COD CRM - 100mg/L in 0.05mol/L H2SO4

Cat. No.: C117605

GRADE & PURITY 100mg/L in 0.05mol/L H2SO4

Storage

Protected from light,Room temperature

Shipped In

Normal

Specifications

Specifications & Purity

100mg/L in 0.05mol/L H2SO4

Storage

Protected from light,Room temperature

Shipped In

Normal

Application Protocols

The following protocol outlines general best practices for using a COD CRM in calibration and QC. It is literature-based and not item-specific; adapt to your method’s instructions and the item’s CoA.

• Calibration (colorimetric sealed-vial method)

  1. Allow CRM and reagents to equilibrate to room temperature. Gently mix the CRM.
  2. Prepare a series of standards spanning your expected sample range by gravimetric dilution with high-purity water, if needed. Record all masses/volumes.
  3. Add prescribed aliquots of each standard to COD reagent vials. Cap, mix, and digest per method (e.g., 150 °C, 2 h).
  4. Cool to room temperature and read absorbance at the method-specified wavelength. Construct a calibration curve and verify correlation (R2) and residuals.

• Quality control

  • Run an LCS/OPR using the CRM at a midpoint concentration each batch. Evaluate recovery versus acceptance criteria and the CRM’s stated uncertainty.
  • Include a continuing calibration verification (CCV) standard after every 10–20 samples.
  • Employ control charts to monitor bias/precision over time; investigate trends or out-of-control events.

• Notes

  • Avoid cross-contamination. Use fresh pipette tips and clean glassware. Do not return excess CRM to the stock container.
  • Record CRM lot number, assigned value, uncertainty, and expiration date in your bench records.

Biological Roles

Not applicable. COD CRM is a certified reference solution for analytical chemistry and does not possess inherent biological roles or metabolic functions. For work related to biological systems in water quality (e.g., BOD testing), refer instead to appropriate biological assays and their dedicated standards.

Buffer Applications

Not applicable. COD CRM is not a buffering reagent and is not intended to prepare or adjust buffer systems. For COD analysis, the digestion chemistry is controlled by method-supplied acidic reagents rather than conventional buffer systems. Refer to Reaction & Applications and Reaction Conditions for practical analytical guidance.

Green Alternatives

COD measurement by dichromate digestion traditionally uses hazardous reagents (e.g., Cr(VI), Hg salts as chloride complexing agents, concentrated H2SO4). When planning QA/QC, consider greener strategies while maintaining method comparability.

• Greener approaches (literature/general; not item-specific)

  • Mercury-free COD methods: Replace HgSO4 with alternative chloride suppression strategies or use method variants validated without mercury. Check regulatory acceptance in your jurisdiction.
  • Alternative oxidants: Permanganate COD or photochemical oxidation can reduce chromium usage, though method equivalence to dichromate COD must be established.
  • Switch endpoints: Consider Total Organic Carbon (TOC) for continuous monitoring or greener assessment of organic load; correlation to COD should be validated per matrix.
  • Waste minimization: Use small-volume sealed-vial methods to reduce acid and oxidant consumption, and consolidate waste streams for proper treatment.

• Comparison snapshot (general)

  • Dichromate COD: High robustness to diverse matrices; uses Cr(VI) and often Hg; strong acid digestion at high temperature.
  • Permanganate COD: Less toxic oxidant; lower oxidizing strength for some organics; may under-report relative to dichromate for certain matrices.
  • TOC: No heavy metals; measures carbon directly; requires instrument capital and separate calibration/CRMs.

• Practical note

  • If substituting methods, select CRMs validated for the target measurand (e.g., TOC CRMs) and document method change control, correlation studies, and uncertainty impacts.

Pharmaceutical Uses

Not applicable as a pharmaceutical ingredient or excipient. COD CRM is a reference standard for environmental/analytical testing and is intended strictly for research and laboratory use. If water systems used in pharmaceutical manufacturing require organic load monitoring, appropriate validated methods (e.g., TOC per pharmacopeial chapters) and corresponding CRMs should be used. No clinical or therapeutic applications are implied.

Physical Properties

Because COD CRM is a reference solution/mixture rather than a single compound, conventional single-substance properties (bp, mp, logP) are not applicable. Properties of the specific lot (e.g., nominal COD value, matrix, density at 20–25 °C) are defined on the CoA.

• Item-specific values

  • Appearance: Not specified for this item; refer to CoA/Spec Sheet.
  • Density: Not specified for this item; refer to CoA/Spec Sheet.
  • Refractive index: Not specified for this item; refer to CoA/Spec Sheet.
  • Solubility: Aqueous solution standards are typically fully miscible with water (literature, general). Exact matrix details: Not specified for this item; refer to CoA/Spec Sheet.

• Literature/general information (not item-specific)

  • Most COD calibration/QC solutions are water-based to match analytical methods requiring aqueous digestion and colorimetric/titrimetric determination (Standard Methods, EPA methods).
  • If the CRM includes chromophoric or oxidizing components, light sensitivity can occur; this aligns with the item’s storage note “Protected from light.”

• Practical notes

  • Prior to use, equilibrate the sealed container to room temperature and gently invert to ensure homogeneity; avoid aeration that could alter analyte content. Always record temperature if the method requires temperature-corrected values.
  • For precise work, consult the CoA for assigned value (mg O2/L), expanded uncertainty (U), coverage factor (k), matrix, and stability statement.

Quality and Grades

This product is designated as a COD CRM, meaning it is a Certified Reference Material intended for calibration, method validation, and quality control in COD determination. Specific grade/purity details are not provided in the product data and should be verified on the CoA.

• Item-specific information

  • Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.
  • Certificate of Analysis: Consult for the assigned COD value(s) (mg O2/L), expanded uncertainty (U) with coverage factor (k), traceability statement, matrix description, shelf-life/stability, and storage conditions.

• What CRM signifies (literature/general)

  • Traceability: CRMs are established with metrological traceability to recognized references, prepared and characterized under accredited quality systems (e.g., ISO 17034 producers; testing under ISO/IEC 17025), ensuring defensible calibration and QC.
  • Uncertainty and homogeneity: Value assignment includes evaluation of homogeneity and stability. The CoA states the uncertainty budget and intended use.
  • Fitness for purpose: CRMs support calibration curves, instrument checks, laboratory control samples (LCS), ongoing precision and recovery (OPR), and proficiency testing comparability.

• Practical guidance

  • Match the CRM’s matrix and concentration range to your method (e.g., low-, mid-, or high-range COD). Use unopened ampoules or single-use aliquots when possible to minimize contamination and evaporation.
  • Record lot number and assigned value on bench sheets and QC charts to maintain traceable records.

Reaction and Applications

Primary application: calibration, verification, and quality control for Chemical Oxygen Demand (COD) assays in environmental analysis (wastewater, surface water, industrial effluents). The CRM provides a known oxygen demand value expressed as mg O2/L for method validation and instrument/sampler performance checks.

• Use cases (literature/general; not item-specific)

  • Calibration standards for spectrophotometric COD vials (pre-dosed dichromate reagents) across defined ranges (e.g., low-range ~0–150 mg/L, high-range up to thousands mg/L, as per kit/method).
  • Laboratory Control Sample (LCS), Ongoing Precision and Recovery (OPR), and matrix spike/matrix spike duplicate (MS/MSD) to assess bias and precision.
  • Method validation: linearity, limit of detection/quantitation verification, and analyst proficiency.

• Practical tips

  • Mix the CRM gently before use; avoid bubbles. Use Class A volumetrics or gravimetric dilutions to minimize uncertainty contribution from preparation.
  • Run reagent blanks and method blanks in parallel. Track recovery using control charts (e.g., Shewhart with warning/action limits based on historical data and stated uncertainty).
  • Align digestion time/temperature and wavelength with your method (e.g., closed reflux at 150 °C; photometric readouts commonly at ~420, 445, 600 nm depending on kit—literature guidance).

• Standards and references

  • Methods include Standard Methods 5220 (D/E) and EPA 410 series (literature). Always verify that the CRM range and matrix are suitable for the specific method employed.

Reaction Conditions

While the CRM itself is not reacted, it is used under the conditions of the COD analytical method. The following are literature-based, method-general conditions and are not item-specific.

• Closed reflux dichromate COD (Standard Methods 5220 D/E; EPA 410 series)

  • Digestion: Typically 150 °C for 2 hours in sealed vials or reflux flasks with concentrated H2SO4, K2Cr2O7, and catalysts (e.g., Ag2SO4). Some methods include HgSO4 to suppress chloride interference.
  • Detection: Colorimetric measurement of Cr(III) formed from Cr(VI), commonly at ~420, 445, or 600 nm depending on reagent formulation; or titrimetric back-titration with Fe(NH4)2(SO4)2 (FAS) using ferroin indicator.
  • Calibration/QC: Prepare a multi-point curve covering the method range. Include reagent blank, LCS/OPR, and check standards from the CRM.

• Practical considerations

  • Volumes: Follow your kit/method for sample and reagent volumes (e.g., 2–3 mL sample in sealed vials); avoid exceeding capacity.
  • Interferences: Chloride, nitrite, and certain reduced species may bias results; apply method-prescribed suppressants or corrections.
  • Quality: Use Class A glassware, high-purity water, and temperature-controlled digestion. Document CRM lot, assigned value, and uncertainty.

Always consult the specific method, instrument manual, and the item’s CoA/SDS for definitive instructions.

Safety and Handling

No specific GHS classifications or hazard statements are provided for this item in the product data. Users must consult the product-specific SDS and CoA for authoritative safety information.

• Item-specific safety details

  • Signal Word: Not specified for this item; refer to SDS.
  • H-Statements: Not specified for this item; refer to SDS.
  • GHS Classification/Pictograms: Not specified for this item; refer to SDS.
  • Storage: Protected from light, room temperature (per product data). Shipments are at ambient conditions (normal).

• General laboratory precautions (literature/good practice; not item-specific)

  • Wear appropriate PPE: lab coat, safety glasses, and chemical-resistant gloves. Use in a well-ventilated area or fume hood if acids/oxidizers are present in the workspace.
  • Avoid contamination of the CRM. Do not pipette from the stock bottle directly into digestion vials that contain strong acids/oxidizers; instead, dispense into a clean intermediate container.
  • In case of skin/eye contact: Rinse with water for at least 15 minutes and seek medical attention per SDS guidance.
  • Incompatibilities depend on composition; where dichromate or strong oxidants are used in COD methods, keep the CRM away from reducing agents and combustible materials. Verify with SDS/CoA for this specific item.

• Waste and spills

  • Manage waste according to local regulations and method-specific guidance for COD reagents. Small spills of aqueous standards can be absorbed with inert material and disposed of per institutional policy.

Solvent Selection

Not typically applicable: COD CRM is an aqueous reference solution used for calibration/QC rather than as a solvent. Solvent choice pertains to your analytical method rather than to this product itself.

• Literature/general guidance for COD methods (not item-specific)

  • Matrix: Aqueous. The standard is intended to be miscible with water-based digestion and colorimetric/titrimetric workflows.
  • Reagent compatibility: Closed-reflux dichromate methods use concentrated sulfuric acid, potassium dichromate, and catalysts (e.g., Ag2SO4, HgSO4 in classic methods). Ensure that the CRM volume introduced does not exceed vial capacity and is compatible with the digestion acid volume.
  • Rinsing and dilutions: Use high-purity water (Type I/ASTM Type I) for dilutions and glassware rinsing to avoid background COD.

• When to choose alternatives

  • If your laboratory employs mercury-free COD methods, verify that the CRM concentration and matrix are appropriate for those methods. For TOC or Permanganate COD workflows, use dedicated CRMs matched to the measurand and detection technique.

Storage and Reconstitution

• Item-specific instructions

  • Storage Conditions: Protected from light, room temperature (per product data).
  • Shipped In: Normal (ambient) conditions.
  • Reconstitution: Not applicable; supplied as a ready-to-use reference solution unless otherwise stated. Any dilution to working levels should use high-purity water and documented gravimetric/volumetric procedures.

• General best practices (literature/general; not item-specific)

  • Keep the container tightly closed to prevent evaporation or contamination. Minimize headspace exposure and avoid repeated opening; consider aliquoting into amber vials if frequent use is anticipated.
  • Protect from intense light sources; use amber glass and secondary light-protective storage where appropriate.
  • Do not freeze unless specified on the CoA, as freezing may alter concentration or cause precipitation.
  • Mark the date opened; follow any CoA recommendations for in-use stability and shelf-life. Discard after expiration or if visual changes occur.
  • Store away from acids/bases, oxidizers/reducers, or reactive chemicals as indicated by the SDS/CoA for the specific composition.

• Documentation

  • Retain the CoA and SDS with the stored material. Record lot number, open date, and storage conditions as part of your quality system. For research use only.

Structure and Identity

This product is a Certified Reference Material (CRM) for Chemical Oxygen Demand (COD) measurements in environmental/analytical chemistry. It is a solution-type reference standard rather than a single, pure compound, and therefore it does not have a single molecular structure or unique InChIKey/SMILES.

• Item-specific identifiers

  • Product Name: COD CRM (Certified Reference Material)
  • SKU: C117605
  • 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.
  • Grade/Purity: Not specified for this item; refer to CoA/Spec Sheet.

• Structural features

  • As a CRM mixture/solution, there is no single 2D structure to depict. Composition, nominal COD value(s), matrix, and stabilizers (if any) are defined in the Certificate of Analysis (CoA).

• Literature/general context (not item-specific)

  • COD reference solutions are commonly prepared in water with organic carbon sources (e.g., potassium hydrogen phthalate, glucose, or other oxidizable organics) or may be provided as dichromate-reactive calibrants; exact composition varies by standard and producer (literature).
  • The measurand is the equivalent oxygen demand (e.g., mg O2/L), traceable to primary standards via validated preparation and value assignment protocols (ISO 17034/17025 concepts, literature).

Synthetic Utility

Not applicable. This product is not a building block, reagent for organic synthesis, or catalyst. Its role is metrological—providing a certified value for COD to support calibration, validation, and QC of analytical methods. For synthesis-related content, please refer to other reagents specific to your transformation.

Target Specificity

Not applicable. COD CRM is not a biological reagent, antibody, or probe with target specificity. Its certified property is the oxygen demand (mg O2/L) of the solution, intended for calibration and QC of COD analytical methods.