Background
Mercaptopropionic acid is an important chemical intermediate and industrial raw material, has multiple purposes due to the fact that molecules of mercaptopropionic acid contain both sulfydryl and carboxyl, is widely concerned by people, and has a very wide market prospect. The mercaptopropionic acid is transparent liquid in appearance character, has strong sulfide smell, and is extremely smelly and toxic. As chemical intermediates and industrial raw materials, if the mercaptopropionic acid contains iron, the product can yellow and influence the product quality, so that the control of the iron content in the mercaptopropionic acid is necessary. The research discovers a simple, convenient, rapid, sensitive, stable and accurate analysis method by selecting the iron determination conditions, is used for determining the iron content in the mercaptopropionic acid, and has a satisfactory effect.
At present, no report is available for measuring the content of iron in mercaptopropionic acid by using inductively coupled plasma mass spectrometry.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides an analysis method for determining the content of iron in mercaptopropionic acid by inductively coupled plasma mass spectrometry. In the method, after the mercaptopropionic acid is treated by adopting a sample pretreatment method of low-temperature volatilization and high-temperature calcination, the iron content in the sample is detected. The method for measuring the iron content in the mercaptopropionic acid by the inductively coupled plasma mass spectrometry is high in sensitivity, wide in linear range and low in detection limit, and meets the requirement of measuring the iron content in the mercaptopropionic acid by adopting a low-temperature volatilization and high-temperature calcination pretreatment method from the results of measuring the precision and the standard addition recovery rate of the iron in a sample.
In order to achieve the purpose, the technical scheme adopted by the application is as follows:
a method for determining the iron content in mercaptopropionic acid by an inductively coupled plasma mass spectrometry method comprises the step of treating the mercaptopropionic acid by adopting a pretreatment method of low-temperature volatilization and high-temperature calcination, and directly determining the iron content in a sample.
The method for determining the iron content in the mercaptopropionic acid by the inductively coupled plasma mass spectrometry comprises the following steps of:
(1) standard solution preparation
Diluting the iron standard stock solution with a nitric acid solution with the volume percentage of 1% to prepare iron standard solutions A, B, C, D, E, F, G with different concentrations;
(2) sample pretreatment
1) Putting a sample into a crucible, putting the crucible into an electric heating plate at 120-150 ℃ to volatilize the sample until the sample is nearly dry, putting the crucible into a muffle furnace, and performing gradient heating calcination according to a program;
2) after the sample is calcined at high temperature, taking out the crucible, cooling to room temperature, adding a concentrated nitric acid solution, placing the crucible on an electric hot plate, dissolving residues at 120-150 ℃, and fixing the volume to 25mL by using primary water;
3) the purpose of low-temperature volatilization is to remove volatile components in the sample, the purpose of high-temperature stage is to remove sulfur elements in the sample, and the purpose of using concentrated nitric acid is to dissolve residues after high-temperature calcination.
(3) Test and data processing
Testing on a computer, setting parameters of an ICP-MS instrument after the ICP-MS instrument is tuned, testing the standard solution A, B, C, D, E, F, G prepared in the step (1) under specified operating conditions, and obtaining a linear equation Y of the concentration of iron in the solution and an instrument response value ICPS (ICPS), wherein Y is the concentration of iron in the sample, unit ug/L and X is the detection response value of iron element in the sample; detecting the solution obtained in the step (2) by adopting an ICP-MS instrument, detecting by the instrument to obtain an ICPS value of the iron content in the solution, substituting the value into a standard curve formula for calculation to obtain the iron concentration in the solution, namely, the concentration is substituted into the formula: the iron content mg/kg is (c × V)/m, wherein V is a mobile volume unit mL and m is a weight unit g.
The parameters of the ICP-MS instrument are as follows;
the muffle furnace is subjected to gradient temperature rise calcination according to a program, and the specific temperature and the corresponding time are as follows:
in the step (2) of sample pretreatment, the mass volume ratio of the sample to the concentrated nitric acid is 1: 1-1: 2 g/ml.
Compared with other analysis methods, the method has the following advantages:
the method adopts a pretreatment method of low-temperature volatilization and high-temperature calcination, so that the iron element in the sample can be effectively transferred into the aqueous solution, and the detection is convenient;
the invention adopts the inductively coupled plasma mass spectrometer to measure the iron, and has the advantages of good precision, high recovery rate and low detection limit.
Detailed Description
Example 1
(I) laboratory instruments and reagents
(1) An experimental instrument: the instruments used were a Saimer Feishale science and technology X2Series ICP-MS inductively coupled plasma mass spectrometer and a stainless steel electric heating plate of Yongguang medical instruments Ltd.
(2) Experimental reagent: nitric acid, ultrapure water, an iron standard solution and a scandium standard solution.
(II) conditions of the Instrument parameters
(1) ICP-MS instrument parameters
ICP-MS instrument parameters
(2) Muffle furnace temperature-rising program
Temperature program condition of muffle furnace
Serial number
|
Temperature of
|
Residence time min
|
1
|
200
|
30
|
2
|
300
|
30
|
3
|
400
|
30
|
4
|
550
|
120 |
(III) drawing of standard curve
Taking 1.0mL of 100mg/L iron standard stock solution (China institute of metrology science), fixing the volume to 100mL by using a 1% nitric acid solution (volume percentage of high-grade pure concentrated nitric acid and first-grade water), respectively taking 0, 0.1, 0.2, 0.4, 0.8 and 1.0mL, fixing the volume to 100mL by using a 1% nitric acid solution, and making a standard curve with the gradient of 0, 10, 20, 40, 80 and 100ug/L, wherein Y is 0.002X-16.146, Y is the concentration of iron in the sample, the unit ug/L and X is the detection response value of the iron element in the sample.
(IV) sample pretreatment
3.0289g of sample is taken into a crucible, the crucible is placed on an electric heating plate at 120 ℃ to volatilize the sample until the sample is nearly dry, and the crucible is placed into a muffle furnace to perform gradient heating calcination according to the program.
After the sample is calcined at high temperature, the crucible is taken out and cooled to room temperature, 3mL of concentrated nitric acid solution is added, the mixture is placed on an electric hot plate, residues are dissolved at 120 ℃, and the volume is determined to be 25 mL.
The purpose of low-temperature volatilization is to remove volatile components in the sample, the purpose of high-temperature stage is to remove sulfur elements in the sample, and the purpose of using concentrated nitric acid is to dissolve residues after high-temperature calcination.
(V) test and data processing
Testing on a computer, after the ICP-MS instrument is tuned, testing the standard curve prepared in the step (III) under the specified operation condition to obtain a linear equation of the iron concentration in the solution and the response value ICPS of the instrument; detecting the solution obtained in the step (four) by adopting an ICP-MS instrument, detecting by the instrument to obtain an ICPS value of the iron content in the solution, substituting the value into a standard curve formula for calculation to obtain the iron concentration in the solution, namely, the concentration is substituted into the formula: the iron content mg/kg is (c × V)/m, wherein V is a mobile volume unit mL and m is a weight unit g.
Calculating the iron content in the sample as follows by a formula: 206.44 ug/kg.
Example 2
(I) laboratory instruments and reagents
(1) An experimental instrument: instruments used are a Saimer Feishale science and technology X2Series ICP-MS inductively coupled plasma mass spectrometer and a stainless steel electric heating plate of Yongguang medical instrument Limited company in Beijing;
(2) experimental reagent: nitric acid, ultrapure water, an iron standard solution and a scandium standard solution.
(II) conditions of the Instrument parameters
(1) ICP-MS instrument parameters
ICP-MS instrument parameters
(2) Muffle furnace temperature-rising program
Temperature program condition of muffle furnace
Serial number
|
Temperature of
|
Residence time min
|
1
|
210
|
35
|
2
|
310
|
35
|
3
|
410
|
35
|
4
|
540
|
120 |
(III) drawing of standard curve
Taking 1.0mL of 100mg/L iron standard stock solution (China institute of metrology science), fixing the volume to 100mL by using a 1% nitric acid solution (volume percentage of high-grade pure concentrated nitric acid and first-grade water), respectively taking 0, 0.1, 0.2, 0.4, 0.8 and 1.0mL, fixing the volume to 100mL by using a 1% nitric acid solution, and making a standard curve with the gradient of 0, 10, 20, 40, 80 and 100ug/L, wherein Y is 0.002X-16.146, Y is the concentration of iron in the sample, the unit ug/L and X is the detection response value of the iron element in the sample.
(IV) sample pretreatment
3.1073g of sample is taken into a crucible, the crucible is placed on an electric heating plate at 130 ℃ to volatilize the sample until the sample is nearly dry, and the crucible is placed into a muffle furnace to perform gradient heating calcination according to the program.
After the sample is calcined at high temperature, the crucible is taken out and cooled to room temperature, 4mL of concentrated nitric acid solution is added, the mixture is placed on an electric hot plate, residues are dissolved at 130 ℃, and the volume is determined to be 25 mL.
The purpose of low-temperature volatilization is to remove volatile components in the sample, the purpose of high-temperature stage is to remove sulfur elements in the sample, and the purpose of using concentrated nitric acid is to dissolve residues after high-temperature calcination.
(V) test and data processing
Testing on a computer, after the ICP-MS instrument is tuned, testing the standard curve prepared in the step (III) under the specified operation condition to obtain a linear equation of the iron concentration in the solution and the response value ICPS of the instrument; detecting the solution obtained in the step (four) by adopting an ICP-MS instrument, detecting by the instrument to obtain an ICPS value of the iron content in the solution, substituting the value into a standard curve formula for calculation to obtain the iron concentration in the solution, namely, the concentration is substituted into the formula: the iron content mg/kg is (c × V)/m, wherein V is a mobile volume unit mL and m is a weight unit g.
Calculating the iron content in the sample as follows by a formula: 206.78 ug/kg.
Example 3
(I) laboratory instruments and reagents
(1) An experimental instrument: instruments used are a Saimer Feishale science and technology X2Series ICP-MS inductively coupled plasma mass spectrometer and a stainless steel electric heating plate of Yongguang medical instrument Limited company in Beijing;
(2) experimental reagent: nitric acid, ultrapure water, an iron standard solution and a scandium standard solution.
(II) conditions of the Instrument parameters
(1) ICP-MS instrument parameters
ICP-MS instrument parameters
Operating parameters
|
|
Set value
|
Power RF
|
Powe
|
1208W
|
Flow of cooling gas
|
Cool gas flow rate(Ar)
|
13.0L/min
|
Auxiliary gas flow
|
Auxiliary gas flow rate(Ar)
|
0.8L/min
|
Flow rate of atomized gas
|
atomization gas flow rate(Ar)
|
0.77L/min
|
Measuring mode
|
Acquistin mode
|
Fully quant
|
Number of scans
|
Number of sweep
|
60
|
Residence time
|
Dwell time
|
70ms
|
Number of channels per mass
|
Channels per mass
|
3
|
Total acquisition time
|
Acquisition duration
|
80s
|
Sample interval rinsing time
|
Washing time between runs
|
60s
|
Selection of iron mass number
|
|
57
|
Internal standard element
|
|
Scandium 45 |
(2) Muffle furnace temperature-rising program
Temperature program condition of muffle furnace
(III) drawing of standard curve
Taking 1.0mL of 100mg/L iron standard stock solution (China institute of metrology science), fixing the volume to 100mL by using a 1% nitric acid solution (volume percentage of high-grade pure concentrated nitric acid and first-grade water), respectively taking 0, 0.1, 0.2, 0.4, 0.8 and 1.0mL, fixing the volume to 100mL by using a 1% nitric acid solution, and making a standard curve with the gradient of 0, 10, 20, 40, 80 and 100ug/L, wherein Y is 0.002X-16.146, Y is the concentration of iron in the sample, the unit ug/L and X is the detection response value of the iron element in the sample.
(IV) sample pretreatment
3.0034g of sample is taken into a crucible, the crucible is placed on an electric heating plate at 140 ℃ to volatilize the sample until the sample is nearly dry, and the crucible is placed into a muffle furnace to carry out gradient heating calcination according to the program.
After the sample is calcined at high temperature, the crucible is taken out and cooled to room temperature, 5mL of concentrated nitric acid solution is added, the mixture is placed on an electric hot plate, residues are dissolved at 140 ℃, and the volume is determined to be 25 mL.
The purpose of low-temperature volatilization is to remove volatile components in the sample, the purpose of high-temperature stage is to remove sulfur elements in the sample, and the purpose of using concentrated nitric acid is to dissolve residues after high-temperature calcination.
(V) test and data processing
Testing on a computer, after the ICP-MS instrument is tuned, testing the standard curve prepared in the step (III) under the specified operation condition to obtain a linear equation of the iron concentration in the solution and the response value ICPS of the instrument; detecting the solution obtained in the step (four) by adopting an ICP-MS instrument, detecting by the instrument to obtain an ICPS value of the iron content in the solution, substituting the value into a standard curve formula for calculation to obtain the iron concentration in the solution, namely, the concentration is substituted into the formula: the iron content mg/kg is (c × V)/m, wherein V is a mobile volume unit mL and m is a weight unit g.
Calculating the iron content in the sample as follows by a formula: 205.56 ug/kg.
Example 4
(I) laboratory instruments and reagents
(1) An experimental instrument: instruments used are a Saimer Feishale science and technology X2Series ICP-MS inductively coupled plasma mass spectrometer and a stainless steel electric heating plate of Yongguang medical instrument Limited company in Beijing;
(2) experimental reagent: nitric acid, ultrapure water, an iron standard solution and a scandium standard solution.
(II) conditions of the Instrument parameters
(1) ICP-MS instrument parameters
ICP-MS instrument parameters
Operating parameters
|
|
Set value
|
Power RF
|
Powe
|
1208W
|
Flow of cooling gas
|
Cool gas flow rate(Ar)
|
13.0L/min
|
Auxiliary gas flow
|
Auxiliary gas flow rate(Ar)
|
0.8L/min
|
Flow rate of atomized gas
|
atomization gas flow rate(Ar)
|
0.77L/min
|
Measuring mode
|
Acquistin mode
|
Fully quant
|
Number of scans
|
Number of sweep
|
70
|
Residence time
|
Dwell time
|
80ms
|
Number of channels per mass
|
Channels per mass
|
3
|
Total acquisition time
|
Acquisition duration
|
90s
|
Sample interval rinsing time
|
Washing time between runs
|
70s
|
Selection of iron mass number
|
|
57
|
Internal standard element
|
|
Scandium 45 |
(2) Muffle furnace temperature-rising program
Temperature program condition of muffle furnace
Serial number
|
Temperature of
|
Residence time min
|
1
|
230
|
40
|
2
|
330
|
40
|
3
|
430
|
40
|
4
|
550
|
100 |
(III) drawing of standard curve
Taking 1.0mL of 100mg/L iron standard stock solution (China institute of metrology science), fixing the volume to 100mL by using a 1% nitric acid solution (volume percentage of high-grade pure concentrated nitric acid and first-grade water), respectively taking 0, 0.1, 0.2, 0.4, 0.8 and 1.0mL, fixing the volume to 100mL by using a 1% nitric acid solution, and making a standard curve with the gradient of 0, 10, 20, 40, 80 and 100ug/L, wherein Y is 0.002X-16.146, Y is the concentration of iron in the sample, the unit ug/L and X is the detection response value of the iron element in the sample.
(IV) sample pretreatment
3.0034g of sample is taken into a crucible, the crucible is placed on an electric heating plate at 140 ℃ to volatilize the sample until the sample is nearly dry, and the crucible is placed into a muffle furnace to carry out gradient heating calcination according to the program.
After the sample is calcined at high temperature, the crucible is taken out and cooled to room temperature, 5mL of concentrated nitric acid solution is added, the mixture is placed on an electric hot plate, residues are dissolved at 140 ℃, and the volume is determined to be 25 mL.
The purpose of low-temperature volatilization is to remove volatile components in the sample, the purpose of high-temperature stage is to remove sulfur elements in the sample, and the purpose of using concentrated nitric acid is to dissolve residues after high-temperature calcination.
(V) test and data processing
Testing on a computer, after the ICP-MS instrument is tuned, testing the standard curve prepared in the step (III) under the specified operation condition to obtain a linear equation of the iron concentration in the solution and the response value ICPS of the instrument; detecting the solution obtained in the step (four) by adopting an ICP-MS instrument, detecting by the instrument to obtain an ICPS value of the iron content in the solution, substituting the value into a standard curve formula for calculation to obtain the iron concentration in the solution, namely, the concentration is substituted into the formula: the iron content mg/kg is (c × V)/m, wherein V is a mobile volume unit mL and m is a weight unit g.
Calculating the iron content in the sample as follows by a formula: 206.07 ug/kg.
Example 5
(I) laboratory instruments and reagents
(1) An experimental instrument: instruments used are a Saimer Feishale science and technology X2Series ICP-MS inductively coupled plasma mass spectrometer and a stainless steel electric heating plate of Yongguang medical instrument Limited company in Beijing;
(2) experimental reagent: nitric acid, ultrapure water, an iron standard solution and a scandium standard solution.
(II) conditions of the Instrument parameters
(1) ICP-MS instrument parameters
ICP-MS instrument parameters
Operating parameters
|
|
Set value
|
Power RF
|
Powe
|
1208W
|
Flow of cooling gas
|
Cool gas flow rate(Ar)
|
13.0L/min
|
Auxiliary gas flow
|
Auxiliary gas flow rate(Ar)
|
0.8L/min
|
Flow rate of atomized gas
|
atomization gas flow rate(Ar)
|
0.77L/min
|
Measuring mode
|
Acquistin mode
|
Fully quant
|
Number of scans
|
Number of sweep
|
80
|
Residence time
|
Dwell time
|
80ms
|
Number of channels per mass
|
Channels per mass
|
3
|
Total acquisition time
|
Acquisition duration
|
100s
|
Sample interval rinsing time
|
Washing time between runs
|
80s
|
Selection of iron mass number
|
|
57
|
Internal standard element
|
|
Scandium 45 |
(2) Muffle furnace temperature-rising program
Temperature program condition of muffle furnace
Serial number
|
Temperature of
|
Residence time min
|
1
|
250
|
40
|
2
|
350
|
40
|
3
|
450
|
40
|
4
|
550
|
120 |
(III) drawing of standard curve
Taking 1.0mL of 100mg/L iron standard stock solution (China institute of metrology science), fixing the volume to 100mL by using a 1% nitric acid solution (volume percentage of high-grade pure concentrated nitric acid and first-grade water), respectively taking 0, 0.1, 0.2, 0.4, 0.8 and 1.0mL, fixing the volume to 100mL by using a 1% nitric acid solution, and making a standard curve with the gradient of 0, 10, 20, 40, 80 and 100ug/L, wherein Y is 0.002X-16.146, Y is the concentration of iron in the sample, the unit ug/L and X is the detection response value of the iron element in the sample.
(IV) sample pretreatment
3.0261g of sample is taken into a crucible, the crucible is placed on an electric heating plate at 150 ℃ to volatilize the sample until the sample is nearly dry, and the crucible is placed into a muffle furnace to perform gradient heating calcination according to the program.
After the sample is calcined at high temperature, the crucible is taken out and cooled to room temperature, 6mL of concentrated nitric acid solution is added, the mixture is placed on an electric hot plate, residues are dissolved at 150 ℃, and the volume is determined to be 25 mL.
The purpose of low-temperature volatilization is to remove volatile components in the sample, the purpose of high-temperature stage is to remove sulfur elements in the sample, and the purpose of using concentrated nitric acid is to dissolve residues after high-temperature calcination.
(V) test and data processing
Testing on a computer, after the ICP-MS instrument is tuned, testing the standard curve prepared in the step (III) under the specified operation condition to obtain a linear equation of the iron concentration in the solution and the response value ICPS of the instrument; detecting the solution obtained in the step (four) by adopting an ICP-MS instrument, detecting by the instrument to obtain an ICPS value of the iron content in the solution, substituting the value into a standard curve formula for calculation to obtain the iron concentration in the solution, namely, the concentration is substituted into the formula: the iron content mg/kg is (c × V)/m, wherein V is a mobile volume unit mL and m is a weight unit g.
Calculating the iron content in the sample as follows by a formula: 206.14 ug/kg.