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Heavy metal instrument digestion solution


 Heavy metal instrument digestion problems encountered and solutions:

1, samples of boiling temperature and intensity and the specific property of the sample has the very big relations. For this problem, first we may consider the digestion instrument preset temperature set low, then ascending to the target temperature; or for the samples in did not affect the outcome of the case, can be less sampling, or the corresponding pretreatment to avoid.

2, if the temperature is low, the speed is very slow digestion, doing experiments an industry to set the corresponding experiment the optimum temperature.

The following is a heavy metal digestion pretreatment reference examples:

The digestion of vegetable

Apparatus: glass tube

Reagent: 1 nitric acid ( HNO3 ): P = 1.42g / mL, Gr

2 perchloric acid ( HClO4 ): P = 1.68g / mL, Gr

Step:

1 fresh vegetables edible part, followed by the tap water, two distilled water cleaning, the surface water to dry, the

Constant temperature drying oven 100-105 C, after removing the fine grinding, placed in the dryer.

The 2 known has crushing fine vegetable samples 0.5g to digestion tube with holes on the pipe plug, plug, join 15mL mixed acid

NO3 + HClO4 ( 4+1 ), placed the night.

The 3 set of digestion temperature for 70--80 C, the digestion tube is inserted into the hole of the acid reflux digestion, cleaning tube inner wall, so that

Sample with acid completely mixed, keeping the 10min.

4 temperature to 100 DEG C, at this time, the digestion tube filled with red brown smoke, keeping the 30min digestion, if the sample is not

Complete digestion, cooling after adding 5mL HNO3 mixed acid + HClO4 ( 4+1 ), to set the temperature, continue to disappear

Solution to the sample solution is transparent, pale yellow.

Tea digestion

Apparatus: glass tube

Reagent: 1 nitric acid ( HNO3 ): P = 1.42g / mL, Gr

2 perchloric acid ( HClO4 ): P = 1.68g / mL, Gr

3 hydrogen peroxide ( H2O2 ): 30%, analysis of pure

Step:

The 1 known has shattered and pass through a 120 mesh screen under 0 5g in tea sample digestion tube, join 10mL nitrate

HNO3, plug with holes on the pipe plug, placed overnight.

2 is inserted into a hole provided in digestion digestion, digestion temperature for 70--80 C, slow heating the foaming mixture sample,

To maintain the set temperature 15min.

The 3 heating to 135 degrees C, keeping the 1H, digestion of sample.

4 if the resolution is not complete, cooling after adding 5mL mixed acid HNO3 + HClO4 ( 4+1 ), or adding hydrogen peroxide in H2O2,

Temperature and maintaining the temperature, solution to transparent.

5 temperature to 160 DEG C, acid rush to about 2mL.

The digestion of sewage

Apparatus: glass tube

Reagent: 1 nitric acid ( HNO3 ): P = 1.42g / mL, Gr

2 sulphuric acid ( H2SO4 ): P = 1.84g / mL, analytical pure

Potassium permanganate ( 3 KMnO4 ): 5%

Step:

1 20mL samples ( or amount ) on digestion tube.

2 joined the 0.5mL HNO3 1mL H2SO4 nitrate, sulfate, mixing samples.

3 3mL5% KMnO4 with potassium permanganate solution for 15 minutes, if the sample from purple or brown fade

Color, then add KMnO4 ml potassium permanganate solution.

4.95 degrees C heated to reflux for 2 hours, keep boiling.

5 after cooling the sample digestion.



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