CN108267421A - The detection method and detecting system of melamine in a kind of milk powder - Google Patents
The detection method and detecting system of melamine in a kind of milk powder Download PDFInfo
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- CN108267421A CN108267421A CN201711488103.7A CN201711488103A CN108267421A CN 108267421 A CN108267421 A CN 108267421A CN 201711488103 A CN201711488103 A CN 201711488103A CN 108267421 A CN108267421 A CN 108267421A
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- terahertz
- reflectance spectrum
- powdered milk
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- 229920000877 Melamine resin Polymers 0.000 title claims abstract description 82
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 title claims abstract description 81
- 238000001514 detection method Methods 0.000 title claims abstract description 74
- 239000000843 powder Substances 0.000 title claims abstract description 44
- 235000013336 milk Nutrition 0.000 title claims abstract description 40
- 239000008267 milk Substances 0.000 title claims abstract description 40
- 210000004080 milk Anatomy 0.000 title claims abstract description 40
- 235000008476 powdered milk Nutrition 0.000 claims abstract description 123
- 238000000985 reflectance spectrum Methods 0.000 claims abstract description 116
- 238000000862 absorption spectrum Methods 0.000 claims abstract description 46
- 238000000034 method Methods 0.000 claims abstract description 22
- 230000009466 transformation Effects 0.000 claims abstract description 16
- 238000010521 absorption reaction Methods 0.000 claims description 54
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 18
- 238000001228 spectrum Methods 0.000 claims description 13
- 229910052757 nitrogen Inorganic materials 0.000 claims description 9
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical compound NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 claims description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 4
- -1 polyethylene Polymers 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- 239000004698 Polyethylene Substances 0.000 claims description 3
- 230000005611 electricity Effects 0.000 claims description 3
- 229920000573 polyethylene Polymers 0.000 claims description 3
- 238000002347 injection Methods 0.000 claims 1
- 239000007924 injection Substances 0.000 claims 1
- 238000005259 measurement Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 13
- 235000013305 food Nutrition 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- 238000012545 processing Methods 0.000 description 3
- 238000001328 terahertz time-domain spectroscopy Methods 0.000 description 3
- 241000208340 Araliaceae Species 0.000 description 1
- 235000005035 Panax pseudoginseng ssp. pseudoginseng Nutrition 0.000 description 1
- 235000003140 Panax quinquefolius Nutrition 0.000 description 1
- 125000004429 atom Chemical group 0.000 description 1
- 238000005102 attenuated total reflection Methods 0.000 description 1
- 230000006854 communication Effects 0.000 description 1
- 238000000205 computational method Methods 0.000 description 1
- 235000013365 dairy product Nutrition 0.000 description 1
- 235000013399 edible fruits Nutrition 0.000 description 1
- 238000000132 electrospray ionisation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 210000003608 fece Anatomy 0.000 description 1
- 235000021393 food security Nutrition 0.000 description 1
- 238000002290 gas chromatography-mass spectrometry Methods 0.000 description 1
- 235000008434 ginseng Nutrition 0.000 description 1
- 229920001903 high density polyethylene Polymers 0.000 description 1
- 238000004128 high performance liquid chromatography Methods 0.000 description 1
- 239000004700 high-density polyethylene Substances 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000001294 liquid chromatography-tandem mass spectrometry Methods 0.000 description 1
- 150000007974 melamines Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 125000004433 nitrogen atom Chemical group N* 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 102000004169 proteins and genes Human genes 0.000 description 1
- 108090000623 proteins and genes Proteins 0.000 description 1
- 238000004885 tandem mass spectrometry Methods 0.000 description 1
Classifications
-
- 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
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3581—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation
- G01N21/3586—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light using far infrared light; using Terahertz radiation by Terahertz time domain spectroscopy [THz-TDS]
-
- 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
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
- G01N21/35—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light
- G01N21/3563—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry using infrared light for analysing solids; Preparation of samples therefor
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- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Toxicology (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
The present invention relates to a kind of detection methods of melamine in milk powder.This method includes：Standard sample is tested using the electromagnetic wave in default Terahertz frequency range, obtains normal clock domain Terahertz reflectance spectrum；Normal clock domain Terahertz reflectance spectrum is subjected to Fourier transformation, obtains standard frequency domain Terahertz reflectance spectrum；Powdered milk sample to be measured is tested using the electromagnetic wave in default Terahertz frequency range, obtains detection time domain Terahertz reflectance spectrum；Detection time domain Terahertz reflectance spectrum is subjected to Fourier transformation, obtains detection frequency domain Terahertz reflectance spectrum；According to standard frequency domain Terahertz reflectance spectrum and detection frequency domain Terahertz reflectance spectrum, absorption spectrum of the powdered milk sample to be measured to the electromagnetic wave of Terahertz frequency range is calculated；Judge whether contain melamine in powdered milk sample to be measured according to absorption spectrum.The invention further relates to a kind of detecting systems of melamine in milk powder.The above method and system are easy to detect, quick.
Description
Technical field
The present invention relates to technical field of food safety, the detection method of melamine and detection in more particularly to a kind of milk powder
System.
Background technology
The protein content of measure food is usually needed in food industry.It is relatively more multiple on DNA techniques due to directly measuring
It is miscellaneous, so commonly using a kind of method for being called Kjeldahl's method, albumen in food is calculated indirectly by measuring the content of nitrogen-atoms
The content of matter.Since melamine (nitrogen content 66%) contains higher proportion of nitrogen compared with protein (average nitrogen content 16%)
Atom so often being utilized by some fake producers, adds the illusion to cause content in food higher in dairy produce, so as to
Cause serious food security accident.
At present, the detection method of melamine is numerous in milk powder and has higher accuracy of detection, such as high performance liquid chromatography
Method, combined gas chromatography mass spectrometry, ultra performance liquid chromatography-Rat Feces by Electrospray Ionization Tandem Mass Spectrometry, liquid chromatography tandem mass spectrometry etc..But
It is that these detection methods are complicated, cause detection time longer, are not easy to field quick detection.
Invention content
Based on this, it is necessary to it is complex for the detection method of current melamine, it is not easy to field quick detection
The problem of, the detection method and detecting system of melamine in a kind of milk powder are provided.
The detection method of melamine in a kind of milk powder, for detecting whether powdered milk sample to be measured contains three on monitor station
Poly cyanamid, standard sample and the powdered milk sample to be measured are placed on the loading surface of the monitor station；The method includes：
Standard sample is tested using the electromagnetic wave of default Terahertz frequency range, obtains normal clock domain Terahertz reflected light
Spectrum；Wherein, the standard sample does not absorb the electromagnetic wave, and the normal clock domain Terahertz reflectance spectrum is in the detection
The electromagnetic wave incident is to the loading surface and the reflectance spectrum that is totally reflected in the loading surface in platform；
The normal clock domain Terahertz reflectance spectrum is subjected to Fourier transformation, obtains standard frequency domain Terahertz reflected light
Spectrum；
The powdered milk sample to be measured is tested using the electromagnetic wave of the default Terahertz frequency range, obtains detection time domain
Terahertz reflectance spectrum；Wherein, the detection time domain Terahertz reflectance spectrum is the electromagnetic wave incident in the monitor station
The extremely loading surface and the reflectance spectrum being totally reflected in the loading surface；
The detection time domain Terahertz reflectance spectrum is subjected to Fourier transformation, obtains detection frequency domain Terahertz reflected light
Spectrum；
According to the standard frequency domain Terahertz reflectance spectrum and the detection frequency domain Terahertz reflectance spectrum, milk to be measured is calculated
Powder sample is to the absorption spectrum of the electromagnetic wave of the default Terahertz frequency range；
Judge whether contain melamine in the powdered milk sample to be measured according to the absorption spectrum.
Absorption of the powdered milk sample to be measured to the electromagnetic wave of the default Terahertz frequency range in one of the embodiments,
Coefficient reflects the absorption spectrum of powdered milk sample to be measured；
According to the standard frequency domain Terahertz reflectance spectrum and the detection frequency domain Terahertz reflectance spectrum, institute is calculated
The expression formula for stating the absorption coefficient of powdered milk sample to be measured is：
Wherein, ω be the preset Terahertz frequency range electromagnetic wave angular frequency, Er (ω) for the standard frequency domain too
Hertz reflectance spectrum energy, Es (ω) are the detection frequency domain Terahertz reflectance spectrum energy.
It is described in one of the embodiments, to judge whether contain in the powdered milk sample to be measured according to the absorption spectrum
Include after the step of melamine：
When containing melamine in the powdered milk sample to be measured, the milk powder sample to be measured is obtained from the absorption spectrum
Product are to the characteristic absorption frequency of the electromagnetic wave of Terahertz frequency range.
It is described in one of the embodiments, to be additionally operable to detect the three of the powdered milk sample to be measured according to reference to powdered milk sample
Poly cyanamid；The type with reference to powdered milk sample is N kinds, and the concentration of each described melamine with reference in powdered milk sample is each
It differs；Wherein N is positive integer；
The method further includes step：
Each electromagnetic wave that the default Terahertz frequency range is utilized respectively with reference to powdered milk sample is tested, is joined
Examine frequency domain Terahertz reflectance spectrum；Wherein, the reference frequency domain Terahertz reflectance spectrum is the electromagnetism in the monitor station
Wave is incident to the loading surface and the reflectance spectrum being totally reflected in the loading surface；
Frequency domain Terahertz reflectance spectrum and the standard frequency domain Terahertz reflectance spectrum are referred to according to described, is calculated each described
With reference to the reference absorption spectrum of powdered milk sample；
Each reference powdered milk sample is obtained at the characteristic absorption frequency to too according to each reference absorption spectrum
The absorption coefficient of the electromagnetic wave of hertz frequency range；
The concentration of melamine and absorption coefficient in milk powder are established according to each absorption coefficient with reference to powdered milk sample
Functional relation, to calculate the concentration of melamine in the powdered milk sample to be measured according to absorption coefficient.
The electromagnetic wave using in default Terahertz frequency range surveys standard sample in one of the embodiments,
Include before the step of trying, obtaining normal clock domain Terahertz reflectance spectrum：
Steam in environment where the monitor station is all discharged.
The step of steam in the environment by where the monitor station is all discharged in one of the embodiments, is wrapped
It includes：
Nitrogen will be full of in environment where the monitor station, so that the relative humidity of the environment where the monitor station is small
In 2%.
The standard sample is polyethylene powders in one of the embodiments,.
The detecting system of melamine in a kind of milk powder, for detecting whether powdered milk sample to be measured contains melamine；Institute
It states detecting system and includes monitor station, Terahertz generating means, Terahertz reception device and processor；
The monitor station includes loading surface, and the loading surface is used to place standard sample and the powdered milk sample to be measured；
The Terahertz generating means is used to generate the electromagnetic wave of preset Terahertz frequency range, and the electromagnetic wave is injected
In the monitor station, the electromagnetic wave incident is made to be totally reflected to the loading surface and in the loading surface；The loading surface
On when being placed as the standard sample, the reflectance spectrum reflected from the loading surface is normal clock domain Terahertz reflectance spectrum；Institute
It states when powdered milk sample to be measured is placed as on loading surface, is detection time domain Terahertz reflection from the reflectance spectrum that the loading surface reflects
Spectrum；
The Terahertz reception device is used to receive the normal clock domain Terahertz reflectance spectrum and the detection time domain too
Hertz reflectance spectrum；
The processor is used to the normal clock domain Terahertz reflectance spectrum carrying out Fourier transformation, obtains standard frequency domain
Terahertz reflectance spectrum；The processor is additionally operable to the detection time domain Terahertz reflectance spectrum carrying out Fourier transformation, obtains
To detection frequency domain Terahertz reflectance spectrum；The processor be additionally operable to according to the standard frequency domain Terahertz reflectance spectrum with it is described
Frequency domain Terahertz reflectance spectrum is detected, calculates absorption light of the powdered milk sample to be measured to the electromagnetic wave of preset Terahertz frequency range
Spectrum, and judge whether contain melamine in the powdered milk sample to be measured according to the absorption spectrum.
The processor is additionally operable to contain melamine in the powdered milk sample to be measured in one of the embodiments,
When, characteristic absorption of the powdered milk sample to be measured to the electromagnetic wave of the default Terahertz frequency range is obtained from the absorption spectrum
Frequency.
The monitor station is made of silicon wafer in one of the embodiments,.
The detection method and detecting system of melamine, detect the melamine pair in powdered milk sample to be measured in above-mentioned milk powder
The detection frequency domain Terahertz reflectance spectrum of the electromagnetic wave of Terahertz frequency range, and with standard sample to the electromagnetic wave of Terahertz frequency range
Standard frequency domain Terahertz reflectance spectrum is the absorption spectrum to the electromagnetic wave of Terahertz frequency range with reference to calculating powdered milk sample to be measured, from
It can judge whether contain melamine in powdered milk sample to be measured in absorption spectrum.In this way, it is utilized in powdered milk sample to be measured
Melamine detects melamine to the method for the absorption of the electromagnetic wave of Terahertz frequency range, does not need to do volume to powdered milk sample to be measured
Outer processing is easy to detect, quick.
Description of the drawings
Fig. 1 is the schematic diagram of the monitor station 100 of an embodiment；
Flow diagrams of the Fig. 2 for the detection method of melamine in the milk powder of first embodiment；
Fig. 3 is the absorption spectrum schematic diagram of the powdered milk sample to be measured of the embodiment according to Fig. 2；
Fig. 4 is milk powder to be measured the showing to the spectrum without absorption of the electromagnetic wave of Terahertz frequency range of the embodiment according to Fig. 2
It is intended to；
Flow diagrams of the Fig. 5 for the detection method of melamine in the milk powder of second embodiment；
Fig. 6 is the present embodiment respectively with reference to the schematic diagram of the absorption spectrum of powdered milk sample；
Fig. 7 is according to the straight line schematic diagram respectively fitted in Fig. 6 with reference to the concentration of powdered milk sample with absorption coefficient.
Specific embodiment
In order to make the foregoing objectives, features and advantages of the present invention clearer and more comprehensible, below in conjunction with the accompanying drawings to the present invention
Specific embodiment be described in detail.
The detection method of melamine in a kind of milk powder, need to use standard sample be used as with reference to come detect in milk powder whether
Contain melamine.
Fig. 1 is the schematic diagram of the monitor station 100 of an embodiment.In present embodiment, the above method can be applied to milk powder
In the detecting system of middle melamine, to be detected to powdered milk sample 200 to be measured.The detecting system can be attenuation total reflection
(Attenuated Total Reflection, ATR) formula terahertz time-domain spectroscopy system.Below to ATR formula terahertz time-domain light
Spectra system is introduced.As shown in Figure 1, monitor station 100, the present embodiment are provided in milk powder in the detecting system of melamine
In, standard sample and powdered milk sample to be measured are placed on the monitor station 100 of monitor station 100 and detected.With powdered milk sample to be measured in Fig. 1
For 200 are placed on monitor station 100.Standard sample is free of melamine, therefore standard sample does not absorb Terahertz frequency range
Electromagnetic wave.If there is melamine in powdered milk sample 200 to be measured, the electromagnetic wave of Terahertz frequency range can be absorbed.
In the present embodiment, the shape of monitor station 100 is triangular prism.Monitor station 100 include loading surface 110, standard sample or
Powdered milk sample to be measured is placed on loading surface 110.The section of monitor station 100 is triangular in shape, the detection where the base of triangle
The face of platform 100 is loading surface 110.Triangle can be right angled triangle.Monitor station 100 is made of silicon wafer.It standard sample and treats
Surveying powdered milk sample and loading surface 110 has good optical contact.To ensure the accuracy of detection.
Electromagnetic wave 300 in default Terahertz frequency range is in monitor station 100 from loading surface 110 away from standard sample or to be measured
The direction of powdered milk sample is incident to loading surface 110, and is reflected in loading surface 110, which is theoretic total reflection.
In the present embodiment, it is as follows to preset communication process of the electromagnetic wave 300 of Terahertz frequency range inside monitor station 100：Default Terahertz
The electromagnetic wave 300 (hereinafter referred electromagnetic wave) of frequency range is incident in monitor station 100 from the one side of monitor station 100 to electromagnetic wave
Incidence angle in the side of monitor station 100 is 90 degree.For electromagnetic wave incident to loading surface 110, the value of incidence angle θ, θ are 45 °.θ
Value it is without being limited thereto, or other numerical value, such as 35 °.Electromagnetic wave reaches loading surface 110 and reflects, this is reflected into reason
By upper total reflection.But during practical paths, because containing melamine in milk powder to be measured, electromagnetic wave is by loading
Face 110 also has part electromagnetic wave to be absorbed by the melamine in the powdered milk sample to be measured on loading surface 110 when reflecting, i.e., by loading
The energy for the electromagnetic wave that face 110 is reflected is less than the energy for the electromagnetic wave for being incident to loading surface 110.The electricity reflected by loading surface 110
Magnetic wave reflects monitor station 100 from the another side of monitor station 100, in order to other portions of terahertz time-domain spectroscopy detecting system
Part detects reflectance spectrum.Standard sample is consistent with the detection environment of powdered milk sample to be measured.
Flow diagrams of the Fig. 2 for the detection method of melamine in the milk powder of first embodiment.Fig. 3 is according to Fig. 2's
The absorption spectrum schematic diagram of the powdered milk sample to be measured of embodiment.Fig. 4 is the milk powder to be measured of the embodiment according to Fig. 2 to Terahertz frequency
The schematic diagram of the spectrum without absorption of the electromagnetic wave of section.
Above-mentioned detection method includes：
Step S110 tests standard sample using the electromagnetic wave in default Terahertz frequency range, obtains normal clock domain
Terahertz reflectance spectrum.
Specifically, preset standard sample is placed on monitor station, the electromagnetic wave for presetting Terahertz frequency range is effective bandwidth
The electromagnetic wave of 0-2.5THz ranges.Since standard sample is without melamine, standard sample does not absorb Terahertz frequency range
Electromagnetic wave, the light energy in the distribution of standard frequency domain Terahertz reflectance spectrum are the functions of wave frequency.Standard sample can be
Polyethylene powders, and be high-density polyethylene powder, ensure that standard sample does not absorb the electromagnetic wave of Terahertz frequency range.It needs
Bright, standard sample can also be vacuum, i.e., there is nothing in the sample bin of monitor station 100.Normal clock domain Terahertz
Reflectance spectrum is the reflectance spectrum that electromagnetic wave incident is totally reflected to loading surface and in loading surface in monitor station.The present embodiment
In, it is assumed that the light energy of normal clock domain Terahertz reflectance spectrum is Er (t).Due to standard sample not electromagnetic wave absorption, so mark
The light energy of punctual domain Terahertz reflectance spectrum is to reflect the light energy for being incident to loading surface 110.
In one embodiment, standard sample is tested using the electromagnetic wave in default Terahertz frequency range, when obtaining standard
Include before the step of domain Terahertz reflectance spectrum, i.e. step S110：
Steam in environment where monitor station is all discharged.
Specifically, steam can be to the electro-magnetic wave absorption of Terahertz frequency range.It therefore, will be in the environment where monitor station 100
Steam is all discharged, i.e., standard sample and powdered milk sample to be measured is placed in dry environment and are detected, to ensure detection knot
The accuracy of fruit.
In one embodiment, nitrogen can will be full of in the environment where monitor station, so that the phase of the environment where monitor station
2% is less than to humidity.
Specifically, nitrogen is inert gas, and therefore, nitrogen will not absorb the electromagnetic wave of Terahertz frequency range.It also, will detection
Air can be discharged, all be discharged together with the steam in air so that in detection environment full of nitrogen in environment where platform
Aridity it is preferable, and humidity be less than 2% so that testing result is accurate.
Normal clock domain Terahertz reflectance spectrum is carried out Fourier transformation, it is anti-to obtain standard frequency domain Terahertz by step S120
Penetrate spectrum.
Specifically, if the angular frequency of the electromagnetic wave of Terahertz frequency range is ω, then the formula of Fourier transformation is carried out to Er (t)
It is as follows：
Er (ω)=∫ Er (t) exp (- i ω t) dt (1)
That is the standard frequency domain Terahertz reflectance spectrum of standard sample is：
In formula (1) and formula (2), ω is the angular frequency of the electromagnetic wave of Terahertz frequency range, and in formula (2), Ar (ω) is
The amplitude of the standard frequency domain Terahertz back wave of standard sample；Phase for standard frequency domain Terahertz back wave.
Step S130 tests powdered milk sample to be measured using the electromagnetic wave in default Terahertz frequency range, is detected
Time domain Terahertz reflectance spectrum.
Specifically, standard sample from monitor station is removed, powdered milk sample to be measured is placed on monitor station.Detect frequency domain too
Hertz reflectance spectrum distribution is the function of wave frequency.It is that electromagnetic wave enters in monitor station to detect time domain Terahertz reflectance spectrum
It is incident upon loading surface and the reflectance spectrum being totally reflected in loading surface.The detection environment phase of standard sample and powdered milk sample to be measured
Together.It has been observed that the frequency of electromagnetic wave can be angular frequency.Assuming that the luminous energy of the time domain Terahertz reflectance spectrum of powdered milk sample to be measured
It measures as Es (t).
Detection time domain Terahertz reflectance spectrum is carried out Fourier transformation, it is anti-to obtain detection frequency domain Terahertz by step S140
Penetrate spectrum.
Specifically, if the angular frequency of the electromagnetic wave of Terahertz frequency range is ω, then the formula of Fourier transformation is carried out to Er (t)
It is as follows：
Es (ω)=∫ Es (t) exp (- i ω t) dt (3)
The detection frequency domain Terahertz reflectance spectrum of powdered milk sample i.e. to be measured is：
In formula (4), the amplitude of the frequency domain Terahertz back wave of As (ω) powdered milk sample to be measured；For detection frequency domain too
The phase of hertz back wave.
Step S150 according to standard frequency domain Terahertz reflectance spectrum and detection frequency domain Terahertz reflectance spectrum, is calculated to be measured
Powdered milk sample is to the absorption spectrum of the electromagnetic wave of preset Terahertz frequency range.
Specifically, powdered milk sample to be measured reflects powdered milk sample to be measured to the absorption coefficient for presetting the electromagnetic wave of Terahertz frequency range
Absorption spectrum.I.e. absorption spectrum can with powdered milk sample to be measured to melamine to the absorption system of the electromagnetic wave of Terahertz frequency range
It counts to characterize.Absorption coefficient, that is, powdered milk sample to be measured is to the proportionate relationship of the absorption of the electromagnetic wave of Terahertz frequency range.By standard frequency
The light energy Er (ω) of domain Terahertz reflectance spectrum and detect frequency domain Terahertz reflectance spectrum light energy Es (ω) can with
To between absorption coefficient and angular frequency have specific functional relation.The computational methods of absorption coefficient are as follows：
Step S160 judges whether contain melamine in powdered milk sample to be measured according to absorption spectrum.
Specifically, judge whether have absorption peak frequency i.e. (characteristic absorption frequency) that can judge milk to be measured in absorption spectrum
Whether there is melamine in powder sample.As shown in figure 3, there is the electricity to Terahertz frequency range in the absorption spectrum of powdered milk sample to be measured
The absorption of magnetic wave, you can judge that there are melamines in powdered milk sample to be measured.Powdered milk sample i.e. to be measured is unqualified.Have in milk to be measured
When containing melamine in powder sample, staff or processor can obtain powdered milk sample to be measured to too from absorption spectrum
The characteristic absorption frequency of the electromagnetic wave of hertz frequency range.Melamine can be obtained from Fig. 3 to the electromagnetic wave of Terahertz frequency range
Characteristic absorption frequency is 1.98THz and 2.24THz.I.e. the milk powder added with melamine occurs at 1.98THz and 2.24THz
Apparent Terahertz absorption peak.Do not occur apparent Terahertz absorption peak, i.e., powdered milk sample to be measured in Fig. 4, in absorption spectrum
In do not contain melamine.
The detection method of melamine in above-mentioned milk powder detects the melamine in powdered milk sample to be measured to Terahertz frequency range
Electromagnetic wave detection frequency domain Terahertz reflectance spectrum, and with standard sample to the standard frequency domain of the electromagnetic wave of Terahertz frequency range too
Hertz reflectance spectrum is the absorption spectrum to the electromagnetic wave of Terahertz frequency range with reference to calculating powdered milk sample to be measured, from absorption spectrum
Can judge whether contain melamine in powdered milk sample to be measured.In this way, the melamine pair in powdered milk sample to be measured is utilized
The method detection melamine of the absorption of the electromagnetic wave of Terahertz frequency range, does not need to do powdered milk sample to be measured additional processing,
It is easy to detect, quick.
Flow diagrams of the Fig. 5 for the detection method of melamine in the milk powder of second embodiment.Fig. 6 is the present embodiment
Respectively with reference to the schematic diagram of the absorption spectrum of powdered milk sample.Fig. 7 is according to the concentration and absorption coefficient that powdered milk sample is respectively referred in Fig. 6
The straight line schematic diagram fitted.
In the present embodiment, the type of powdered milk sample to be measured is N kinds, each is dense with reference to the melamine in powdered milk sample
Spend different, N is positive integer.In the present embodiment, N is equal to 5.Assuming that 5 kinds of concentration point with reference to melamine in powdered milk sample
It Wei 1%, 5%, 9%, 13%, 21%.
As shown in figure 5, the detection method of melamine further includes in milk powder：
Step S210 tests each electromagnetic wave being utilized respectively in default Terahertz frequency range with reference to powdered milk sample, obtains
To with reference to frequency domain Terahertz reflectance spectrum.
Specifically, each electromagnetic wave being utilized respectively in default Terahertz frequency range with reference to powdered milk sample is tested, obtained
With reference to frequency domain Terahertz reflectance spectrum.It is to be incident to loading surface simultaneously in monitor station electromagnetic wave with reference to frequency domain Terahertz reflectance spectrum
In the reflectance spectrum that loading surface is totally reflected.Method specifically can refer to step S130, step S140.
Step S220 according to frequency domain Terahertz reflectance spectrum and standard frequency domain Terahertz reflectance spectrum is referred to, calculates each ginseng
Examine the reference absorption spectrum of powdered milk sample.
Specifically, it is calculated according to reference to frequency domain Terahertz reflectance spectrum and standard frequency domain Terahertz reflectance spectrum with reference to absorption
The method of spectrum can refer to step S150.
Step S230 obtains each reference powdered milk sample at characteristic absorption frequency to Terahertz according to each with reference to absorption spectrum
The absorption coefficient of the electromagnetic wave of frequency range.
Specifically, for example, obtaining each as shown in Figure 6 with reference to absorption spectrum.It can be obtained from Fig. 6 each with reference to powdered milk sample
Absorption coefficient at characteristic absorption frequency (in 1.98THz or 2.24THz).Alternatively, processor from each with reference to absorption spectrum
It can be calculated in light energy equation and learn each absorption coefficient with reference to powdered milk sample.Specific accounting equation can refer to step S150.
Step S240 establishes the concentration of melamine in milk powder according to each absorption coefficient with reference to powdered milk sample and absorbs system
Several functional relations.
Specifically, it can be fitted not according to the concentration of the melamine of each powdered milk sample to be measured and corresponding absorption coefficient
Know the concentration of the melamine of powdered milk sample and the functional relation of absorption coefficient.It is for example, as shown in fig. 7, to be measured according to above-mentioned 5 kinds
The absorption coefficient of powdered milk sample and the concentration of melamine fit a straight line (straight line in such as Fig. 7), the functional relation of straight line
It is a linear equation, it is as follows：
Ab=19.299C+0.1495 (6)
In formula (6), Ab refers to absorption coefficient, and C refers to the concentration of melamine in unknown powdered milk sample.
Therefore, if detecting the absorption system of melamine in unknown powdered milk sample with terahertz time-domain spectroscopy detecting system
Number can calculate the concentration of melamine in the unknown powdered milk sample according to formula (6), and force data card is provided with for testing result
It is bright.
It should be noted that the type of above-mentioned powdered milk sample to be measured can be other quantity, as long as can realize that function closes
The fitting of system.
The detecting system of melamine in a kind of milk powder, for detecting whether milk powder contains melamine.The detecting system
Including monitor station, Terahertz generating means, Terahertz reception device and processor.
Monitor station includes loading surface, standard sample and to be measured powdered milk sample of the loading surface for placing milk powder.The present embodiment
In, the setting of monitor station can refer to embodiment shown in FIG. 1.Monitor station is made of silicon wafer.
Terahertz generating means is used to generate the electromagnetic wave of preset Terahertz frequency range, and electromagnetic wave is injected monitor station
It is interior, electromagnetic wave incident is made to be totally reflected to loading surface and in loading surface；When standard sample is placed as on loading surface, loading surface
Reflectance spectrum is normal clock domain Terahertz reflectance spectrum；When powdered milk sample to be measured is placed as on loading surface, the reflected light of loading surface
It composes to detect time domain Terahertz reflectance spectrum.
Terahertz reception device is used to receive normal clock domain Terahertz reflectance spectrum and detection time domain Terahertz reflectance spectrum.
Processor is used to normal clock domain Terahertz reflectance spectrum carrying out Fourier transformation, and it is anti-to obtain standard frequency domain Terahertz
Penetrate spectrum；Processor is additionally operable to detection time domain Terahertz reflectance spectrum carrying out Fourier transformation, obtains detection frequency domain Terahertz
Reflectance spectrum；Processor is additionally operable to, according to standard frequency domain Terahertz reflectance spectrum and detection frequency domain Terahertz reflectance spectrum, calculate
Powdered milk sample to be measured judges milk powder sample to be measured to the absorption spectrum of the electromagnetic wave of preset Terahertz frequency range according to absorption spectrum
Whether contain melamine in product.
The detection method of melamine in above-mentioned milk powder detects the melamine in powdered milk sample to be measured to Terahertz frequency range
Electromagnetic wave detection frequency domain Terahertz reflectance spectrum, and with standard sample to the standard frequency domain of the electromagnetic wave of Terahertz frequency range too
Hertz reflectance spectrum is the absorption spectrum to the electromagnetic wave of Terahertz frequency range with reference to calculating powdered milk sample to be measured, from absorption spectrum
Can judge whether contain melamine in powdered milk sample to be measured.In this way, the melamine pair in powdered milk sample to be measured is utilized
The method detection melamine of the absorption of the electromagnetic wave of Terahertz frequency range, does not need to do powdered milk sample to be measured additional processing,
It is easy to detect, quick.
In one embodiment, when processor is additionally operable to contain melamine in powdered milk sample to be measured, obtained from absorption spectrum
Take characteristic absorption frequency of the powdered milk sample to be measured to the electromagnetic wave of Terahertz frequency range.
Each technical characteristic of above example can be combined arbitrarily, to make description succinct, not to above-described embodiment
In each technical characteristic it is all possible combination be all described, as long as however, the combination of these technical characteristics be not present lance
Shield is all considered to be the range of this specification record.
Above example only expresses the several embodiments of the present invention, and description is more specific and detailed, but can not
Therefore it is construed as limiting the scope of the patent.It should be pointed out that for those of ordinary skill in the art,
Under the premise of not departing from present inventive concept, various modifications and improvements can be made, these belong to protection scope of the present invention.
Therefore, the protection domain of patent of the present invention should be determined by the appended claims.
Claims (10)
1. the detection method of melamine in a kind of milk powder, which is characterized in that for detecting powdered milk sample to be measured on monitor station
Whether melamine is contained, and standard sample and the powdered milk sample to be measured are placed on the loading surface of the monitor station；The side
Method includes：
Standard sample is tested using the electromagnetic wave of default Terahertz frequency range, obtains normal clock domain Terahertz reflectance spectrum；
Wherein, the standard sample does not absorb the electromagnetic wave, and the normal clock domain Terahertz reflectance spectrum is in the monitor station
The interior electromagnetic wave incident is to the loading surface and the reflectance spectrum that is totally reflected in the loading surface；
The normal clock domain Terahertz reflectance spectrum is subjected to Fourier transformation, obtains standard frequency domain Terahertz reflectance spectrum；
The powdered milk sample to be measured is tested using the electromagnetic wave of the default Terahertz frequency range, obtains detection time domain terahertz
Hereby reflectance spectrum；Wherein, the detection time domain Terahertz reflectance spectrum be in the monitor station electromagnetic wave incident to institute
State loading surface and the reflectance spectrum being totally reflected in the loading surface；
The detection time domain Terahertz reflectance spectrum is subjected to Fourier transformation, obtains detection frequency domain Terahertz reflectance spectrum；
According to the standard frequency domain Terahertz reflectance spectrum and the detection frequency domain Terahertz reflectance spectrum, milk powder sample to be measured is calculated
Product are to the absorption spectrum of the electromagnetic wave of the default Terahertz frequency range；
Judge whether contain melamine in the powdered milk sample to be measured according to the absorption spectrum.
2. the method according to claim 1, which is characterized in that the powdered milk sample to be measured is to the electricity of the default Terahertz frequency range
The absorption coefficient of magnetic wave reflects the absorption spectrum of powdered milk sample to be measured；
According to the standard frequency domain Terahertz reflectance spectrum and the detection frequency domain Terahertz reflectance spectrum, described treat is calculated
The expression formula of absorption coefficient for surveying powdered milk sample is：
Wherein, ω is the angular frequency of the electromagnetic wave of the preset Terahertz frequency range, and Er (ω) is the standard frequency domain Terahertz
Reflectance spectrum energy, Es (ω) are the detection frequency domain Terahertz reflectance spectrum energy.
3. according to the method described in claim 1, it is characterized in that, described judge the milk powder to be measured according to the absorption spectrum
Include after the step of whether containing melamine in sample：
When containing melamine in the powdered milk sample to be measured, the powdered milk sample pair to be measured is obtained from the absorption spectrum
The characteristic absorption frequency of the electromagnetic wave of Terahertz frequency range.
4. according to the method described in claim 3, it is characterized in that, described be additionally operable to treat according to reference to described in powdered milk sample detection
Survey the melamine of powdered milk sample；The type with reference to powdered milk sample be N kinds, each it is described with reference in powdered milk sample three
The concentration of poly cyanamid is different；Wherein N is positive integer；
The method further includes step：
Each electromagnetic wave that the default Terahertz frequency range is utilized respectively with reference to powdered milk sample is tested, is obtained with reference to frequency
Domain Terahertz reflectance spectrum；Wherein, the reference frequency domain Terahertz reflectance spectrum is that the electromagnetic wave enters in the monitor station
It is incident upon the loading surface and the reflectance spectrum being totally reflected in the loading surface；
Frequency domain Terahertz reflectance spectrum and the standard frequency domain Terahertz reflectance spectrum are referred to according to described, calculates each reference
The reference absorption spectrum of powdered milk sample；
Each reference powdered milk sample is obtained at the characteristic absorption frequency to Terahertz according to each reference absorption spectrum
The absorption coefficient of the electromagnetic wave of frequency range；
The function of the concentration of melamine and absorption coefficient in milk powder is established according to each absorption coefficient with reference to powdered milk sample
Relationship, to calculate the concentration of melamine in the powdered milk sample to be measured according to absorption coefficient.
5. the method according to claim 1, which is characterized in that the electromagnetic wave using in default Terahertz frequency range is to standard sample
Product are tested, and are included before the step of obtaining normal clock domain Terahertz reflectance spectrum：
Steam in environment where the monitor station is all discharged.
6. the method according to claim 1, which is characterized in that the steam in the environment by where the monitor station is all arranged
The step of going out includes：
Nitrogen will be full of in environment where the monitor station, so that the relative humidity of the environment where the monitor station is less than
2%.
7. the method according to claim 1, which is characterized in that the standard sample is polyethylene powders.
8. the detecting system of melamine in a kind of milk powder, which is characterized in that for detecting whether powdered milk sample to be measured contains three
Poly cyanamid；The detecting system includes monitor station, Terahertz generating means, Terahertz reception device and processor；
The monitor station includes loading surface, and the loading surface is used to place standard sample and the powdered milk sample to be measured；
The Terahertz generating means is used to generate the electromagnetic wave of preset Terahertz frequency range, and will be described in electromagnetic wave injection
In monitor station, the electromagnetic wave incident is made to be totally reflected to the loading surface and in the loading surface；It is put on the loading surface
When being set to the standard sample, the reflectance spectrum reflected from the loading surface is normal clock domain Terahertz reflectance spectrum；The load
It is detection time domain Terahertz reflected light from the reflectance spectrum that the loading surface reflects when powdered milk sample to be measured is placed as on object plane
Spectrum；
The Terahertz reception device is used to receive the normal clock domain Terahertz reflectance spectrum and the detection time domain Terahertz
Reflectance spectrum；
The processor is used to the normal clock domain Terahertz reflectance spectrum carrying out Fourier transformation, obtains standard frequency domain terahertz
Hereby reflectance spectrum；The processor is additionally operable to the detection time domain Terahertz reflectance spectrum carrying out Fourier transformation, is examined
Frequency measurement domain Terahertz reflectance spectrum；The processor is additionally operable to according to the standard frequency domain Terahertz reflectance spectrum and the detection
Frequency domain Terahertz reflectance spectrum calculates absorption spectrum of the powdered milk sample to be measured to the electromagnetic wave of preset Terahertz frequency range,
And judge whether contain melamine in the powdered milk sample to be measured according to the absorption spectrum.
9. detecting system according to claim 8, which is characterized in that the processor is additionally operable in the powdered milk sample to be measured
During containing melamine, electromagnetism of the powdered milk sample to be measured to the default Terahertz frequency range is obtained from the absorption spectrum
The characteristic absorption frequency of wave.
10. detecting system according to claim 8, which is characterized in that the monitor station is made of silicon wafer.
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