echemi logo
Product
  • Product
  • Supplier
  • Inquiry
    Home > Chemicals Industry > Chemical Technology > Industrial 40% dimethylamine aqueous solution (2)

    Industrial 40% dimethylamine aqueous solution (2)

    • Last Update: 2021-10-08
    • Source: Internet
    • Author: User
    Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com

    5 Test method

    5.


    It is determined according to HG/T2971-1999, and the impurity content of ammonia, monomethylamine and trimethylamine is determined according to 5.


    5.


    5.


    The impurity of methylamine aqueous solution was determined by gas chromatography, detected by thermal conductivity detector, and quantified by external standard method


    5.


    5.


    5.


    5.


    5.


    5.


    5.


    5.


    5.


    5.


    5.


    5.
    2.
    3.
    2.
    1 Gas chromatograph
    .

    Equipped with thermal conductivity detector, the thermostat temperature accuracy is ±0.
    1℃, and the sensitivity of the whole machine is greater than or equal to 1000mV·mL/mg
    .

    5.
    2.
    3.
    2.
    2 Chromatographic column
    .

    Column tube: a stainless steel column with a column length of 2m and an inner diameter of 2mm or 3mm, or a column length and inner diameter that can meet the separation requirements selected by the user
    .

    Stationary phase ratio: 201 Red carrier: cetyl alcohol : polyethylene glycol 600: potassium hydroxide = 10: 1.
    2: 0.
    5: 0.
    1
    .

    Wash the 201 red support body with water to remove the ash, soak it with hydrochloric acid solution for 24 hours, wash with water until it is neutral, then soak it with potassium hydroxide solution for 24 hours, and wash it with water until it is neutral
    .
    Drain the water, place it in a high-temperature furnace, bake at 450°C for 4h-8h, cool to room temperature, and put it in a ground bottle for later use
    .
    Weigh about 10g of the 201 red carrier treated above, weigh about 1.
    2g cetyl alcohol , about 0.
    5g polyethylene glycol 600, and about 0.
    1g potassium hydroxide in a 250mL beaker , add 40mL-50mL methanol , and mix them evenly , Pour the support into a beaker and shake it up quickly to make the solution submerge the support
    .
    Place the beaker on a constant temperature water bath at 65°C, shake the beaker frequently, bake it until it is loose and dry, and bake it in an oven at 75°C for 4 hours, then take it out and put it in a silica gel dryer for later use
    .

    Packing of the chromatographic column: After the outlet end of the chromatographic column (the end with the detector) is blocked with a little glass wool and gauze, vacuumize, tap the colored columns lightly with a small wood, and slowly pour the stationary phase until the stationary phase can no longer Load and remove the chromatographic column, and plug glass wool on the other end
    .
    The packing amount of the stationary phase is about 2.
    2g for a column with an inner diameter of 2mm and about 4.
    8g for a column with an inner diameter of 3mm
    .

    Aging of the chromatographic column: The newly prepared chromatographic column should be aged for at least 16h under a carrier gas (nitrogen) with a column temperature of 80°C and a flow rate of about 30mL/min
    .
    The end of the column should be disconnected from the detector during aging
    .

    5.
    2.
    3.
    2.
    3 Chromatographic data processor or recorder
    .

    5.
    2.
    3.
    2.
    4 Sampler: 10uL micro syringe
    .

    5.
    2.
    3.
    3 Standard sample

    The standard sample of methylamine aqueous solution containing each impurity component is prepared by weighing method, and its concentration is close to the concentration of the tested sample
    .

    The pure sample requirements for preparing standard samples are: monomethylamine , dimethylamine , trimethylamine , and ammonia solution samples are injected with 2μL under the following instrument operating conditions without impurity peaks
    .
    When there is no pure sample, the impurity blank can be reduced
    .

    5.
    2.
    3.
    4 Analysis steps

    5.
    2.
    3.
    4.
    1 Start-up of the chromatograph

    Start the chromatograph and make necessary adjustments to make it work stably under the best operating conditions
    .

    5.
    2.
    3.
    4.
    2 Recommended instrument operating conditions

    Column temperature: about 50℃ or a suitable temperature selected by the user;

    Detector temperature: suitable temperature higher than 120℃;

    Vaporization chamber temperature: suitable temperature higher than 100℃;

    Thermal conductivity bridge current: 180mA or the bridge current value selected by the user that can meet the measurement requirements;

    Carrier gas flow rate: Hydrogen is used as the carrier gas, and the flow rate is about 60 mL/min or the carrier gas flow rate that meets the separation requirements can be selected by the user
    .

    After the chromatograph is stabilized under the above working conditions, a stable baseline will be obtained and the test can be carried out
    .

    5.
    2.
    3.
    4.
    3 External standard calibration

    Before or after each analysis of the sample, use the standard sample to perform external standard calibration.
    The prepared standard sample is injected more than twice in a row, and the peak area AE or peak height hE of each impurity is measured, or determined by the chromatographic data processor The correction factor of each impurity peak is used as an external standard for quantitative calculation
    .

    5.
    2.
    3.
    4.
    4 Determination

    Under the same operating conditions as the analytical standard, use a micro syringe to inject 2μL of the sample from the injection port (the injection volume of the sample and the standard sample is the same), the number of injections is more than two, and the area of ​​each impurity peak is measured A, or peak height h, is used for external standard quantitative calculation
    .
    The typical chromatogram of this method is shown in Appendix A (standard appendix)
    .

    5.
    2.
    3.
    5 Calculation of analysis results

    The impurity content expressed in mass percentage (X 0 , X 1 , X 2 , X 3 ) is calculated according to formula (1), formula (2), formula (3), formula (4) or directly obtained by chromatographic data processor The content of each impurity:

    In the formula: X 0 , X 1 , X 2 , X 3 -the mass percentage of ammonia, monomethylamine, dimethylamine, and trimethylamine impurities in the sample;

    E 0 , E 1 , E 2 , E 3 -the mass percentage of ammonia, monomethylamine, dimethylamine, and trimethylamine impurities in the standard sample;

    A 0 , A 1 , A 2 , A 3 -the peak areas of ammonia, monomethylamine, dimethylamine, and trimethylamine impurities in the sample;

    A E0 , A E1 , A E2 , A E3 - the average peak area of ammonia, monomethylamine , dimethylamine , and trimethylamine impurity in two or more standard samples when calibrating
    .

    When the peak height is used for quantification, formulas (1) to (4) replace the peak area with the corresponding peak height
    .

    5.
    2.
    3.
    6 Allowable difference

    Same as 3.
    2.
    5 in HG/T 2971-1999
    .

    6 Marking, packaging, transportation and storage

    6.
    1 The packaging container should have obvious signs, including: manufacturer name, factory address, product name, trademark, production date or batch number, net content, number of this standard, and signs that comply with GB190 "flammable liquid" and "drug"
    .

    6.
    2 Each batch of products that leave the factory should be accompanied by a quality certificate, which includes: the name of the manufacturer, the date of production, the grade, the batch number, the net content, and the number of this standard
    .

    6.
    3 The products can be installed in carbon steel tank cars or steel drums
    .
    Tank trucks and steel drums must be clean and intact, and packaging steel drums should be checked and accepted according to GB/T325
    .
    After filling the barrel, the lid of the barrel should be tight and not leaking
    .

    6.
    4 Dimethylamine is very volatile.
    Steel drums containing this product should not be stored in the open air.
    They should be stored in a dry, ventilated warehouse away from fire and other dangerous goods, and avoid high temperature exposure
    .

    6.
    5 The transportation of this product should be carried out in accordance with the railway dangerous goods transportation management rules and other regulations related to the transportation of dangerous goods
    .

    7 Security

    7.
    1 This product is flammable, avoid high temperature exposure and contact with open flames
    .

    7.
    2 This product is toxic and corrosive.
    Avoid contact with eyes and skin during use
    .

    7.
    3 This product should be stored separately from acid chemicals and strong oxidizing chemicals
    .

    Related links: Industrial 40% dimethylamine aqueous solution (1)

     

    This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

    Contact Us

    The source of this page with content of products and services is from Internet, which doesn't represent ECHEMI's opinion. If you have any queries, please write to service@echemi.com. It will be replied within 5 days.

    Moreover, if you find any instances of plagiarism from the page, please send email to service@echemi.com with relevant evidence.