CN109959622A - The method that continuous still detects nitrogen content in multiple batches of metal sample - Google Patents
The method that continuous still detects nitrogen content in multiple batches of metal sample Download PDFInfo
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- G—PHYSICS
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- G—PHYSICS
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- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
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Abstract
The invention belongs to technical field of analysis and detection, the method that specially a kind of continuous still detects nitrogen content in multiple batches of metal sample, first processing digest tube increases spheroid shape structure in its bottom and side wall increases charge pipe, its volume is set to increase original 1/3, determine sample quality, sodium hydroxide solution is added toward digest tube feed inlet and carries out distillation cleaning, it carries out blank test and measures sample absorbance, draw working curve, it obtains regression curve equation, the percentage composition of the nitrogen of sample is finally determined using the nitrogen quantity that equation calculation determines from working curve.By the adjustment to digestion pipe volume and shape, increase the volume of azotometer digest tube, reserve a part of elliposoidal space, the cushion space of steam is allowed to increase, reduces the pressure in digest tube.After the test of longer period of time, the phenomenon that piston is opened without punching.
Description
Technical field
The invention belongs to technical field of analysis and detection, and in particular to the measuring method of nitrogen content in a kind of metal sample.
Background technique
Nitrogen auto analyzer general at present is the distilling apparatus according to classical triumphant formula nitriding design, design principle and ammonia
Nitrogen (NH4+) analysis principle is consistent, which is now primarily adapted for use in the organic nitrogen-containings such as plant nutrient, grain and oil, feed, nitrogenous fertilizer
The analysis of object, existing digestion reaction pipe (also known as digest tube) are straight tube pattern, and caliber is smaller, are not suitable for meeting water reaction fierceness
Sample analysis.My company lithium metal product produced needs to carry out being analyzed to identify for nitrogen content, in order to improve analysis efficiency,
Manual steps are reduced, labor intensity etc. is reduced, full-automatic azotometer is just applied to lithium metal sample analysis, but current city
Without matched digest tube on face.
The existing matching used digest tube form of nitrogen auto analyzer is straight tube pattern, and caliber is smaller.When analysis metal-like
When the active metal of product especially chemical property (such as alkali metal lithium), sample, which meets water, can occur intense reaction, the nitrogen in sample
Exist in the form of Li3N compound, part nitrogen can be volatilized in the form of ammonia in reaction process.If from the digest tube of straight pipe type
Sample metal lithium, which is added, in mouth can generate a large amount of steam, steam is with boiling with the propulsion of distillation time during distilling nitrogen
The exuberant entire digest tube of the droplet risen.This straight tube structure, steam do not buffer leeway, and feed opening piston cannot bear steam
The pressure of generation, goes out piston by steam, and such dosing operation mode can not achieve collects nitrogen completely, to cause to analyze
Error；Charging must all remove digest tube every time simultaneously, complex for operation step in this way, not can guarantee the accuracy rate of analysis also.And
And existing digest tube is not used to the detection of the analysis of nitrogen content in nitrogen auto analyzer alkali metal sample metal lithium, directly affects survey
Measure the accuracy of result.
Summary of the invention
The object of the present invention is to provide a kind of methods that continuous still detects nitrogen content in multiple batches of metal sample, realize certainly
Dynamic continuous detection of the azotometer to large batch of metal sample nitrogen content.
Technical scheme is as follows:
A kind of method that continuous still detects nitrogen content in multiple batches of metal sample, includes the following steps:
1) digest tube is handled
Spheroid shape structure is processed in its bottom, increases feeding inlet structure in its side wall；
2) sample quality is determined
Weighed dry coupon is sent into drying box, sample metal lithium is packed into, moves back outlet with plug seal
Outside, it weighs again, is accurate to 0.0001g, their difference is sample quality；
3) sodium hydroxide solution is added toward digest tube feed inlet and carries out distillation cleaning；
4) it carries out blank test and measures sample absorbance；
5) working curve is drawn, obtains regression curve equation
It is ordinate that absorbance, which subtracts matrix absorbance, and nitrogen content is that abscissa draws working curve, and it is bent to list recurrence
Line equation；
6) percentage composition of nitrogen is determined
In formula: w is the percentage composition of nitrogen, and m is the nitrogen quantity that equation calculation determines from working curve.m0To weigh sample
Quality.
The step 4) carries out blank test and measures sample absorbance, specifically:
4.1) cucurbit is rinsed with water three times from digest tube injection port, add water 100mL, hydroxide toward nitrogen cucurbit through funnel
The 50mL receiving bottle for filling 10mL sulfuric acid is connect with digest tube by condensation pipe by sodium solution 10mL；
4.2) vapourizing furnace connects digest tube, distillation time 80-120s, and absorbing liquid reaches 30mL and stops instrument distillation；
4.3) reception capacity bottle is removed, is rinsed with water connector glass tube three times, 1~2mL is incorporated in volumetric flask every time, toward steaming
Add Nessler's reagent 1.0mL in distillate, be diluted with water to scale, shake up, places 10~20min, survey its absorbance.
The step 4.3) surveys absorbance and uses 3cm cuvette, using water as reference solution, spectrophotometer wavelength
443nm。
The step 5) specifically:
5.1) the high-purity monohydrate lithium hydroxide of 120g is weighed in 800mL beaker, is then dissolved with water, is moved into 1000mL and is held
In measuring bottle, it is diluted with water to scale, is shaken up, is transferred to spare in plastic bottle；
5.2) divide and nitrogen standard working solution 0,1.0,2.0,3.0,4.0,5.0mL taken to be respectively placed in 6 25ml beakers,
It is transferred in nitrogen cucurbit respectively again, each that Matrix Solution 10.0mL is added, water flowing steam is distilled, and repeats step 4), true respectively
Fixed each working solution absorbance；
5.3) measuring absorbance and subtracting matrix absorbance is ordinate, draws working curve by abscissa of nitrogen content, and
List regression curve equation.
The step 3) uses 10~30mL of sodium hydroxide solution, and scavenging period is 80~120s.
The processing digest tube specific steps are as follows:
1.1) use quartz glass production lower end for the tubular structure of ellipsoid structure, upper end opening；
1.2) opening is processed on the side wall of above-mentioned tubular structure, and feed opening is installed；
1.3) frosted processing on the inside of feed opening nozzle；
1.4) frosted of pipe upper end opening is handled；
1.5) the processed nozzle plug of outer wall frosted is processed, is installed in feed opening nozzle；
1.6) upper end tube nozzle plug is installed in straight tube mouth upper end opening.
The lower end is the volume of the tubular structure of ellipsoid compared with level straight tube, increases 1/3.
The ratio between the long diameter of the ellipsoid structure and the height of entire straight tube structure are preferably 1/3.
The feed opening tilts upwards, and tilt angle is 40~45 °.
The quartz glass thickness is 2mm to 4mm.
Remarkable result of the invention is as follows: processing feed inlet on the side wall of original digest tube, changes digestion tube shape, add
Big digestion volume, can satisfy the analysis needs that azotometer continuously detects nitrogen content in metal sample.
In nitrogen cucurbit, sample is reacted with water, and the nitrogen compound in sample is converted into ammonium salt, is subsequently added into sodium hydroxide
Solution is passed through steam and is distilled after so that solution is kept alkalinity.Ammonia and matrix and separation of foreign elements, steam containing ammonia is with dilute
It is reacted after sulfuric acid absorption with Nessler's reagent, forms orange-yellow stable comple, with 3cm cuvette, using water as reference solution, in
At spectrophotometer wavelength 443nm, its absorbance value is surveyed, to detect the nitrogen content in detection metal sample.
Contain after being absorbed using the full-automatic azotometer distillation of mating digest tube through the nitrogen in spectrophotometric determination lithium metal
Data are measured, are coincide with classical triumphant formula for nitrogen analysis data in lithium metal, full-automatic azotometer meets nitrogen in lithium metal
The quality requirement of measurement.
By the adjustment to digestion pipe volume and shape, increases the volume of azotometer digest tube, reserve a part of elliposoidal
Space allows the cushion space of steam to increase, and reduces the pressure in digest tube.After the test of longer period of time, piston without
The phenomenon that punching is opened.
The nitrogen content detected in multiple batches of metal sample using azotometer continuous still is realized, has been filled up at present by complete
Nitrogen auto analyzer tests and analyzes the blank of nitrogen content in alkali metal.
Specific embodiment
Below by specific embodiment, the invention will be further described.
Lithium nitride reacts the nitrogen generated with water when collecting treatments of the sample completely to realize, to the original digest tube knot of utilization
Structure carries out processing, forms structure made of plastics on new materials, the specific steps are as follows:
1) use quartz glass production lower end for the straight tube of ellipsoid structure, upper end opening
The lower end of the tubular structure processes ellipsoid structure, upper end opening, the quartz glass thickness used for 2mm extremely
4mm, preferably 3mm；
The ratio between the long diameter of ellipsoid structure and the height of entire straight tube structure are preferably 1/3；
It is preferred that the length diameter of ellipsoid structure is respectively 100mm, 70mm；
It is preferred that straight tube interior diameter is 36mm, overall diameter 39mm；
2) opening is processed on the side wall of above-mentioned straight tube, and feed opening is installed
It is added simply in order to which operation is added in sample, and can ensure that ammonia is not excessive in sample adition process, therefore digesting
The side of pipe is open, and installs feed opening；
Feed opening tilts upwards, and tilt angle is 40~45 °, preferably 42 °；
Feed opening nozzle interior diameter is preferably 22mm；
3) frosted processing on the inside of feed opening nozzle
4) frosted of straight tube upper end opening is handled
The height of frosted processing is 20~25mm, preferably 22mm；
5) the processed nozzle plug of outer wall frosted is processed, is installed in feed opening nozzle；
Nozzle plug is quartz glass material, need to carry out frosted processing with nozzle contact portion；
6) upper end tube nozzle plug is installed in straight tube mouth upper end opening
Upper end tube nozzle plug material is rubber, convenient for reserved logical steam hole；
It is found during nitrogen distillation, with the progress of distillation time, the increasing of quantity of steam is generated, when distillation time reaches
To after 70s, steam does not buffer leeway, feed opening with droplet exuberant entire straight tube structure digest tube, the steam of boiling
Piston cannot bear the pressure of steam generation, go out piston by steam, will certainly if analyzing sample in such a situa-tion
Influence the precision of detection.Bottom is designed as spherical structure, reserves the cushion space of steam, therefore the piston of adding mouth is not steamed
Vapour punching is opened.
The method for detecting nitrogen content in multiple batches of metal sample using azotometer continuous still
1) digest tube is handled
In order to be suitable for lithium metal detection and analysis, to digestion pipe portion position design is optimized, its side wall increase into
Material mouth structure, while spheroid shape structure is processed in its bottom, increase its volume under the premise of height is constant, reserves the slow of steam
Space is rushed, can satisfy the analysis needs that azotometer continuously detects nitrogen content in metal sample；
2) sample quality is determined
Weighed dry coupon is sent into drying box, about 0.20g lithium metal is packed into.With being removed after plug seal
It outside case, weighs again, is accurate to 0.0001g, their difference is sample quality；
3) cleaning of Distallation systm
20mL is filled the water into digest tube, and sodium hydroxide solution 10mL is added toward digest tube feed inlet and carries out distillation cleaning, when
Between be 80~120s；
4) blank test is carried out
4.1) cucurbit is rinsed with water three times from digest tube injection port, add water 100mL, hydroxide toward nitrogen cucurbit through funnel
The 50mL receiving bottle for filling 10mL sulfuric acid is connect with digest tube by condensation pipe by sodium solution 10mL；
4.2) vapourizing furnace connects digest tube, distillation time 80-120s, and absorbing liquid reaches 30mL and stops instrument distillation；
4.3) reception capacity bottle is removed, is rinsed with water connector glass tube three times, 1~2mL is incorporated in volumetric flask every time, toward steaming
Add Nessler's reagent 1.0mL in distillate, be diluted with water to scale, shake up, places 15min, it is molten by reference of water with 3cm cuvette
Liquid surveys its absorbance in spectrophotometer, wavelength 443nm；
Distilling reagent blank is answered before distillation sample；
5) it measures
It measures absorbance and subtracts blank absorbency and cuvette absorbance, corresponding nitrogen is calculated by slope on working curve
Amount.
5.1) the high-purity monohydrate lithium hydroxide of 120g is weighed in 800mL beaker, is then dissolved with water, is moved into 1000mL and is held
In measuring bottle, it is diluted with water to scale, is shaken up, is transferred to spare in plastic bottle
5.2) divide and nitrogen standard working solution 0,1.0,2.0,3.0,4.0,5.0mL taken to be respectively placed in 6 25ml beakers,
It is transferred in nitrogen cucurbit respectively again, each that Matrix Solution 10.0mL is added, water flowing steam is distilled, and repeats step 4), true respectively
Fixed each working solution absorbance；
5.3) measuring absorbance and subtracting matrix absorbance is ordinate, draws working curve by abscissa of nitrogen content, and
List regression curve equation；
5.4) percentage composition of nitrogen is determined
It is calculated as follows
In formula: w-nitrogen percentage composition, %；
M-is from working curveIt calculatesThe nitrogen quantity obtained, μ g
m0- weigh the quality of sample, g.
Blank distillation is distilled in the case where sample without analyse, and blank value is lower, and dispersion degree is smaller, analysis
The precision of data is higher.When blank value is higher, performance, water, reaction vessel etc. to instrument check one by one, so as to true
Determine influence factor.Nitrogen auto analyzer is as a whole new set of applications in lithium metal analysis, it is necessary to want in blank assay value satisfaction
In the case where asking, just can ensure that final precision of analysis, in order to reduce systematic error, water sky is carried out before the experiments
It is white, alkali blank assay.
Table 1 distills blank absorbency
As can be seen from Table 1: as the extension blank value of distillation time reduces and tends towards stability, meeting wanting for analysis margin
It asks.
Detect the nitrogen content in lithium metal sample, it is necessary first to the nitrogen digestion in sample be dissolved and distill release, then
It is absorbed and is fixed with acid, the process measured through spectrophotometric colo.Therefore it is distilled in the method for nitrogen standard distillation to verify digestion
Etc. processes feasibility.
The nitrogen standard that concentration is 10.0ug/ml nitrogen standard solution different volumes is added from the injection port of digest tube to carry out 3 times
Lai Sile reagent, constant volume is added in distillation test, the liquid after distillation absorbs, and through spectrophotometric colo, experiment be the results are shown in Table
2。
2 nitrogen standard distillation analysis value of table
As can be seen from Table 2: the nitrogen standard of different content by distillation after, absorbance value fluctuation it is small, show its content compared with
Stablize, it was demonstrated that apply the process feasible that this digest tube carries out digestion distillation.
Optional different batches lithium metal sample, is respectively adopted full-automatic azotometer and original kjeldahl determination device to sample nitrogen
Content is measured, and measurement result is shown in Table 3.
The comparison of 3 sample nitrogen analysis of table
| Analyze lot number | Triumphant formula distillation analysis result (%) | Nitrogen auto analyzer analyzes result (%) |
| D16-SP-979 | 0.0108 | 0.0106 |
| D16-SP-981 | <0.0050 | <0.0050 |
| D16-GN-730 | 0.0173 | 0.0175 |
| D16-GN-732 | 0.0082 | 0.0080 |
| D16-SPJ-700 | 0.0289 | 0.0288 |
| D16-SPJ-703 | 0.0078 | 0.0080 |
Contain after being absorbed using the full-automatic azotometer distillation of mating digest tube through the nitrogen in spectrophotometric determination lithium metal
Data are measured, are coincide with classical triumphant formula for nitrogen analysis data in lithium metal, full-automatic azotometer meets nitrogen in lithium metal
The quality requirement of measurement.
Claims (10)
1. a kind of method that continuous still detects nitrogen content in multiple batches of metal sample, which comprises the steps of:
1) digest tube is handled
Spheroid shape structure is processed in its bottom, increases feeding inlet structure in its side wall；
2) sample quality is determined
Weighed dry coupon is sent into drying box, sample metal lithium is packed into, is moved back outside outlet with plug seal, then
Secondary weighing, is accurate to 0.0001g, their difference is sample quality；
3) sodium hydroxide solution is added toward digest tube feed inlet and carries out distillation cleaning；
4) it carries out blank test and measures sample absorbance；
5) working curve is drawn, obtains regression curve equation
It is ordinate that absorbance, which subtracts matrix absorbance, and nitrogen content is that abscissa draws working curve, and lists regression curve side
Journey；
6) percentage composition of nitrogen is determined
In formula: w is the percentage composition of nitrogen, and m is the nitrogen quantity that equation calculation determines from working curve.m0For the quality for weighing sample.
2. the method that continuous still as described in claim 1 detects nitrogen content in multiple batches of metal sample, which is characterized in that institute
The step 4) stated carries out blank test measurement sample absorbance, specifically:
4.1) cucurbit is rinsed with water three times from digest tube injection port, add water 100mL toward nitrogen cucurbit through funnel, sodium hydroxide is molten
The 50mL receiving bottle for filling 10mL sulfuric acid is connect with digest tube by condensation pipe by liquid 10mL；
4.2) vapourizing furnace connects digest tube, distillation time 80-120s, and absorbing liquid reaches 30mL and stops instrument distillation；
4.3) reception capacity bottle is removed, is rinsed with water connector glass tube three times, 1~2mL is incorporated in volumetric flask every time, toward distillate
In plus Nessler's reagent 1.0mL, be diluted with water to scale, shake up, place 10~20min, survey its absorbance.
3. the method that continuous still as claimed in claim 2 detects nitrogen content in multiple batches of metal sample, it is characterised in that: institute
The step 4.3) stated surveys absorbance using 3cm cuvette, using water as reference solution, spectrophotometer wavelength 443nm.
4. the method that continuous still as described in claim 1 detects nitrogen content in multiple batches of metal sample, which is characterized in that institute
The step 5) stated specifically:
5.1) the high-purity monohydrate lithium hydroxide of 120g is weighed in 800mL beaker, is then dissolved with water, and 1000mL volumetric flask is moved into
In, it is diluted with water to scale, is shaken up, is transferred to spare in plastic bottle；
5.2) divide and nitrogen standard working solution 0,1.0,2.0,3.0,4.0,5.0mL is taken to be respectively placed in 6 25ml beakers, then distinguish
It is transferred in nitrogen cucurbit, each that Matrix Solution 10.0mL is added, water flowing steam is distilled, and is repeated step 4), is determined each work respectively
Make solution absorbance；
5.3) measuring absorbance and subtracting matrix absorbance is ordinate, draws working curve by abscissa of nitrogen content, and list
Regression curve equation.
5. the method that continuous still as described in claim 1 detects nitrogen content in multiple batches of metal sample, it is characterised in that: institute
The step 3) stated uses 10~30mL of sodium hydroxide solution, and scavenging period is 80~120s.
6. the method that continuous still as described in claim 1 detects nitrogen content in multiple batches of metal sample, which is characterized in that institute
The processing digest tube specific steps stated are as follows:
6.1) use quartz glass production lower end for the tubular structure of ellipsoid structure, upper end opening；
6.2) opening is processed on the side wall of above-mentioned tubular structure, and feed opening is installed；
6.3) frosted processing on the inside of feed opening nozzle；
6.4) frosted of pipe upper end opening is handled；
6.5) the processed nozzle plug of outer wall frosted is processed, is installed in feed opening nozzle；
6.6) upper end tube nozzle plug is installed in straight tube mouth upper end opening.
7. the method that continuous still as claimed in claim 6 detects nitrogen content in multiple batches of metal sample, it is characterised in that: institute
The lower end stated is the volume of the tubular structure of ellipsoid compared with level straight tube, increases 1/3.
8. the method that continuous still as claimed in claim 7 detects nitrogen content in multiple batches of metal sample, it is characterised in that: institute
The ratio between the long diameter for the ellipsoid structure stated and the height of entire straight tube structure are preferably 1/3.
9. the method that continuous still as claimed in claim 6 detects nitrogen content in multiple batches of metal sample, it is characterised in that: institute
The feed opening stated tilts upwards, and tilt angle is 40~45 °.
10. the method that continuous still as claimed in claim 6 detects nitrogen content in multiple batches of metal sample, it is characterised in that:
The quartz glass thickness is 2mm to 4mm.
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Application publication date: 20190702 |