[Analysis Overview]

Industrial Hydroxypropyl Methyl Cellulose Detection Gas ChromatographyImplement the national standard GB/T 34263-2017

Methoxy and Hydroxypropyl Content

Warning--Some of the reagents used in this experimental method are toxic and harmful,Operators need to be careful and cautious!If it splashes onto the skin, rinse immediately with water,Severe cases should be treated immediately. When using flammable materials,It is strictly prohibited to use open flames for heating. Exploring the contents in a fume hoodWhen making steps,Use goggles, acid resistant gloves, and other safety equipment. When handling hot headspace bottles,Be careful,Because they have pressure. In case of accidental contact with acid,Rinse with plenty of water,And immediately seek medical assistance.

The reagents and water used in this standard,When no other requirements are specified,All refer to analytical purity andGB/T6682The third level water specified in the regulations. When no other regulations are specified for the standard solutions, preparations, and products required in the experiment,All pressGB/T601、GB/T603Preparation of regulations

Method Summary

Reaction with hydroxypropyl methylcellulose catalyzed by succinic acid,Convert methoxy and hydroxypropyl to methane and iodoisopropane,Determination of methane and iodoisopropane content using toluene as internal standard and internal standard method,Thus, the content of methoxy and hydroxypropyl groups to be tested in the sample can be calculated.

Reagents and materials

Adipic acid.

O-Xylene

toluene(HPLC)

Iodinated isopropanol

Chromatographic data processor or chromatographic workstation.

chromatographic column: 5%phenyl(95%)Capillary chromatography column or equivalent chromatography column with methyl polysiloxane as the stationary liquid

microsyringe: 5uL,10μL,50μL.

10 mLHeadspace bottle.

Electric constant temperature drying oven:The temperature can be controlled within105℃,Precision specialist2℃.

analytical balance:accuracy0.1mg.

Analysis Steps

Preparation of test solution

1、Internal standard solution:Accurately weigh2.5gtoluene(Accurate to0.0001g),added to100ml,The volumetric flask,Dilute with o-xylene to the mark,Mix well.

2、Standard solution:direction10ml,Add people to the headspace bottle60mg~70mgadipate,Accurately drip with a pipette2.0mLInternal standard solution and2.0mlh2 dianAcid in the headspace bottle,Accurately weigh the mass of the headspace bottle after sealing it tightly. Then use a microinjector to inject people into the bottle45μL,Accurately weigh the mass of the headspace bottle. Inject into the bottle again with a microsyringe15L,Iodide Isopropane,Accurately weigh the mass of the headspace bottle. Shake and mix evenly,Placed in a dark place30min~45minBackup use. The weighing of the above substances should be accurate to0.00018Sample solution:Weighing in advance105℃Dry down2hThe sample65mgIn the headspace bottle,join60mg~70 mgadipate,Use a pipette to aspirate2.0mlInternal standard solution and2.0ml,Qing Dian acid,Drip into the headspace bottle,Accurately weigh after sealing. The weighing of the above substances should be accurate to0.0001g.

3、Oscillatory headspace bottle30s,Place the headspace bottle at a temperature that has been adjusted to150℃Reaction in the drying oven20min,Take out the headspace bottle and shake it30s,Put it back into the drying oven to continue the reaction40 minCool to room temperature,weigh,Require weight loss not to exceed10mg,Otherwise, a new sample needs to be prepared

Product solution.

Industrial Hydroxypropyl Methyl Cellulose Detection Gas ChromatographyOperation method

The recommended chromatographic columns, operating conditions, and typical chromatograms in this standard can be found in the appendixAOther chromatographic columns and operating conditions that can achieve the same degree of separation can also be used.

After the instrument stabilizes,Inject the upper liquid of the standard solution into the gas chromatograph,And repeat it5order,Record the chromatogram Relative standard deviation of peak area ratio between iodinated isopropanol and toluene(RSD)Not greater than5%.

Inject the upper liquid of the sample solution into the gas chromatograph,repeat2order,Record chromatogram,Calculate the content of methoxy and hydroxypropyl groups using the internal standard method.

[Instrument Configuration]

1. Instrument: GC2030 Gas Chromatography Hydrogen Flame Detector (FID) Tengzhou Zhongke Spectrum

ZKP-2020 Chromatography Workstation Dual Channel (Computer, Printer Self Equipped)

Hydrogen generator HK-3 hydrogen flow rate 300ml/min

Air generator AK-2 air flow rate 2000ml/min

High purity nitrogen cylinder 40L nitrogen flow rate 300ml/min

Standard solution (provided by Tengzhou Zhongkepu)

2. Chromatographic conditions

Chromatography column: 30m * 0.32mm capillary column

Column temperature: 120 ℃.

Detector: 150 ℃.

Gasifier: 150 ℃.

Gas carrying capacity: Nitrogen: 5mL/min.

Hydrogen gas: 35 mL/min.

Air: 350mL/min.

[Instrument Case]