Overview
Phenolphthalein indicator solution is a classic chemical reagent used to visually detect pH transitions in acid-base reactions. It transitions from colorless (acidic/neutral pH) to pink/fuchsia (basic pH) at approximately pH 8.2-10.0. First synthesized in 1871 by Adolf von Baeyer, it remains a staple in laboratories worldwide due to its clear color change and stability. While largely replaced in medical applications due to safety concerns, it maintains prominence in analytical chemistry and education.
Physical and Chemical Properties
The solution typically contains 0.1-1% phenolphthalein dissolved in ethanol or ethanol-water mixtures. Its color change is reversible – pink in bases (pH >8.3) but colorless in acids when protonated. The compound itself is a weak acid (pKa ~9.4) with limited water solubility. Ethanol-based solutions remain stable for years if stored properly. At very high pH (>13), the solution may turn colorless again due to further structural changes.
Main Applications
Primary use is in volumetric analysis for acid-base titrations, especially when weak acids are titrated with strong bases. It provides a sharp endpoint detection for reactions completing in the pH 8-10 range. Other applications include testing concrete carbonation (where it detects alkaline conditions), classroom chemistry demonstrations, and quality control in pharmaceutical manufacturing. Some forensic labs use it as a presumptive test for blood (though not specific).
Safety and Storage
Though low-risk in diluted form, concentrated solutions may cause skin/eye irritation. Ethanol carriers are flammable – store away from ignition sources. Shelf life exceeds 3 years if kept in amber glass bottles at 15-25°C. Disposal should follow local regulations for organic solvents. Some jurisdictions restrict use due to phenolphthalein's former classification as a laxative (now discontinued in pharmaceuticals). Always review SDS before handling.
B2B Procurement Guide
When sourcing, specify: 1) Solvent (ethanol vs. ethanol-water mix), 2) Concentration (standard is 0.1% w/v), 3) Packaging (amber glass preferred for stability). Bulk orders (5+ liters) typically offer 15-30% cost savings. Reputable suppliers provide certificates of analysis (CoA) with batch-specific pH transition ranges. For educational institutions, pre-diluted dropper bottles may be more practical than bulk solutions. Verify carrier solvent compatibility with your application – absolute ethanol may be required for some uses.
Related Manufacturers
- 主营：指示剂、化学实验试剂
- 主营：乙氨酸、噻唑兰、喷雾剂、染色液、转膜液、te缓冲液、pbs缓冲液、检测溶液、mes缓冲液、faa固定液、ctab抽提液、封片剂、清除剂、试剂盒、研试剂、dpph试剂、page凝胶、核酸染料、中性树胶、胰蛋白酶、纤维素酶、染色试剂、甲苯胺蓝、生化试剂、实验试剂
- 主营：无水乙醇、乙酸乙酯、磷酸、酚酞、甲醇、乙二醇、二氯甲烷、异丙醇、二甲苯、各种化学试剂、化工原料
- 主营：环氧环己烷、异丙叉丙酮、四甲基氢氧化铵、百里香酚酞指示剂、双乙烯酮、均苯四甲酸二酐、三聚甲醛、氯甲基三氯硅烷、双季戊四醇、五水合四甲基氢氧化铵、月桂酸钠、二苯甲酮、聚硫橡胶、邻氯溴苯、水杨羟肟酸、甲基纤维素、甲基丙烯酸十八酯、氨基磺酸、硫氢化钠、甲基磺酸、吐温、司盘、芥酸pko、pko-e
- 主营：阻燃剂、催化剂、洗涤剂、百里香酚酞指示剂、硫酸铵、醋酸镧、起泡剂、清洗剂、碳酸钙、抗氧剂、灭火剂、交联剂、粘合剂、封头剂、丙二醇、酸二氢铝、聚乙烯醇、对氯溴苯、生物试剂、息香乙醚、异戊二醇、香精香料、4-丁二醇、2-氯丙烯腈、2-己基癸酸、二甲胺硼烷
- 主营：化学试剂、日用化工品、医药中间体、酚酞指示液、生化试剂、过渡金属、高端材料
- 主营：分析仪、0-1000ntu、弹簧管、指示剂、粉尘仪、真空表、测量仪、水分仪、高度计、给皂机、粉碎机、计量片、辐射仪、cr-100-tu、活度仪、混匀仪、润滑油、露点仪、水质铁、涂布器、0-2000ppm、台式带、测尘仪、测氡仪、pm240-iii、粘度计
- 主营：爬树鞋、抛光膏、拉杆袋、指示剂、行李车、小拉车、小推车、爬杆器、压榨机、脚爬树、榨汁机、手拉车、老花镜、润滑油、木工凿、拉铆枪、拉钉枪、铆钉枪、润滑脂、擦亮膏、抛光蜡、抹泥刀、购物车、泡酒瓶、欧文木凿、树脚扎子
- 主营：润滑油、氯化铵、磷酸二氢钾、酸碱指示显色剂、白油、减水剂、氯化钾、乙二醇、柠檬酸、辛醇
- 主营：四氢噻吩、二甲基亚砜、二甲基二硫醚、酚酞、乙酰氯、氢氟酸、二甲苯、甲酰胺、丙烯腈、正丙醇、水杨酸、甲酸钠、正丙醛、苯甲醛、丙二腈、二甲基硫醚、硬脂酸、石油醚、水合肼、氯乙酸、乙二醛、乙二醇、异戊烷、苯乙烯、仲丁胺、叔丁醇
- 主营：环乙烷、苯乙烯、丁醇nba、酸碱指示剂、二甲苯、缩甲醛、石油醚、燃料油、石脑油、异辛醇、清洗剂、环己烷、溶剂d80、甲缩醛、增塑剂、稀释剂、溶剂油、黄腐酸、正丁醇、工业丁醇、工业酒精、油漆涂料、溴丁烷、辛醇、航空煤油
- 主营：akd蜡粉、138树脂、黑松香、络合指示剂、咪唑烷酮、合成材料、氢氧化镧、环氧树脂、无水乙醇、制造树脂、环烷酸铅、树脂色号、偏硼酸钙、十八烷酸、三十烷醇、古马隆树脂、聚醋酸乙烯酯、偏钒酸钠、氧化铈、氧化锆、酚醛树脂
- 主营：防冻液、乙二醇、甘油、丙三醇
- 主营：异丙醇、苯甲醇、二丁酯、指示剂、酸酯dbe、二甲苯、醋酸乙酯、醋酸丁酯、二辛酯、醋酸甲酯、醋酸正丙酯、醋酸仲丁酯、纯苯、三甲苯、四甲苯、溶剂油、正丁醇、甲醇、乙醇、乙二醇、碳酸二甲酯、三乙醇胺、磷酸、三氯乙烯
- 主营：检测仪、电子天平、菌落分析仪、合成血液测试仪、总有机碳分析仪、防护服检测、生化霉菌培养箱、生物安全柜、医用冷藏柜、阻湿态微生穿透测试仪、颗粒过滤效率检测仪、织物涨破、静电衰减测试仪、针尖穿刺力测试、气调保鲜箱、微生物限度、口罩检测仪器、多功能拉力机、过氧化氢消毒、微粒检测仪、风量仪、超净工作台、恒温恒湿箱、防护服手术衣检测仪器、导管流量测试仪
- 主营：异辛醇、乳化剂、乙烯醚、指示剂、醚羧酸、脂肪醇、分散剂、染色助剂、聚乙二醇、异构醇醚、泊洛沙姆、椰油酰胺、基羟乙基、烷基糖苷、特辛基酚、聚氧乙烯、嵌段聚醚、单油酸酯、异构十三醇、丙烯磺酸钠、氢化蓖麻油、丙烯酰胺基、醇醚葡糖苷、低泡渗透剂、甲酯乙氧基、癸基葡糖苷
- 主营：甘氨酸、水苏糖、阻燃剂、亚铁指示液、硫酸锌、硫酸锆、硫酸锂、硫酸锶、硫酸锰、铝酸锌、1680-21-3、牛磺酸、褪黑素、磷酸铁、丙酸铵、苏云金、碳酸镁、麝香酮、肉桂醛、磷酸铝、王浆酸、椰油胺、赖氨酸、增塑剂、浸膏粉、乙氧基
- 主营：全氟三丁胺、二苄叉山梨醇、六氟丙烯二聚体、对二甲酚酞、六氟环氧丙烷二聚体、异丙醇铝、纳米勃姆石、二异戊基硫醚、隐色结晶紫、邻菲罗啉
- 主营：威兰胶、古尔胶、L-精氨酸、指示剂、瓜尔胶、L-抗坏血酸、瓜尔豆胶、甘氨酸、半胱氨酸、维生素C/vc、核黄素(维生素B2)、胍基乙酸、牛磺酸、L-蛋氨酸、L-半胱氨酸、L-半胱氨酸盐酸盐、工业级VC、L-谷氨酰胺、L-苯丙氨酸、DL-蛋氨酸、L-丙氨酸、酪蛋白酸钠、酪蛋白/干酪素、海藻酸钠/海藻酸钠、硒代蛋氨酸、烟酸/烟酰胺
- 主营：杜仲素、对位酯、丙烯酸酯、指示剂、二氧化硫脲、乙基麦芽酚、饲料添加剂、油酸基硬脂酸、二苯基硅二醇
- 主营：异丙醇、冰醋酸、化工原料、酸碱指示剂、正庚烷、甲基环己烷、乙二醇、苯酚、江苏异丙醇、江苏化工原料、工业吡啶、工业苯酚、正丁醇、MIBK、无水乙醇、正己烷
- 主营：冰醋酸、乙二醇、冰乙酸、防冻液、纯吡啶、丙二醇、羟基苯、14丁二醇、3-丙三醇、四氢呋喃、环保乙腈、化工苯酚、1.4丁二醇、医用苯酚、工业苯酚、精制苯酚、价位四氢、乙腈工业、乙酸乙酯、吡啶化工、甲酸乙酯、吡啶工业、求购苯酚、高纯三氯、实验乙腈