CN110231375A - A kind of detection method of standard addition method to fluorine content in phosphoric acid and its phosphate - Google Patents
A kind of detection method of standard addition method to fluorine content in phosphoric acid and its phosphate Download PDFInfo
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Abstract
A kind of detection method of standard addition method to fluorine content in phosphoric acid and its phosphate, the present invention is will be after sample dissolving with hydrochloric acid, in the solution that pH is 5.5~6.0, using saturated calomel electrode as reference electrode, make indicator electrode with fluoride ion selective electrode, the electrode potential for directly measuring solution, using the content of standard addition method measurement fluorine, with formula calculated result.Detection method do not need draw fluorine standard working curve, but have with the comparable detection limit of working curve method and accuracy, and the present invention than working curve method operate it is simpler, faster, analysis cost is low, measurement range is wide, method is applied widely.The present invention is applicable not only to the higher phosphorus ore of fluorine content, two water of wet process/half water phosphoric acid；It is also applied for the slightly lower ardealite of fluorine content, phosphoric acid defluorination, fertilizer grade/feed-grade phosphate class sample；Fluorine content is applied also for down to 0.001% or so and its above purifying phosphoric acid, phosphoric acid for food and industrial phosphoric acid etc..
Description
Technical field
The invention belongs to technical field of analysis and detection, and in particular to a kind of standard addition method is to fluorine in phosphoric acid and its phosphate
The detection method of content, phosphoric acid sample and its phosphoric acid salt sample and phosphorus ore and phosphorus suitable for different phase difference fluorine content
The measurement of content of fluoride ion in the samples such as gypsum.
Background technique
Fluorine is a kind of non-metal chemical element, and chemical property is very active, can hardly individualism, in nature all
It is to exist with the states of various compounds, is widely present in rock, soil, in ocean；By taking phosphorous chemical industry as an example, fluorine is rock phosphate in powder
Main component, largely enter atmosphere in the form of hydrogen fluoride in the producing process of phosphoric acid, ardealite is entered there are also fraction,
Remaining is fully entered in phosphoric acid, therefore fluorine is largely present in phosphoric acid, phosphide and other phosphoric acid salt products；It is in external environment
And the various intracorporal contents of biology are to measure the important logo of eco-environmental quality and human health.Therefore, the analysis measurement of fluorine
It is an important issue, so far, the analysis of fluorine is usually to use colorimetric method, spectrophotometry, titration, fluorine ion choosing
Selecting property electrode method and the chromatography of ions in modern times；Either precision is not high or complicated for operation or needs for these analysis methods
Expensive analytical equipment, detection method provided by the invention do not need to draw fluorine standard working curve, but have and working curve
The comparable detection limit of method and accuracy, and detection method provided by the invention is simpler, more faster than working curve method operation,
Analysis cost is low, measurement range is wide, method is applied widely.It is higher to be suitable for fluorine content for detection method provided by the invention
Phosphorus ore, two water of wet process/half water phosphoric acid；It is also applied for the slightly lower ardealite of fluorine content, phosphoric acid defluorination, fertilizer grade/feed grade phosphoric acid
Salt sample；Fluorine content is applied also for down to 0.0010% or so and its above purifying phosphoric acid, phosphoric acid for food and industrial phosphoric acid
Deng.
Summary of the invention
It is high that the technical problem to be solved by the present invention is to provide a kind of detection accuracy, and measurement range is big and simple and quick, no
Need expensive detection device that can quickly obtain the detection method of fluorine content of accurate data；
In view of this, the present invention provides a kind of standard addition methods to the detection side of fluorine content in phosphoric acid and its phosphate
Method, detecting step are as follows:
Step 1, fluorine standard solution, concentration 1mg/ml are provided；Specific preparation steps are as follows: accurately weighed with electronic balance
0.221g benchmark sodium fluoride is fully transferred in 100ml volumetric flask after being dissolved in water, is diluted with water to scale, shakes up；
Step 2, provide (1+1) hydrochloric acid solution, (1+19) nitric acid solution, (200g/L) sodium hydroxide solution, pH be 5.5~
6.0 citric acid-sodium citrate buffers, (1g/L) bromocresol green indicator solution；
It is specific to prepare are as follows: (1+1) hydrochloric acid solution: to measure 500ml analysis pure hydrochloric acid solution and 500ml pure water with burette
It is uniformly mixed, is placed in the thin mouth vial of 1000ml；(1+19) nitric acid solution: it is molten that the pure nitric acid of 25ml analysis is measured with burette
Liquid is uniformly mixed with 475ml pure water, is placed in the thin mouth vial of 500ml brown and is kept in dark place；200g/L sodium hydroxide solution: claim
It takes 200g (being accurate to 0.02g) to analyze pure cerium hydroxide sodium, is dissolved in water, be settled to 1000ml volumetric flask after cooling, shake up postposition
In the thin mouth polyethylene bottle of 1000ml；The citric acid-sodium citrate buffer that pH is 5.5~6.0: it is single to weigh 24g analysis
Citric acid monohydrate, 270g analyze pure two citric acid monohydrate trisodiums, are dissolved in water, and be diluted to 1000ml, mix；1g/L bromocresol green
Indicator solution: weighing 0.1g bromocresol green and be dissolved in 20ml dehydrated alcohol, be diluted with water to 100ml, mixes；
Step 3, prepared by sample prepare liquid:
1. liquid phosphoric acid sample treatment: with electronic balance accurately weigh 0.5~5g phosphoric acid sample (be accurate to ±
0.0002g), the dissolution of 1~10ml (1+1) hydrochloric acid solution is added, is placed in 50ml volumetric flask, make in 50ml volumetric flask liquid fluorine to be measured from
Sub- content is in 50 μ of μ g~150 g；If phosphoric acid sample fluorine content is excessively high, need to dilute；The appropriate increase if sample fluorine content is too low
Claim sample quality；
2. solid phosphate sample treatment: with electronic balance accurately weigh 1~1.5g Phosphate Sample (be accurate to ±
0.0002g) in 100ml beaker, the heating of 10~15ml (1+1) hydrochloric acid solution, which is added, is completely dissolved sample, is transferred to v2Body
Product volumetric flask, is diluted with water to scale, shakes up, accurately pipette v with pipette1The solution of volume is to 50ml volumetric flask；
3. phosphorus ore and ardealite sample treatment: weighing 0.1~0.5g sample (being accurate to ± 0.0002g), be placed in 100ml modeling
Expect in beaker, soaked with a small amount of water, 8~12ml (1+1) hydrochloric acid solution is added and is transferred in stirring 30min on magnetic stirring apparatus
v2Volume capacity bottle is diluted with water to scale, shakes up, and does filtering, accurately pipettes v with pipette1The limpid filtrate of volume is to 50ml
Volumetric flask；
Step 4, prepare liquid pH is adjusted: citric acid-citric acid that 3~6 drop pH are 5.5~6.0 being added in test solution
Sodium buffer solution and 2~5 drop 1g/L bromocresol green indicator solutions, are adjusted to blue or blue-green with 200g/L sodium hydroxide solution, then
It is adjusted to just be in that 15~20ml citric acid-sodium citrate buffer is added after yellow with (1+19) nitric acid solution, be diluted with water to
Scale mixes；
Step 5, potential measurement: step 4 gained test solution is all poured into dry 50ml plastic beaker, insertion fluorine from
Sub- electrodes selective and saturated calomel electrode measure potential value when balance under magnetic stirring, and 0.5ml fluorine standard solution is added
(1mg/ml) records the potential value after balancing again, while measuring solution temperature；
Step 6, it calculates fluorine content: fluorine content being calculated using formula according to Δ U: its formula are as follows:Wherein Δ U refers to the difference for the potential value that front and back measures twice, is 40~60 ranges
It is best；M refers to the numerical value for weighing the quality of sample, unit g；Antilog refers to antilogarithm；0.0005 refers to the fluorine of addition
Standard solution is equivalent to the content of fluorine, unit g；K refers to the theory of this special slope of the actual slope acquired with laboratory or energy
Value, looks into subordinate list according to solution temperature and obtains；v1/v2Refer to extension rate, v1Refer to and takes volume, v2Refer to constant volume, unit
It is ml.
Liquid solution concentration uses " v1+v2 " (such as " concentration of hydrochloric acid solution 1+1 ", " nitric acid solution concentration is in the present invention
1+19 ") it indicates, each mean that the solute of v1 volume is mixed with the solvent of v2 volume, shaken up, the present invention is subsequent to there are same solution lattice
Formula, it is identical as this explanation, it is not repeated to illustrate；
If 1. phosphoric acid sample fluorine content is excessively high in the preparation of the sample liquids phosphoric acid prepare liquid in step 3 of the present invention,
Its operation need to be diluted are as follows: accurately weigh the sample (being accurate to ± 0.0002g) of 1~1.5g with electronic balance, 10~15ml is added
The dissolution of (1+1) hydrochloric acid solution, is transferred to a v2In the volumetric flask of volume, v is accurately pipetted with pipette after being shaken up with water constant volume1
Volume is placed in 50ml volumetric flask, makes in 50ml volumetric flask prepare liquid content of fluoride ion in 50 μ of μ g~150 g；
2. the solid phosphate sample and 3. the prepare liquid system of the phosphorus ore and ardealite sample in step 3 of the present invention
It is standby, different sample treatments should be taken according to the difference of properties of samples or increases heating or dry filter process, make to enter
The prepare liquid of 50ml volumetric flask cannot contain undissolved sample or color, in order to avoid interfere subsequent measurement.
It is adjusted to just be in that yellow refers to that (1+19) nitric acid is slowly added dropwise is molten with (1+19) nitric acid solution described in step 4 of the present invention
Liquid adjusts color, can stop when color becomes yellow, cannot be excessively too many, this is after causing in order to avoid solution acidity is excessively high
The continuous citric acid-sodium citrate buffer being added impact analysis result more than the range that can be buffered；
Be added described in step 4 of the present invention the pH range of 15~20ml citric acid-sodium citrate buffer 5.5~
6.0, this is because when pH<can extend equilibration time, therefore by liquid acidity control to be measured when can reduce fluorine ion activity and pH>8 when 5.0
System is 5.5~6.0.Be added citric acid-sodium citrate buffer be control prepare liquid acidity can also eliminate iron aluminium etc. from
The interference of son；
Core requirement is in step 3 prepare liquid of the present invention preparation: making in 50ml volumetric flask prepare liquid content of fluoride ion in 50 μ
The μ of g~150 g；Concrete operations are that adjustment claims sample quality and v1/v2Value, making Δ U is best in 40~60 ranges.
Core requirement is in step 5 potential measurement of the present invention: using the measuring pipette or big tripe pipette etc. for passing through calibration
Be capable of accurate draw solution measures the accurate 0.5ml fluorine standard solution (1mg/ml) of formula weight device, and after answering equipotential value to balance again
Record numerical value.
The invention has the advantages that the present invention utilizes fluoride ion selective electrode Standard Addition Method for Determination fluorine content, no
Need to draw fluorine standard working curve, but have with the comparable detection limit of working curve method and accuracy, and it is provided by the invention
Detection method is simpler, more faster than working curve method operation, and analysis cost is low, measurement range is wide, method is applied widely.
Detection method provided by the invention is suitable for the higher phosphorus ore of fluorine content, two water of wet process/half water phosphoric acid；It is also suitable
In the slightly lower ardealite of fluorine content, phosphoric acid defluorination, fertilizer grade/feed-grade phosphate class sample；Apply also for fluorine content down to
0.001% or so and its above purifying phosphoric acid, phosphoric acid for food and industrial phosphoric acid etc..
Attached K value table is calculated for the present invention
With the theoretical k value for testing this special slope of the actual slope acquired or energy when measuring fluorine content.
Specific embodiment
Below in conjunction with case study on implementation of the present invention, the technical solution in case study on implementation of the present invention is carried out according to different samples
Clear and complete description, including method detection range, detection limit, the detailed description such as tolerance.Described case study on implementation is only
It is only a part of case study on implementation of the present invention, rather than all.
It is specific implementation case below, elaborates concrete scheme of the invention.
Embodiment 1
The measurement of content of fluoride (in terms of F) in commercial wet process purifying phosphoric acid and food grade phosphoric acid
1. analytical implement instrument and reagent
Conventional analysis utensil, Mei Tele ME204E electronic balance, acidometer or potentiometer (precision is 2mV/ lattice), magnetic force stir
Mix device；1mg/ml fluorine standard solution, (1+1) concentration of hydrochloric acid solution, (1+19) nitric acid solution, 200g/L sodium hydroxide solution, pH
Citric acid-sodium citrate buffer, 1g/L bromocresol green indicator solution for 5.5~6.0；
2. the specific preparation steps of reagent
1mg/ml fluorine standard solution: 0.221g benchmark sodium fluoride is accurately weighed with electronic balance, is all shifted after being dissolved in water
Into 100ml volumetric flask, it is diluted with water to scale, is shaken up；
(1+1) hydrochloric acid solution: 500ml analysis pure hydrochloric acid solution is measured with burette and is uniformly mixed with 500ml pure water, is set
In the thin mouth vial of 1000ml；(1+19) nitric acid solution: the pure nitric acid solution of 25ml analysis is measured with burette and 475ml is pure
Water is uniformly mixed, and is placed in the thin mouth vial of 500ml brown and is kept in dark place；200g/L sodium hydroxide solution: it is (accurate to weigh 200g
Pure cerium hydroxide sodium is analyzed to 0.02g), is dissolved in water, 1000ml volumetric flask is settled to after cooling, shakes up and be placed on the thin mouth of 1000ml
In polyethylene bottle；The citric acid-sodium citrate buffer that pH is 5.5~6.0: weigh 24g analyze single citric acid monohydrate,
270g analyzes pure two citric acid monohydrate trisodiums, is dissolved in water, and be diluted to 1000ml, mixes；1g/L bromocresol green indicator solution: it weighs
0.1g bromocresol green is dissolved in 20ml dehydrated alcohol, is diluted with water to 100ml, mixes.
3. prepared by prepare liquid: accurately weighing the phosphoric acid sample (being accurate to 0.0002g) of 2.5~5g with electronic balance, be added 1
~2ml (1+1) hydrochloric acid solution, is placed in 50ml volumetric flask, makes in 50ml volumetric flask prepare liquid content of fluoride ion in 50 μ of μ g~150
g；
4. determination step:
The citric acid-sodium citrate buffer and 2~5 drop 1g/L that 3~6 drop pH are 5.5~6.0 are added in prepare liquid
Bromocresol green indicator solution is adjusted to blue or blue-green with 200g/L sodium hydroxide solution, then is adjusted to just with (1+19) nitric acid solution
In 15~20ml citric acid-sodium citrate buffer is added after yellow, it is diluted with water to scale, is mixed；All pour into drying
50ml plastic beaker in, fluoride ion selective electrode and saturated calomel electrode are inserted into, when measuring balance under magnetic stirring
0.5ml fluorine standard solution is added in potential value, records the potential value after balancing again, while measuring solution temperature；
5. fluorine content calculates: in terms of the mass fraction of fluorine (F) quality, numerical value is indicated with %, is calculated as follows:Wherein Δ U refers to the difference for the potential value that front and back measures twice, is 40~60 ranges
It is best；M refers to the numerical value for weighing the quality of sample, unit g；Antilog refers to antilogarithm；0.0005 refers to the fluorine of addition
Standard solution is equivalent to the content of fluorine, unit g；K refers to the theory of this special slope of the actual slope acquired with laboratory or energy
Value, looks into subordinate list according to solution temperature and obtains；v1/v2Refer to extension rate, v1Refer to and takes volume, v2Refer to constant volume, unit
It is ml.
6. content of fluoride (in terms of F) data are shown in Table 1 in commercial wet process purifying phosphoric acid and food grade phosphoric acid, when chlorine in sample
Ion concentration is lower than 0.002%, allowing relative deviation no more than 50% between two parallel samples；When chloride ion contains in sample
Amount is greater than 0.002%~less than 0.04% when, allowing relative deviation no more than 25% between two parallel samples.
Table 1
7. by case study on implementation 1 as can be seen that detection method provided by the invention detect phosphoric acid sample in fluorine content when
Preci-sion and accuracy with higher and have lower detection limit.
Embodiment 2
The measurement of fluorine content (in terms of F) in organic solvent extractionprocess commercial wet process purifying phosphoric acid meso sample；
1. meso sample described in present case include raw material phosphoric acid by wet process (after defluorinate), raffinate phosphoric acid, phosphoric acid extraction, wash it is remaining
Phosphoric acid and back extraction phosphoric acid；
2. the area of the implementation case and case study on implementation 1 is sample treatment, due to each meso sample fluorine content difference and
Causing each sample to weigh, quality is different, and extension rate is also different；
3. the operation such as analytical implement, reagent needed for the implementation case and prepare liquid pH adjusting, potential measurement, fluorine content calculating
It is identical as case study on implementation 1；
4. raw material phosphoric acid by wet process (after defluorinate) and raffinate phosphoric acid sample treatment: accurately weighing 1~1.5g of sample and (be accurate to
0.0002g), it is placed in 100ml beaker, 10~15ml (1+1) hydrochloric acid solution is added, 250ml volumetric flask is transferred to after dissolution, use
Water is diluted to scale, shakes up.10ml or 15ml test solution is accurately pipetted with pipette to 50ml volumetric flask；
5. phosphoric acid extraction washes remaining phosphoric acid sample treatment: (being accurate to the sour sample that electronic balance accurately weighs 0.5~1g
0.0002g), 2~5ml (1+1) hydrochloric acid solution is added, is placed in 50ml volumetric flask；
6. back extraction phosphoric acid sample treatment: (being accurate to the phosphoric acid sample that electronic balance accurately weighs 2.5~5g
0.0002g), 1~2ml (1+1) hydrochloric acid solution is added, is placed in 50ml volumetric flask；
7. the detection method provided according to the present invention, the implementation case each sample fluorine content measurement data are shown in Table 2；Work as sample
Between middle content of fluoride ion 0.002%~0.01%, allowing relative deviation no more than 25% between two parallel samples；Work as sample
Content of fluoride ion is greater than 0.01% in product, allowing relative deviation no more than 15% between two parallel samples；
Table 2
8. by case study on implementation 2 as can be seen that detection method provided by the invention fluorine ion in detection phosphoric acid sample contains
Have very strong sample applicability when amount, detection provided by the invention can be used for the phosphoric acid sample that content of fluoride ion differs greatly
Method Accurate Determining, data precision is high, and detection range is big.
Embodiment 3
The measurement of fluorine content (in terms of F) in phosphoric acid salt sample；
1. present case mainly describes detection side provided by the invention by taking calcium hydrophosphate fodder and calcium dihydrogen phosphate as an example
Method；
2. the difference of the implementation case and case study on implementation 1 and 2 is the sample that present case describes for solid sample, at sample
Reason slightly has difference with fluid sample, and extension rate is also to be determined according to the fluorine content in sample；Electricity is increased on analytical implement
Hot plate, remaining equal indifference；
3. remaining is identical as case study on implementation 2 in addition to increasing electric hot plate for analytical implement needed for the implementation case, required
The operations such as reagent and prepare liquid pH adjusting, potential measurement, fluorine content calculating are identical as case study on implementation 2；
4. sample treatment: accurately weighing 1~1.5g of sample (being accurate to 0.0002g), be placed in 100ml beaker, with a small amount of
Water wetting is transferred to 250ml capacity after addition 10~15ml (1+1) hydrochloric acid solution is completely dissolved sample with electric hot plate low-grade fever
Bottle, is diluted with water to scale, shakes up, 20ml test solution is accurately pipetted with pipette to 50ml volumetric flask；
5. carrying out prepare liquid pH adjusting, potential measurement according to case study on implementation 1；Extension rate v1/v2=in the implementation case
20/250, fluorine content, which is calculated, using formula calculates；
6. the detection method provided according to the present invention, the implementation case sample fluorine content measurement data are shown in Table 3；Two parallel
Allowing relative deviation no more than 15% between sample；
Table 3
7. by case study on implementation 3 as can be seen that detection method provided by the invention detection phosphoric acid salt sample in fluorine from
Relative deviation when sub- content between national standard measuring method is not more than 15%, and collimation between sample illustrates this
The detection method that invention provides can be used for the measurement of phosphoric acid salt sample.
Embodiment 4
The measurement of total fluorine content (in terms of F) in phosphorus ore and ardealite sample；
1. the implementation case mainly describes detection method provided by the invention by taking phosphorus ore and ardealite as an example；
2. title sample quality and processing method difference that the difference of the implementation case and the case of front three is sample；
3. the operations such as remaining analytical implement, reagent needed for the implementation case and prepare liquid pH adjusting, potential measurement with reality
It is identical to apply case 1, is not repeated to describe in the implementation case；
4. phosphorus ore sample treatment: weighing 125 μm of testing sieves and in the phosphorus ore sample 0.1 of 105~110 DEG C of dry 2h or more
~0.2g (is accurate to 0.0002g), is placed in 100ml beaker, is soaked with a small amount of water, and 8~12ml (1+1) hydrochloric acid solution is added,
In stirring 30min on magnetic stirring apparatus, it is transferred to 250ml volumetric flask, scale is diluted with water to, shakes up, after being filtered with Filter Paper Dry,
The limpid filtrate of 10ml is accurately pipetted with pipette to 50ml volumetric flask；
5. ardealite sample treatment: weighing butt ardealite sample about 0.4~0.5g (being accurate to 0.0002g), be placed in
It in 100ml beaker, is soaked with a small amount of water, 8~12ml (1+1) hydrochloric acid solution is added, in stirring 30min on magnetic stirring apparatus, turned
250ml volumetric flask is moved to, scale is diluted with water to, shakes up, after being filtered with Filter Paper Dry, the limpid of 10ml is accurately pipetted with pipette
Filtrate is to 50ml volumetric flask；
6. carrying out prepare liquid pH adjusting, potential measurement according to case study on implementation 1；Extension rate v1/v2=in the implementation case
10/250, fluorine content, which is calculated, using formula calculates；
7. the detection method provided according to the present invention, the implementation case sample fluorine content measurement data are shown in Table 4；Two parallel
Allowing relative deviation no more than 15% between sample；
Table 4
8. by case study on implementation 4 as can be seen that detection method provided by the invention is in detection rock phosphate in powder and ardealite sample
Relative deviation when middle content of fluoride ion between national standard measuring method is not more than 15%, collimation between sample,
Illustrate that detection method provided by the invention is completely suitable for the measurement of rock phosphate in powder and ardealite class sample.
With the theoretical k value for testing this special slope of the actual slope acquired or energy when subordinate list measures fluorine content
| Temperature DEG C | K | Temperature DEG C | K | Temperature DEG C | K |
| 0 | 54.20 | 15 | 57.17 | 30 | 60.15 |
| 1 | 54.30 | 16 | 57.37 | 31 | 60.35 |
| 2 | 54.59 | 17 | 57.57 | 32 | 60.55 |
| 3 | 54.79 | 18 | 57.77 | 33 | 60.74 |
| 4 | 54.99 | 19 | 57.97 | 34 | 60.94 |
| 5 | 55.19 | 20 | 58.17 | 35 | 61.14 |
| 6 | 55.39 | 21 | 58.36 | 36 | 61.34 |
| 7 | 55.59 | 22 | 58.56 | 37 | 61.54 |
| 8 | 55.78 | 23 | 58.76 | 38 | 61.74 |
| 9 | 55.98 | 24 | 58.96 | 39 | 61.93 |
| 10 | 56.18 | 25 | 59.16 | 40 | 62.13 |
| 11 | 56.38 | 26 | 59.36 | 41 | 62.33 |
| 12 | 56.58 | 27 | 59.55 | 42 | 62.53 |
| 13 | 56.77 | 28 | 59.75 | 43 | 62.73 |
| 14 | 56.97 | 29 | 59.95 |
Claims (9)
1. a kind of standard addition method, to the detection method of fluorine content in phosphoric acid and its phosphate, detecting step is as follows:
Step 1, fluorine standard solution, concentration 1mg/ml are provided；Preparation steps are as follows: accurately weigh 0.221g benchmark with electronic balance
Sodium fluoride is fully transferred in 100ml volumetric flask after being dissolved in water, is diluted with water to scale, shakes up；
Step 2, providing (1+1) hydrochloric acid solution, (1+19) nitric acid solution, 200g/L sodium hydroxide solution, pH is 5.5~6.0 lemons
Lemon acid-sodium citrate buffer, 1g/L bromocresol green indicator solution；
It prepares are as follows: (1+1) hydrochloric acid solution: measuring 500ml analysis pure hydrochloric acid solution with burette and mixed with 500ml pure water
It is even, it is placed in the thin mouth vial of 1000ml；(1+19) nitric acid solution: with burette measure 25ml analyze pure nitric acid solution with
475ml pure water is uniformly mixed, and is placed in the thin mouth vial of 500ml brown and is kept in dark place；200g/L sodium hydroxide solution: it weighs
200g analyzes pure cerium hydroxide sodium, is dissolved in water, and is settled to 1000ml volumetric flask after cooling, shakes up and be placed on the poly- second of the thin mouth of 1000ml
In alkene bottle；The citric acid-sodium citrate buffer that pH is 5.5~6.0: it weighs 24g and analyzes single citric acid monohydrate, 270g point
Pure two citric acid monohydrate trisodiums are analysed, are dissolved in water, and be diluted to 1000ml, are mixed；1g/L bromocresol green indicator solution: 0.1g bromine is weighed
Cresols is green to be dissolved in 20ml dehydrated alcohol, is diluted with water to 100ml, mixes；
Step 3, prepared by sample prepare liquid:
1. liquid phosphoric acid sample treatment: accurately weighing the phosphoric acid sample of 0.5~5g with electronic balance, 1~10ml (1+1) salt is added
Acid solution dissolution, is placed in 50ml volumetric flask, makes in 50ml volumetric flask prepare liquid content of fluoride ion in 50 μ of μ g~150 g；If phosphoric acid
Sample fluorine content is excessively high, then needs to dilute；Appropriate increase claims sample quality if sample fluorine content is too low；
2. solid phosphate sample treatment: the Phosphate Sample of 1~1.5g is accurately weighed in 100ml beaker with electronic balance,
10~15ml (1+1) hydrochloric acid solution, which is added, is completely dissolved sample, is transferred to v2Volume capacity bottle is diluted with water to scale, shakes
It is even, v is accurately pipetted with pipette1The solution of volume is to 50ml volumetric flask；
3. phosphorus ore and ardealite sample treatment: weighing 0.1~0.5g sample, be accurate to 0.0002g, be placed in 100ml plastic beaker
In, it is soaked with a small amount of water, 8~12ml (1+1) hydrochloric acid solution is added in stirring 30min on magnetic stirring apparatus and is transferred to v2Volume
Volumetric flask is diluted with water to scale, shakes up, and does filtering, accurately pipettes v with pipette1The limpid filtrate of volume is to 50ml capacity
Bottle；
Step 4, prepare liquid pH is adjusted: it is slow that the citric acid-sodium citrate that 3~6 drop pH are 5.5~6.0 being added in test solution
Solution and 2~5 drop 1g/L bromocresol green indicator solutions are rushed, is adjusted to blue or blue-green with 200g/L sodium hydroxide solution, then with (1+
19) nitric acid solution is adjusted to just be in that 15~20ml citric acid-sodium citrate buffer is added after yellow, is diluted with water to scale,
It mixes；
Step 5, potential measurement: step 4 gained test solution is all poured into dry 50ml plastic beaker, insertion fluorine ion choosing
Selecting property electrode and saturated calomel electrode measure potential value when balance under magnetic stirring, and 0.5ml fluorine standard solution 1mg/ is added
Ml records the potential value after balancing again, while measuring solution temperature；
Step 6, it calculates fluorine content: fluorine content being calculated using formula according to the difference (being indicated with Δ U) of potential value twice: its formula
Are as follows:
Wherein Δ U refers to the difference for the potential value that front and back measures twice, is 40~60
Range is best；M refers to the numerical value for weighing the quality of sample, unit g；Antilog refers to antilogarithm；0.0005 refers to addition
Fluorine standard solution be equivalent to the content of fluorine, unit g；K refers to the actual slope acquired with laboratory or can this special slope
Theoretical value is looked into subordinate list according to solution temperature and is obtained；v1/v2Refer to extension rate, v1Refer to and takes volume, v2Refer to constant volume,
Unit is ml.
2. a kind of standard addition method according to claim 1 is to the detection method of fluorine content in phosphoric acid and its phosphate,
It is characterized in that, the concentration of fluorine standard solution described in step 1 is the specific preparation steps of 1mg/ml are as follows: is accurately claimed with electronic balance
0.221g benchmark sodium fluoride is taken, is fully transferred in 100ml volumetric flask after being dissolved in water, is diluted with water to scale, shakes up.
3. a kind of standard addition method according to claim 1 is to the detection side of fluorine content in phosphoric acid and its phosphate
Method, which is characterized in that liquid solution concentration is indicated using " v1+v2 " in the present invention, each means the solute and v2 volume of v1 volume
Solvent mixing, shake up.
4. a kind of standard addition method according to claim 1 is to the detection method of fluorine content in phosphoric acid and its phosphate,
It is characterized in that, if 1. phosphoric acid sample fluorine content is excessively high in the preparation of the sample liquids phosphoric acid prepare liquid in step 3, needs to dilute
It is operated are as follows: accurately weighs the sample of 1~1.5g with electronic balance, (1+1) the hydrochloric acid solution dissolution of 10~15ml, transfer is added
To a v2In the volumetric flask of volume, v is accurately pipetted with pipette after being shaken up with water constant volume1Volume is placed in 50ml volumetric flask, makes
Prepare liquid content of fluoride ion is in 50 μ of μ g~150 g in 50ml volumetric flask.
5. a kind of standard addition method according to claim 1 is to the detection method of fluorine content in phosphoric acid and its phosphate,
It is characterized in that, 2. the solid phosphate sample and the 3. preparation of the prepare liquid of the phosphorus ore and ardealite sample, Ying Gen in step 3
Different sample treatments is taken according to the difference of properties of samples or increases heating or dry filter process, makes to enter 50ml volumetric flask
Prepare liquid cannot contain undissolved sample or color, in order to avoid interfere subsequent measurement.
6. a kind of standard addition method according to claim 1 is to the detection method of fluorine content in phosphoric acid and its phosphate,
It is characterized in that, is adjusted to just be in that yellow refers to (1+19) nitric acid solution tune is slowly added dropwise with (1+19) nitric acid solution described in step 4
Color is saved, can be stopped when color becomes yellow.
7. a kind of standard addition method according to claim 1 is to the detection method of fluorine content in phosphoric acid and its phosphate,
It is characterized in that, the pH range of 15~20ml citric acid-sodium citrate buffer is added described in step 4 5.5~6.0.
8. a kind of standard addition method according to claim 1 is to the detection method of fluorine content in phosphoric acid and its phosphate,
Be characterized in that, core requirement is in the preparation of step 3 prepare liquid: make in 50ml volumetric flask prepare liquid content of fluoride ion 50 μ g~
150μg；Concrete operations are that adjustment claims sample quality and v1/v2Value, making Δ U is best in 40~60 ranges.
9. a kind of standard addition method according to claim 1 is to the detection method of fluorine content in phosphoric acid and its phosphate,
It is characterized in that, core requirement is in step 5 potential measurement: can be quasi- using measuring pipette or big tripe pipette for passing through calibration etc.
True draw solution measures the accurate 0.5ml fluorine standard solution 1mg/ml of formula weight device, and re-records numerical value after answering equipotential value to balance.
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