Section
| HS Code | 760149 |
| Productname | Auramine O Conc |
| Chemicalname | Auramine O hydrochloride |
| Casnumber | 2465-27-2 |
| Molecularformula | C17H22ClN3 |
| Molecularweight | 303.83 g/mol |
| Colorindex | CI 41000 |
| Appearance | Yellow to orange-yellow |
| Physicalform | Concentrated dye product |
| Solubility | Soluble in water and ethanol |
| Primaryapplication | Fluorescent acid-fast staining |
| Storageconditions | Cool, dry, dark place at room temperature |
| Hazardinformation | Suspected carcinogen; harmful if swallowed; irritant |
| Handlingprecautions | Use gloves, eye protection, and ventilation |
| Concentration | Concentrated; dilute before use |
As an accredited Auramine O Conc factory, we enforce strict quality protocols—every batch undergoes rigorous testing to ensure consistent efficacy and safety standards.
| Packing | Auramine O Conc is packaged in 100 g amber glass screw-cap bottles, individually labeled with batch details and hazard warnings. |
| Container Loading (20′ FCL) | Auramine O Conc loaded in a 20′ FCL container, securely palletized in sealed drums with proper labeling and lashing for safe transport. |
| Shipping | Auramine O Conc is generally not regulated for transport under DOT/IATA/IMDG when shipped as the dye alone. Use a closed, labeled container and follow the SDS. Phenol-containing or environmentally hazardous formulations may require UN 2821 or UN 3077, with the appropriate class, packing group, and labels. |
| Storage | Store Auramine O Conc in a tightly closed, labeled container in a cool, dry, well-ventilated area away from direct sunlight, heat, ignition sources, and incompatible materials such as strong oxidizers and acids. Protect from moisture and segregate from food, drink, and animal feed. Follow local regulations and use appropriate personal protective equipment when handling. |
| Shelf Life | Stable under recommended storage conditions; protect from light and moisture, and use within the manufacturer’s stated shelf life, typically several years. |
Fluorescence screening protocols for acid-fast bacilli in clinical mycobacteriology laboratories use Auramine O Conc as the primary fluorochrome in a Truant-type formulation: 0.15 g Auramine O, 0.075 g rhodamine B, 7.5 mL glycerol, 1.0 mL liquefied phenol, and 5.0 mL deionized water. Heat-fixed smears are flooded for 15 min, rinsed with water, decolorised for 2 min in 0.5% v/v HCl in 70% v/v ethanol, rinsed, counterstained for 2–4 min in 0.5% w/v potassium permanganate, rinsed again, air-dried, and examined with a fluorescence microscope fitted with a 450–490 nm excitation filter and a 515–530 nm barrier filter. The cationic dye binds to mycolic acid-containing cell envelopes; acid-alcohol treatment removes non-acid-fast background while mycobacteria retain the Auramine O–rhodamine B complex. Under a 40× objective, acid-fast bacilli appear as yellow-green rods against a dark background, permitting lower total magnification scanning than conventional carbol fuchsin stains. CLSI M48-A requires fluorescent smear-positive results to be confirmed by Ziehl–Neelsen staining or culture because non-specific rhodamine B fluorescence from cellular debris can produce false-positive interpretation. Working solutions are prepared under a chemical fume hood; Auramine O is governed by institutional chemical hygiene plans as a suspected occupational carcinogen, with nitrile glove containment and absorbent bench protection specified for handling the concentrated powder. The same dye stock is unsuitable for live-cell imaging because the phenol-containing vehicle is cytotoxic and the dye concentration produces non-selective adsorption to polysaccharide matrices.
In acrylic exhaust dyeing, Auramine O Conc is pasted with 1 part dry dye and 0.5–1.0 part of 40% v/v acetic acid, then diluted with water at 70 °C before introduction into a dye bath prepared with sodium acetate trihydrate to hold pH at 4.5–5.0. A cationic retarder, typically a quaternary ammonium salt with a short alkyl chain, is added at 0.5–2.0% o.w.f. to compete with dye cations for anionic fibre sites; retarder demand is increased as shade depth is reduced because higher dye concentrations provide partial self-levelling through site competition. The dyeing vessel is usually a package or hank machine with reversible flow; the bath is set at 60 °C and heated at 1.0–1.5 °C/min to 98 °C for conventional acrylic fibre, with a 15 min hold at 85 °C to control the strike zone before the final temperature is reached. Modacrylic fibre is processed at a maximum of 80–85 °C because higher temperatures cause fibre softening and package deformation. At the end of the cycle, the exhausted bath is cooled to 60 °C before overflow rinsing; residual cationic dye is cleared with a nonionic surfactant and acetic acid rinse rather than an anionic detergent, which would precipitate unexhausted Auramine O. The resulting yellow shades on acrylic are restricted to indoor textiles such as curtains, blankets, and fashion knitwear because the lightfastness of Basic Yellow 2 is not better than grade 1–2 under ISO 105-B02. Wash fastness under ISO 105-C06 is acceptable only when the final rinse is free of unfixed dye; deep shades may require an aftertreatment with tannic acid and tartar emetic to reduce dye migration to adjacent fabrics. pH above 6.0 must be avoided because alkaline conditions hydrolyse Auramine O to Michler’s ketone and produce irreversible dulling; simultaneous addition of anionic levelling or dispersing agents must also be avoided because coacervation with the cationic dye forms a gummy precipitate in the dye bath.
Wet-end addition of Auramine O Conc to bleached sulfite and kraft furnishes is carried out at 0.05–0.40% dry-fibre mass at the thin-stock stage after alum addition but before the fan pump, with a contact time of 15–30 min before sheet formation. The dye is dissolved in water at 50 °C and filtered through a 100 µm screen before metering to the machine chest or silo to avoid undissolved particles that create yellow specks in the sheet. Stock pH is maintained at 4.5–5.5 with alum or sulfuric acid; at pH above 6.0 fibre carboxylate groups are fully ionised and unretained dye rises in the white water. For fully bleached kraft, alum at 0.25–0.75% on dry fibre improves fixation, while mechanical pulps retain Auramine O without additional mordant because of higher lignin sulfonate and carboxyl content. The dye is substantive to anionic pulp surfaces and produces a bright greenish-yellow shade; final yellowness is measured as CIE b* or assessed under ISO 11475 when controlled whiteness is specified. Accelerated ageing under ISO 5630-3 reveals significant yellow shade loss, and the dye is therefore restricted to short-life paper products such as coloured envelope stock, poster paper, tissue, and directory-grade paper rather than archival documents. Production issues on open paper machines include tinted backwater and cross-machine shade variation; these are controlled by online colour measurement after the dryer section and by limiting broke addition to 10–15% of the furnish because broke carrying fixed Auramine O shifts final shade and increases two-sidedness.
Auramine O Conc is soluble in methanol, ethanol, and water, but its solubility in ethyl acetate and n-propanol is low; solvent-based flexographic ink formulations therefore predissolve the dye in an 85:15 v/v ethanol:water mixture at 50 °C before cold-cut addition to a nitrocellulose or shellac varnish. The final ink carries 1.5–3.0 wt% dye based on total ink weight and is let down with ethanol or n-propyl acetate only after the dye stock is fully dissolved; direct addition of dry powder to the varnish creates hard agglomerates that deposit on the anilox roll and produce print mottling. On absorbent kraft and paperboard, the dye penetrates the surface and provides high colour strength without a separate binder; on non-absorbent films the same ink does not adhere and shows severe water and oil bleed. Bleed resistance is assessed by ISO 2836:2004 for printed matter; Auramine O typically exhibits poor resistance to water, ethanol, and alkaline soap solution because the dye remains water-reducible after drying. The use window is therefore confined to bag, wrapper, envelope, and corrugated overprint applications where post-print contact with water is not part of the product lifecycle. Lightfastness under ISO 105-B02 is no better than grade 1, so printed stock exposed to daylight for even limited periods undergoes visible fading and should not be specified for window display packaging. Regulatory compliance excludes this dye from food-contact printing inks because it is not listed in the positive list of EU Regulation 10/2011; producers supplying food-safe packaging must switch to pigment-based yellow concentrates.
For vegetable-tanned crust leather, Auramine O Conc is brought into the finishing line as a 10 g/L stock solution prepared by pasting the dye with 1 part water and 1 part of 30% v/v acetic acid, heating to 50 °C, and filtering through a 50 µm screen. Drum application on shaved weight is performed at 0.1–0.8% dye in a float of 200–300% at 50 °C and pH 4.0–5.0 for 30 min; spray application uses the same stock diluted to 0.05–0.20% in water and applied in two or three cross-coats to avoid streaking on glazed or aniline-type crust. The cationic dye is attracted to anionic carboxyl groups of vegetable-tanned leather, but exhausted colour has poor wet rub fastness; fixation is improved by a post-treatment with 1.0% tannic acid and 0.5% tartar emetic on wet leather weight. Rub fastness is measured according to ISO 11640, with acceptable results only for low-stress uses such as bookbinding covers, decorative hides, and fashion accessories; lightfastness under ISO 105-B02 remains in the 1–2 range, which excludes automotive and outdoor upholstery specifications. The dye bath must not be combined with anionic syntans or sulfated fatliquors in the same operation because the resulting coacervate deposits on the grain and produces dull, uneven yellow areas that cannot be corrected without re-tanning.
Basic Yellow 2 is converted to an insoluble pigment lake by adsorbing the cationic dye onto freshly precipitated aluminium hydrate or bentonite from an aqueous dye solution at 60 °C. The aluminium hydrate is generated in situ by slow addition of sodium carbonate solution to aluminium sulfate solution until pH reaches 6.0–7.0; Auramine O Conc stock at 20 g/L is then added under high-shear dispersion and stirred for 30 min before filtration, washing with deionized water, and tray drying at 60–70 °C. The resulting lake typically contains 25–35% dye on extender mass and is used in low-cost printing inks, paper coating colours, and wallpaper grounds where high transparency and high tinting strength are more important than external durability. The lake is dispersed into aqueous binder systems with a high-speed disperser at 1500–2000 rpm for 20 min; glass bead milling is not required for aluminium hydrate lakes because the average particle size after precipitation is below 10 µm. Lightfastness of the lake is not better than the soluble dye and is rated below 2 in ISO 105-B02, which restricts use to interior graphic products without prolonged daylight exposure. The pigment also shows sensitivity to alkaline pH above 8.0, where aluminium hydrate loses its positive charge and the dye desorbs into aqueous contact media; suspension pH in water is evaluated by ISO 787-9.
Competitive Auramine O Conc prices that fit your budget—flexible terms and customized quotes for every order.
For samples, pricing, or more information, please contact us at +8615365186327 or mail to sales3@liwei-chem.com.
We will respond to you as soon as possible.
Tel: +8615365186327
Email: sales3@liwei-chem.com
Flexible payment, competitive price, premium service - Inquire now!
Auramine O Conc is supplied as a concentrated liquid preparation of Auramine O (C.I. 41000, Basic Yellow 2, CAS 2465-27-2), a cationic diarylmethane fluorochrome with the molecular formula C17H22ClN3 and a formula weight of 303.83 g/mol. The product is used to prepare acid-fast bacterial staining solutions and as a stock dye for polyacrylonitrile fibre, paper, and leather coloration. No single universal model identifier applies; procurement is specified by supplier catalog code, lot-specific active dye content, residual solvent matrix, and absorbance calibration at 432 nm. The concentrated liquid reduces dry powder dust exposure during bulk weighing and permits automated metering in production dye kitchens. Typical aqueous spectral characteristics include a visible absorbance maximum at 432 nm and a fluorescence emission maximum near 505 nm when excited at 435 nm; emission intensity is highly dependent on solvent viscosity and pH, not solely on dye concentration. Lot certificates should be reviewed before volumetric dilution because active content and stabilizer composition vary by supplier.
Concentrated Auramine O solutions are susceptible to precipitation at low temperature, hydrolytic degradation under alkaline pH, and flocculation in high-ionic-strength matrices. Storage between 15 °C and 25 °C in sealed high-density polyethylene or stainless steel 316L containers is recommended; freeze-thaw cycling can produce crystal growth that does not redissolve under low-shear agitation. The cationic dye is incompatible with anionic surfactants, sulfonated dispersants, and hard water. Dilution into water with total hardness above 150 mg/L CaCO₃ may reduce solubility and generate insoluble lake deposits on heat exchangers and filter housings. Process water should therefore be deionized or reverse-osmosis permeate. The pH of the concentrate is typically maintained in the range 4.0–6.0 with dilute acetic acid to suppress carbinol base formation; above pH 8.0, fluorescence intensity declines markedly. Production-scale liquid handling systems with low-shear rotary lobe pumps are preferred over high-speed centrifugal pumps because excessive shear and air entrainment can destabilise the dispersion and increase foam. Silicone-based antifoam agents should be avoided unless compatibility is confirmed by a filtered-nephelometric stability test. Published data for this specific configuration is limited; batch-specific stability under shear must be validated.
The fluorescence signal of Auramine O arises from viscosity-sensitive restriction of internal rotation when the dye binds to mycolic acid-containing cell wall structures. Working stains are prepared by dilution of Auramine O Conc in acidified phenol-glycerol or dilute acetic acid matrices; however, the exact formulation is procedure-dependent and must be validated against a certified positive control smear. A representative starting point is a 0.1% w/v Auramine O equivalent in 5% phenol, but this value is not a universal formulation. The diluted stain is filtered through a 0.45 µm membrane to remove dye aggregates before application. Concentrations above 0.3% w/v can increase nonspecific fluorescence and shorten working-solution shelf life to less than 24 hours; concentrations below 0.05% w/v may produce false-negative results in weakly acid-fast organisms. Slides are examined with a fluorescence microscope fitted with a 450–490 nm band-pass excitation filter, a 510 nm dichromatic mirror, and a 515–560 nm emission filter. Laboratories accredited under ISO 15189:2022 should verify each new lot against reference slides of Mycobacterium tuberculosis H37Ra or an equivalent strain and include negative controls with each batch. CLSI M48-A provides procedural guidance for mycobacteriology stain validation. Published data for this specific concentrated product in automated slide stainers is limited; stainers with positive-displacement dispensing are preferred to avoid volumetric drift caused by viscosity differences.
Photostability of Auramine O in glycerol or phenol-based mounting media is limited; slides exposed to continuous high-intensity excitation at 450–490 nm can lose more than 20% of initial fluorescence intensity within 10 minutes in the absence of antifade reagents. Published data for this specific concentrated formulation under LED illumination is limited, but the phenomenon is consistent with photobleaching of basic diarylmethane fluorochromes. Quantitative fluorescence microscopy should therefore use fixed exposure times, neutral-density reference slides, and image capture within the first 5 minutes of illumination to reduce variability. Antifade mountants based on p-phenylenediamine or DABCO are used to slow photobleaching; their compatibility with the stain must be confirmed because some antifade formulations lower the pH and reduce binding affinity. In flow-through staining systems, the working solution should be replaced after 8 hours or after 120 slides, whichever occurs first, to avoid signal drift from evaporation and dye oxidation.
Quantitative control of Auramine O Conc requires spectrophotometric measurement against a certified reference material. A stock solution is diluted in 0.1 M acetate buffer at pH 4.5 to an absorbance between 0.3 and 0.8 AU at 432 nm; molar attenuation coefficient values in the literature vary with pH and solvent, so lot-specific calibration is preferred over fixed published constants. For fluorometric applications, the inner filter effect must be considered at dye concentrations exceeding 0.1% w/v, and emission scans should be corrected with the manufacturer’s photomultiplier correction curves. In textile production, colour strength is evaluated under D65 illumination according to ISO 105-J01 or equivalent; liquid concentrates should be homogenised by low-shear stirring for 15–20 minutes before sampling to avoid stratification. Batch-to-batch shade differences attributable to residual anionic surfactants on incoming fibre are a recognised production bottleneck; pre-scouring of acrylic tow at 60 °C with nonionic detergent reduces the risk of dye precipitation and filter blockage.
Industrial dyeing with Auramine O Conc is carried out in polyacrylonitrile fibre coloration, paper surface sizing, and leather finishing. The liquid concentrate is prediluted in a stainless steel 316L stock tank with acetic acid/sodium acetate buffer at pH 4.5–5.5 before being metered into the main dye bath. Basic dyes have high tinctorial strength; pale-to-medium shades on acrylic are commonly produced at 0.05–0.5% owf, while deeper shades may require up to 1.5% owf. Exceeding 2.0% owf on acrylic fibre can cause unlevel strike because exhaustion accelerates near the fibre glass transition temperature and migration at the boil is limited. Dye-bath temperature is controlled at 98–100 °C for 45–60 minutes, followed by cooling to 70 °C before overflow rinsing. Light fastness of C.I. Basic Yellow 2 on acrylic under ISO 105-B02 is typically low, generally not exceeding 2 on the blue wool scale; the dye is therefore specified for applications where high light fastness is not required or where UV stabilisation is provided. In package dyeing machines with a liquor-to-goods ratio of 1:10, liquor turnover should be at least 2–3 cycles/min; low flow can cause package-to-package shade variation. Published data for this specific product in beam dyeing equipment is limited, and trial operations should confirm dispersibility after storage.
Substitution of dry Auramine O powder with Auramine O Conc on an established acrylic dyeing line is not a direct mass-for-mass replacement. The active content of the concentrate must be determined at 432 nm against a calibration curve prepared from a certified reference standard, and the dosing pump output must be adjusted to deliver the equivalent of dry dye at the required shade depth. On a 100 kg production batch, a 5% deviation in active content can produce a visible shade shift under D65 illumination; metering pumps with a dosing accuracy of ±1% or better are therefore recommended. The concentrate should be predissolved in a separate tank before addition to the main dye bath to avoid localised high concentration and fibre shock. Stainless steel 316L is the preferred tank material; carbon steel and aluminium are unsuitable because the chloride salt and acetic acid buffer can initiate corrosion and metal ion precipitation. Unlike dry powder, which can be stored for extended periods under dry conditions, the liquid concentrate has a shorter shelf life and requires first-in-first-out rotation. Residual water in the concentrate can also affect the liquor-to-goods calculation, particularly in low-ratio dyeing equipment. Published data for this specific replacement calculation in industrial acrylic tow dyeing is limited; plant validation should include shade reproducibility, filtration pressure drop, and effluent colour discharge monitoring under local permits.
In paper surface coloration, Auramine O Conc is metered into size-press starch or polyvinyl alcohol solutions. The cationic dye has strong affinity for bleached pulp fibre, but dosing above 0.1% on dry fibre weight can cause mottling due to rapid exhaustion and poor migration. Papermakers monitor tint strength by continuous UV-Vis absorbance at 432 nm in the recirculating size solution; abrupt absorbance drift indicates dye aggregation or alum interaction. Alum and cationic retention aids can compete with the dye and should be added after dye fixation to avoid reduced shade depth. Leather finishing uses the concentrate in spray or curtain-coating formulations; penetration into wet-blue leather is low, and surface fixation is rapid. Published data for this specific product in paper and leather applications is limited; production trials should confirm compatibility with optical brighteners and anionic fatliquors.
Differences among Auramine O Conc, dry Auramine O powder, and Rhodamine B arise from physical form, spectral emission, and handling behaviour. The table below summarises reported identifiers and performance parameters used for product selection in staining and dyeing.
| Parameter | Auramine O Conc | Dry Auramine O | Rhodamine B |
|---|---|---|---|
| C.I. designation | C.I. 41000 | C.I. 41000 | C.I. 45170 |
| CAS registry number | 2465-27-2 | 2465-27-2 | 81-88-9 |
| Visible absorbance maximum in aqueous solution | 432 nm | 432 nm | 554 nm |
| Fluorescence emission maximum | 505 nm | 505 nm | 627 nm |
| Primary acid-fast staining role | Primary fluorochrome | Primary fluorochrome | Primary or counterstain in combined formulations |
| Textile light fastness on acrylic under ISO 105-B02 | Typically below 2 | Typically below 2 | Typically below 2 |
| Handling risk | Liquid; no dust formation | Powder; dust formation | Powder; dust formation |
Auramine O Conc is incompatible with strong oxidising agents, anionic surfactants, sulfonated dispersants, and sulfite-based reducing agents. In biological staining, prolonged potassium permanganate counterstaining can quench the fluorescence signal; counterstain timing must be controlled to 2–3 minutes unless the laboratory protocol specifies otherwise. In textile applications, residual anionic levelling agents can precipitate the cationic dye and cause filtration blockage; substrate pre-scouring and compatibility screening are required before full-scale production. The product is hazardous under GHS classification according to Regulation (EC) No 1272/2008; concentrated liquid may cause skin irritation and eye damage, and closed dispensing systems with local exhaust ventilation are used in production environments. Biological use as a diagnostic component is subject to manufacturer regulatory status under EU IVDR 2017/746 or regional equivalents; the generic chemical concentrate is not automatically marketed as a diagnostic reagent. Wastewater discharge must be treated by coagulation or activated carbon because non-compliant dye release can exceed visible colour limits. Published data for detailed toxicological and ecotoxicological endpoints of this specific concentrated formulation are limited; users should consult the supplier safety data sheet and lot-specific certificate of analysis before each application. No performance claim in this document replaces lot-specific validation.
