Introduction to moisture measurement method for special samples

1. Determination of the moisture content of the surfactant. Add 25 mL of methanol to the titration vessel and titrate to anhydrous (pre-titration). A sample of 0.3...0.5 g was added to determine the moisture. The analyzed materials were: betaine, alginate, cetylpyridinium chloride, dimethylmethylimidazole, haming 1622 and nonylphenol.

The water in the dodecylbenzenesulfonic acid (and the mixture of residual sulfuric acid) was determined as follows: 30 mL of methanol and 5 g of imidazole were added to the titration vessel and titrated to dryness (pre-titration). Approximately 1 g of sample was added and the moisture was measured.

Sodium dodecyl sulfonate (sodium lauryl sulfonate) and soap can be measured by a moisture analyzer under heating conditions: add 30 mL of a 2:1 methanol/formamide mixed solvent and a titration vessel, heat to 50 C, and titrate to Anhydrous (pre-titration). Approximately 0.5 g (and possibly pulverized) the sample was injected and the moisture was measured at the same temperature.

Coco fatty acid aminoxide and animal fatty acid amine must be added to the working medium buffer: add 25Ml 4:1 methanol / chloroform mixed solvent and titration cup, add about 5g benzoic acid, titrated to anhydrous (pre-titration). A 1...2 g sample was added and the moisture was measured.

The sodium polyphosphate (300C), moisture in the soap tablets and washing powder can be determined by heating (Carnsite method) (120C)

Comment

If the sample contains a lot of water, dilute with anhydrous methanol. .

2, industrial products

- Pulverized coal, coal dust, carbon black and spectral carbon powder can be determined by heating combined with coulometric titration, heating temperature 200...270C. The sample amount is 0.3...1g. The 768 Cartesian furnace is suitable for fine particle samples with large sample volumes.

- Oxygen phase and silicon oxide, a bulky and light SiO2, with two different analytical methods:

a) In a methanol solvent, the sample amount is about 0.2g

b) Measured by a heating method of 768 Cartesian heating furnace (200C), the sample amount is 50...100 mg, Coulomb method.

- Glass wool and glass powder can only measure the auxiliary moisture. Determined by the Coulomb method. Glass wool: about 1g, 180...200C. Glass powder: about 0.5g, 280...300C.

- Nitrifying acid (a mixture of H2SO4 and HNO3)

50 g of pyridine was weighed into a dry conical flask with a septum plug. While shaking the bottle, carefully add about 1g of sample, then

Seal with a stopper and mix the solution.

Add 25 mL methanol titration cup and titrate to anhydrous (pre-titration). Add 4...5g of sample solution (weigh the difference in weight of the syringe before and after the injection to obtain the sample amount), and titrate the water. The blank value of pyridine was measured and subtracted from the calculation.

—gypsum, plaster

Gypsum does not completely release moisture. It must be determined by heating (200C) in combination with coulometric titration. The sample volume is about 50g...100mg

- The plaster of Paris contains about 0.5 mol of H2O. Add 25 mL of methanol to the titration vessel, heat to 50 C, and titrate to anhydrous (pre-titration) to add about 1 g of sample, and measure the moisture at the same temperature.

-cement

- Add 25 mL of methanol to the titration vessel, heat to 50 C, and titrate to dryness (pre-titration). Approximately 0.2 g of sample was added and the moisture was measured at the same temperature.

- water glass

Add 30 mL of methanol to the titration vessel, add about 7 g of salicylic acid, and titrate to anhydrous (pre-titration). About 0.1 g of the sample (the amount of the sample obtained by weight reduction) was added using a dry syringe, and the water was titrated. Also suitable for high frequency homogenizers (such as Polytron or Ultra-Turrax) large magnetic stirrers.

3. Inorganic compounds

The moisture content of the following salts was determined by heating (sample size, heating temperature):

Potassium cyanide (KCN) 1g 280...300C

Lithium cobaltite (LiCoO2) 0.5...1g 100C

Magnesium stearate 0.1g 140...160C

Sea salt 0.5g 150C

- Determination of the following substances by volumetric method under elevated temperature conditions:

Hydrogen fluoride: Weigh 0.3g of sample, add 30mL of 2:1 methanol / formamide solvent, and add about 3g of imidazole.

Monohydrate and sodium hypophosphite: 0.3 g of the sample was weighed and determined by adding 30 mL of 2:1 methanol/formamide solvent.

Add the mixed solvent and the titration vessel, heat to 50C, and titrate to anhydrous. A sample was added and the moisture was measured at the same temperature.

- Antimony trichloride: Add 30 mL of working solution (specific solvent for ketone) and titration cup, titrate to anhydrous. Add about 1g sample

, measure moisture.

4. Agricultural products

- Fertilizer (granular fertilizer, chemical fertilizer) samples, mainly interested in attached water, when it is necessary to determine the total water content

the amount.

Attached water: A 30 mL of 1:2 methanol / chloroform mixed solvent and titration cup, titrated to anhydrous (pre-titration). Approximately 0.5 g...1 g of sample was added and the moisture was measured (rapid titration). Replace the solvent mixture after each titration.

Total water content: Add 30 mL of methanol and about 7 g of salicylic acid to the titration vessel, heat to 50 C, and titrate to dryness (pre-titration). About 0.5 g of the sample was added, and the moisture was measured at the same temperature, and the delay time was stopped for 15 s.

- There is no problem in determining the moisture in the urea.

Add 25 mL of methanol to the titration vessel and titrate to dryness (pre-titration). Approximately 2 g of sample was added and moisture was measured (rapid titration). Replace the solvent after each measurement.

- Pesticide such as: Dimethoate and omethoate (dissolved in cyclohexanone) The moisture determination procedure is as follows: Add 30 mL of working medium (ketone-specific solvent) and titration cup, titrate to anhydrous (pre-titration). About 2 g of the sample solution was added with a dry syringe (accurate sample amount was obtained by weight reduction), and moisture was measured.

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