Method for measuring yellow phosphorus content in seawater

Abstract

The invention relates to the technical field of ocean testing, and discloses a method for measuring the content of yellow phosphorus in seawater, the method for detecting the content of the yellow phosphorus in the seawater is established for the first time, the problem that a seawater matrix inhibits the extraction effect is effectively solved by modifying a working curve, and the accuracy of a detection result is ensured. The content of yellow phosphorus in seawater is measured in a vortex oscillation extraction mode, a vortex oscillator is high in extraction efficiency, easy and convenient to operate and low in cost, meanwhile, n-octane is adopted as an extraction agent, the extraction efficiency is high, and harm to human bodies and the environment is avoided.

Description

Technical Field

[0001] The invention relates to the field of marine testing technology, and in particular to a method for measuring the content of yellow phosphorus in seawater. Background Art

[0002] In the field of environmental monitoring and chemical analysis, accurately determining the concentration of trace organic pollutants in water is a crucial task. Yellow phosphorus is a toxic and hazardous substance that may pose a serious threat to the ecosystem and human health even at extremely low concentrations in the environment. Therefore, it is particularly necessary to develop a highly sensitive and accurate method to detect the content of yellow phosphorus in seawater.

[0003] Traditional yellow phosphorus detection methods usually rely on standard curves for quantitative analysis, where a linear regression equation is used to establish the relationship between the concentration of the target compound and the instrument response, such as Chinese patent CN109991182B. However, these methods often fail to fully consider the influence of sample matrix effects (such as salinity) on extraction efficiency, resulting in possible deviations in measurement results. Especially in complex matrices such as seawater, due to the presence of high salinity and other coexisting substances, traditional methods are easily interfered, thus affecting the accuracy of detection. Summary of the invention

[0004] In order to solve the technical problems of poor recovery rate, complicated operation and excessive use of toxic and harmful reagents in the prior art in the above-mentioned background technology, the present invention provides a method for determining the yellow phosphorus content in seawater, establishes a method for determining the yellow phosphorus content in seawater for the first time, and effectively solves the problem of seawater matrix inhibiting the extraction effect, while having a lower detection limit and lower cost.

[0005] The specific technical solution of the present invention is: a method for determining the yellow phosphorus content in seawater, comprising the following steps: 1) Add 5-10 vol% isooctane to the seawater sample for vortex extraction, add 0.4-0.5 g anhydrous sodium sulfate and 0.1-0.15 g N-propylethylenediamine to the surface organic phase after the first centrifugation, shake well and perform dispersed solid phase extraction; 2) performing a second centrifugation and taking the upper liquid phase for gas chromatography flame photometric detection analysis; 3) Compare and analyze the analysis result in step 2) with the seawater matrix working curve to calculate the content of yellow phosphorus.

[0006] The present invention establishes a correlation model for detecting yellow phosphorus content in seawater for the first time, and uses isooctane as an extraction solvent instead of toluene used in the current yellow phosphorus detection method standard, so that the extraction efficiency is better while ensuring that the recovery rate meets the laboratory quality control requirements (80-105%). At the same time, vortex oscillation extraction is used instead of large-volume separatory funnel liquid-liquid extraction, so that a large number of samples can be extracted quickly at one time, which is more efficient than full-automatic liquid-liquid extraction, has low equipment cost and short extraction time. At the same time, due to the interference effect of seawater matrix in seawater, the team of the present invention has conducted a large number of creative experiments on the working curve of the seawater matrix, obtained the required seawater matrix working curve, and effectively solved the matrix effect problem of seawater on yellow phosphorus testing.

[0007] Furthermore, the seawater matrix working curve is: y = 8.8492x-549.87, R 2 =0.998.

[0008] Furthermore, the vortex extraction time is 5 to 8 minutes.

[0009] Furthermore, the first centrifugation speed is 3000-5000 r / min, and the first centrifugation time is 2-3 min.

[0010] Furthermore, the time of dispersed solid phase extraction is 1 to 2 minutes.

[0011] Furthermore, the rotation speed of the second centrifugation is 3000-5000 r / min, and the time of the second centrifugation is 2-3 min.

[0012] Furthermore, the enrichment concentration of seawater samples was 14 to 15 times.

[0013] Furthermore, the carrier gas of the gas chromatography flame photometric detector is nitrogen, and the nitrogen flow rate is 60-62 ml / min.

[0014] Furthermore, the air flow rate in the gas chromatography flame photometric detector is 300-310 ml / min.

[0015] Furthermore, the injection port temperature of the gas chromatography flame photometric detector is 240-245°C.

[0016] Preferably, the heating rate of the chromatographic column is 60°C / min.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1) The present invention establishes for the first time a method for detecting yellow phosphorus content in seawater, and by modifying the working curve, effectively solves the problem of seawater matrix inhibiting the extraction effect, thereby ensuring the accuracy of the detection results.

[0018] 2) The present invention adopts a vortex oscillation extraction method to determine the content of yellow phosphorus in seawater. The vortex oscillator has high extraction efficiency, simple operation and low cost. At the same time, n-octane is used as the extraction agent, which has high extraction efficiency and is harmless to the human body and the environment.

[0019] 3) The present invention adopts dispersed solid phase extraction to purify the yellow phosphorus extraction solvent, which has better effect, simple operation and low cost.

[0020] 4) Under the same analytical conditions, the present invention has a lower detection limit. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with the embodiments.

[0022] Example 1 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 2 ml of isooctane solvent as the extractant, place it on a vortex oscillator for 5 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 3000r / min for 2 minutes. The upper organic phase is the enriched yellow phosphorus.

[0023] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.5 g of anhydrous sodium sulfate and 0.1 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0024] Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two.

[0025] Determine the detection limit of the method: In order to ensure that the calculation of the detection limit of the method conforms to conventional logic and the results are accurate and reliable, blank seawater without yellow phosphorus was first selected as the matrix, and 20 μL of 1000 μg / L yellow phosphorus standard solvent was added to it. After enrichment treatment, the actual concentration of the final sample was 0.67 μg / L; then the spiked sample was independently measured 7 times under the above conditions, and the results of each test were accurately recorded. The average and standard deviation (SD) of the 7 test results were calculated. MDL=t (n-1,0.99) ×SD Where: MDL is the method detection limit; n is the number of parallel measurements of the sample; t is the distribution (one-sided) with n-1 degrees of freedom and 99% confidence level; SD is the standard deviation of n parallel measurements.

[0026] Substitute the calculated SD value and the determined T value to calculate the MDL, and round the calculated result to an appropriate precision according to the principle of "only increase, not decrease", and the calculated result is 0.14μg / L; then check whether the spiked concentration is between 3 and 5 times the MDL, that is, 0.42 to 0.70μg / L. This step verifies the validity and accuracy of the method. If the spiked concentration does fall within the above range, it indicates that the method can accurately detect concentration levels close to the detection limit and meets the analysis requirements; the method detection limit (MDL) calculated this time is 0.14μg / L, and the spiked concentration verification results show that the method has good sensitivity and accuracy, which meets the analysis requirements.

[0027] Sampling was performed at the same sampling point as in Example 1 (i.e., ensuring that the seawater in this comparative example was consistent with that in Example 1), and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate, wherein the calculation formula for the recovery rate was: Recovery rate = (measured value of spiked sample - measured value of sample) / spiked amount * 100%.

[0028] Comparative Example 1 The difference between this comparative example and Example 1 is that in this comparative example, anhydrous sodium sulfate is not added in step 2), and the rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 2 ml of isooctane solvent as the extractant, place it on a vortex oscillator for 5 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 3000r / min for 2 minutes. The upper organic phase is the enriched yellow phosphorus.

[0029] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.5 g of anhydrous sodium sulfate and 0.1 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0030] 3) Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two.

[0031] Sampling was performed at the same sampling point as in Example 1 (ie, the concentration in this comparative example was ensured to be consistent with that in Example 1), and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate.

[0032] Comparative Example 2 The difference between this comparative example and Example 1 is that in this comparative example, the amount of anhydrous sodium sulfate added in step 2) is 1 g, and the rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 2 ml of isooctane solvent as the extractant, place it on a vortex oscillator for 5 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 3000r / min for 2 minutes. The upper organic phase is the enriched yellow phosphorus.

[0033] 2) Dispersive solid phase extraction Take a 15ml centrifuge tube, add 1g of anhydrous sodium sulfate and 0.1g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15ml centrifuge tube, shake and vibrate for 1min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000r / min for 2min, and take 0.8ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0034] 3) Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two.

[0035] Sampling was performed at the same sampling point as in Example 1 (ie, ensuring that the seawater in this comparative example was consistent with that in Example 1), and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate.

[0036] Table 1 Effect of the addition amount of anhydrous sodium sulfate on the recovery rate of yellow phosphorus Addition amount of anhydrous sodium sulfate / g Recovery rate % Example 1 0.5 98.0 Comparative Example 1 0 88.3 Comparative Example 2 1 91.2 From the data in Table 1, it is impossible to effectively remove all moisture without adding anhydrous sodium sulfate, and the residual moisture may interfere with the extraction efficiency of the target compound. Especially in gas chromatography analysis, the presence of moisture may damage the chromatographic column or affect the separation effect, reducing the recovery rate; too much anhydrous sodium sulfate may cause the solid particles to fail to settle completely and mix into the organic phase, increasing the complexity of the sample matrix. This may affect the recovery rate of the target compound and introduce additional interfering substances, reducing the accuracy and sensitivity of the analysis.

[0037] Comparative Example 3 The difference between this comparative example and Example 1 is that the vortex oscillation extraction in this comparative example is changed to liquid-liquid extraction with a separating funnel, and the rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 2 ml of isooctane solvent, and place it on a vortex shaker for 5 minutes. After the extraction, place it in a centrifuge at 3000 rpm for 2 minutes.

[0038] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.5 g of anhydrous sodium sulfate and 0.1 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0039] 3) Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two. Sampling was performed at the same sampling point as in Example 1 (ie, ensuring that the seawater in this comparative example remained consistent), and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate.

[0040] Table 2 Effect of vortex oscillation extraction on recovery rate Extraction method Recovery rate % Example 1 Vortex extraction 98％ Comparative Example 3 Liquid-Liquid Extraction 55.2 From the data in Table 2, the conventional operation uses liquid-liquid extraction, which requires column purification and volume adjustment after extraction, which is costly, toxic, cumbersome, and has a poor recovery rate. However, when vortex oscillation extraction is used, the recovery rate can reach more than 90%.

[0041] Comparative Example 4 The difference between this comparative example and Example 1 is that in this comparative example, in step 1), no isooctane is added, and 2 ml of toluene solution is added as an extractant. The rest of the process is the same as that in Example 1, and the specific steps are as follows: 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 2 ml of toluene solvent as the extractant, place it on a vortex oscillator for 5 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 3000r / min for 2 minutes. The upper organic phase is the enriched yellow phosphorus.

[0042] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.5 g of anhydrous sodium sulfate and 0.1 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0043] 3) Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two. Sampling was performed at the same sampling point as in Example 1 (ie, ensuring that the seawater in this comparative example was consistent with that in Example 1), and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate.

[0044] Table 3 Effect of the type of extractant on the recovery rate Extraction agent Recovery rate % Example 1 Isooctane 98.2 Comparative Example 4 Toluene 75.3 The gas extraction efficiency using isooctane as the extraction agent is better than the recovery efficiency of toluene as the extraction agent, and the toluene solvent is highly toxic. Acute toxicity of toluene: Inhalation of high concentrations of toluene vapor in a short period of time can cause symptoms such as headache, dizziness, nausea, vomiting, and coma. In severe cases, it may cause central nervous system depression, leading to respiratory failure or even death. It also has chronic toxicity: long-term exposure to low concentrations of toluene may cause chronic poisoning, manifested as damage to the nervous system, such as memory loss, inattention, sleep disorders, emotional instability, etc. In addition, it may cause damage to the liver and kidney function. Isooctane belongs to the alkane class of compounds, which is environmentally friendly and basically non-toxic to the human body.

[0045] Example 2 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 2 ml of isooctane solvent as the extractant, place it on a vortex oscillator for 5 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 3000r / min for 2 minutes. The upper organic phase is the enriched yellow phosphorus.

[0046] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.5 g of anhydrous sodium sulfate and 0.1 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0047] 3) Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two. Sampling was performed at different sampling points from Example 1, and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate. The average value of the added concentration was 4.69 μL / ml, and the recovery rate was 93.8%.

[0048] Example 3 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 2 ml of isooctane solvent as the extractant, place it on a vortex oscillator for 5 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 3000r / min for 2 minutes. The upper organic phase is the enriched yellow phosphorus.

[0049] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.5 g of anhydrous sodium sulfate and 0.1 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0050] 3) Calculation results Sampling was performed at sampling points different from those in Example 1 and Example 2, and three sets of parallel experiments were performed. The average value of the added concentration and the recovery rate were calculated, and the average value of the added concentration was 19.3 μL / ml, and the recovery rate was 96.5%.

[0051] Example 4 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 1.5 ml of isooctane solvent as the extractant, place it on a vortex oscillator for 8 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 4000r / min for 3 minutes. The upper organic phase is the enriched yellow phosphorus.

[0052] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.5 g of anhydrous sodium sulfate and 0.1 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0053] 3) Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two. Sampling was performed at the same sampling point as in Example 1 (ie, the seawater in this comparative example was ensured), and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate.

[0054] Example 5 1) Enrichment of yellow phosphorus Take 30 ml of seawater and place it in a 50 ml centrifuge tube, add 3 ml of isooctane solvent as the extractant, place it on a vortex oscillator for 5 minutes of shaking extraction, and after the extraction is completed, place it on a centrifuge and centrifuge it at 3000r / min for 2 minutes. The upper organic phase is the enriched yellow phosphorus.

[0055] 2) Dispersive solid phase extraction Take a 15 ml centrifuge tube, add 0.45 g of anhydrous sodium sulfate and 0.09 g of N-propylethylenediamine, transfer the upper organic phase in step 1) into the above 15 ml centrifuge tube, shake and vibrate for 1 min for dispersed solid phase extraction, place it on a centrifuge for centrifugation at 3000 r / min for 2 min, and take 0.8 ml of the surface sample for gas chromatography analysis, wherein the analysis conditions of the gas chromatograph are: inlet temperature 240°C, chromatographic column flow rate 1.0 ml per minute, carrier gas nitrogen, chromatographic column specification model: HP-5 (30m*0.25mm*0.25μm); air flow rate 300 ml per minute, hydrogen flow rate 60 ml per minute; heating program: 60°C for 1 minute, then rise to 290°C at a rate of 30°C / min.

[0056] 3) Calculation results According to the standard sample with known concentration, repeated measurements were performed under the same conditions to draw a linear relationship diagram between the yellow phosphorus content and the FPD response value, wherein the working curve equation of the present invention is: The working curve equation of the present invention is y=8.8492x-549.87, R 2 =0.998, indicating that there is a high correlation between the two. Sampling was performed at the same sampling point as in Example 1 (ie, the concentration in this comparative example was ensured to be consistent with that in Example 1), and three sets of parallel experiments were performed to calculate the average value of the added concentration and the recovery rate.

[0057] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0058] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for determining the yellow phosphorus content in seawater, characterized in that: The following steps are involved: 1) Add 5-10 vol% isooctane to the seawater sample for vortex extraction, add 0.4-0.5 g anhydrous sodium sulfate and 0.1-0.15 g N-propylethylenediamine to the surface organic phase after the first centrifugation, shake well and perform dispersed solid phase extraction; 2) performing a second centrifugation and taking the upper liquid phase for gas chromatography flame photometric detection analysis; 3) Compare and analyze the analysis result in step 2) with the seawater matrix working curve to calculate the content of yellow phosphorus.

2. A method for measuring yellow phosphorus content in seawater according to claim 1, characterized in that: The vortex extraction time is 5 to 8 minutes.

3. A method for measuring yellow phosphorus content in seawater according to claim 1 or 2, characterized in that: The speed of the first centrifugation is 3000-5000r / min.

4. A method for measuring yellow phosphorus content in seawater according to claim 1 or 2, characterized in that: The first centrifugation time is 2 to 3 minutes.

5. A method for measuring yellow phosphorus content in seawater according to claim 1, characterized in that: The time for dispersed solid phase extraction is 1 to 2 minutes.

6. A method for measuring yellow phosphorus content in seawater according to claim 1 or 5, characterized in that: The speed of the second centrifugation is 3000-5000 r / min, and the time of the second centrifugation is 2-3 min.

7. A method for measuring yellow phosphorus content in seawater according to claim 1, characterized in that: The enrichment concentration of seawater samples was 14 to 15 times.

8. A method for measuring yellow phosphorus content in seawater according to claim 1, characterized in that: The carrier gas of the gas chromatography flame photometric detector is nitrogen, and the nitrogen flow rate is 60-62 ml / min.

9. A method for measuring yellow phosphorus content in seawater according to claim 1, characterized in that: The air flow rate in the gas chromatography flame photometric detector is 300-310 ml / min.

10. A method for determining yellow phosphorus content in seawater according to claim 1, characterized in that: The injection port temperature of the gas chromatography flame photometric detector is 240-245°C.