Solid waste leachate—Determination of Toxaphene—Gas Chromatography (1)

1.

This method is suitable for the determination of toxaphene content in solid waste leaching solution.

Second, the principle of the method

The toxaphene in the extract was extracted with dichloromethane , and the extract was dehydrated and dried with anhydrous sodium sulfate, concentrated, purified, changed the solvent, and fixed to volume, and then separated by a gas chromatograph with an electron capture detector (ECD) And detection, qualitatively based on retention time, and quantified by external standard method

3.

(1) Ultra-pure water: No experimental interference, can be purchased or prepared in the laboratory

(2) Dichloromethane : pesticide residue level

(3) N-hexane : pesticide residue level

(4) Anhydrous sodium sulfate : pure superior grade

(5) Sodium chloride : pure superior grade

(6) Concentrated sulfuric acid: pure superior grade

(7) Concentrated nitric acid: pure superior grade

(8) Extractant: Add a mixture of concentrated sulfuric acid and concentrated nitric acid with a mass ratio of 2:1 to ultrapure water (about 2 drops of 1L water) to make the pH 3.

(9) Organochlorine standard solution: purchase certified standard materials or standard solutions with different contents as required

Four, instruments and equipment

(1) Gas chromatograph: with electron capture detector (ECD)

(2) Chromatographic column:

Front column: HP-17 (30m×0.

Back column: HP-5 (30m×0.

(3) Extraction bottle: 2L PTFE jar with screw cap and inner cap
.

(4) Separation funnel: 250mL
.

(5) Flip-type oscillating device
.

(6) Concentration device: equipment with equivalent performance such as nitrogen blowing concentrator and rotary evaporator
.

Five, pre-treatment

(1) Preparation of solid waste leachate

"Semi-Volatile Organic Compound Analysis Technology-Preparation of Sulfuric Acid and Nitric Acid from Leachate"

(2) Extraction

Take 100 mL of the extract in a separatory funnel, add an appropriate amount of sodium chloride and 15 mL of dichloromethane to fully shake, shake, and stand still.
The organic phase is passed through a funnel containing an appropriate amount of anhydrous sodium sulfate to remove water, and the organic phase is collected
.
The extraction was repeated twice as described above, the sodium sulfate was washed thoroughly with dichloromethane , and the organic phases were combined and collected in a pear-shaped flask for concentration
.

(3) Concentration and purification,

1.
Concentrate

When using a rotary evaporator for concentration, the temperature of the water bath is 30°C
.
Concentrate to 4mL, add 4mL of n-hexane , continue to concentrate and dilute to 1.
0mL for GC-ECD analysis and determination
.

2.
Purification

If the color of the extract is dark, it needs to be purified by sulfuric acid before it can be analyzed on the machine
.
The sulfuric acid purification method is as follows:

Transfer the extracted and concentrated sample (about 5mL, n-hexane as solvent) to a 20mL vial, then add 5mL of concentrated sulfuric acid, vortex for 1min and then let it stand.
After the layers are completely separated, aspirate the organic phase into a separatory funnel.
Then add 5 mL of n-hexane (2 times in succession) to wash the sulfuric acid layer, and combine the organic phases in a separatory funnel; add 10 mL of pure water to wash the n-hexane layer to neutrality (generally need to wash about 3 times)
.
The organic phase was dried and concentrated with anhydrous sodium sulfate and then tested on the machine
.

Related Links: Solid Waste Leachate—Determination of Chlordane—Gas Chromatography (2)