My thoughts on the new version of the **phenol standard GB/T 21892-2008

I agree very much with the first point mentioned by the original poster. As for the second point, I can’t agree with it!

I am sending you the work I have done; please take a look. Aminophenol 1 – Scope: This standard specifies the requirements for aminophenol, as well as the procedures for sampling, testing methods, inspection rules, and also matters related to labeling, packaging, transportation, storage, and safety. This standard applies to p-aminophenol produced by the liquid-phase catalytic hydrogenation of ***phenol. 2 Normative reference documents The provisions in the following documents become standard provisions through reference to this standard. For any referenced document dated, all subsequent amendment sheets (excluding corrections) or revised versions shall not be applicable to this standard ； However, parties encouraged to reach an agreement under this standard are advised to explore whether the latest versions of these documents can be used. For reference documents without a date, the latest version applies to this standard. GB 190-2000 Marks for Packaging of Dangerous Goods; GB/T 601-2002 Chemical Reagents – Preparation of Standard Solutions for Titrimetric Analysis (Volumetric Analysis); GB/T 603-2002 Chemical Reagents – Preparation of Preparations and Products Used in Test Methods; GB/T 617-1988 Chemical Reagents – General Method for Determining Melting Point Range; GB/T 6679-1988 General Rules for Sampling Solid Chemical Products; GB/T 1250-1989 Methods for Expressing and Determining Limit Values; GB/T 6682-1992 Specifications and Test Methods for Water Used in Analytical Laboratories. 3 Requirements: 3.1 Appearance: White to light brown crystals. 3.2 p-Aminophenol shall meet the requirements specified in Table 1. Table 1: Item, Specification, Premium Grade, Conforming Grade; Content, %: ≥ 98.0%, 97.0%; Loss on Drying, %: ≤ 0.6%, 1.0%; Ash Content, %: ≤ 1.0%, 2.0%; Melting Point, °C: 183.0–190.2. 4 Sampling: From each batch of products, samples shall be taken at a rate of n+1 per batch, with a minimum of 3 samples. Full sampling when less than 3 items. During sampling, use a probe in accordance with Q/ABH 001-2003 to collect samples from the upper, middle, and lower sections; the total sample weight must be no less than 200 g. After grinding the samples to be taken and mixing them evenly, they are divided and placed in two clean, dry wide-mouth flasks with ground glass stoppers (or aluminum foil bags). Attach a label indicating the manufacturer’s name, product name, batch number, and sampling date. One bottle (or bag) is reserved for testing, while another bottle is sealed with paraffin (bags are sealed using a sealer) for future reference. 5 Test Methods Unless otherwise specified, only analytically pure reagents and water of grade 3 as specified in GB/T 6682 or water of equivalent purity shall be used in the analysis. The standard solutions, preparations, and products required for the tests shall be prepared in accordance with GB/T 601, GB/T 602, and GB/T 603 unless otherwise specified. 5.1 Appearance: Determined by visual inspection. 5.2 Determination of p-aminophenol content (diazotization method) 5.2.1 Principle of the method: Under low temperature and in the presence of an excess of inorganic acid, p-aminophenol can react with sodium nitrite to form a diazonium salt. The end point of the diazotization reaction is detected by the slight blue color appearing on the starch-iodide paper strip. 5.2.2 Reagents 5.2.2.1 Hydrochloric acid: 1+1 5.2.2.2 Potassium bromide: 100 g/L solution ； 5.2.2.3 Sodium nitrite: A standard titration solution with C(NaNO2) = 0.5 mol/L, prepared and standardized in accordance with GB/T601, but starch-iodide test strips are used to determine the endpoint. 5.2.3 Instruments: General laboratory instruments. 5.2.4 Measurement procedure: Weigh 1.0 g of p-aminophenol sample (with an accuracy of 0.0002 g) and place it in a 500 mL beaker. Add 200 mL of water, stir well, then add 20 mL of hydrochloric acid to dissolve the substance. Add 10 mL of a 100 g/L potassium bromide solution. Cool the mixture to below 15°C. Then insert the tip of a burette into the solution, and while stirring continuously, add the 0.5 mol/L sodium nitrite standard solution in one go – this amount corresponds to approximately 95% of the total amount required. Then lift the tip of the burette above the liquid surface and add the 0.5 mol/L sodium nitrite standard titrant drop by drop until the starch-iodide test strip turns slightly blue. After 3 minutes, if it remains slightly blue when tested in the same manner, that is the endpoint. Do the blank at the same time. 5.2.5 Calculation of results The mass fraction X2 of p-aminophenol, expressed as a percentage, is given by equation (2): C(V1–V0)×0.1091 X2 = × 100 …………………(2) where M is the molar mass. In this equation, V1 represents the volume of sodium nitrite solution consumed in the titration, in mL ； V0 —— Volume of the sodium nitrite standard titrant solution used in the blank test (mL) ； Q/ABH 001-2003 M—— Mass of the sample (g) ； ; 0.1091 —— the mass of p-aminophenol in grams, equivalent to 1.00 ml of the sodium nitrite standard titrant solution. 5.2.6 Allowable tolerance: The difference between the results of two parallel determinations shall not be greater than 0.3%. The arithmetic mean of the parallel test results is used as the reported value. 5.3 Loss on Drying 5.3.1 Procedure: Weigh 4–5 g of the sample (with accuracy to 0.0002 g), place it in a clean, dry weighing flask of known constant weight, and put it in an oven. Dry it at a constant temperature of 100–105°C for 2.0 hours. After that, take it out and place it in a desiccator to cool to room temperature, then weigh its mass. 5.3.2 Calculation of results The mass fraction of loss on drying, X3, expressed as a percentage, is given by equation (3): (W1 – W2) × X3 = -------------- × 100 …………………(3) where: W1 —— the mass of the sample and the weighing bottle before drying (g) ； W2 —— Mass of the sample after drying and the weighing bottle (g) ； M sample mass (g). 5.4 Ash determination 5.4.1 Procedure: Weigh 2–3 g of the sample (with accuracy to 0.0002 g) into a 30 mL porcelain crucible that has been heated to a constant weight. First, heat it at low temperature in an electric furnace to cause carbonization, and then place it in a muffle furnace and heat it to 800±10°C until a constant weight is reached. 5.4.2 Calculation of results The mass fraction of loss on drying, X4, expressed as a percentage, is given by equation (4): G X4 =————×100 …………………………(4) M Where: G —— mass of the residue remaining after burning the sample (g) ； m —— sample mass (g). 5.5 Melting point: Aminophenol decomposes simultaneously when it melts. A certain amount of p-aminophenol sample that has been dried to a constant weight is ground into a powder and placed in a clean, dry melting point tube. A dry glass tube about 300 mm long is placed upright on a glass plate, and the melting point tube containing the sample is dropped into it several times until the sample inside the tube is compressed to a height of 2.5–3.0 mm. Then, the other end of the tube is sealed. Q/ABH 001-2003: Install the melting point testing apparatus in accordance with the requirements of GB/T 617-1988. Before 150°C, the heating rate is 10–15°C/min; after 150°C, the heating rate is maintained at a constant level of 3–4°C/min. The temperature at which the sample begins to turn brown, then starts to liquefy, and shows obvious localized melting is the onset melting temperature ； Subsequently, the sample will turn dark brown and melt completely (decompose), and at this point the temperature is the final melting point. Record the initial melting point temperature and the final melting point temperature. 6 Inspection Rules 6.1 For the determination of the quality specifications for aniline phenol in this standard, the \"rounding value comparison method\" specified in GB/T 1250 is adopted. 6.2 All the inspection items specified in this standard are type inspection items; among them, the content of p-aminophenol, loss on drying, and ash content are factory inspection items within the type inspection items ； Melting point is an item subject to sampling inspection within the type inspection procedures; under normal circumstances, a type inspection should be carried out at least once per month. 6.3 p-Aminophenol shall be inspected by the quality control department of the manufacturer in accordance with the requirements of this standard, and the manufacturer shall ensure that all products leaving its facility meet the requirements of this standard. Each batch of products leaving the factory should be accompanied by a quality certificate in a specified format. 6.4 The using unit shall have the right to inspect the received p-aminophenol in accordance with these standards and relevant regulations, to determine whether it meets the requirements of these standards. 6.5 If one of the test results does not meet the standard requirements, representative samples should be taken again from the packaging unit and retested, in double quantities. If even one parameter in the retest results does not meet the requirements of this standard, the entire batch of products is considered unqualified. 7 Marking, Labels, Packaging, Transportation, Storage 7.1 Marking The packaging of p-aminophenol must have secure markings. The contents include: manufacturer’s name, address, product name, trademark, net weight, production date, batch number, grade, etc. And mark the “Toxic du product” label in accordance with the provisions of GB 190. 7.2 Labels The labels must indicate the product name, net weight, gross weight, grade, batch number, production date, and the name of the manufacturer. 7.3 Packaging Aminophenol is packed in iron drums (cardboard drums) lined with polyethylene bags (or in woven bags lined with polyethylene bags), with a net weight of 50±0.2 kg per piece. Other forms of packaging can also be used upon the user’s request. 7.4 Transportation During transportation, it should be protected from exposure to sunlight, collisions, and rain. 7.5 Storage Aminophenol should be stored in a well-ventilated and dry warehouse. The container must be kept sealed and protected from sunlight; it should not be stored together with flammable materials or oxidizers, and it must be kept away from sources of fire and heat to ensure safety. Q/ABH 001-2003: p-Aminophenol is a toxic substance, and those who come into contact with it must wear glasses and protective gloves, as well as protective clothing when necessary.

Impurities detected by mass spectrometry: 1. O-aminophenol 2. O-methylp-aniline 3. 4,4-Diaminodiphenyl ether 4. p-Phenol 5. p-Quinone 6. Aniline 7. p-Chloroaniline 8. p-*-phenol. Last edited by lifanwang on 2009-3-16 16:28.]

Is there a PDF version of the p-aminophenol **standard? Please upload it; I need it urgently! ! !

I have the text here, but no scanner; so I’ll give you the standard numbers and analysis results first. GB/T 21892-2008: Appearance – off-white to light brown crystals. Amine value: 97, 96.5, 96. Purity of p-aminophenol by HPLC: 98, 98, 97. Organic impurities: 1.2, 1.2, 1.5. Loss on drying: 0.5, 0.7, 1.0. Iron content in mg/Kg: 50, 150, 200. Ash content: 1.5, 2.0, 3.0. Melting range: 183–190.2. Here’s a link: http://www.zjbooks.com/book.asp?bookid=57641; it might cost 14 RMB. I’ve searched on that website as well as on GOOGLE and Baidu, but there seems to be no free version. This post was last edited by lifanwang on 2009-3-16 at 16:35