CN113624748B - Method for measuring formaldehyde content in indoor air - Google Patents
Method for measuring formaldehyde content in indoor air Download PDFInfo
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- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 title claims abstract description 246
- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000000243 solution Substances 0.000 claims abstract description 56
- 239000012086 standard solution Substances 0.000 claims abstract description 30
- 239000003153 chemical reaction reagent Substances 0.000 claims abstract description 28
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 claims abstract description 17
- 238000005259 measurement Methods 0.000 claims abstract description 14
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 13
- 238000011161 development Methods 0.000 claims abstract description 11
- 238000003860 storage Methods 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims description 45
- 238000010521 absorption reaction Methods 0.000 claims description 42
- 238000005070 sampling Methods 0.000 claims description 25
- 238000004519 manufacturing process Methods 0.000 claims description 17
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- FPFSGDXIBUDDKZ-UHFFFAOYSA-N 3-decyl-2-hydroxycyclopent-2-en-1-one Chemical group CCCCCCCCCCC1=C(O)C(=O)CC1 FPFSGDXIBUDDKZ-UHFFFAOYSA-N 0.000 claims description 12
- 238000004364 calculation method Methods 0.000 claims description 11
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 6
- 238000002360 preparation method Methods 0.000 claims description 6
- 239000011550 stock solution Substances 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 4
- IYXXQOGEFHAQGU-GPWRMYTLSA-N [(z)-(3-methyl-1,3-benzothiazol-2-ylidene)amino]azanium;chloride;hydrate Chemical group O.Cl.C1=CC=C2S\C(=N/N)N(C)C2=C1 IYXXQOGEFHAQGU-GPWRMYTLSA-N 0.000 claims description 3
- 239000008367 deionised water Substances 0.000 claims description 3
- 229910021641 deionized water Inorganic materials 0.000 claims description 3
- 238000004090 dissolution Methods 0.000 claims description 3
- 238000005406 washing Methods 0.000 claims description 3
- 238000005303 weighing Methods 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims 1
- 238000004445 quantitative analysis Methods 0.000 abstract description 10
- 238000001514 detection method Methods 0.000 abstract description 9
- 239000000523 sample Substances 0.000 description 46
- DWDGSKGGUZPXMQ-UHFFFAOYSA-N OPPO Chemical compound OPPO DWDGSKGGUZPXMQ-UHFFFAOYSA-N 0.000 description 4
- BCHZICNRHXRCHY-UHFFFAOYSA-N 2h-oxazine Chemical compound N1OC=CC=C1 BCHZICNRHXRCHY-UHFFFAOYSA-N 0.000 description 2
- 238000002835 absorbance Methods 0.000 description 2
- 230000036541 health Effects 0.000 description 2
- 238000012423 maintenance Methods 0.000 description 2
- VTLYFUHAOXGGBS-UHFFFAOYSA-N Fe3+ Chemical compound [Fe+3] VTLYFUHAOXGGBS-UHFFFAOYSA-N 0.000 description 1
- 239000002250 absorbent Substances 0.000 description 1
- 230000002745 absorbent Effects 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000012490 blank solution Substances 0.000 description 1
- 230000000711 cancerogenic effect Effects 0.000 description 1
- 231100000315 carcinogenic Toxicity 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 238000005034 decoration Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000010790 dilution Methods 0.000 description 1
- 239000012895 dilution Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910001447 ferric ion Inorganic materials 0.000 description 1
- 239000003112 inhibitor Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008520 organization Effects 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000013102 re-test Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000012488 sample solution Substances 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000002798 spectrophotometry method Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/75—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated
- G01N21/77—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator
- G01N21/78—Systems in which material is subjected to a chemical reaction, the progress or the result of the reaction being investigated by observing the effect on a chemical indicator producing a change of colour
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- Life Sciences & Earth Sciences (AREA)
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- Biochemistry (AREA)
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Abstract
The invention discloses a method for measuring formaldehyde content in indoor air, which belongs to the technical field of air detection, wherein a phenol reagent is adopted to collect indoor air to be detected, then a color developing agent is added, a photo of the color developing condition of the color developing solution is obtained by shooting the color developing solution after color development by a camera, the color saturation of the color developing solution in the photo of the color developing condition of a sample color developing solution is measured, meanwhile, the saturation of a formaldehyde standard solution series is measured, a standard curve is drawn, the relation between the saturation and the formaldehyde content is obtained, so that the mass concentration of formaldehyde in the indoor air is calculated, and finally the photo of the color developing condition of the sample and the formaldehyde standard solution series obtained by shooting is saved by a photo storage device as a negative. The invention solves the problems of high detection cost, poor stability of the processed sample and influenced accuracy of the measurement result due to untimely quantitative analysis of the sample in the phenol reagent method in the prior art.
Description
Technical Field
The invention belongs to the technical field of air detection, and particularly relates to a method for measuring formaldehyde content in indoor air.
Background
Formaldehyde is colorless and water-soluble liquid, has strong volatility and pungent smell, and is widely used as an adhesive and a corrosion inhibitor in home decoration, so that formaldehyde pollution is commonly existing in indoor environment and has long latency time, the formaldehyde is a main control project in GB50325-2010 "civil construction engineering indoor environment control Specification", excessive formaldehyde in indoor air can harm human health, and the international cancer research institution of the world health organization has determined formaldehyde as a kind of cancerogenic substance. The problem of formaldehyde pollution in indoor air is getting more and more attention, and in order to distinguish whether the formaldehyde content in indoor air reaches the living standard, the formaldehyde content in indoor air needs to be measured.
In the existing technology for detecting formaldehyde content in indoor air, a phenol reagent method based on spectrophotometry is a common detection method, and is a detection method for formaldehyde content in indoor air specified in GB/T18883-2002 'indoor air quality standard', the basic principle is that formaldehyde in air reacts with a phenol reagent to generate oxazine, the oxazine is oxidized by ferric ions in an acid solution to form a blue-green compound, a chromogenic solution after color development is used for measuring absorbance by a spectrophotometer, and simultaneously, the absorbance of a formaldehyde standard solution series and a reagent blank solution is measured, a standard curve is drawn, and the concentration of formaldehyde in air is calculated. The phenol reagent method has simple operation, high sensitivity and low detection limit, and is suitable for measuring trace formaldehyde in indoor air.
However, in the prior art, a spectrophotometer is needed to be used for detecting the formaldehyde content in the air based on a phenol reagent method detected by the spectrophotometer, and the spectrophotometer is high in price and maintenance cost, so that the detection cost is high; in the prior art, a phenol reagent is used as an absorption liquid for collecting a gas sample, the stability of the phenol reagent is poor, the stability of an untreated sample at room temperature is poor, quantitative analysis is required to be performed within 24 hours, the stability of the sample after color development treatment at room temperature is poorer, quantitative analysis is required to be performed within shorter time, and because a spectrophotometer is not portable to a sampling site, colorimetric quantitative analysis is required to be performed in a laboratory, in actual operation, unavoidable factors such as time occupied by grouping sampling, transportation and handover of the sample and the like can cause that quantitative analysis cannot be performed within 24 hours after sampling, and the accuracy of a measurement result is affected.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides the method for measuring the formaldehyde content in the indoor air, which has the advantages of low detection cost, good stability of the processed sample, long-term storage, no influence on the accuracy of the measurement result due to untimely quantitative analysis of the sample and good accuracy of the measurement result.
The technical scheme for solving the technical problems is as follows:
A method for measuring formaldehyde content in indoor air comprises the following steps:
1) Sample collection: before sample collection, the room to be detected is sealed for 12 hours, a large bubble absorption tube filled with 5ml of absorption liquid is used for collecting 10L of room gas to be detected at the flow rate of 0.5L/min, and the temperature and the atmospheric pressure of a sampling point are recorded.
2) Sample treatment: the sample collection is carried out by transferring all the absorption liquid into a box, washing the absorption tube with a small amount of absorption liquid, merging to make the total volume 10ml, shaking for 10-20 seconds, adding 0.4ml of color-developing agent, shaking for 15-30 seconds to make the color-developing agent and the absorption liquid uniformly mixed, standing for 15 minutes at room temperature of 23+/-2 ℃ to obtain the color-developing liquid, placing the box into a small studio, turning over the box cover, standing for 30 seconds, adjusting the focal length of a camera to make the color-developing liquid in the box all shoot in a photo, and taking a photo of the color-developing condition of the color-developing liquid in the box, wherein the picture of the color-developing liquid accounts for 10% -30% of the whole photo area in the photo.
3) Drawing a standard curve: 10 mu g/ml of formaldehyde standard solution (10.00 ml) is put into a volumetric flask (100 ml), the volume is fixed to 100ml by using the absorption liquid, the same boxes as in the step 2) are taken, formaldehyde standard solution series with different concentrations are prepared by using the absorption liquid, and the total volume of each box is 10.00ml.
Adding 0.4ml of color developing agent into each box, shaking for 15-30 seconds to uniformly mix the color developing agent with formaldehyde standard solution, standing for 15 minutes at the room temperature of 23+/-2 ℃ to obtain color developing solution, keeping the shooting setting and shooting angle of the camera consistent with those of the step 3) in a small studio and a camera which are the same as those of the step 3), opening a box cover, standing for 30 seconds, adjusting the focal length of the camera to enable all the color developing solution in the box to be shot in the photo, wherein the picture of the color developing solution in the box accounts for 10% -30% of the whole photo area in the photo, thereby shooting the photo of the condition of color developing solution of formaldehyde standard solution series, and measuring the color saturation of the color developing solution in each photo by adopting software of the prior art.
And drawing a standard curve by taking formaldehyde content as an abscissa and saturation as an ordinate, calculating linear correlation coefficients and regression line slopes, and taking the inverse of the slopes as a calculation factor for sample measurement.
4) Sample measurement: and determining the color saturation of the color developing solution in the photo of the color developing condition of the sample color developing solution by adopting software in the prior art.
5) And (3) calculating results: and (3) converting the gas sampling volume of the sample in the step (1) into the gas sampling volume in a standard state, and calculating the mass concentration of formaldehyde in indoor air.
6) Preserving the negative film: the photo of the condition of the color development of the sample and the formaldehyde standard solution series color development liquid obtained by shooting is stored as a negative film by a photo storage device.
Preferably, the absorption liquid is 0.005% phenol reagent, the phenol reagent is 3-methyl-2-benzothiazolinone hydrazone hydrochloride hydrate, the molecular formula is C 8H12ClN3 OS, the absorption liquid is prepared immediately after sampling, and the preparation method of the absorption liquid is as follows: weighing 0.05g of phenol reagent, adding water for dissolution, pouring into a 50mL volumetric flask, adding water to a scale to prepare an absorption stock solution, measuring 5mL of the absorption stock solution, and adding 95mL of water to prepare the absorption solution.
Preferably, the box is a round box with a cover, the inner surface of the round box is pure white and opaque, the inner diameter of the box is 4.0cm, and the inner height of the box is 2.5cm.
Preferably, the color developing agent is a ferric ammonium sulfate solution with the concentration of 1%, the molecular formula of the ferric ammonium sulfate is NH 4Fe(SO4)2·12H2 O, and the preparation method of the ferric ammonium sulfate solution with the concentration of 1% comprises the following steps: 1.0g of ferric ammonium sulfate was weighed, dissolved with 0.1mol/L hydrochloric acid, and diluted to 100mL.
Preferably, the small studio is a stereoscopic studio, the length, the width and the height of the small studio are respectively 22cm, 23cm and 24cm, and the small studio comprises a back surface, a top surface, a bottom surface, a left side surface and a right side surface which are all pure white; the top surface comprises a circular opening with the diameter of 10cm and an LED lamp group arranged in the top surface, the circular opening is positioned in the middle of the top surface, and the LED lamp group is white light with the power of 3.5w and the color temperature of 6000 k; the middle of the bottom surface is provided with a circular marking with the diameter of 4.5cm, and the inside of the circular marking is the place where the box is placed.
Preferably, the camera is a mobile phone camera, and the mobile phone camera model: OPPO A37, specification: rear-mounted 800 ten thousand pixel cameras, performance: support full-automatic shooting mode, manufacturing unit: OPPO Guangdong Mobile communications Co.
Preferably, the camera shooting is set to a full-automatic shooting mode, and the photos are stored in a JPEG format.
Preferably, the shooting angle is that the camera lens is arranged at an opening of the top surface of the small shooting shed and faces the round box.
Preferably, the software in the prior art is program drawing software carried by a computer operating system of Windows XP or Windows7 series version, a photograph in a JPEG format is imported into the drawing software, the color saturation of a developing solution in the photograph is measured, and the color saturation of the developing solution in the photograph is the saturation of a circle center point of a circular developing solution area in the photograph measured by the software.
Preferably, the sample gas production volume is converted into a gas production volume formula under a standard state as follows: v 0=Vt ; Wherein V 0 is the gas production volume in the standard state, and the unit is L; v t is the actual gas production volume, and the unit is L; t is the air temperature of the sampling point, and the unit is the temperature; t 0 is the absolute temperature in the standard state, 273K; p is the atmospheric pressure of the sampling point, and the unit is kPa; p 0 is the atmospheric pressure in the standard state, 101kPa.
Preferably, the mass concentration of formaldehyde in the indoor air is calculated as follows: ρ=Wherein: ρ is the mass concentration of formaldehyde in air in mg/m 2; s is the color saturation of the color developing solution in the photo of the color developing condition of the sample color developing solution; b s is a calculation factor, and the unit is μg/saturation; v 0 is the gas production volume under the standard state, and the unit is L.
Preferably, in the present invention, the water used is deionized water, and the reagent used is of analytical purity.
Preferably, in the present invention, the linear correlation coefficient of the standard curve is not less than 0.995.
The beneficial effects of the invention are as follows:
1. The invention does not need expensive instruments, and the used instruments and equipment are simple, the price is low, the maintenance cost is low, and the detection cost is low.
2. The invention can firstly sample and process the sample on site, the processed sample can be stored in the form of pictures, the picture has good stability, the quantitative analysis is not needed immediately, the processed sample has good stability, the processed sample can be stored for a long time, the storage method is simple, the storage cost is low, the quantitative analysis is not limited by time, the accuracy of the measurement result is not influenced by the untimely quantitative analysis of the sample, the accuracy of the measurement result is good, and the sample stored for a long time has retest value.
Drawings
FIG. 1 is a standard curve drawn in example 1 of the present invention;
FIG. 2 is a standard curve drawn in example 2 of the present invention;
FIG. 3 is a standard curve drawn in example 3 of the present invention;
FIG. 4 is a schematic view of a small and medium-sized studio structure according to the present invention.
Detailed Description
The invention will be further illustrated by the following examples in conjunction with the accompanying drawings.
Example 1
The room to be detected is sealed for 12 hours before collection, and 10L of the room to be detected is collected by a large bubble absorption tube filled with 5ml of absorption liquid at the flow of 0.5L/min, and meanwhile, the indoor air temperature and the atmospheric pressure are recorded.
And (3) transferring all the absorption liquid into a round box with a cover after sample collection, washing the absorption tube with a small amount of the absorption liquid, combining to make the total volume be 10ml, oscillating for 10-20 seconds, adding 0.4ml of the color developing agent, oscillating for 15-30 seconds to uniformly mix the color developing agent and the absorption liquid, and standing for 15 minutes at the room temperature of 23+/-2 ℃ to obtain the color developing liquid.
The box is placed in a small studio, the box cover is turned over, the box cover is kept stand for 30 seconds, the camera shooting is set to be in a full-automatic shooting mode, the photo is stored in a JPEG format, as shown in the small studio in fig. 4, the camera lens is arranged at a circular opening 6 on the top surface 3 of the small studio and faces the box, the box is placed in a circular marking line 8 on the bottom surface 2 of the small studio, the focal length of the camera is adjusted to enable the color developing liquid in the box to be entirely shot in the photo, the picture of the color developing liquid in the box accounts for 10% of the whole picture area, and therefore the photo of the condition of color developing liquid is obtained, the photo is transmitted to a computer of a Windows XP operating system, the photo can be stored for a long time, and the accuracy of quantitative analysis and measurement results cannot be influenced by untimely analysis of samples.
10.00Ml of a formaldehyde standard solution of 10. Mu.g/ml was placed in a 100ml volumetric flask, the volume was fixed to 100ml with an absorbent, 9 capped round boxes of 4.0cm in inner diameter and 2.5cm in inner height were taken, and formaldehyde standard solution series were prepared according to Table a.
Table a Formaldehyde standard solution series
Adding 0.4ml of color reagent into each box, shaking for 15-30 seconds to uniformly mix the color reagent with formaldehyde standard solution, standing for 15 minutes at the room temperature of 23+/-2 ℃ to obtain color reagent, placing the box in a circular marking line 8 on the bottom surface 2 of a small studio, adopting the same camera as a shooting sample, keeping the shooting setting and shooting angle of the camera consistent with those of the sample, opening a box cover, standing for 30 seconds, adjusting the focal length of the camera to enable the color reagent in the box to be fully shot in a photo, wherein the picture of the color reagent in the box accounts for 10% of the whole photo area in the photo, thereby shooting the photo of the condition of color reagent color development of formaldehyde standard solution series, and transmitting the photo to a computer of a Windows XP operating system.
And (3) introducing the photo into program drawing software of a Windows XP computer operating system, measuring the saturation of the center point of a circular color development liquid area in the photo, and measuring to obtain the saturation of the formaldehyde standard solution series in the table b.
TABLE b saturation of Formaldehyde Standard solution series
Drawing a standard curve by taking formaldehyde content as an abscissa and saturation as an ordinate, and obtaining the standard curve as shown in fig. 1: s=66.64912x+12.5731, where x is formaldehyde content in μg; s is saturation; linear correlation coefficient: r 2 = 0.99867; the slope of the regression line is 66.64912, and the reciprocal of the slope of the regression line is calculated to obtain the calculation factor of sample measurement: b s = 0.015 μg/saturation.
And (3) measuring the color saturation of the color developing solution in the photo of the color developing condition of the sample color developing solution in accordance with the serial operation steps of the formaldehyde standard solution.
Converting the gas sampling volume of the sample into the gas sampling volume in a standard state: v 0=Vt ; Wherein V 0 is the gas production volume in the standard state, and the unit is L; v t is the actual gas production volume, and the unit is L; t is the air temperature of the sampling point, and the unit is the temperature; t 0 is the absolute temperature in the standard state, 273K; p is the atmospheric pressure of the sampling point, and the unit is kPa; p 0 is the atmospheric pressure in the standard state, 101kPa.
Calculating the mass concentration of formaldehyde in indoor air: ρ=Wherein: ρ is the mass concentration of formaldehyde in air in mg/m 2; s is the color saturation of the color developing solution in the photo of the color developing condition of the sample color developing solution; b s is a calculation factor, and the unit is μg/saturation; v 0 is the gas production volume under the standard state, and the unit is L.
Finally, the photo storage device stores the photo of the sample and the serial color development liquid of the formaldehyde standard solution as a negative film.
In this embodiment, the absorption liquid is 0.005% phenol reagent, the phenol reagent is 3-methyl-2-benzothiazolinone hydrazone hydrochloride hydrate, the molecular formula is C 8H12ClN3 OS, the absorption liquid is prepared immediately after sampling, and the preparation method of the absorption liquid is as follows: weighing 0.05g of phenol reagent, adding water for dissolution, pouring into a 50mL volumetric flask, adding water to a scale to prepare an absorption stock solution, measuring 5mL of the absorption stock solution, and adding 95mL of water to prepare the absorption solution.
In this embodiment, the box is a round box with a cover and a pure white inner surface, the inner diameter of the box is 4.0cm, and the inner height of the box is 2.5cm.
In this embodiment, the color developing agent is a 1% ferric ammonium sulfate solution, the molecular formula of the ferric ammonium sulfate is NH 4Fe(SO4)2·12H2 O, and the preparation method of the 1% ferric ammonium sulfate solution is as follows: 1.0g of ferric ammonium sulfate was weighed, dissolved with 0.1mol/L hydrochloric acid, and diluted to 100mL.
In this embodiment, as shown in fig. 4, the small studio is a stereoscopic studio, and the length, width and height of the small studio are 22cm, 23cm and 24cm respectively, and the small studio includes a back surface 1, a top surface 2, a bottom surface 3, a left side surface 4 and a right side surface 5, which are all pure white; the top surface 2 comprises a circular opening 6 with the diameter of 10cm and an LED lamp group 7 arranged in the top surface 2, the circular opening 6 is positioned in the middle of the top surface 2, and the LED lamp group 7 is white light with the power of 3.5w and the color temperature of 6000 k; the middle of the bottom surface 3 is provided with a circular marking line 8 with the diameter of 4.5cm, and the circular marking line 8 is arranged at the box placement position.
In this embodiment, the camera is a mobile phone camera, and the mobile phone camera model: OPPO A37, specification: rear-mounted 800 ten thousand pixel cameras, performance: support full-automatic shooting mode, manufacturing unit: OPPO Guangdong Mobile communications Co.
In this example, in the present invention, water used was deionized water, and the purity of the reagent used was analytical purity.
In this embodiment, when the saturation measured by the sample is greater than the standard curve range, the sample color developing solution may be diluted with the absorption solution and then measured and analyzed, and when the sample concentration is calculated, the mass concentration of the sample is calculated by multiplying the dilution multiple of the sample solution.
In this embodiment, when the linear correlation coefficient R 2 of the standard curve is less than 0.995, the standard curve is re-drawn.
Example 2
Example 2 differs from example 1 in that: a series of formaldehyde standard solutions consistent with the examples was prepared again; when a box containing a sample and a formaldehyde standard solution series color developing solution is shot, the focal length of a camera is adjusted to enable the color developing solution in the box to be shot in the photo, the picture of the color developing solution in the box accounts for 20% of the whole picture area in the photo, so that the picture of the color developing condition of the color developing solution is shot, the picture is transmitted to a computer of a Windows 7 operating system, program drawing software carried by the Windows 7 computer operating system is adopted, the picture is imported into the software, the saturation of the center point of a circular color developing solution area in the picture is measured, the saturation of the sample is measured, and the saturation of the formaldehyde standard solution series in the table c is measured.
Table c saturation of Formaldehyde Standard solution series
Drawing a standard curve with formaldehyde content as an abscissa and saturation as an ordinate, and obtaining the standard curve as shown in fig. 2: s=64.947368x+13.38596, where x is formaldehyde content in μg; s is saturation; linear correlation coefficient: r 2 = 0.99949; the slope of the regression line is 64.947368, and the reciprocal of the slope of the regression line is calculated to obtain the calculation factor of sample measurement: b s = 0.0154 μg/saturation.
Converting the gas sampling volume of the sample into the gas sampling volume in a standard state: v 0=Vt ; Wherein V 0 is the gas production volume in the standard state, and the unit is L; v t is the actual gas production volume, and the unit is L; t is the air temperature of the sampling point, and the unit is the temperature; t 0 is the absolute temperature in the standard state, 273K; p is the atmospheric pressure of the sampling point, and the unit is kPa; p 0 is the atmospheric pressure in the standard state, 101kPa.
Calculating the mass concentration of formaldehyde in indoor air: ρ=Wherein: ρ is the mass concentration of formaldehyde in air in mg/m 2; s is the color saturation of the color developing solution in the photo of the color developing condition of the sample color developing solution; b s is a calculation factor, and the unit is μg/saturation; v 0 is the gas production volume under the standard state, and the unit is L.
Example 3
Example 2 differs from example 1 in that: a series of formaldehyde standard solutions consistent with the examples was prepared again; when a box containing a sample and a formaldehyde standard solution series color developing solution is shot, the focal length of a camera is adjusted to enable the color developing solution in the box to be shot in a photo, the picture of the color developing solution in the box accounts for 30% of the whole picture area in the photo, so that a picture of the color developing condition of the color developing solution is shot, the picture is transmitted to a computer of a Windows XP operating system, program drawing software of the Windows XP computer operating system is adopted, the picture is imported into the software, the saturation of the sample is measured, and the saturation of the formaldehyde standard solution series in the table d is measured.
Table d saturation of Formaldehyde Standard solution series
Drawing a standard curve by taking formaldehyde content as an abscissa and saturation as an ordinate, and obtaining the standard curve as shown in fig. 3: s=66.4736x+12.0818, where x is formaldehyde content in μg; s is saturation; linear correlation coefficient: r 2 = 0.99658; the slope of the regression line is 66.4736, and the reciprocal of the slope of the regression line is calculated to obtain the calculation factor of sample measurement: bs=0.015 μg/saturation.
Converting the gas sampling volume of the sample into the gas sampling volume in a standard state: v 0=Vt ; Wherein V 0 is the gas production volume in the standard state, and the unit is L; v t is the actual gas production volume, and the unit is L; t is the air temperature of the sampling point, and the unit is the temperature; t 0 is the absolute temperature in the standard state, 273K; p is the atmospheric pressure of the sampling point, and the unit is kPa; p 0 is the atmospheric pressure in the standard state, 101kPa.
Calculating the mass concentration of formaldehyde in indoor air: ρ=Wherein: ρ is the mass concentration of formaldehyde in air in mg/m 2; s is the color saturation of the color developing solution in the photo of the color developing condition of the sample color developing solution; b s is a calculation factor, and the unit is μg/saturation; v 0 is the gas production volume under the standard state, and the unit is L.
The foregoing embodiments are merely illustrative of the principles and functions of the present invention, and thus are not intended to limit the scope of the invention, which is defined by the appended claims. Accordingly, equivalent modifications and variations are intended to be included within the scope of this disclosure, as defined in the claims and the following description.
Claims (10)
1. A method for measuring formaldehyde content in indoor air is characterized by comprising the following steps: the method comprises the following steps:
1) Sample collection: sealing the room to be detected for 12 hours before sample collection, collecting 10L of gas in the room to be detected at the flow rate of 0.5L/min by using a large bubble absorption tube filled with 5ml of absorption liquid, and simultaneously recording the air temperature and the atmospheric pressure of a sampling point;
2) Sample treatment: the sample collection is carried out, the absorption liquid is completely transferred into a box, a small amount of absorption liquid is used for washing an absorption tube, the total volume is 10ml, shaking is carried out for 10-20 seconds, then 0.4ml of color developing agent is added, shaking is carried out for 15-30 seconds, the color developing agent and the absorption liquid are uniformly mixed, standing is carried out for 15 minutes at the room temperature of 23+/-2 ℃ to obtain color developing liquid, the box is placed in a small studio, a box cover is turned over, standing is carried out for 30 seconds, the focal length of a camera is adjusted, the color developing liquid in the box is completely shot in a photo, and the picture of the color developing liquid in the box accounts for 10% -30% of the area of the whole photo, so that the photo of the color developing condition of the color developing liquid is obtained;
3) Drawing a standard curve: 10 mu g/ml formaldehyde standard solution 10.00ml is put into a volumetric flask of 100ml, the volume is fixed to 100ml by using the absorption liquid, the same boxes as in the step 2) are taken, formaldehyde standard solution series with different concentrations are prepared by using the absorption liquid, and the total volume of each box is 10.00ml;
Adding 0.4ml of color developing agent into each box, shaking for 15-30 seconds to uniformly mix the color developing agent with formaldehyde standard solution, standing for 15 minutes at the room temperature of 23+/-2 ℃ to obtain color developing solution, keeping the shooting setting and shooting angle of the camera consistent with those of the step 3) in a small studio and a camera which are the same as those of the step 3), opening a box cover, standing for 30 seconds, adjusting the focal length of the camera to enable all the color developing solution in the box to be shot in a photo, wherein the picture of the color developing solution in the box accounts for 10% -30% of the whole photo area in the photo, thereby shooting a photo of the condition that the formaldehyde standard solution series color developing solution is developed, and measuring the color saturation of the color developing solution in each photo by adopting software of the prior art;
Drawing a standard curve by taking formaldehyde content as an abscissa and saturation as an ordinate, calculating linear correlation coefficients and regression line slopes, and taking the inverse of the slopes as a calculation factor for sample measurement;
4) Sample measurement: determining the color saturation of the color developing solution in the photo under the condition of color development of the sample color developing solution by adopting software in the prior art;
5) And (3) calculating results: converting the gas sampling volume of the sample in the step 1) into the gas sampling volume in a standard state, and calculating the mass concentration of formaldehyde in indoor air;
6) Preserving the negative film: the photo of the condition of the color development of the sample and the formaldehyde standard solution series color development liquid obtained by shooting is stored as a negative film by a photo storage device.
2. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: the absorption liquid is 0.005% of phenol reagent, the phenol reagent is 3-methyl-2-benzothiazolinone hydrazone hydrochloride hydrate, the molecular formula is C 8H12ClN3 OS, the absorption liquid is prepared immediately when being sampled, and the preparation method of the absorption liquid is as follows: weighing 0.05g of phenol reagent, adding water for dissolution, pouring into a 50mL volumetric flask, adding water to a scale to prepare an absorption stock solution, measuring 5mL of the absorption stock solution, and adding 95mL of water to prepare the absorption solution.
3. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: the box is a round box with a cover, the inner surface of the round box is pure white and opaque, the inner diameter of the box is 4.0cm, and the inner height of the box is 2.5cm.
4. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: the color reagent is ferric ammonium sulfate solution with the concentration of 1%, the molecular formula of the ferric ammonium sulfate is NH 4Fe(SO4)2·12H2 O, and the preparation method of the ferric ammonium sulfate solution with the concentration of 1% comprises the following steps: 1.0g of ferric ammonium sulfate was weighed, dissolved with 0.1mol/L hydrochloric acid, and diluted to 100mL.
5. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: the small studio is a stereoscopic studio, and the length, the width and the height of the small studio are respectively 22cm, 23cm and 24cm, and the small studio comprises a back surface (1), a top surface (2), a bottom surface (3), a left side surface (4) and a right side surface (5) which are all pure white; the top surface (2) comprises a circular opening (6) with the diameter of 10cm, an LED lamp group (7) is arranged in the top surface (2), the circular opening (6) is positioned in the middle of the top surface (2), and the LED lamp group (7) is white light with the power of 3.5w and the color temperature of 6000 k; the middle of the bottom surface (3) is provided with a circular marking line (8) with the diameter of 4.5cm, and the circular marking line (8) is arranged at the box placement position.
6. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: the shooting angle is that a camera lens is arranged at a round opening (6) of the top surface (2) of the small shooting shed and faces the box.
7. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: the prior art software is program drawing software of a computer operating system with Windows XP or Windows7 series version, a photograph in a JPEG format is imported into the drawing software, and the color saturation of a developing solution in the photograph is measured.
8. The method for measuring formaldehyde content in indoor air according to claim 7, wherein the method comprises the following steps: the color saturation of the color developing liquid in the photo is the saturation of the center point of the circular color developing liquid area in the photo measured by software.
9. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: the mass concentration calculation formula of formaldehyde in indoor air is: ρ=Wherein: ρ is the mass concentration of formaldehyde in air in mg/m w; s is the color saturation of the color developing solution in the photo of the color developing condition of the sample color developing solution; b s is a calculation factor, and is in μg/saturation; v 0 is the gas production volume in standard state, unit L.
10. The method for measuring formaldehyde content in indoor air according to claim 1, wherein the method comprises the following steps: in the present invention, the water used was deionized water, and the purity of the reagents used was analytical purity.
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