preferred over complex buffers to avoid chelation and pH shifts.

Green Alternatives

Fehling chemistry uses copper salts and strong alkali, generating metal-containing waste. Depending on your analytical goals, greener or lower-hazard alternatives may be considered.

• Comparative options (literature/general)

| Method | Hazards/Waste | Selectivity | Notes | |---|---|---|---| | DNS (3,5-dinitrosalicylic acid) assay | Organic nitro compound; waste colored; no heavy metals | Reducing sugars broadly | Absorbance ~540 nm; still involves hazardous chemicals; often more tolerant to matrix than Fehling. | PAHBAH (p-hydroxybenzhydrazide) | Organic reagents; less corrosive than strong alkali | Aldoses/ketoses | Good sensitivity; fewer heavy metals; requires heating. | Phenol–sulfuric acid (total carbohydrates) | Concentrated acid; phenol hazard | Total carbohydrates (not just reducing) | Very sensitive; measures all glycosidic forms after dehydration. | Enzymatic glucose/fructose assays | Minimal hazardous waste | High specificity | Narrow analyte scope but excellent green profile and accuracy.

• Process improvements within Fehling (general)

  • Miniaturize reaction volumes to reduce copper waste.
  • Implement microplate colorimetry at controlled temperature to limit energy use and improve throughput.
  • Segregate Cu-containing waste for recycling/recovery where available.

• Item-specific

  • This listing does not specify special low-hazard formulations. Refer to the IFU for any kit-specific waste minimization guidance.

Pharmaceutical Uses

No therapeutic or clinical use is claimed. In a research and manufacturing context (literature/general), reducing sugar assays can support non-clinical workflows:

• Raw material and excipient assessment: Estimating reducing sugar content in carbohydrate-based excipients (e.g., lactose grades for solid dosage development) to anticipate Maillard reactivity with amines during processing.
• Process development/QA (research use): Monitoring sugar content in fermentation broths for bioprocess optimization or in syrupal formulations during bench-scale studies.
• Stability studies (research): Tracking formation/consumption of reducing sugars in model formulations under stress conditions to predict discoloration risk.

Item-specific notes

• This kit is provided as BioReagent for research use only (per Product Data). It is not validated to pharmacopeial monograph methods nor intended for clinical diagnostics. For compendial testing, verify method suitability and conduct appropriate validation (specificity, linearity, precision, accuracy, robustness) against pharmacopeial procedures if required.

Physical Properties

• Item-specific (Product Data)

  • Physical state/appearance: Not specified for this item; refer to CoA/Spec Sheet.
  • Concentrations of solutions: Not specified for this item; refer to CoA/Spec Sheet.
  • pH, density, refractive index: Not specified for this item; refer to CoA/Spec Sheet.

• Typical properties of Fehling reagents (literature/general, for context only; not specifications)

  • Fehling Solution A: aqueous copper(II) sulfate, typically deep blue; density close to water depending on concentration.
  • Fehling Solution B: clear, strongly alkaline solution of sodium/potassium tartrate in NaOH; pH commonly >12.
  • When A and B are mixed, a deep blue copper(II)–tartrate complex forms; on heating with reducing sugars, the blue color diminishes and Cu2O (brick-red) can precipitate.
  • Temperature of reaction: classically near boiling (≈95–100°C) for endpoint/titrimetric detection; colorimetric adaptations may use controlled heating below boiling to stabilize signals.
  • Spectral behavior: Cu(II)–tartrate complexes absorb strongly in the visible (blue color); colorimetric readouts may monitor decrease at ~600–750 nm depending on implementation and optical path (literature/general). Exact wavelength for this kit is not specified.

• Solubility considerations (literature/general)

  • Aqueous reagents; compatible with water-miscible matrices. Organic solvents dilute the complex and may affect equilibrium; ethanol and strong chelators can suppress color development.

For verified numeric values and measurement wavelengths of this kit, consult the kit insert and CoA.

Quality and Grades

• Item-specific (Product Data)

  • Grade: BioReagent
  • What this means: BioReagent grade indicates the product is suitable for general biological and biochemical laboratory use, with quality controls aligned to research applications. It does not imply clinical/diagnostic use.

• Implications for this kit

  • Consistency: BioReagent-grade components are intended to provide reproducible color development and background, enabling reliable calibration against reducing sugar standards in research workflows.
  • Documentation: For lot-specific specifications (e.g., acceptance criteria for blank absorbance, linear range verification, and component concentrations), refer to the CoA/Spec Sheet and kit insert.

• Stabilizers and additives

  • Item-specific stabilizers are not specified for this kit; refer to CoA/Spec Sheet.
  • In general, Fehling-type reagents rely on complexation (tartrate) and alkalinity to keep Cu(II) soluble and stable prior to reaction; some modern kits may include buffers or masking agents to enhance linearity—check the IFU for this item.

• Fit-for-purpose guidance (general best practice)

  • Calibration with freshly prepared reducing sugar standards (e.g., D-glucose) is recommended each use to verify linearity and slope.
  • Run procedural blanks and matrix-matched spikes to assess bias from sample components (ascorbate, sulfite, metal chelators) that may consume Cu(II) or alter color.

Note: This listing does not define UV cutoff, metal limits, or other analytical-grade solvent specs.

Reaction and Applications

• Principle (literature/general)

  • Reducing sugars (e.g., glucose, lactose, maltose) in alkaline medium reduce Cu(II)–tartrate complexes to Cu(I), forming Cu2O and diminishing the blue Cu(II) absorbance. The extent of reduction is proportional to reducing sugar equivalents under controlled time/temperature, enabling colorimetric quantitation.

• Application domains (literature/general)

  • Food and beverages: Determination of reducing sugars in juices, honey, molasses, dairy (lactose), and brewing mashes (wort/beer).
  • Fermentation/bioprocess: Monitoring carbohydrate consumption and byproduct formation.
  • Carbohydrate chemistry: Assessing reduction capacity during polysaccharide hydrolysis or derivatization.

• Practical tips (general)

  • Use freshly mixed Fehling A and B to maintain consistent Cu(II) complex concentration.
  • Maintain consistent heating profile; near-boiling water bath or dry block with tight timing improves precision. Pre-warm glassware to minimize thermal lag.
  • Calibrate with the same sugar species as the major analyte when possible (response factors can differ among sugars).
  • Interferences: Ascorbate, sulfites, aldehydes, and strong chelators reduce/complex copper and bias results. Protein-rich matrices can precipitate in strong base—clarify prior to assay.
  • Endpoint/readout: Classical Fehling is titrimetric with methylene blue as an internal indicator; colorimetric kits often monitor absorbance change of the blue complex. Follow the IFU for the specific detection wavelength and pathlength.

• Item-specific note

  • Manufacturer-expanded applications are not specified in the Product Data. Use cases above are representative literature applications; verify compatibility with your samples using kit controls.

Reaction Conditions

Item-specific conditions for this kit are not provided in the Product Data; consult the kit insert for definitive instructions. The following represents generalized literature guidance for Fehling-based colorimetric assays and should be adapted only if aligned with the kit IFU.

• Typical workflow (literature/general)

  • Reagent preparation: Mix equal volumes of Fehling A (CuSO4) and Fehling B (alkaline tartrate) immediately before use to form the active blue complex.
  • Standards: Prepare a calibration series of the target sugar (e.g., D-glucose) in water across the expected range (for microplate/colorimetric formats, linear ranges often fall within low mM to low tens of mM; exact range depends on pathlength and protocol).
  • Reaction: Combine sample/standard with freshly mixed Fehling reagent. Heat in a boiling water bath or controlled 90–100°C block for a fixed time (commonly 5–15 minutes). Cool rapidly to stabilize color.
  • Readout: Measure absorbance decrease of the blue complex in the visible range (often 600–750 nm) or quantify Cu2O formation by appropriate optical method. Use reagent blank for baseline correction.

• Quality controls and acceptance (general)

  • Include matrix blanks and spike recoveries (80–120% typical target in simple matrices) to assess interference.
  • Replicates (n≥3) improve precision; relative standard deviation ≤5% is a common goal for well-controlled assays.

• Notes

  • Strong chelators and reductants can invalidate the assay. If present, consider cleanup (e.g., desalting) or alternative methods.

Safety and Handling

• Item-specific (Product Data)

  • GHS classification, signal word, H-statements, pictograms: Not specified for this item; refer to the SDS for each component.
  • Storage conditions: Store at 2–8°C, Room temperature (per label); see Storage & Reconstitution for details.
  • Shipment: Shipped on wet ice.

• General hazards of Fehling-type reagents (literature/general; not a substitute for the SDS)

  • Copper(II) sulfate solutions: Eye/skin irritant; harmful if swallowed; hazardous to aquatic life. Strongly alkaline tartrate/NaOH solution: corrosive, causes severe skin burns/eye damage.
  • Mixed reagent is strongly basic; heating may generate aerosols. Cu-containing waste is environmentally hazardous and must be collected for proper disposal.

• Handling practices

  • PPE: Lab coat, safety goggles, and appropriate chemically resistant gloves (e.g., nitrile). Use face shield when heating or handling large volumes of alkaline solutions.
  • Engineering controls: Work in a fume hood for heated reactions and when preparing/mixing alkaline solutions.
  • Incompatibilities: Avoid acids (violent neutralization), strong oxidizers/reducers beyond intended assay, complexing agents (EDTA, ammonia), and sulfide (forms CuS).

• First-aid overview (general)

  • Skin/eye contact with alkaline or Cu solutions: Immediate decontamination with copious water for ≥15 minutes; seek medical attention for eye exposure.
  • Ingestion/inhalation: Rinse mouth; do not induce vomiting; move to fresh air and obtain medical attention.

Always defer to the kit’s SDS and IFU for authoritative safety, spill response, and waste disposal guidance.

Solvent Selection

This product is an aqueous, colorimetric assay kit; solvent selection primarily concerns sample preparation and dilution rather than reagent solubilization.

• Item-specific (Product Data)

  • No solvent specifications are provided; reagents are typically aqueous. Consult the kit insert for required diluents and any supplied buffers.

• Practical guidance (literature/general)

  • Preferred matrix: Deionized water. Maintain ionic strength and pH within the kit’s recommended range (not specified here).
  • Avoid strong complexing agents: EDTA, citrate, ammonia, and high phosphate can chelate Cu(II) and suppress color development.
  • Organic content: Keep alcohols and other organic solvents low; >5–10% v/v ethanol or acetone can perturb complexation and absorbance baselines. If organic extraction is required, evaporate and reconstitute in water before assay.
  • Sugary/food matrices: Clarify turbid samples by centrifugation/filtration. For colored matrices, consider matrix blanks and standard addition.
  • pH adjustment: Fehling chemistry requires strong alkalinity; do not pre-neutralize the reaction mixture. Adjust sample pH only if instructed by the kit IFU.

• Choosing alternatives

  • If samples contain strong interferents or high color background, consider alternative reducing-sugar assays (e.g., DNS, PAHBAH) or enzymatic glucose/fructose assays; see Green Alternatives for trade-offs.

For definitive diluent and matrix tolerance limits, follow the kit’s instructions for use.

Storage and Reconstitution

• Item-specific (Product Data)

  • Storage conditions: Store at 2–8°C, Room temperature. Where labels differ by component, follow the most conservative condition (2–8°C) for unopened reagents. During use, temporary room-temperature handling is acceptable unless otherwise stated by the IFU.
  • Shipment: Shipped on wet ice to maintain stability in transit.

• Stability and handling (general)

  • Protect copper-containing solutions from prolonged light exposure to minimize photochemical changes; store tightly closed to limit CO2 absorption that could alter alkalinity.
  • Do not freeze alkaline solutions unless specified by the manufacturer, as precipitation or component degradation may occur.

• Reconstitution

  • Specific reconstitution details (e.g., whether concentrates or powders require dilution, and exact diluents/volumes) are not specified for this item; refer to the kit insert.
  • If concentrates are provided, bring to room temperature, mix gently to ensure homogeneity, and use high-purity water for dilution as directed.

• Working solutions

  • Mix Fehling A and B immediately before use; do not store the mixed reagent for extended periods as performance can drift.

• Shelf life

  • Not specified for this item; refer to CoA/Spec Sheet and the label for expiration and open-bottle stability.

Always consult the kit IFU for component-specific storage, reconstitution, and in-use stability guidance.

Structure and Identity

Brief description: This is an analytical kit for quantifying reducing sugars using the classical Fehling colorimetric chemistry. It is a multi-component reagent system rather than a single defined compound.

• Item-specific (Product Data)

  • Product name: Reducing Sugar Content Assay Kit (Fehling, Colorimetric Method)
  • SKU: P1509420
  • Grade: BioReagent
  • CAS: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular formula: Not specified for this item; refer to CoA/Spec Sheet.
  • Molecular weight: Not specified for this item; refer to CoA/Spec Sheet.
  • SMILES: Not applicable (multi-reagent kit)
  • InChIKey: Not applicable (multi-reagent kit)

• What is in a Fehling kit? (literature/general)

  • Fehling’s reagent is classically supplied as two solutions mixed immediately before use:
    • Solution A: aqueous CuSO4 (Cu2+ source).
    • Solution B: alkaline tartrate (e.g., potassium sodium tartrate) in strong base (typically NaOH) forming soluble copper-tartrate complex.
  • Upon heating with reducing sugars, Cu(II) is reduced to Cu(I) forming red/orange Cu2O and/or producing a measurable loss in the blue Cu(II) chromophore.

• Structural features discussed (literature/general)

  • The analytical signal arises from coordination chemistry of Cu(II)–tartrate complexes (intense blue color) and their reduction to sparingly soluble Cu(I) oxide (brick-red precipitate), altering visible absorbance.
  • The assay is stoichiometrically linked to the reducing equivalents provided by open-chain aldehyde forms of hexoses/pentoses or by α-hydroxyketoses via enediolization.

Note: Exact kit composition, concentrations, and component identities for this catalog item are not specified here; consult the kit insert/CoA for definitive details.

Synthetic Utility

This product is an analytical assay kit, not a synthetic reagent. Consequently, it is not typically employed to drive chemical transformations in synthesis.

• When relevant to chemistry labs (literature/general)

  • Method development: Used to monitor progress of starch/cellulose hydrolysis or glycosylation/deprotection workflows by quantifying residual reducing ends in samples.
  • Reaction workup control: Quick screening of reducing sugar content in fractions during purification of carbohydrate derivatives.

• Not applicable

  • Named reactions, catalyst systems, and stoichiometric transformations are outside the scope of this kit. For reductive chemistry or copper-mediated organic reactions, choose dedicated reagents and follow reaction-specific protocols.

Target Specificity

This is not an antibody or affinity reagent; there is no molecular target specificity in the immunochemical sense.

• Analytical specificity (literature/general)
  • The assay responds to compounds capable of reducing Cu(II) under strongly alkaline, heated conditions. Primary contributors are reducing sugars (aldoses and some ketoses via enediolization).
  • Other reducing agents (e.g., ascorbate, sulfite, certain aldehydes, and polyphenols) can also reduce Cu(II) and may cause positive bias. Specificity is therefore chemical and conditional rather than biological.

For selectivity details specific to this kit’s formulation (e.g., masking agents, wavelength), refer to the IFU/CoA.

Perguntas frequentes

What does BioReagent mean?

BioReagent indicates that the product has been processed and tested for biological and biochemical applications. Specifications may include endotoxin limits, microbial controls, sterility, low DNase/RNase/protease activity, and verified biological activity where relevant.

How should this product be stored?

Store at 2–8 °C. Refrigerated storage is required to maintain the specified shelf life.

How is this product shipped?

This product ships chilled on wet ice. Unpack on arrival and transfer it to the storage condition stated above.

What documentation is provided?

Available product documentation, including Certificates of Analysis (COA), Safety Data Sheets (SDS), and specification sheets, is shown in the product document area. Document availability and access follow the current site policy.