CN101051027A - Method for water phase detecting micro mercury in water or waste water by spectrophotometry - Google Patents

Abstract

A method for determining trace amount Hg in water by utilizing water phase of spectrophotometry includes preparing dithzone solution being able to be dissolved in water for making bivalent Hg ion be complexed and color-displayed with dithzone in water phase, changing Hg all to be bivalent Hg ion after water sample is resolved in order to directly determine out total Hg content in water at water phase.

Description

A kind of method of measuring Trace Mercury in water or the waste water with the spectrophotometric method water

Technical field

The invention belongs to the analytical approach of measuring mercury content in the water, particularly a kind of method of measuring Trace Mercury content in water or the waste water with the spectrophotometric method water.

Background technology

As everyone knows, mercury pollution has great harm to the mankind, human body can't be drained food chain or other approach accumulation Trace Mercury in vivo by the metabolism of self, and Trace Mercury accumulation in vivo will directly cause diseases such as heart, liver, thyroid gland, even cause nerve problems, slow poisoning and dysnoesia.In the middle of industrialized process, the quantity that is discharged into the mercury in the environment increases year by year, because the accumulative total effect in food chain is shown by statistical data, at present the content of mercury has improved 3 times before than the several years in water, soil, the atmosphere, and relevant in the world regional poisoning happens occasionally.The threat that the pollution of mercury is serious human existence and development.In the today of advocating social economy and harmonious development, for the whole mankind's common interests and sustainable development, monitor and control the discharging of mercury effectively, strengthen administering mercury pollution, become the task that we must pay much attention to.

Detection method to mercury has a lot, and atomic spectroscopy is arranged, neutron activation method, modified electrode-voltammetry, ion selective electrode method, capillary electrophoresis, spectrophotometric method etc.Atomic spectroscopy and neutron activation method analytical instrument complicated operation cost an arm and a leg; Modified electrode-voltammetry is disturbed bigger, uses inconvenience, and electrode is made trouble; Ion selective electrode method poor stability, sensitivity are low; Capillary electrophoresis is subjected to sample size restriction and concentration limit is big and instrument is expensive.The most widely used is exactly GB dithizone (its formal name used at school is diphenyl sulphur crust hydrazone) extraction spectrophotometric method, the method need be prepared dithizone (its formal name used at school is a diphenylthiocarbazone) solution with methenyl choloride, uses the remaining dithizone developer of alkali lye flush away again after extracting the mercury ion of aqueous phase.Running program is loaded down with trivial details, and the extractant consumption is big, is harmful to analyst's health, also can cause environmental pollution

Summary of the invention

The objective of the invention is to overcome the deficiency that prior art exists, a kind of method with Trace Mercury in spectrophotometric method water mensuration water or the waste water is provided, have nontoxic, simple and efficient, economical and practical characteristics.

The objective of the invention is to realize by the following technical solutions:

A kind of method with Trace Mercury in spectrophotometric method water mensuration water or the waste water, it is characterized in that: with absolute ethyl alcohol or 95% ethanol is solvent, is solubilizer dissolving dithizone with Triton X-100 (Triton X-100), makes dithizone solution.Under acid pH=1～2 condition, dithizone and mercury ion reaction generate water-soluble coloured ion complex compound, survey its absorbance at the 495nm place with spectrophotometer, try to achieve the content of mercury in the sample to be tested with the typical curve of mercury.

Above-mentioned a kind of method of measuring Trace Mercury in water or the waste water with the spectrophotometric method water, its described dithizone solution that makes, its concentration is 0.005g/L, its preparation method is: the dithizone of 0.001g is put into container, dip in from the described alcohol solvent of 40ml with glass bar and to get the ethanol that can make the dithizone wetting amount, and after not having fine particle with Glass rod grinding to dithizone, the ethanol of surplus is poured in the said vesse, stir the solubilizer polyethylene glycol octyl phenyl ether 150ml that adds 5% (mass ratio) down, be settled to 200mL with ultrapure water behind ultrasonic concussion 15～30min.

A kind of method with Trace Mercury content in spectrophotometric method water mensuration water or the waste water of the present invention compared with prior art has obvious improvement and positive effect:

1. the present invention small amount of ethanol is solvent, Triton X-100 (Triton X-100, C ₃₄H ₆₂O ₁₁) be solubilizer, water-fast dithizone is mixed with water-soluble dithizone solution, thereby, can directly measures the content of mercury at aqueous phase without organic solvent extraction.Solve the problem that described extraction exists poisonous and harmful, complex operation, had nontoxic, simple and efficient, economical and practical characteristics.

2. relative standard deviation of the present invention is 5.39%, and the relative error absolute value is 3.57%, and the recovery is 108.3%.

3. the present invention compares simple to operate with cold-vapour atomic absorption method with atomic fluorescence method, low price, compare with traditional dithizone spectrophotometric method simple and efficient, pollution is little, precision is high, be to have nontoxic, simple and efficient, economical and practical directly to measure in the water or Trace Mercury analysis on Content method in the waste water at aqueous phase

4, the present invention directly measures Trace Mercury analysis on Content method at aqueous phase, can be applicable to day-to-day supervision, the sewage treatment plant or three of pollutant discharge of enterprise, the detection of level Four environmental monitoring station.

Description of drawings

Accompanying drawing is a kind of mercury canonical plotting of measuring the method for Trace Mercury content in water or the waste water with the spectrophotometric method water of the present invention.Wherein

R ²=0.999 be linearly dependent coefficient square, be ordinate with the absorbance, (μ g/L) is horizontal ordinate with ion concentration of mercury.

Embodiment

Now in conjunction with the accompanying drawings and embodiment, the present invention is further described as follows:

Embodiment 1

1, used reagent and the preparation thereof of the present invention:

(1) sulfuric acid;

(2) nitric acid;

(3) salpeter solution: 0.8mol/L

The 50ml red fuming nitric acid (RFNA) is diluted with water to 1000mL;

(4) liquor potassic permanganate: 50g/L

25g potassium permanganate is dissolved in the low amounts of water, be transferred in the 500ml volumetric flask, (potassium permanganate is that top grade is pure to be diluted to graticule and mixing, recrystallization in case of necessity, preparation manipulation is careful, avoid not the dissolved particles precipitation or be suspended in the solution, can heat hydrotropy in case of necessity, solution is stored in the brown vial with grinding port plug);

(5) potassium persulfate solution: 50g/L

The 25g potassium persulfate is dissolved in the low amounts of water, is transferred in the 500ml volumetric flask, be diluted to graticule and mixing (using preparation on the same day, 90 ℃ of hydrotropies of water-bath);

(6) oxammonium hydrochloride solution: 100g/L

The 50g oxammonium hydrochloride is dissolved in the low amounts of water, is transferred in the 500ml volumetric flask, be diluted to graticule and mixing;

(7) sodium sulfite solution: 200g/L

The 100g sodium sulphite is dissolved in the low amounts of water, is transferred in the 500ml volumetric flask, be diluted to graticule and mixing;

(8) potassium bichromate solution: 4g/L acid solution

The 4g potassium dichromate is dissolved in the 500mL water, slowly adds 500mL sulfuric acid or nitric acid then;

(9) mercury storing solution: 1g/L;

Take by weighing 0.1354g mercuric nitrate (analyzing pure),, be transferred in the 1000ml volumetric flask, add low amounts of water and 25ml nitric acid, add the acid potassium bichromate solution of 50ml again, be diluted with water to graticule and mixing (this solution can be stablized three months at least) accurately to 0.0001g;

(10) mercury intermediate liquid: 50mg/L (using preparation on the same day)

The mercury storing solution of 25.0ml is transferred in the 500ml volumetric flask, is diluted to graticule and mixing with the 0.8mol/L salpeter solution;

(11) mercury standard solution: 1mg/L (preparation before using)

10ml mercury intermediate liquid is put in the 500ml volumetric flask, be diluted to graticule and mixing with the 0.8mol/L salpeter solution;

(12) as Triton X-100 (Triton X-100, the C of solubilizer ₃₄H ₆₂O ₁₁) solution (Xin Xi of Shenyang City chemical reagent work, chemical pure): 5% (mass ratio);

Take by weighing 10g Triton X-100 (Triton X-100, C ₃₄H ₆₂O ₁₁), be dissolved in the 190mL ultrapure water.Use the magnetic stirrer hydrotropy.

(13) ethanol: 95% or 100% ethanol, analyze pure;

Here need to prove: above-described reagent is not marked to be and to analyze purely, and test water is a ultrapure water.All glass apparatus should not allow its drying before twice operation, and should be full of the 0.8mol/L salpeter solution, face with leaning forward out salpeter solution, rinse well with ultrapure water.

2, the used device of the present invention is as follows:

(1) 721 type spectrophotometer (Shanghai exact instrument company limited)

(2) JB-2 type constant temperature blender with magnetic force (the new river rising in Ningxia and flowing into central Shaanxi of thunder magnetic, Shanghai Instr Ltd.)

(3) supersonic wave cleaning machine (the new sesame biotechnology research in Shanghai institute)

(4) water-bath (Tianjin Tai Site Instr Ltd.)

(5) common vessel and the instrument used of laboratory.

3, a kind of method of the present invention with Trace Mercury content in spectrophotometric method water mensuration water or the waste water, its operation steps is as follows:

(1) preparation of dithizone chromogenic reagent solution

The 0.001g dithizone is put into container, dip in from 40ml absolute ethyl alcohol or 95% ethanol with glass bar and to get the ethanol that can make the dithizone wetting amount, with the Glass rod grinding dithizone after do not have fine particle, remaining ethanol is poured in the said vesse, stir the Triton X-100 aqueous solution 150ml that adds 5% (mass ratio) down, ultrasonic concussion 15～30min is settled to 200mL with ultrapure water then, makes Dithizone in Aqueous Solution.

(2) drafting of mercury typical curve

Shown in the according to the form below 1, draw the mercury standard solution and place 8 100ml volumetric flasks respectively, add 5ml dithizone solution then respectively, be diluted to scale with ultrapure water, mixing was placed 3 minutes.Is the absorbance that reagent blank is surveyed dithizone-mercury complex at wavelength 495nm place with the ultrapure water with the 3cm cuvette.

Table 1 mercury typical curve tables of data

Numbering No.	The volume of mercury standard solution (ml)	The concentration of mercury standard solution (μ g/L)	Absorbance
				1	0	0	0.017
2	0.5	5	0.021
				3	1	10	0.025
4	2	20	0.032
				5	3	30	0.039
6	4	40	0.046
				7	5	50	0.055
8	6	60	0.061

Concentration (μ g/L) with the mercury standard solution is horizontal ordinate, and corresponding absorbance is an ordinate, and the drawing standard curve is seen accompanying drawing, and the content of mercury meets Beer law in 10-120 μ g/L scope.

By accompanying drawing as can be known, the typical curve equation is y=0.0007x+0.0172, and linearly dependent coefficient is r=0.9995.Critical table by checking in the check related coefficient as can be known, when f=n-2=8-2=6, degree of confidence is that 99.9% related coefficient is 0.925.This experiment gained linearly dependent coefficient is 0.9995＞0.925, can think that this typical curve has good linear relationship.In addition, try to achieve the ε value by described typical curve.

$\mathrm{\ϵ}=\frac{\frac{0.0007L/\mathrm{\μg}}{{10}^6}\×200.59g/\mathrm{mol}}{3\mathrm{cm}}=4.7\×{10}^{4}L\·{\mathrm{mol}}^{-1}\·{\mathrm{cm}}^{-1}.$

(3) mensuration of interfering ion

Compound concentration is the accurate solution of the silver label of 1 μ g/L, adding mercury mark liquid concentration respectively with the different amounts of pipette, extract is in the 100ml volumetric flask of 10 μ g/L, 50 μ g/L and 120 μ g/L, experimentize by experimental technique, at the 495nm place, survey its absorbance with the 3cm cuvette, investigate when measuring variable concentrations mercury Ag ^1-To its annoyance level.The same, prepare the iron (Fe of sodium standard solution, calcium standard solution, magnesium standard solution, barium standard solution, zinc standard solution, aluminum standard solution and the 1mg/L of 1g/L respectively ²⁺) standard solution, 1mg/L iron (Fe ³⁺) copper standard solution, the tin (Sn of standard solution and 1 μ g/L ²⁺) standard solution, tin (Sn ⁴⁺) standard solution, bismuth standard solution, investigate when measuring variable concentrations mercury its annoyance level of these ion pairs.As shown in table 2, each ion pair is measured and is not produced the maximum adding quantity of interference when being 10 μ g/L, 50 μ g/L and 120 μ g/L for measuring mercurous mark liquid concentration.

Table 2 interfering ion maximum acceptable concentration (MPC) tables of data

Aluminium (Al 3+)

10g/L

10g/L

10g/L

As seen from the above table, Na ⁺, Ca ²⁺, Mg ²⁺, Ba ²⁺, Zn ²⁺, Al ³⁺Existence this method is not disturbed.Fe ³⁺Do not form complex compound with dithizone, but itself color has interference to this method, it allows amount is 10mg/L.Ag ⁺, Sn ⁴⁺(Sn ²⁺), Co ²⁺And Bi ³⁺Though this method is produced interference, and their content in water sample is few.Cu ²⁺(10 μ g/L) promptly produce to disturb this method on a small quantity, if contain copper ion in the sample, and its concentration must remove earlier when surpassing 10 μ g/L, in order to avoid interference measurement.

(4) sample determination method

Clear up: 50ml puts into conical flask with sample, adds 10ml sulfuric acid and 2.5ml nitric acid carefully, mixes after adding at every turn.Add the 3ml liquor potassic permanganate,, add 3ml again so that color can be lasting after then mixing as can not in 15min, keeping darkviolet.Add the 8mL potassium persulfate solution then, cover bottle stopper, and be cooled to about 40 ℃ after 2 hours in (temperature is controlled at 95 ℃) heating in the water-bath.The oxygenant that adds oxammonium hydrochloride solution reduction surplus is till the color of solution just disappears.Open plug and place 5-10min.Solution is transferred in the 100mL volumetric flask, moves in the volumetric flask in the lump for twice with a small amount of washing conical flask.

Sample test: in the 100mL volumetric flask that the water sample after clearing up is housed, add the above-mentioned dithizone solution for preparing of 5ml, be diluted to scale with ultrapure water, placing 3 minutes, is that reagent blank is surveyed dithizone-mercury complex solution absorbency at wavelength 495nm place with the ultrapure water with the 3cm cuvette.

(5) mensuration of water sample

Sample 50mL is put into the 250mL conical flask, add as previously mentioned and after reagent is cleared up solution is transferred in the 100mL volumetric flask, move in the lump in the volumetric flask for twice with a small amount of washing conical flask, be diluted to scale with ultrapure water, mixing was placed 3 minutes.Is the absorbance that reagent blank is surveyed dithizone-mercury complex at wavelength 495nm place with the ultrapure water with the 3cm cuvette.Calculate the content of mercury in the water outlet according to the typical curve of mercury.

(6) the present invention and additive method relative merits are relatively

The present invention and additive method relative merits relatively see Table 3.

Table 3 the present invention and additive method relative merits are relatively

	The present invention	Dithizone-extraction spectrophotometric method (National Standard Method)	Cold-vapour atomic absorption method (National Standard Method)	Atomic fluorescence method (National Standard Method)
					Measurement range (ppb)	10-120	2-40	0.2-10	0.4-20
Relative standard deviation (%)	5.39	40.3	5.8	1.8
					Relative error (%)	3.57	13.7	2.0	1.0
Cost	Low	Low	High	High

As seen from the above table, though minimum detectability of the present invention is higher than dithizone spectrophotometric method, cold-vapour atomic absorption method and atomic fluorescence method, but measurement range broad of the present invention, and aspect relative standard deviation and relative error, the present invention is better than the dithizone-extraction spectrophotometric method, because it is more even than extraction that the present invention directly measures at aqueous phase, good reproducibility; Though cold-vapour atomic absorption method and atomic fluorescence method have fast, matrix disturbs less, sensitivity characteristics such as high and low detection limit very, but its analytical instrument complicated operation costs an arm and a leg, and easily causes the mercury loss after the gasification, and pre-service is lengthy and tedious, and the present invention is simple and efficient, economic and practical; The dithizone spectrophotometric method is to measure the universal method of different kinds of ions, need during this method operation strictly to grasp reaction conditions, and used extractant not only is harmful to analyst's health, and organic solvent also can pollute.The present invention has not only avoided in the dithizone spectrophotometric method Comparatively speaking having simple and efficient, economical and practical characteristics with the poisonous and harmful that organic solvent extraction brought, the shortcoming of complex operation.

(7) precision experiment of the present invention and result:

Described precision is represented with relative standard deviation.

Get 4 100mL volumetric flasks, add 0.5mL, 2.0mL, 5.0mL, 6.0mL mercury mark liquid respectively, add 5mL dithizone solution again, be diluted to scale with ultrapure water, placing 3min, is the absorbance of reagent blank survey dithizone-mercury complex at wavelength 495nm place with the ultrapure water with the 3cm cuvette.Repeat above test 8 times, experimental result sees Table 4.

Table 4 precision test figure table

This shows that the relative standard deviation when the present invention measures mercury content in the water body is 5.39%, precision is good.

(8) accuracy experiment of the present invention and result:

Accuracy is represented with relative error.

Get 4 100mL volumetric flasks, add 1.5mL, 2.5mL, 3.5mL, 4.5mL respectively, 5.5mL marks liquid, add 5mL dithizone solution again, be diluted to scale with ultrapure water, placing 3 minutes, is the absorbance that reagent blank is surveyed dithizone-mercury complex at wavelength 495nm place with the ultrapure water with the 3cm cuvette.Experimental result sees Table 5.

Table 5 accuracy experimental data table

Mercury mark liquid addition (ml)	The absorbance calculated value	The absorbance measuring value	Relative error
				1.5	0.028	0.028	0
0.029	3.57％
		0.028	0
2.5	0.036					0.035	-2.78％
		0.036	0
				0.036	0
		3.5	0.043			0.043	0
0.042	0
				0.043	-2.33％
4.5	0.051					0.050	-1.96％
		0.051	0
				0.050	-1.96％
		5.5	0.058			0.057	-1.72％
0.057	-1.72％
				0.058	0

(9) the present invention and National Standard Method are measured water sample and comparison thereof:

Get the 3L water sample from Song Hua River, add the pH value that about 21 milliliters of nitric acid are regulated sample, make it to be less than or equal to 1.Sample is stored in the Pyrex bottle.Because in advance the mercury content that records water sample with National Standard Method is lower than 10ppb, not within the measurement range of this method, therefore adds mercury mark liquid 1mL in every 100mL water sample, as the actual water sample of this measurement, claims water sample 1.

Get and carry out assay determination with this experimental technique after 50ml water sample 1 is cleared up, get and use the national standard method assay determination after 250ml water sample 1 is cleared up, calculate the content of mercury ion according to each typical curve.Experimental result sees Table 6.

The concentration establishing criteria curvilinear equation y=0.106x+0.3524 of the mercury of National Standard Method calculates, and brings absorbance into y, tries to achieve the concentration that x is actual mercury; The concentration of mercury of the present invention should be according to standard equation y=0.0007x+0.0172 calculate 2 times of concentration, because the 50ml water sample of being got, when measuring, need add clear up reagent and developer and constant volume to 100mL, concentration after the dilution is original 1/2, therefore, the concentration of actual mercury should be 2 times of concentration of the mercury that directly records.

Table 6 actual water sample measurement result table

	Dithizone-extraction method (National Standard Method)	The present invention
			The concentration of actual mercury (ppb)	21.8	22.4

As seen from the above table, ion concentration of mercury is more or less the same in the present invention and the National Standard Method survey water sample 1, shows that this method has good accuracy.

(10) mark-on of the present invention reclaims experiment and result thereof:

Add 1ml, 2ml, 3ml mercury titer respectively in water sample 1, clear up the back and carry out assay determination with this experimental technique, calculate recovery of standard addition, test findings sees Table 7.

Table 7 mark-on reclaims the experimental result table

	Hg 2+Content (ppb)	Hg 2+Addition (ppb)	Measure Hg 2+Content (ppb)	Recovery %
					1	11.2	10	22.6	114.0
2	11.2	20	32.5	106.5
					3	11.2	30	42.5	104.3
Mean value				108.3

As seen from the above table, average recovery of standard addition of the present invention is 108.3%.

Trace Mercury Determination on content in embodiment 2 waste water

Carry out identical described in the mensuration of Trace Mercury in the waste water used instrument, reagent and preparation and operation steps and the embodiment 1 with the present invention.The organism that contains in the waste water can melt at sample digestion process chats.Then be noted that Fe if also contain other inorganic ions ³⁺Content do not allow to surpass 10mg/L, Cu ²⁺Content is no more than 10 μ g/L, otherwise must remove these ions earlier, in order to avoid influence measurement result.And Fe ³⁺, Cu ²⁺The removal method to one skilled in the art, be common sense knowledge.

Claims (2)

1, a kind of method with Trace Mercury in spectrophotometric method water mensuration water or the waste water, it is characterized in that: with absolute ethyl alcohol or 95% ethanol is solvent, is solubilizer with the Triton X-100, and the dithizone dissolving is made dithizone solution; Under pH=1～2 conditions, the reaction of dithizone and mercury ion generates water-soluble coloured ion complex compound, in its absorbance of 495nm place survey, tries to achieve in water or the content of Mercury in Wastewater with the canonical plotting of mercury with spectrophotometer.

2, a kind of method according to claim 1 with Trace Mercury in spectrophotometric method water mensuration water or the waste water, it is characterized in that: the concentration of the described dithizone solution that makes is 0.005g/L; The preparation method of this solution is: the 0.001g dithizone is put into container, dip in from 40ml absolute ethyl alcohol or 95% ethanol with glass bar and to get the ethanol that can make the dithizone wetting amount, with the Glass rod grinding dithizone after do not have fine particle, remaining ethanol is poured in the said vesse, stir the Triton X-100 aqueous solution 150ml of the quality percentage composition of adding 5% down, ultrasonic concussion 15～30min is settled to 200mL with ultrapure water then and makes Dithizone in Aqueous Solution.