Practical Guide to Sodium Carboxymethyl Cellulose (CMC-Na): Thickening/Stabilizing Mechanisms, Key Controls for Solution Preparation, and Selection Navigation (including Table 1 and Tables A–C)

1.What is CMC, and why is it one of the most common “thickening/stabilizing knobs” in formulations?

In foods, personal care, pharmaceutical excipients, and many other water-based systems, you often see a seemingly “plain” name: CMC.

CMC is neither a small-molecule additive nor a simple blend of natural gums. It is a class of chemically modified cellulose polymers: some hydroxyl groups (–OH) on native cellulose are substituted with anionic carboxymethyl groups (–O–CH₂–COO⁻) in the sodium salt form. This converts otherwise poorly water-soluble cellulose into an anionic polyelectrolyte that can form viscous colloidal solutions in water. In the international food additive system it is also commonly called cellulose gum / Na CMC, corresponding to INS 466 (E 466).

Note: In industry, “CMC” usually refers to its sodium salt (CMC-Na). Unless otherwise specified below, CMC = sodium carboxymethyl cellulose.

2.From “cellulose” to a water-soluble polymer with controllable swelling–dispersion–thickening

2.1 Definition of CMC-Na

CMC-Na is produced by alkali treatment of cellulose, followed by reaction with chloroacetic acid (or its sodium salt) to form sodium carboxymethyl cellulose. Commercial products are typically further subdivided by viscosity grade.

In structural notation, JECFA (FAO/WHO Joint Expert Committee on Food Additives) gives the general formula:

 

Where:

• n is the degree of polymerization (how long the chain is)
• y is the degree of substitution (DS) (average number of carboxymethyl substituents per anhydroglucose unit)
• x + y = 3 (because each unit theoretically has three hydroxyl sites available for substitution)

Note: In the JECFA specification, the allowable range for y (i.e., DS) is 0.2–1.5, with x + y = 3.

2.2 Background and application positioning: it addresses “system state,” not “chemical reaction”

Why is CMC so common? Because in aqueous systems it excels at three things:

• Thickening: significantly increases apparent viscosity at relatively low addition levels;
• Stabilizing: reduces the risks of coalescence and sedimentation of particles/oil droplets/bubbles;
• Suspending: helps insoluble solids disperse more uniformly and “stay up” more effectively.

2.3 Two key structural parameters: DS (degree of substitution) and molecular weight/degree of polymerization (chain length)

2.3.1 DS (Degree of Substitution) = “how many charged side chains are installed per repeat unit”

• Definition: DS = y, i.e., the average number of carboxymethyl substitutions per anhydroglucose unit.
• Typical compliance range: JECFA requires 0.20 ≤ DS ≤ 1.50.
• Interpretation: Higher DS means more charged/hydrophilic sites along the chain, which generally makes it easier to fully disperse in water and form a viscous solution. At the same time, it becomes more sensitive to ionic conditions—because it is fundamentally a charged polymer.

You can view DS as a “hydrophilicity/charge knob”: it primarily determines whether the polymer can fully hydrate in water and form a stable solution/colloid, and it also implies greater sensitivity to ionic strength (especially added salts). Viscosity and clarity often need to be verified by small-scale testing under salt/hard-water challenge conditions to confirm the workable boundary.

2.3.2 Molecular weight / degree of polymerization (n) = “how long the chain is” → often expressed as “viscosity grade”

• In practice, the most visible external indicator of “chain length/molecular weight” is often the apparent viscosity under a specified standard condition.
• For the same CMC, different grades are associated with different weight-average molecular weights and corresponding standard solution viscosity windows (often along with a DS range/bin), enabling rapid formulation selection.

You can treat molecular weight/chain length as the primary “thickening power knob.” However, a viscosity grade is an apparent viscosity window defined under specified concentration–temperature–shear conditions. It reflects a composite outcome dominated by molecular weight, but also influenced by DS/substitution distribution and salts. Therefore, it is not appropriate to compare grades across manufacturers or methods without aligning the test conditions.

Reminder: CMC solutions are typical non-Newtonian systems. The “viscosity” in catalogs should be understood as apparent viscosity under specified test conditions. This is why specifications often clearly state pH, solution ratio, and other conditions (e.g., pH determined in a “1 in 100” solution).

3.Dissolution of CMC in water and key points for solution preparation

3.1 Why does CMC tend to form lumps?

• CMC particles are highly hydrophilic and will hydrate and swell immediately upon contacting water. If wetting is uneven locally, the particle surface can first form a high-viscosity “hydrated shell” that encapsulates the dry powder inside—creating classic lumps / “fish eyes”: the outside has gelled while the inside remains dry, and it becomes difficult to break apart later.
• Nouryon’s CMC Book puts this very directly: particles hydrate and swell immediately, so mixing must keep the entire liquid moving to avoid agglomeration.

3.1.1 Relationship to structural parameters

• Higher molecular weight / higher viscosity grade: once local hydration occurs, the shell viscosity develops faster and “seals” more strongly, making lumping more likely (more process-sensitive).
• More uniform DS (degree of substitution) and substitution distribution: generally favors full dispersion and formation of a homogeneous solution; DS specifications commonly fall in 0.2–1.5 (food additive standards).

3.2 Three key solution-making principles: practical rules to speed dissolution and reduce lumping

• Get the system moving first, then add powder: agitation must cover the entire liquid volume and avoid dead zones; otherwise local lumping is very likely.
• Sprinkle slowly and disperse—don’t dump it in all at once: sprinkle powder evenly into the periphery of the vortex, so each portion can be quickly separated and wetted.
• Give it enough time to “build viscosity”: grades and mixing intensity differ widely; depending on mixing conditions and grade, it commonly takes 10–60 min to reach basic full hydration and a viscosity-stable region (a useful empirical window).

3.3 Three commonly used “anti-lumping” approaches

Method A: Dry-blend dilution (most robust, most universal)

• Thoroughly dry-blend CMC with other dry ingredients in the formulation (sugars, salts, fillers, etc.) before adding water. The essence of dry blending is to “separate” CMC particles and reduce fish-eye risk caused by particle-to-particle sticking.
• Literature also notes that a common strategy to reduce fish eyes is pre-dispersing CMC with other components at a sufficient mass ratio.

Method B: Pre-wetting before adding to water (useful for high-viscosity grades / systems prone to lumping)

• First wet and disperse the powder with a small amount of an allowed water-miscible medium or plasticizer, then add into the main aqueous phase. A common idea is to gently wet particle surfaces to avoid instant hydration and shell formation upon direct contact with water. Some formulation/process references explicitly mention that pre-wetting with oils/alcohols can slow overly rapid hydration.
• Note: For food/pharmaceutical systems, the pre-wetting medium must meet regulatory requirements and be allowed by the formulation.

Method C: Prepare a low-concentration stock solution first, then dilute to the target concentration (best for reproducibility)

• First prepare a uniform 0.5–1% stock solution (easier to fully wet and complete hydration). After viscosity stabilizes, dilute proportionally to the target concentration. This can markedly reduce batch-to-batch viscosity variability and differences caused by incomplete dissolution, improving consistency and reproducibility.

3.4 Troubleshooting checklist (quickly pinpoint the cause)

• Lumps form immediately upon powder addition: powder added too fast / inadequate mixing coverage → switch to slow sprinkling + strengthen circulation/flow field (use dry blending or pre-wetting if needed).
• Dissolved, but viscosity won’t build: insufficient hydration (not enough time) / salt level too high or multivalent ions interfering / pH too far off → first confirm mixing and hydration time, then check system compatibility.
• Fine “particles/micro-lumps” persist and never disappear: often due to insufficient pre-dispersion or powder self-adhesion → prioritize the dry-blend dilution route.

4.Viscosity/Rheology: How to correctly interpret “viscosity grade”?

4.1 CMC “viscosity” is an apparent value—it depends on how you measure it

• For non-Newtonian fluids, viscosity changes with shear (stirring, pumping, rpm). For pseudoplastic CMC solutions, the common experience is: the more you stir, the “thinner” it feels (apparent viscosity decreases).
• Therefore, a specification such as “X mPa·s (cP)” essentially means: an apparent viscosity measured under a defined concentration, temperature, and instrument/rotation speed (shear condition).

4.2 How to read a product data sheet

When you see “viscosity grade / xx mPa·s,” check these three items first (if any one is missing, you should not force a direct cross-comparison):

1. Concentration (% w/w)

• For the same CMC (same model/grade), changing solution concentration will significantly change the measured apparent viscosity—typically, higher concentration → higher viscosity. Therefore, a supplier’s “viscosity grade” usually refers to a viscosity range measured at a specified concentration (e.g., 1% or 2%), with fixed accompanying temperature and instrument/rpm conditions.

2. Temperature (°C)

• CMC aqueous solutions generally become “thinner” as temperature increases (apparent viscosity decreases), and viscosity typically rises again upon cooling—this change is mostly a reversible physical effect. However, if the solution is heated for a long time at elevated temperature (especially under harsh conditions such as strong alkali/oxidation), the polymer chains may degrade, causing an irreversible viscosity loss—meaning it may not recover to the original viscosity even after cooling.

3. Shear conditions (rpm/spindle/shear rate)

• For pseudoplastic systems like CMC, “viscosity” is typically an apparent viscosity under specific shear conditions: if rpm (shear rate), spindle/geometry, or temperature changes, the reading will change. This is the material’s rheological response, not a “measurement error.” Therefore, data are comparable only when the test conditions are consistent.

4.3 Why can “poor solution preparation” make viscosity look lower than expected?

The “lumps/fish eyes” discussed in Part 2 directly affect viscosity readings—the most common underlying reason is incomplete hydration.

A practical diagnostic logic:

• Low viscosity right after preparation: often not “bad material,” but hydration is still ongoing; continue stirring/allow standing time, and viscosity will continue to “build.” (Structure development takes time and is influenced by mixing and shear.)
• Lower and lower readings as you measure: if you increased rpm/shear during measurement, a lower reading is typically the normal shear-thinning behavior of CMC solutions—apparent viscosity changes with shear; it does not mean the material suddenly degraded.
• Doesn’t come back after heating: be alert to irreversible viscosity loss from prolonged high-temperature degradation.

5.Compatibility and application quick view

The most common real-formulation pain points: pH / salt / multivalent metal ions / temperature.

Table 5-1 | Common formulation issues → mechanism → priority checks → solution levers

Observed phenomenon (typical issue)	Possible underlying mechanism	Priority troubleshooting sequence (from most common to most critical)	Solution levers
Viscosity “won’t build” after dissolution	Incomplete hydration / fish-eye micro-lumps; or system conditions suppress chain expansion	① Fully hydrated? (time/shear) ② Any micro-lumps? ③ Dissolve in pure water first, then introduce into complex system?	First make a “fully hydrated stock solution” per Part 2, then dilute; high-viscosity grades require stronger dispersion and more hydration time
Pronounced viscosity drop / thinning after salt addition	Monovalent salts (e.g., NaCl) increase ionic strength and screen chain charges; chains coil more → apparent viscosity decreases	① How high is salt concentration? ② Addition order (CMC first? salt first?)	Fully dissolve CMC in pure water first, then add salt; if needed, choose a more suitable DS/grade to improve salt tolerance
Turbidity, gelation, or even precipitation in the presence of divalent/trivalent ions (Ca²⁺/Mg²⁺/Fe³⁺/Al³⁺, etc.)	Multivalent ions “bridge/crosslink” –COO⁻ groups or form insoluble salts → networking/precipitation	① Any Ca/Mg/Fe/Al in the system? ② Water hardness/metal-ion contamination? ③ Any metal-containing raw materials in the formula?	Avoid trivalent ions where possible; control hardness and metal ions; if necessary, mitigate via formulation strategy/chelation/substituting raw materials (rule of thumb: trivalent risk highest; divalent moderate)
Viscosity drops under acidic pH, possibly with flocculates	–COO⁻ becomes protonated (tending toward the acid form), changing dissolution/swelling state	① Final pH ② How acid was added (local over-acidification?)	Adjust to a more suitable pH range; add acids/bases diluted, slowly, with thorough mixing to avoid local over-acidification
Viscosity drops after heat treatment and does not recover upon cooling	Excessive or too-long thermal exposure (temperature × time too large) causes chain degradation or structural rearrangement → irreversible viscosity loss	① Temperature and time ② Whether in strong alkali/strong oxidizing environment	Reduce heat severity and duration; avoid long heating under strong alkali/oxidizing conditions
Large batch-to-batch variation in the same formula	Particle size/dispersion differences change hydration rate; differing shear conditions change “apparent viscosity”	① Powder addition method ② Equipment and rpm for shear/mixing ③ Are viscosity test conditions consistent?	Standardize addition and mixing procedures; in viscosity reports, specify “concentration–temperature–shear conditions”

Reminder:

• DS affects not only solubility but also stability under salt/ionic environments. Empirically, very low DS (e.g., < 0.3) often struggles to be truly water-soluble; when DS increases (commonly ≥ 0.4 for water-soluble grades), full hydration and maintained dissolution are more achievable. Note that apparent viscosity typically still decreases in the presence of monovalent salts; divalent/trivalent ions may induce association/gelation/precipitation. It is recommended to validate via small-scale “salt/hard-water challenge” tests.

Table 5-2 | Application quick view

Application scenario (what you need to solve)	Role of CMC	What to prioritize in selection	Process key points
Suspension/anti-settling (particulate systems)	Suspension + protective colloid	Prioritize viscosity grade (molecular weight), while considering salt/hardness environment	Prepare a fully hydrated stock solution first; assess multivalent ions/hard water in advance
Thickening & tactile rheology (personal care / household / coating)	Rheology modifier (shear-thinning, smooth spread)	Define target viscosity window first, then choose grade	Viscosity must be benchmarked under the specified shear condition; otherwise it will “look inconsistent”
Stabilizing emulsions/foams (reducing coalescence and syneresis)	Stabilizer + thickener	Evaluate system ionic strength/electrolyte content first, then choose a more robust grade	For high-salt systems, verify “viscosity retention after salt addition” first
Bonding/film formation (paper, coatings, adhesives, etc.)	Binder + film formation/flow control	Consider film-forming/binding needs and solids content	Ensure uniform dispersion first; avoid micro-lumps that cause coating defects
Food/pharmaceutical excipient (compliance first)	Thickening/stabilizing/suspending	Prioritize compliance specs (DS, purity, free glycolate/NaCl, etc.)	Align compliance-critical items first (DS + impurity/residual salt limits), then select by viscosity grade under specified conditions; viscosity comparison must use unified concentration/temperature/shear conditions.

6.Product Navigation Table | CMC Core Products and Supporting Chemicals: Quickly Locate Table 1 / Tables A–C by “Practical Task”

Your need / scenario (typical research or formulation question)	Look at which table first	Why start there	Representative products
You need CMC itself / a core grade for thickening, suspending, film-forming, or rheology modification: which CMC/CMC-Na should you pick first?	Table 1 | Core CMC product table	First decide “what the main material is / which grade.” The viscosity window (low/medium/high), whether it is USP/pharmacopeia grade, and whether it is crosslinked or co-processed define the application boundary.	CMC/CMC-Na grades; USP/pharmacopeia grades; low-/high-viscosity windows; research grades (molecular weight/DS); crosslinked CMC-Na; co-processed MCC + CMC-Na; functionalized derivatives such as CMCMA
You are developing oral solid dosage forms and need a disintegrant, not a thickener (slow tablet/capsule disintegration, unstable disintegration)	Table 1 | Core CMC product table	The disintegrant crosslinked CMC-Na (croscarmellose sodium) is a distinct category. First confirm whether it is pharmacopeia grade and its DS window.	Crosslinked sodium carboxymethyl cellulose (with JP/Ph.Eur/NF alignment and DS window): two SKUs and their positioning
You are making suspensions/creams/gels and need “suspension anti-settling + thixotropic feel,” with better stability at low shear	Table 1 | Core CMC product table	Many systems are better served by building a structured network directly with co-processed MCC + CMC-Na, rather than blindly selecting a CMC viscosity grade.	Co-processed “microcrystalline cellulose + CMC-Na” excipient (pharmacopeia/E-number/NF), suitable for stabilization and thixotropy
In materials / biohydrogels, you want a photo-curable / crosslinkable CMC derivative	Table 1 | Core CMC product table	This is no longer a “viscosity grade” question, but whether the polymer carries crosslinkable handles.	CMCMA (methacrylated CMC) and key information such as degree of substitution/labeling and residual control
Reaction/process development: you want to synthesize CMC or reproduce a literature route (alkalization → etherification → workup) and build a reagent set	Table A | Synthesis raw materials and workup	Lock in the route around “cellulose substrate + NaOH + chloroacetic acid / sodium chloroacetate + acidification/neutralization,” and track the byproduct chain in parallel.	Cellulose; NaOH; CAA / sodium chloroacetate; HCl / glacial acetic acid; glycolic acid / sodium glycolate (byproduct/impurity references)
You encounter fish eyes/lumping/slow dissolution and want robust solution preparation and better wetting/dispersion	Table B | Process solvents and preparation aids	This is a typical process/preparation problem: start with pre-wetting/solvent/dispersion-assist systems instead of repeatedly switching CMC grades.	Ethanol/IPA/methanol (process washing / pre-wetting strategies); glycerol/propylene glycol (pre-wetting/humectancy/dispersion aids)
Viscosity drops markedly after salt addition: you need to evaluate salt sensitivity / ionic strength effects (or run salt-tolerance controls)	Table C | Compatibility strategies and testing/analysis	Salt sensitivity is fundamentally an ionic strength issue: use NaCl as a standardized challenge first, then decide whether to change materials or grades.	Sodium chloride; (with) buffer systems and follow-up QC titration chain (AgNO₃, etc.)
Using tap water/hard water causes turbidity, viscosity loss, or instability: suspected Ca²⁺/Mg²⁺ interference	Table C | Compatibility strategies and testing/analysis	For hard-water issues, prioritize divalent-ion challenge tests and provide countermeasures (chelation/buffering/addition order).	CaCl₂, MgCl₂ (hard-water challenge), EDTA (hardness countermeasure), citric acid/citrates (buffering + partial chelation)
Metal ions/metal impurities are present (or you want a worst-case stress test) and worry about precipitation/incompatibility	Table C | Compatibility strategies and testing/analysis	Multivalent/heavy-metal salts can strongly change the behavior of carboxylate polymers; do a metal-ion stress test first, then decide the route.	Representative salts such as CuSO₄·5H₂O, FeSO₄·7H₂O, SnCl₂·2H₂O, plus EDTA as a countermeasure
QC/method development: measure chloride/residual salts or build an analytical chain (post-synthesis desalting verification, formulation salt control)	Table C | Compatibility strategies and testing/analysis	QC most often stalls on having a complete reagent chain—prepare the titration/indicator system first.	Silver nitrate + potassium chromate (common titration pair), plus method-development reference substances (e.g., 1-naphthol)
You have defined the target application but are still unsure which low/medium/high viscosity window is the most robust choice	Table 1 → (if needed) Table C	Screen candidates by viscosity window/grade in Table 1, then validate workable boundaries via small “salt/hard-water/pH challenge” tests in Table C.	Table 1 provides candidate grades; Table C provides challenge systems (salt/hard water/buffer/chelation) to form a minimal validation loop

Table 1 | Sodium Carboxymethyl Cellulose (CMC) and Derivatives / Co-processed Excipients

Category	Aladdin Cat. No.	Product name	CAS No.	Specification / purity	Key features / selection notes (CMC-related)
Pharmaceutical excipient | Disintegrant (crosslinked CMC-Na)	C304547	Crosslinked sodium carboxymethyl cellulose	74811-65-7	Degree of substitution: 0.60–0.85	A typical tablet/capsule disintegrant (rapid water uptake and swelling + capillary “wicking”), suitable for direct compression and post-granulation addition in wet granulation; used to improve disintegration speed and batch consistency. Selection focus: DS window, particle size/bulk density, and how salts/multivalent ions in the formulation affect swelling behavior.
Pharmaceutical excipient | Disintegrant (crosslinked CMC-Na, pharmacopeia grade)	C494293	Crosslinked sodium carboxymethyl cellulose	74811-65-7	JP, European Pharmacopoeia (Ph.Eur), NF	Also a crosslinked CMC-Na disintegrant, with JP/Ph.Eur/NF alignment—better suited for regulated formulation development and release; used to optimize disintegration and dispersion performance in oral solid dosage forms.
Co-processed excipient | Suspension/emulsion stabilization (MCC + CMC-Na blend)	M498254	Microcrystalline cellulose and sodium carboxymethyl cellulose	—	European Pharmacopoeia (Ph.Eur), E 460(i), E 466, NF	A typical co-processed “MCC + CMC-Na” system: forms a structured network under low shear, enhancing suspension anti-settling, thixotropy, and overall stability; commonly used in oral suspensions, topical creams/gels, and food stabilization (E460(i)/E466 context). Selection focus: target thixotropic feel, solids content, and shear conditions.
Functionalized derivative | Crosslinkable / hydrogel material	C775151	Methacrylated carboxymethyl cellulose (CMCMA)	—	Degree of methacrylation 40–50%; residual methacrylate ≤100 ppm	Carries methacrylate side groups enabling free-radical/photo-crosslinking to form gels: applicable to hydrogels, coatings/adhesion, cell encapsulation/biomaterials, and delivery systems. “Residual ≤100 ppm” supports compliance and risk control for bio-applications.
Biochemistry/chromatography | CM-cellulose (ion exchange / biochemical use)	C1455160	Carboxymethyl cellulose CM-32	9000-11-7	—	CM-cellulose is commonly used as a weak cation-exchange material / biochemical separation medium (proteins, enzymes, etc.), and also for research-grade cellulose-derivative applications. Selection focus: buffer system, ionic strength, and column packing/separation requirements.
Research grade | Controlled molecular weight/DS series (high viscosity / high MW)	C104977	Carboxymethyl cellulose I	9004-32-4	M.W. 700000 (DS = 0.9), 2500–4500 mPa·s	Ultra-high molecular weight and high viscosity: suitable as a rheology benchmark, strong thickening/structural network construction, gel/sustained-release matrices, and high water-retention systems. Key notes: more sensitive to dissolution/dispersion; recommended workflow “pre-wet → high-shear dispersion → full hydration.”
Research grade | Controlled molecular weight/DS series (high DS; clearer solutions)	C104978	Carboxymethyl cellulose II	9004-32-4	M.W. 250000 (DS = 1.2), 1500–3100 mPa·s	Higher DS (1.2): typically favors full hydration and solution clarity/homogeneity (easier to form stable solutions under comparable conditions); used for R&D and formulation screening requiring relatively strong thickening but improved uniformity.
Research grade | Controlled molecular weight/DS series (balanced)	C104979	Carboxymethyl cellulose III	9004-32-4	M.W. 250000 (DS = 0.9), 1500–3100 mPa·s	Balanced DS and molecular weight: a “thickening vs. processability” compromise option; applicable to suspension stabilization, film-forming/binding, and general rheology studies.
Research grade | Controlled molecular weight/DS series (lower DS)	C104981	Carboxymethyl cellulose IV	9004-32-4	M.W. 250000 (DS = 0.7), 1500–3100 mPa·s	DS = 0.7: leans toward “swelling/network contribution”; useful for studying how DS affects salt sensitivity and compatibility/flocculation windows. In complex ionic environments, run small-scale compatibility challenges first (salt/divalent ions).
Research grade | Controlled molecular weight/DS series (low viscosity / easy processing)	C104983	Carboxymethyl cellulose V	9004-32-4	M.W. 90000 (DS = 0.7), 50–100 mPa·s	Low MW and low viscosity: suitable for low-viscosity stabilization/protective colloid use, coating and spray systems, and binder/film-forming precursor solutions; process-friendly and pumpable.
General grade | Thickening/stabilizing (medium–high viscosity)	C501052	Carboxymethyl cellulose	9004-32-4	800–1000 mPa·s	Medium–high viscosity thickening and stabilization: suitable for aqueous systems needing noticeable thickening, water retention, and suspension stability (detergent/personal care, coatings, adhesives, etc.). Selection note: higher viscosity at the same concentration → faster “viscosity build” and higher lumping risk; consider making a stock solution before introducing into the main system.
General grade | Thickening/film forming (low–medium viscosity, DS specified)	C294622	Carboxymethyl cellulose	9004-32-4	DS = 0.7, 200–500 mPa·s	DS = 0.7 with low–medium viscosity: a more “easy-to-disperse/pump” thickening and stabilization option; suitable for coatings, bonding, stabilization/protective colloid roles. Selection note: DS affects water solubility and salt-tolerance tendency; 200–500 mPa·s improves process operability and transparency control.
General grade | CMC-Na low viscosity grade	C299502	Sodium carboxymethyl cellulose	9004-32-4	Low viscosity: 50–200 mPa·s	Low-viscosity CMC-Na: suitable for systems requiring “light thickening + stabilization/suspension” while maintaining good flow (coatings, cleaners, low-solids stabilization, etc.); advantages include fast dispersion and lower equipment demand.
Pharmaceutical excipient | CMC-Na (USP grade, lower viscosity)	C104984	Sodium carboxymethyl cellulose	9004-32-4	Viscosity: 300–800 mPa·s, USP grade	USP-grade, relatively lower viscosity: favors flowability, filling/pumping, and fast dissolution; suitable for oral/topical systems requiring light-to-moderate thickening, and often used where viscosity must be controlled while improving stability.
Pharmaceutical excipient | CMC-Na (USP grade, medium viscosity)	C104987	Sodium carboxymethyl cellulose	9004-32-4	Viscosity: 600–1000 mPa·s, USP grade	USP-grade medium viscosity: commonly used for thickening/stabilizing suspensions and syrups, and rheology tuning in topical gels/creams; also a candidate for tableting binder/film-forming excipient roles. Selection focus: system pH, salts/multivalent ions, and viscosity test conditions (concentration/temperature/shear).
Pharmaceutical excipient | CMC-Na (USP grade, medium–high viscosity)	C104985	Sodium carboxymethyl cellulose (CMC)	9004-32-4	Viscosity: 800–1200 mPa·s, USP grade	USP-grade medium–high viscosity: suitable for more pronounced thixotropy and structural support (e.g., topical gels, suspension stabilization). Key note: fully hydrate as described in Part 2 to avoid “false low viscosity” (from incomplete hydration).
Pharmaceutical excipient | CMC-Na (USP grade, high viscosity)	C104986	Sodium carboxymethyl cellulose (CMC)	9004-32-4	Viscosity: 1000–1400 mPa·s, USP grade	USP-grade high viscosity: for stronger thickening and suspension anti-settling, water retention, and structure building. More sensitive to dispersion; recommended: prepare a low-concentration stock and/or use high-shear dispersion before adding to the main system to reduce lumping risk.
Pharmaceutical/formulation use | CMC-Na (medium–high viscosity)	C304951	Sodium carboxymethyl cellulose	9085-26-1	Viscosity: 600–3000 mPa·s	Covers medium to relatively high viscosity windows: suitable for systems requiring stronger structure and anti-settling (high-solids suspensions, pastes/gels).

CMC Supporting Chemical List | Aladdin SKUs grouped by “Synthesis feedstocks → process preparation → compatibility strategies → testing & impurities” (for selection and promotion)

Table A | Synthesis raw materials and workup (CMC preparation / neutralization / byproduct chain)

Category	CAS No.	Aladdin Cat. No.	Product name	Specification / purity	Key features and applications (CMC-related)
Feedstock/substrate | Cellulose source (parent polymer)	9004-34-6	C434462	Cellulose	Microcrystalline powder	Parent material for CMC synthesis: starting substrate for the alkalization–etherification route in research and benchmarking; also useful for comparing how different fibrillation/physical forms affect reaction uniformity and final viscosity.
Synthesis reagent/process control | Alkalization / salt formation	1310-73-2	S111498	Sodium hydroxide	Reagent grade, ≥96%	Key base for CMC preparation and system control: used for cellulose alkalization, driving carboxymethylation and forming the sodium salt; also used for pH adjustment in formulations. Selection focus: moisture/CO₂ (carbonate) uptake, solution preparation, and safe handling.
Synthesis reagent | Etherifying agent (main reaction)	79-11-8	C485697	Chloroacetic acid (CAA)	≥99%	Core etherifying reagent for CMC carboxymethylation (reacts with alkalized cellulose to introduce –CH₂COO⁻). Selection focus: purity and moisture; impurity profile influences DS and the fraction of side reactions (glycolate formation).
Synthesis reagent | Etherifying agent (common salt form)	3926-62-3	S108371	Sodium chloroacetate	AR, ≥98%	Salt-form etherifying reagent: convenient for dosing/charging in alkaline systems; commonly used in CMC synthesis routes; useful for studying how salt-form charging affects DS and salt/byproduct distribution.
Synthesis/workup | Neutralization/acidification (H-form, pH adjustment)	7647-01-0	H485806	Hydrochloric acid 25% (controlled substance)	Suitable for analysis, premium grade	Used for acidification/neutralization during workup (e.g., returning to target pH, preparing acid form / pH control during desalting); also used for pH scans and acid-side compatibility challenges.
Synthesis/workup | Neutralization/acidification (mild organic acid)	64-19-7	A116166	Glacial acetic acid	Reagent grade, ≥99.5%	Common mild acid for workup/neutralization and fine pH adjustment; also serves as a gentler acid source for aqueous controls (vs. strong inorganic acids).
Key impurity/byproduct chain | Byproduct (acid form)	79-14-1	G434198	Glycolic acid	Suitable for analysis, premium grade	Acid-form reference in the glycolic acid/glycolate chain related to CMC side reactions: useful for impurity identification, method development, and control experiments (to understand side reactions and workup).
Key impurity/byproduct chain | Byproduct (salt form; frequent spec item)	2836-32-0	S102872	Sodium glycolate	≥98%	Important byproduct/impurity reference: associated with side reactions in chloroacetic acid/alkali systems and often discussed as a control item in specifications; useful for impurity referencing and QC/process-optimization verification.

Table B | Process solvents and preparation aids (dissolution / anti-lumping / process washing)

Category	CAS No.	Aladdin Cat. No.	Product name	Specification / purity	Key features and applications (CMC-related)
Process solvent/washing | Alcohol medium	67-56-1	M116128	Methanol	For protein sequencing, ≥99.9%	One of the common alcohols in CMC synthesis/workup and lab solvent systems: used for washing/solvent exchange/dehydration and process controls; also for exploring “pre-wet then add to water” dispersion strategies (subject to end-use compliance).
Process solvent/washing | Alcohol medium	64-17-5	E111963	Ethanol	Pharmaceutical grade, PharmPure™, ≥99.5%	Pharmaceutical-grade ethanol: suitable for regulated process/preparation; can be used for powder pre-wetting, process washing, or water–alcohol compatibility studies (ensure end-use compliance).
Process solvent/washing | Alcohol medium	67-63-0	I434894	Isopropanol (IPA)	Pharmaceutical grade, PharmPure™	A typical process solvent/washing medium: widely used in cellulose-derivative processing; also commonly used for powder pre-wetting to reduce “fish-eye/lumping” risk.
Preparation aid | Pre-wetting/humectancy/dispersion assist	56-81-5	G116213	Glycerol	For electrophoresis, ≥99%	A typical pre-wetting and humectant aid: helps reduce lumping risk caused by instantaneous hydration/film formation during CMC/CMC-Na solution preparation; also used to tune water retention and feel (depending on the target system).
Preparation aid | Pre-wetting/humectancy/dispersion assist	57-55-6	P103429	1,2-Propanediol (propylene glycol)	Standard for GC, ≥99.5% (GC)	A common pre-wetting/humectant aid: improves dispersion and dissolution and reduces localized lumping; also used for fine-tuning rheology and stability in personal care/pharma systems (subject to application compliance).

Table C | Compatibility strategies and testing/analysis (salt/buffer/hard water/metal ions + QC reagents)

Category	CAS No.	Aladdin Cat. No.	Product name	Specification / purity	Key features and applications (CMC-related)
Formulation/compatibility | Monovalent salt (ionic strength)	7647-14-5	S433744	Sodium chloride	Anhydrous, high purity, reagent grade, ≥99%	Standard “challenge salt” for ionic strength: used to evaluate CMC salt sensitivity (viscosity retention, clarity changes); also relevant to common residual salts/byproduct matrices after CMC synthesis.
Formulation/compatibility | pH/buffering (base)	497-19-8	S432764	Sodium carbonate	Anhydrous, reagent grade, suitable for analysis	Common weak base and buffer component: used for pH adjustment and buffering; in CMC systems, useful for defining the “alkaline-side window” and stability controls.
Formulation/compatibility | Buffering/chelation (citrate system)	77-92-9	C434175	Citric acid	Anhydrous, PharmPure™, USP, JP, BP, Ph.Eur, pharmaceutical grade, powder	Multi-pharmacopeia citric acid: for pH adjustment/buffer construction and provides some chelating capacity; used for acid-side window mapping and hard-water/metal-ion mitigation strategies.
Formulation/compatibility | Buffering/chelation (citrate salt)	68-04-2	T774745	Trisodium citrate	Anhydrous, USP	USP buffer salt: used to build citrate buffers with some chelating capacity; suitable for pH/ionic environment control in regulated CMC formulations.
Formulation/compatibility | Buffering/chelation (citrate salt)	6132-04-3	S434901	Sodium citrate, dihydrate	Pharmaceutical grade, PharmPure™	Pharmaceutical-grade sodium citrate dihydrate: for buffering and ionic-strength management; in suspensions/gels, helps stabilize pH and reduce batch variation.
Formulation/compatibility | Hard-water/divalent-ion challenge	10043-52-4	C431202	Calcium chloride	Anhydrous, ≥97%	Representative divalent ion: evaluates viscosity changes and turbidity/gel risks of CMC under hard-water/Ca²⁺ systems; also simulates real water sources and compatibility boundaries.
Formulation/compatibility | Hard-water/divalent-ion challenge	7786-30-3	M113689	Magnesium chloride, anhydrous	Anhydrous, ≥99.9% metals basis, powder	Mg²⁺ hard-water representative: for hard-water challenge and ionic-strength impact evaluation; strongly affects CMC chain conformation and rheology—high-frequency reagent in compatibility testing.
Formulation/compatibility | Metal-ion/precipitation risk (heavy-metal salt)	7758-99-8	C657076	Copper(II) sulfate pentahydrate	Animal-free, low endotoxin, for cell culture, ≥98%	Representative reagent for metal-ion compatibility “stress testing”: Cu²⁺ may affect stability/viscosity and induce complexation/incompatibility; this grade emphasizes low endotoxin and cell-culture suitability for bio-related studies.
Formulation/compatibility | Metal-ion/precipitation risk (reducing Fe²⁺ salt)	7782-63-0	I434044	Iron(II) sulfate heptahydrate	Ph.Eur, suitable for analysis, ACS, premium grade	Fe²⁺ representative salt: evaluates impacts of metal ions on color/stability/viscosity and simulates risks from metal impurities in formulations or processes.
Formulation/compatibility | Metal-ion/precipitation risk (tin salt)	10025-69-1	T478535	Tin(II) chloride dihydrate	Reagent grade, 98%	Sn²⁺ representative salt: for studying interactions between metal ions and carboxylate polymers and turbidity/precipitation risks; also a control reagent for “heavy-metal incompatibility” scenarios.
Compatibility countermeasure | Chelation/softening (EDTA)	6381-92-6	E118595	Disodium EDTA, dihydrate	Suitable for electrophoresis, molecular biology grade	Common chelator: reduces interference from Ca²⁺/Mg²⁺ and improves CMC system stability and batch consistency; molecular biology grade suits higher cleanliness requirements.
Compatibility countermeasure | Chelation/softening (EDTA)	139-33-3	D684233	Disodium EDTA	≥99%	Anhydrous EDTA-2Na: chelates divalent and some trivalent metal ions; a general countermeasure reagent for “hard-water/metal-ion issues” in CMC systems. Selection note: differences between hydrates and anhydrous forms and how solutions are prepared.
Testing/analysis | Halide/salt titration chain	7761-88-8	S433976	Silver nitrate (explosive precursor)	Ph.Eur, suitable for analysis, ACS, premium grade	Core titrant for chloride/halide titration and salt analysis (e.g., precipitation titration with an indicator system); used for QC and method development related to residual salts/chloride after CMC synthesis.
Testing/analysis | Titration indicator / method support	7789-00-6	P116403	Potassium chromate	PrimorTrace™, ≥99.99% metals basis	Common indicator in precipitation titration (e.g., Mohr method) to form an “AgNO₃ + indicator” analytical chain; high-purity metals basis helps reduce background interference (choose per method).
Testing/analysis | Identification/reference standard	90-15-3	N103798	1-Naphthol	Analytical standard	Reference material for method development/identification: used to build or validate specific colorimetric/derivatization/identification workflows (method-dependent); can be included in a QC “test kit” for supplemental verification and method confirmation.
Testing/analysis | Identification/reference standard (method development)	90-15-3	N128915	1-Naphthol	Ultrapure, ≥99%	Higher-purity option for the same use: suitable when background interference sensitivity is higher in colorimetry/identification or method evaluation (method-dependent); helps reduce blank/background and improve repeatability in QC/method confirmation.

Note: The above are representative Aladdin products. For additional specifications, please refer to the product list at the end of the article or search the Aladdin website by product name/CAS.

Aladdin: https://www.aladdinsci.com/