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Looking back, phosphoric acid traces its use in medicine to a time long before standardized grades even existed. Chemists in the 18th century first isolated phosphoric acid by oxidizing phosphorus with nitric acid. By the late 1800s, industrial chemistry started shifting focus toward the realization that purity isn’t just academic; for something injected or swallowed, even tiny contaminants count. Over the years, regulatory groups in Europe, the United States, and globally hammered out strict monographs—BP (British Pharmacopoeia), EP (European Pharmacopoeia), and USP (United States Pharmacopeia)—outlining what pharmaceutical grade actually means. Watching the pharmaceutical space evolve, the push for sheer reliability isn’t just about ticking bureaucratic boxes. Problems such as poor filtration leading to insoluble grit, or unintentional heavy metal contamination, once led to recalls, and in some cases, tragic patient outcomes. That experience drives the standardization push, pushing for advanced purification, batch testing, and much tighter controls—so every bottle that lands in a lab or drug factory does what it says.
Phosphoric acid at pharmaceutical grade sits near the center of lots of processes. In pharma, manufacturers use the dilute version—usually a solution running between 8% and 20%—to adjust pH in liquid medicines, reconstitute antibiotics, and sometimes help with chelation chemistry. The BP, EP, and USP grades guarantee low levels of arsenic, heavy metals, and fluorides, with the additional reassurance that microbes don’t sneak in and spoil production runs. Production lots must match test results on clarity, acidity, and identity, so when I’ve seen buyers request this material, it’s clear they trust nothing less than full traceability from batch records back to the raw yellow phosphorus or refinery processes making the core chemical.
Dilute phosphoric acid, clear and odorless, behaves as an oily liquid with moderate viscosity—about like thick maple syrup when pushed past 75% strength, but the dilute form is much closer to water. Its strong acidity comes from three available protons. In large facilities, you’ll see the concentrated version cut down with purified water to reach pharma grade. pH at 10% solution lands in the 1.5 to 2 range. This low pH, paired with the chemical’s gentle nature compared to the likes of hydrochloric or sulfuric acid, suits it for medicines that go inside the body. Chemical stability stays high, as it doesn’t break down in storage, doesn’t corrode most plastics, and doesn’t emit fumes that trigger respiratory problems among workers—something I’ve seen manufacturers praise in busy labs. The acid’s ability to act as a buffer keeps sensitive formulations within a safe acidity window, protecting delicate drugs from decomposition or ineffectiveness.
A proper bottle or drum of pharma-grade dilute phosphoric acid carries a detailed label. There’s batch number, date of manufacture, expiry, and all mandated symbols for hazards. Each grade mandates its impurity limits—arsenic below 2 ppm, heavy metals under 10 ppm, as per pharmacopoeial monographs. Chloride and sulfate get spot checks, too. Labels include storage instructions—usually recommending cool, dry conditions, with plastic or glass preferred over metal. Anything packaged for pharma must also bear manufacturer details, confirming full traceability for audit trails or product recalls. The Certificate of Analysis stands as the critical proof, confirming actual lab test results for the key specs alongside the bottle. In my view, these requirements protect everyone down the supply chain—chemist, pharmacist, and ultimately, the patient.
Production starts with food- or technical-grade phosphoric acid, itself an output of either wet-process (mineral phosphate ore and acid) or thermal-process (direct combustion of phosphorus). To reach true pharma grade, the acid undergoes a series of purification steps: solvent extraction removes organic impurities, precipitation with ammonia or lime clears out heavy metals, and activated carbon treatment pulls out organics and color bodies. Reverse osmosis or further ion-exchange polishes off any remaining trace contaminants. The concentrated acid is then diluted to the precise strength needed, under validated cleanroom conditions, using water that itself meets strict purity criteria. Each batch runs through a battery of analytical controls—ICP-MS for metals, ion chromatography for anions, titration for concentration—to back up the label claims.
Phosphoric acid leans on its triprotic nature, shedding each hydrogen with different strength. This makes it a useful buffering agent, with a strong hand in multistep chemical syntheses. In drug plants, it helps control reaction pH—critical in enzyme reactions, or for forming soluble phosphate salts of antibiotics and other drugs. Reacting it with bases yields mono- or disodium phosphates, common in parenteral formulations or as buffering agents in biological assays. Chemical modification—such as partial esterification with sugars—produces phosphate esters seen in key medicines, vaccine components, and solubilizers. Its non-volatile profile (no fumes), high compatibility, and predictable reactivity make it a staple in scale-up, whether in new drug development or routine generics manufacturing.
The IUPAC calls it orthophosphoric acid. Some catalogs also list it under E338 (food additive number). Older texts may refer to it as phosphoric(V) acid. Trade brands use a mix of monikers: “Phosphoric Acid, USP Grade,” “Orthophosphoric Acid BP/EP/USP,” “E338, 10% Solution, Pharma Grade.” Any pharmaceutical buyer looks past branding to the test certificate—the only mark of authenticity in my experience.
Handling any strong acid brings risks, and even phosphoric acid—less aggressive than many—still burns on prolonged skin contact, and stings in eyes. Pharma standards require PPE: nitrile gloves, splash goggles, and lab coats as a minimum. Proper acid-resistant plastics (HDPE or polypropylene) line storage tanks and dispensers. Eye wash and emergency showers stand nearby. On the GMP floor, automated dispensers reduce manual handling, protecting workers from dangerous splashes. Spills, treated with sodium bicarbonate or similar neutralizers, need prompt cleaning, with full documentation for every incident. Tracking environmental emissions, routine air and water checks help lock down compliance with local and international discharge norms. Worker safety takes strict priority, not only because of compliance fines, but because workplace accidents can derail production schedules and harm reputations built over decades.
Dilute pharma-grade phosphoric acid gets deployed daily across pharma, biotech, and even some novel delivery systems in gene therapy. It helps produce antibiotics that rely on precise pH management; it flavors and stabilizes oral liquid medicines; and it preserves vaccines. In diagnostic test kits, it helps balance sensitive reaction environments. Dental cements and etching agents rely on its buffering and cleansing action. It acts as a source for phosphate ions—crucial in the formulation of cardiac infusions, dialysis solutions, and even in some novel slow-release medications. Whenever a process calls for robust acidification—without hostile by-products or aggressive reactivity—this acid often claims its place. With digital tracking, every container gets logged, every usage recorded; pharmaceutical manufacturing can’t afford hazy traceability, so robust digital inventory systems—something I’ve seen transform inventory audits firsthand—keep every drop accountable.
Research labs lean on pharma-grade phosphoric acid during both the early discovery phase and the late-stage product improvement cycle. Researchers seeking better oral bioavailability for tricky new molecules experiment with phosphates to create more soluble or stable drug forms. Increasingly, work on nanoparticle encapsulation or liposomal delivery uses precise pH controls that only the purest acid supports. During my own lab days, using lower quality acid in chromatography often muddied results—ghost peaks, baseline drift, and poor reproducibility. That experience taught me how crucial regular sourcing and standardization truly become for experimental reproducibility. Quality teams screen every new batch, often retesting to confirm supplier claims. As pharma and biopharma look to continuous manufacturing or automated formulation systems, the purity and handling convenience of this acid—backed by solid documentation—keep it at the heart of these technological upgrades.
Toxicity research on dilute phosphoric acid mostly shows low hazard at pharmaceutical concentrations, as our own bodies encounter low levels of phosphates daily in food and cellular metabolism. Inhalation, accidental injection, or prolonged skin contact in concentrated form still carries risk, particularly for burns, eye injuries, and stomach upset. Animal studies at high doses reveal little systemic toxicity unless paired with other caustic conditions. Regulatory monographs rely on this history of relative safety, layering on precautions to prevent mix-ups or misuse. I’ve seen lab mishaps—mixing with bleach, for instance, releases hazardous chlorine gas—and most are preventable with careful SOPs. In terms of chronic exposure, occupational monitoring looks for cumulative impact, particularly among chemical operators handling drum after drum. Today’s standards reflect deep learning from past accidents—training, robust engineering controls, and medical oversight all working together to prevent issues before they start.
Looking to the future, the demand for phosphoric acid in pharmaceuticals ties closely to drug innovation pipelines and the shift toward more complex biological medicines. With gene therapies, cell-based therapies, and personalized medicines entering clinical use, the need for ultra-pure reagents—including dilute acids—keeps rising. As regulators press for even cleaner manufacturing, suppliers will invest in more advanced purification, real-time monitoring, and sustainable, phosphate-friendly production routes. Automation—robotic dispensing, bulk RFID tracking, AI-driven inventory—will likely keep pushing safety and compliance ahead. Recycling and environmental footprint reduction efforts may drive a push for phosphate recovery systems and green-chemistry process upgrades in manufacturing. Based on conversations with manufacturers, more customers want not only traceability, but also sustainability credentials, as pharma and biotech watch their own carbon footprints. Behind every innovation, though, the acid’s reputation for doing its job—gently, reliably, without fanfare—means it will stick around for decades, critical to keeping the world’s medicines both effective and safe.
In my years working around pharmaceutical quality control, consistency always keeps everyone on their toes. Every batch of tablets, syrups, or injectables has to match the last. Dilute phosphoric acid, especially at BP, EP, and USP specs, ends up in so many formulations for good reason. Companies rely on it to keep the pH of their products in check. That might sound a bit nerdy, but the body notices even tiny changes in drug chemistry. Get the acidity wrong, and the medicine won’t work as expected or might even upset the gut. With its dependable character, this acid helps create that “just right” environment for various active ingredients, whether that’s a painkiller or an antibiotic.
I’ve watched production teams struggle with poorly soluble drugs. Some powders just refuse to dissolve, and nothing frustrates a formulation scientist more. Enter dilute phosphoric acid: its gentle acidity does more than add tartness—it coaxes tricky drugs into dissolving. Some medications would separate out and sink during storage if not for this acid. You see it especially helping with oral solutions and injectable drugs, reducing the need for harsh chemicals or artificial agents.
Pharmaceutical plants take cleanliness to the next level. Floors gleam, suits crinkle, and every corner gets attention. After seeing what happens if bacteria grow inside equipment lines, no one overlooks sterilization protocols. Here, dilute phosphoric acid stands tall. Workers use it to tackle mineral build-up in pipes and tanks, which if left alone can cripple production or seed contamination. The FDA and EMA both take a hard stance on cleanliness, and this acid shows up in many “clean-in-place” routines. It helps prolong the life of expensive machinery, too—something finance departments definitely track.
Modern drug development leans heavily on biological molecules. Monoclonal antibodies and other protein drugs shake up the rules. Manufacturers need reliable buffering agents to stabilize these delicate products, especially during storage and transportation. Dilute phosphoric acid frequently pairs with sodium or potassium phosphates to deliver that strong, steady pH environment proteins crave. Without this, valuable medicines would clump, fall apart, or lose potency before reaching patients.
Using any ingredient in pharma demands paperwork, traceability, and trust. Dilute phosphoric acid that meets BP, EP, and USP marks ticks all the right boxes. Batch-to-batch analysis shows low levels of heavy metals and consistent acid strength. That kind of reliability matters—health authorities investigate any slip-ups. Patients might think chemistry ends at the pill or bottle, but manufacturers see the bigger picture: one contaminated batch could shut down an entire production line and put patients at risk.
Not every solution will come from a new molecule or a high-tech gadget. Sometimes, established compounds like dilute phosphoric acid silently grease the wheels of progress. I remember touring a factory and hearing a chemist describe it as “humble but essential.” It wasn’t a fancy answer, but it stuck with me. Across pH control, solubility, cleaning, and biotech, this acid’s quiet dependability keeps it in the pharmaceutical toolkit—something both patients and staff take for granted, but would instantly miss if it disappeared.
Concentration spells the difference between a drug that helps and a drug that causes harm. Regulators don’t leave this to chance. In my years working within the quality assurance side of pharmaceutical production, I watched dozens of batches get rejected because the active ingredient veered slightly above or below the accepted limit set by pharmacopeias. Imagine a child’s medicine being too strong or too weak—the outcomes can be serious, even tragic. So, it makes sense that BP (British Pharmacopoeia), EP (European Pharmacopoeia), and USP (United States Pharmacopeia) each set their own requirements. Their concentration standards draw a clear boundary for those who manufacture, test, and use these products.
The numbers don’t always match across continents, but the intent stays consistent: patient safety comes first. For instance, paracetamol oral suspension generally lists a concentration of 120 mg/5 mL or 250 mg/5 mL—across BP, EP, and USP, those are the typical accepted strengths. In hospital pharmacies, source containers arrive with documentation stamped by these standards. Even a minor deviation means a failed lot. BP might demand the same 120 mg/5 mL concentration for a solution as EP or USP, but each document spells out precise impurities, shelf life, and permitted excipients. I once worked on a generic where USP listed slightly looser limits for degradation products, so product development had to target the strictest requirement just to sell globally.
It’s easy to ask why so many authorities seem to duplicate each other's work. Working inside a regulatory team resolved that question for me. Patients in Europe have different tolerance for additives like parabens than patients in the U.S. Production sites in India or China need clear, harmonized standards just to export without delays. One time, our team received raw material from a supplier who claimed “USP grade.” We caught labeling errors and a lower concentration than the USP monograph permitted. The supplier faced suspension; our batch got destroyed; hard lesson learned, but no patient suffered.
Most people see only the finished medicine in their hand, not the complex pathway that started with an official monograph. The reason BP, EP, and USP state exact concentrations is to keep patients, pharmacies, and insurers on the same page. In my work, our site went through unannounced audits. Inspectors would ask about concentration targets before anything else. Companies don’t guess at these figures; they follow monographs to the letter. Overdosing or underdosing—both can trigger recalls, lawsuits, and lost trust. I’ve seen how a consistent global approach works best, even if keeping up with updates and translations means extra work.
Harmonization gets talked about all the time in the industry. BP, EP, USP experts now meet to iron out differences in concentration requirements. The International Council for Harmonisation works to close the gaps, so manufacturers don’t sacrifice patient safety to chase narrow approvals. At my last company, we implemented software to track every update in these standards. Within minutes, teams could adjust specifications to match the latest requirements worldwide. The hope is that, step by step, patients receive consistent, safe dosing—no matter which name appears on the label.
Working with chemicals, especially ones like dilute phosphoric acid, carries real responsibility. This compound helps cleanse heat exchangers, fine-tune pharmaceutical products, and control pH in sensitive processes. But it’s not household vinegar. Even diluted, phosphoric acid brings risk to people and property if overlooked.
Phosphoric acid hates moisture swings and wild temperatures. Even a little fluctuation can change its concentration and, in turn, its behavior. So, a cool, well-ventilated room – away from sunlight and direct heat – keeps things stable. I’ve seen labs where acid was stored next to bases like sodium hydroxide: one tiny spill could mean a toxic gas cloud or burns. Segregation matters. Never stick incompatible substances in the same area, no matter how tight the storage space seems.
Metal shelving often beckons because it’s sturdy, but acids and metal mix badly. If you’ve ever seen a rust bloom under a leaky bottle, you know what I mean. I go for chemical-resistant shelving: high-density polyethylene or similar plastics. Secure containers upright. If somebody drops a jug or the seal fails after sitting too long, secondary containment – like a deep-sided tray – keeps a small spill from turning into a crisis.
Handling isn’t something to rush. Gloves matter. Phosphoric acid eats through common latex, so I rely on nitrile or butyl gloves. In splash-prone work, goggles and a full face shield give peace of mind; there’s nothing worse than urgently fumbling for an eyewash after a surprise drip. If you’re working on a bench, line it with absorbent mats. Once, a careless colleague left acid on a bare bench – it stained and pitted the surface badly, costing time and money.
Pouring always goes slow. I never add water to acid – acid into water, gently and in small amounts, disperses the heat safely. Adding acid to a water bath, never the other way around, keeps exothermic reactions under control. Dilute phosphoric acid isn’t as reactive as stronger acids, but complacency invites accidents.
Every container should be clearly labeled. If there’s a transfer from the original container, fresh labeling reduces confusion. Relying on "memory" or color-coded caps is a trap—labels must include concentration, hazards, and opening date. In practice, regular staff training roots out risky habits. A lab culture that encourages people to double-check safety data sheets and follow procedures means fewer close calls.
Emergency plans shouldn’t gather dust. Quick access to eyewash stations, showers, and neutralizing agents shortens response time. Employees should practice spill drills, know how to raise the alarm, and never clean up serious spills on their own. Acute exposure to phosphoric acid does more than sting the skin; enough contact can lead to deeper burns and respiratory problems.
Safe disposal completes the story. Never pour leftover acid down the sink. Licensed chemical disposal providers neutralize and handle waste better than any ad-hoc solution. Some larger companies reclaim or recycle acid, reducing both costs and hazard.
Health and safety rules serve for a reason. In my experience, the best teams don’t cut corners on safe storage and handling. They realize prevention beats crisis every time.
Packaging isn’t just about wrapping something up so it can get from point A to B. The type of package picked often says a lot about how well a company knows its customers, how it values safety, and whether it cares about the planet. Over the years, working with manufacturers across food, tech, and household goods, I’ve seen packaging eat up big chunks of budgets or become the reason a product fails in stores. Let’s sift through some of the more common packaging styles and what they mean for folks buying and selling the product.
Flexible pouches show up everywhere these days—from granola to powdered drink mixes to eco-friendly detergents. They pack up light and use fewer materials than sturdy boxes or canisters. Shipping costs can drop, and suppliers often point out that pouches squeeze into tight shelf spaces. On the flipside, pouches rarely offer much protection. One squeeze, a rogue box in shipping, and there’s a mess waiting on arrival. That risk can hit businesses in the bottom line with returns or wasted product.
Hard plastic jars or metal tins work better for fragile content. With these, stacking in shipments gets easier and tampering stands out. During the peanut butter scare years ago, extra-strong canister seals reassured customers that nobody else had poked around. The downside comes from the extra plastic or metal used. Households end up tossing out more packaging, and recycling centers complain about odd-sized lids and coated materials. But for health or premium products, many customers are willing to pay extra for peace of mind.
Bulk bags—think flour sacks or rice—often fill restaurant supply stores. Big bags lower per-unit shipping costs for commercial buyers. If the product doesn’t spoil or get crushed, bulk packaging is usually the go-to for value-conscious shoppers. Single-use plastic bags create headaches for waste management programs, which have to deal with non-recyclable film. I’ve worked on projects where switching to brown paper bags created a marketing boost, but they needed better sealing to avoid spoilage.
Glass bottles or jars have come roaring back with the public’s eye on microplastics. They make sense for products that need to avoid chemical reactions—like certain snacks, sauces, and creams. With glass, people appreciate seeing what’s inside. But glass ships heavy, breaks in rough transit, and sometimes adds hidden costs for both seller and buyer. Even so, some companies run return-deposit schemes, letting shoppers bring bottles back for cleaning and reuse. That takes genuine effort, but consumers looking to cut single-use waste keep flocking back.
The debate over packaging doesn’t slow down. Customers want packaging that’s easy to open, reseal, or recycle. Companies face new regulations on plastic content and carbon emissions. My experience has shown me that working closely with packaging suppliers early in the design saves money and frustration down the road. Moving toward compostable plastics, introducing QR codes for recycling instructions, or even bringing in lighter filler materials can all make a difference. While there’s still no “perfect” option, listening to customers, watching new laws, and testing real-use cases often leads to the smartest choice on the shelf.
Working in pharmaceuticals, you can’t help but notice that questions about compliance with pharmacopeial standards come up every single week. More than a checklist, these standards offer a safety net for patients and a sense of security for companies. I remember a time early in my career when a shipment showed slightly different impurity profiles than required by the latest United States Pharmacopeia. It caused huge problems, not only in terms of delays but also trust. Even a minor deviation reignites discussions about oversight, transparency, and responsibility because lives could be at risk.
People often overlook how vital a Certificate of Analysis (CoA) can be. This is not some trivial piece of paper; it documents all the hard details—like purity, moisture content, and tests for contamination. Years ago, I requested a CoA from a supplier and received a simple two-page document, but the information provided helped us track a contamination issue before it reached patients. That CoA mattered more than any sales pitch. It spelled out turbidities, microbial counts, and chemical assays—pieces of data crafted by a lab following recognized pharmacopeial procedures. That is how a company builds trust, not just within its own team but among hospitals, pharmacists, and the people who rely on these products for survival.
There’s often pressure to cut corners in the interest of speed or cost. Once, a manager suggested buying from a new supplier who promised faster timelines but couldn’t show detailed compliance test results. We turned them down. A few weeks later, we heard that another facility using them landed in hot water—because their supplies failed European Pharmacopoeia limits for certain metals. Those failures made headlines locally, temporarily damaging community confidence in everyone’s products.
Ignoring or skipping these standards rarely stays a secret for long. Regulatory authorities conduct unannounced inspections. They review records. They look for substantiated data backing up every single batch. A missing test or a forged document leads to shut doors and lost business, fast. The need for official validation from groups like the USP or EP isn’t debatable; it affects whether a product ever reaches a hospital, a pharmacy, or an at-risk patient.
No matter how advanced the lab, problems show up without ongoing employee training and clear guidelines. At one company, I saw dramatic improvement after a series of hands-on seminars focused on reading, interpreting, and double-checking analytical reports. Staff got better at spotting inconsistencies. More improvement came from a clear, stepwise protocol: every product needed linked documents, direct reference to current pharmacopeial chapters, and a CoA including every spec listed by the customer and regulators.
Partnering with accredited labs and trusted suppliers eases the burden on in-house teams. Digital tracking speeds up review processes—no more digging through file cabinets for a four-month-old CoA. A practical approach also relies on transparency: make every document available for client audits and questions. Nothing builds loyalty better than showing, plainly and simply, that a product matches every required standard—and having the paperwork to prove it.
| Names | |
| Preferred IUPAC name | Phosphoric acid |
| Other names |
Orthophosphoric Acid Phosphoric Acid Solution H₃PO₄ Solution Phosphoricum Acidum E338 |
| Pronunciation | /daɪˈluːt fɒsˈfɒr.ɪk ˈæs.ɪd biː piː iː piː juː ɛs piː ˈfɑː.mə ɡreɪd/ |
| Identifiers | |
| CAS Number | 7664-38-2 |
| Beilstein Reference | Beilstein Reference 1693601 |
| ChEBI | CHEBI:43474 |
| ChEMBL | CHEMBL1356 |
| ChemSpider | 22909 |
| DrugBank | DB09149 |
| ECHA InfoCard | 03-2119486970-46-0000 |
| EC Number | 231-633-2 |
| Gmelin Reference | Gmelin Reference: 1652 |
| KEGG | CID1004 |
| MeSH | Dilute Phosphoric Acid"[MeSH] |
| PubChem CID | 1004 |
| RTECS number | TB6300000 |
| UNII | WVX2N60C5Z |
| UN number | UN1805 |
| CompTox Dashboard (EPA) | XT9B63S2X1 |
| Properties | |
| Chemical formula | H₃PO₄ |
| Molar mass | 97.99 g/mol |
| Appearance | Clear, colourless, odourless liquid |
| Odor | Odorless |
| Density | 1.18 g/cm³ |
| Solubility in water | Miscible |
| log P | -1.1 |
| Vapor pressure | < 0.01 mmHg (20°C) |
| Acidity (pKa) | 2.1 |
| Basicity (pKb) | 1.6 |
| Magnetic susceptibility (χ) | -0.72×10⁻⁶ |
| Refractive index (nD) | 1.333 |
| Viscosity | 3 mPa·s |
| Dipole moment | 0 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 110 J·K⁻¹·mol⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | -1276 kJ/mol |
| Pharmacology | |
| ATC code | A01AB12 |
| Hazards | |
| Main hazards | Causes serious eye damage. Causes skin irritation. May cause respiratory irritation. |
| GHS labelling | GHS02, GHS07 |
| Pictograms | GHS05 |
| Signal word | Danger |
| Hazard statements | Hazard statements: Causes severe skin burns and eye damage. |
| Precautionary statements | P264, P280, P301+P330+P331, P305+P351+P338, P310 |
| NFPA 704 (fire diamond) | 2-0-0-A |
| Lethal dose or concentration | LD50 (oral, rat): 1,530 mg/kg |
| LD50 (median dose) | LD50 (oral, rat): 1530 mg/kg |
| NIOSH | MN0400000 |
| PEL (Permissible) | PEL: 1 mg/m³ |
| REL (Recommended) | 1 mg/m³ (as string) |
| IDLH (Immediate danger) | 1000 mg/m³ |
| Related compounds | |
| Related compounds |
Orthophosphoric acid Phosphorous acid Polyphosphoric acid Sodium dihydrogen phosphate Disodium hydrogen phosphate Trisodium phosphate Monopotassium phosphate Dipotassium phosphate |
Chengguan District, Lanzhou, Gansu, China
