Does talc contain starch? included. Talc is very cheap, starch is very expensive, who will add expensive things to cheap things? However, some illegal vendors may add talcum powder to starch. Talc manufacturer
Identification of talc in starch
The content of minerals (in ash) in normal starch is generally below 0.5%. If gypsum talcum powder are mixed into starch, the ash content of small starch can be increased. If calcium ion, sulfate radical silicon dioxide are detected in the ash, they can be qualitatively mixed.
(1) Ash determination method: weigh 2G of sample, put it into a crucible with constant weight of burning at 550 ℃, heat it on the electric furnace until carbonization, then put it into a muffle furnace at 550 ℃ for 2 hours, then take it out to cool down. If the ashing is complete, add water nitric acid to wet the ash, slightly warm it to dry, then put it in a muffle furnace for ashing for 2 hours, take it out cool it to 200 ℃, move it to a dryer, weigh it after 30 minutes, calculate the ash content.
Production of industrial talc powder
The ash content of normal starch is 0.5%. If the ash content in the starch is much higher than 0.5%, it indicates that gypsum other inorganic substances are mixed into the starch.
(2) Qualitative method of silica: add more than twice the amount of refined potassium hydroxide into the ash after ash content determination, mix evenly, melt at 600 ℃, dissolve with water after cooling, drop (1:1) hydrochloric acid into the water solution to make it acid. If there is colloidal precipitation (h3sio3), it indicates that silica is detected blank control.
Silica can be detected by this method for normal small starch, but it can be detected by adding talcum powder other inorganic substances.
(3) Test method for calcium ion sulfate radical: add 10 ml of (1:1) hydrochloric acid solution to the ash content of the sample, heat it to dissolve filter, divide the filtrate into two parts. Add 1 ml of 1% barium oxide solution into one part of the solution. If a large amount of precipitation occurs, it indicates that sulfate radical is detected blank control is conducted at the same time. Then add 1 ml saturated ammonium oxalate solution into another part of filtrate, drop add (1:1) ammonia water to show weak alkaline, produce a large amount of precipitation, it is positive, at the same time as the blank control.
If only calcium ion sulfate radical are detected in the ash, it can be considered as adding gypsum. If silica the above two ions are detected at the same time, talcum powder white powder can be considered as detected. At present, the big white powder on the market is refined processed talc powder with the same composition as talc powder.
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