JP2012052957A - Method for measuring infrared absorption spectrum - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring an infrared absorption spectrum of skin accurately, regardless of a degree of adhesion between the skin and a sample contact part of a device for measuring an infrared absorption spectrum.SOLUTION: A method for measuring an infrared absorption spectrum includes the steps of: applying an infrared ray to a skin surface of a human from an infrared ray irradiation unit via a sample contact part; detecting an infrared ray which is reflected from the skin surface of the human and is transmitted through the sample contact part; and performing correction at operation means which corrects, regarding the infrared ray detected, an amount of contribution to infrared absorption by skin at a contact portion where the skin surface comes into contact with the sample contact part, and an amount of contribution to infrared absorption by skin at a noncontact portion where the skin surface is out of contact with the sample contact part.

Description

  The present invention relates to a method for measuring an infrared absorption spectrum.

  In order to recommend cosmetics most suitable for customers in sales of cosmetics, skin cleansing products, etc., services for measuring moisture, oil content, form, etc. of customers' skin at stores are widely performed. Also, in the process of research and development of cosmetics and skin cleansers, it is indispensable to develop more effective cosmetics, skin cleansers, etc., by indexing the skin condition by instrument measurement. It has become a thing. Furthermore, the amount of moisture in the skin greatly varies depending on the skin condition and environment of the individual. Therefore, it is important to properly grasp the skin state in evaluating the moisture content, oil content, form, etc. of the skin and characterizing individual differences and site differences.

As a method for non-invasively measuring the skin state, it is known to measure an infrared absorption spectrum of a sample surface by IR-ATR (infrared attenuated total reflection) method. For example, Patent Document 1 describes a method for measuring the amount of a natural moisturizing factor in a skin stratum corneum using infrared spectroscopy.
In the IR-ATR method, an infrared absorption spectrum is measured by irradiating a sample with infrared light through an ATR crystal and detecting reflected infrared light transmitted through the ATR crystal. Therefore, in the IR-ATR method, the degree of adhesion between the sample and the ATR crystal is considered to be important. Therefore, a method is known in which the sample surface is sucked and brought into contact with the sample contact portion of the infrared absorption spectrum measuring apparatus to measure the infrared absorption spectrum (see, for example, Patent Document 2). However, since the shape of the infrared absorption spectrum differs depending on the degree of skin adhesion to the ATR crystal, when the infrared absorption spectrum is measured by sucking the sample surface, the component composition of the skin cannot be measured accurately.
Furthermore, a method for measuring an infrared absorption spectrum by correcting a change in absorbance associated with a change in contact area between the skin and an infrared probe of an infrared absorption spectrum measuring apparatus is known (for example, Patent Document 3). reference). In general, in the IR-ATR method, the depth that can be analyzed (the penetration depth of the evanescent wave) is several μm or less from the surface of the measurement object. Therefore, the method described in Patent Document 3 has a large unevenness on the surface of the measurement object, and the air in the non-contact portion where the skin surface and the infrared probe do not contact compared to the penetration depth of the evanescent wave. This is effective when the layer is very thick and no infrared light absorption from the measurement object occurs from the non-contact portion. However, since there are many fine irregularities of several μm or less on the surface of the skin, in the measurement of the infrared absorption spectrum of the skin sample, the irradiated infrared light is not completely in contact with the infrared probe. Even non-contact parts are absorbed by the skin. Therefore, in the method described in Patent Document 3 in which the attenuation of the detected reflected infrared light is derived only from the contact portion where the skin surface and the infrared light probe are in contact, the component composition of the skin is accurately measured. Can not do it.

JP 2009-210567 A JP 2009-183636 A JP 2007-68857 A

  An object of the present invention is to provide a method for accurately measuring the infrared absorption spectrum of the skin regardless of the degree of adhesion between the skin and the sample contact portion of the infrared absorption spectrum measuring apparatus.

  As a result of intensive studies in view of the above problems, the present inventors have determined that the infrared absorption spectrum of the measured skin is infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion of the infrared absorption spectrum device are in contact. Correct infrared absorption spectrum of the skin can be obtained by correcting the contribution of the skin and the contribution of infrared absorption by the skin of the non-contact part where the skin surface and the sample contact part do not contact I found out. The present invention has been completed based on this finding.

The present invention
Irradiating the human skin surface with infrared light from the infrared light irradiation part through the sample contact part,
A step of detecting infrared light reflected from the human skin surface and transmitted through the sample contact portion; and infrared absorption by the skin of the contact portion where the skin surface and the sample contact portion contact in the detected infrared light. A step of performing correction processing by a calculation means for correcting the contribution and the contribution of infrared absorption by the skin of the non-contact portion where the skin surface and the sample contact portion do not contact,
And a method for measuring an infrared absorption spectrum.

  Further, the present invention irradiates the human skin surface with infrared light from the infrared light irradiation part through the sample contact part, and detects infrared light reflected from the human skin surface and transmitted through the sample contact part. A method for correcting the measured infrared absorption spectrum, in the detected infrared light, the contribution of infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion contact, and the skin surface and the sample contact portion The present invention relates to a method for correcting an infrared absorption spectrum, in which correction processing is performed by a calculation unit that corrects the contribution of infrared absorption by the skin of a non-contact portion that does not touch.

Furthermore, the present invention provides
Irradiating the human skin surface with infrared light from the infrared light irradiation part through the sample contact part,
Detecting infrared light reflected from the human skin surface and transmitted through the sample contact portion;
In the detected infrared light, the contribution of infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion contact, and the infrared absorption by the skin at the non-contact portion where the skin surface and the sample contact portion do not contact each other A step of performing correction processing by a calculation means for correcting the contribution, and a step of analyzing the skin composition based on the infrared absorption spectrum obtained by the correction processing;
The present invention relates to a method for analyzing skin composition.

Furthermore, the present invention provides
A sample contact portion that contacts the human skin surface;
An infrared irradiation unit that irradiates the human skin surface with infrared light through the sample contact unit;
Infrared light detection means for detecting infrared light reflected from the human skin surface and transmitted through the sample contact portion;
In the detected infrared light, the contribution of infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion contact, and the infrared absorption by the skin at the non-contact portion where the skin surface and the sample contact portion do not contact each other Arithmetic means for correcting the contribution,
It is related with the infrared absorption-spectrum measuring apparatus provided with.

  The infrared absorption spectrum of the skin can be accurately measured without being influenced by the degree of adhesion between the skin and the sample contact portion of the infrared absorption spectrum measuring apparatus.

It is a figure which shows typically the infrared absorption spectrum measuring apparatus of this invention. In Example 1, it is a figure which shows the infrared absorption spectrum of the human skin computed by the method of this invention. In Example 1, it is a figure which shows the infrared absorption spectrum acquired by pressing and measuring a human skin against the sample contact part of the infrared absorption spectrum measuring apparatus which apply | coated the oil immersion oil. In Example 1, it is a figure which shows the infrared absorption spectrum acquired by pressing skin directly on the sample contact part of an infrared absorption spectrum measuring device, and measuring. It is a figure which shows the infrared absorption spectrum of oil immersion oil. It is a figure which shows the infrared absorption spectrum of the human skin computed in the comparative example. 6 is a diagram showing an infrared absorption spectrum measured in Example 2. FIG. In Example 2, it is a figure which shows the infrared absorption spectrum which correct | amended the infrared absorption spectrum shown in FIG. 7 by the method of this invention.

Hereinafter, the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to this.
Infrared absorption spectrum measuring apparatus 10 shown in FIG. 1 is in contact with the surface of sample (human skin) 5, sample contact portion 3 provided on sample stage 4, and sample 5 via sample contact portion 3. An infrared absorption spectrum measurement unit 1 having an infrared light irradiation unit 2 that irradiates light 9 and a detection unit 6 that detects infrared light 9 reflected from the sample 5 and transmitted through the sample contact unit 3 is provided. Furthermore, an infrared absorption spectrum calculation unit 7 such as a computer having a built-in recording medium such as a CPU (Central Processing Unit), a memory, and a hard disk is provided. The infrared absorption spectrum calculation unit 7 includes calculation means 8.

  The infrared absorption spectrum measuring unit 1 is preferably configured to measure an infrared absorption spectrum using a Fourier Transform infrared spectrophotometer (FT-IR). FT-IR is a method of converting the infrared light 9 irradiated from the infrared light irradiation unit 2 into interference light and irradiating the sample 5. The intensity of the light reflected from the sample 5 is measured as a function of the moving distance of the movable mirror, and the infrared absorption spectrum is measured by Fourier transforming the interference waveform obtained by the detection unit 6.

  As the infrared light irradiation part 2, the same structure as the infrared light irradiation part of a normal infrared spectrometer is mentioned. For example, a combination of an infrared light source and an interferometer or a combination of an infrared light source and a spectroscope can be used.

The infrared absorption spectrum can be measured by an attenuated total reflection spectroscopy (ATR method) using a sample contact portion 3 such as a plate prism, an optical fiber probe, or a diamond prism. Although there is no restriction | limiting in particular as a material of the sample contact part 3, A thing with a refractive index of 2.4 or more is preferable, and germanium, a diamond, etc. can be used.
The number of reflections is not particularly limited, and may be once or twice or more.

  There is no restriction | limiting in particular as the detection part 6, The structure similar to the detection part of a normal infrared spectrometer is mentioned. Examples include a MCT (Mercury Cadmium Tellurium) detector, a DLATGS (Deuterated L-Alanine Triglycine Sulphate) detector, a DTGS (Deuterated TriGlycine Sulfate) detector, and a TGS (Triglycine Sulfate) detector.

  In this invention, as shown in FIG. 1, it is preferable that the infrared light irradiation part 2 and the detector 6 are integrated. Moreover, when using a portable apparatus as the infrared absorption spectrum measuring unit 1, it is preferable that the apparatus has excellent vibration resistance and is driven by a battery.

  In the IR-ATR method, the adhesion between the sample contact portion 3 and the sample 5 affects the absorption intensity of infrared light. Therefore, in order to keep the adhesion constant when measuring the infrared absorption spectrum, the sample contact portion 3 And sample 5 are preferably brought into close contact under a certain pressure. Therefore, in the present invention, it is preferable that the infrared absorption spectrum measurement unit 1 includes pressure maintaining means for applying pressure to the sample 5 from above the sample 5. Any pressure maintaining means may be used as long as the pressure can be applied so that the adhesion between the sample contact portion 3 and the sample 5 is constant. For example, the sample 5 may be fixed on the sample table 4 using a rubber band, or the pressure may be automatically applied from above the sample 5 to a constant pressure by the pressurizing unit. However, in the present invention, it is not necessary to bring the entire infrared absorption spectrum measurement site of the sample 5 into complete contact with the sample contact portion 3, and the pressure maintaining means is the same as that of a normal method so that the infrared absorption spectrum can be measured. What is necessary is just to apply the pressure of a grade.

For the infrared absorption spectrum detected by the detection unit 6, in the infrared absorption spectrum calculation unit 7 provided with the calculation means 8, the infrared absorption by the sample 5 at the contact portion where the surface of the sample 5 and the sample contact portion 3 are in contact with each other. Correction processing for correcting the contribution and the contribution of infrared absorption by the sample 5 in the non-contact portion where the surface of the sample 5 and the sample contact portion 3 are not in contact is performed.
The correction process will be described in detail below. However, the present invention is not limited to this.

  In the present invention, the contribution of infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion contact in advance, and the contribution of infrared absorption by the skin at the non-contact portion where the skin surface and the sample contact portion do not contact each other It is preferable to perform the correction process by the calculation means 8 using the standard spectrum of human skin that has been corrected for the minute.

The human skin surface is mainly composed of protein and water, and its refractive index is considered to be about 1.5. Therefore, the liquid having a refractive index of about 1.5 (preferably 1.3 to 1.6) and not affecting the composition of the skin surface even when applied to the skin is the sample 5 and the sample stage 4 or the sample contact portion. Infrared absorption spectrum is measured in a state of being arranged between 3 and 3, and the contribution of infrared absorption by the skin at the contact part where the skin surface and the sample contact part are in contact with each other, and the skin surface and the sample contact part are not in contact with each other A standard spectrum of human skin can be obtained by performing a correction process on the contribution of infrared absorption by the liquid present in the non-contact portion.
The liquid that can be preferably used in the present invention preferably has a refractive index close to that of the human skin surface. For example, in an optical microscope measurement, an oil usually used for eliminating a difference in refractive index between glass elements such as an optical lens is used.

A method for preparing a standard spectrum of human skin will be specifically described.
The infrared absorption spectrum (absorbance) A _oil of _oil- immersed oil usually used in the method for measuring the infrared absorption spectrum of a biological sample is represented by the following formula (1).

In the formula (1), R _oil represents the reflectance of oil-immersed oil of infrared light.
In the infrared absorption spectrum measurement unit 1, when measurement is performed with oil immersion oil disposed between the sample 5 and the sample stage 4, the oil immersion oil is placed in a non-contact portion where the sample 5 and the sample contact portion 3 do not contact each other. Enters. At this time, the observed infrared absorption spectrum (absorbance) A _obs is expressed by the following formula (2).

In the formula (2), R _obs represents the reflectance of the sample 5 of infrared light.
R _obs can be derived from the following formulas (3) to (5).

here,
R _skin indicates the reflectance at the contact portion of infrared light,
x represents the ratio (contact degree) of the contact area at the measurement site,
d indicates the thickness of the air layer of the non-contact portion,
d _p represents the penetration depth of the evanescent wave,
n ₁ represents the refractive index of the sample contact portion 3,
n ₂ represents the refractive index of the sample 5;
θ represents the incident angle of the irradiated infrared light 9 with respect to the sample 5,
λ represents the wavelength (nm) of the irradiated infrared light 9.
It is known that the penetration depth d _p of the evanescent wave depends on the incident angle to the total reflection surface. The incident angle on the total reflection surface from the sample contact portion 3 or the like can be easily determined, and the penetration depth of the evanescent wave can be calculated.

Therefore, the infrared absorption spectrum A _skin of the sample 5 can be derived from the following formulas (6) to (7).

The calculation means 8 of the infrared absorption spectrum calculation unit 7 performs a correction process for determining appropriate values for d in the equation (4) and x in the equation (6). Although there is no particular limitation on the correction processing method, in the infrared absorption spectrum (A _skin ) of the skin after correction processing calculated from the equation (7), a peak derived from the absorption spectrum (A _oil ) of the _oil immersion oil is present. The values of d and x are determined so as to be minimized.

The liquid that can be used to prepare the standard spectrum of the human skin is not particularly limited, but the refractive index is preferably about the same as the refractive index of human skin (about 1.5). 3-1.6 is more preferable. Furthermore, those that do not affect the composition of the skin surface even when applied to the skin are preferred. Specific examples include glycerin, silicone oil, polyethylene glycol, liquid paraffin, and petrolatum. In the present invention, an optical oil (refractive index n _d = 1.51 to 1.52) generally commercially available for optical microscope measurement is particularly preferable.
In the present invention, the spectrum may be measured by placing the skin on a sample table or sample contact portion coated with a liquid having a refractive index of 1.3 to 1.6, and the refractive index of 1.3 to 1 at the measurement site. .6 liquid may be applied, and the spectrum may be measured by bringing the measurement site into contact with the sample contact portion.

The correction processing method by the calculation means is performed so that the spectrum pattern after the correction processing matches a typical skin spectrum pattern. For example, the spectral pattern of the wave number region of 650 to 1000 cm ⁻¹ derived from the stretching vibration of water, and the spectral pattern of the amide II absorption band of the wave number region of 1480 to 1580 cm ⁻¹ derived from protein are relatively individual differences, sites It is known that the difference is small. Therefore, correction is performed so that the shape of these regions of the spectrum after correction processing matches that of a typical skin spectrum.

Hereinafter, although the correction processing method by a calculating means is demonstrated concretely, this invention is not restrict | limited to this.
Since the refractive index of air is 1, the penetration depth d _p ^air of the evanescent wave into the air layer (non-contact portion) is expressed as follows.

  Further, energy ΔI absorbed by the skin in the non-contact portion is represented by the following formula.

In the above equation, E ₀ represents the amplitude of the evanescent wave at the sample contact portion and the skin interface.
Further, the reflectance R _non-contact at the non-contact portion is expressed by the following formula.

  Here, D is represented by the following formula.

From the above formula, the reflectance R _obs of the sample 5 of infrared light is expressed by the following formula.

Therefore, the reflectance R _skin of the _skin is

The infrared absorption spectrum A _skin expressed and observed by the above formula (2):

It becomes.
Here, for example, in the wave number regions of 650 to 1000 cm ⁻¹ and 1480 to 1580 cm ⁻¹ , the values of x and d are determined so that A _skin obtained by the above formula matches the standard spectrum of the skin.

  In the present invention, the correction processing performed by the calculation means 8 may be performed by a data processing device integrated with the infrared absorption spectrum measurement unit 1 or independent of (connected to) the infrared absorption spectrum measurement unit 1. Not) may be performed by a data processing device. That is, for example, after obtaining an infrared absorption spectrum by using an infrared absorption spectrum apparatus not provided with the calculation means 8, the infrared absorption spectrum data is transferred via a recording medium such as a flexible disk or a communication line. Independent of the infrared absorption spectrum measuring apparatus, the correction processing can be performed by inputting the data into a data processing apparatus (for example, a personal computer) having a correction program for executing the correction processing.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, this invention is not limited to this.

Example 1
(1) Measurement of infrared absorption spectrum Regarding the way of contact between the skin and the ATR prism, part of the skin is completely in contact with the ATR prism (contact part), and the remaining part has an air layer between the ATR prisms. (Non-contact part). Although it is considered that the thickness of the air layer in the non-contact portion varies depending on the part, it is assumed here that the air layer exists as a uniform thickness. Furthermore, it was assumed that infrared light was absorbed by the skin even in the non-contact portion. In this case, the absorption of infrared light by the skin at the non-contact portion is less than the absorption at the contact portion.
Oil immersion oil (Nikon, TYPE NF, refractive index: 1.515 (23 ° C)) was dropped on the ATR prism, and the skin (wrist) of a man in his 20s was pressed onto it to measure the infrared absorption spectrum. . (Hereinafter, it is assumed that the non-contact portion is completely filled with the oil-immersed oil.) Measurement is performed by attaching a universal ATR accessory to the infrared spectrometer of SpectrumOne (trade name, manufactured by PerkinElmer). The following measurement conditions were used.
<Measurement conditions>
Resolution: 4cm ^-1
Integration count: 32 times Light source: Infrared light source (manufactured by PerkinElmer)
Detector: MCT (Mercury Cadmium Tellurium) detector (Perkin Elmer)
Measurement range: 515-4000cm ^-1
ATR condition: Reflected infrared light incident angle: 45 degrees
ATR prism: Diamond applied pressure: about 33000Pa

(2) Correction of infrared absorption spectrum The absorption of infrared light by the skin at the non-contact part is the absorption of infrared light by oil-impregnated oil depending on the thickness d (mm) of the air layer at the non-contact part. The abundance ratio (contribution) of infrared light absorption by the skin is different. Therefore, if the ratio (contact degree) of the contact area at the measurement site is x (0 <x ≦ 1), the penetration depth d _p (mm) of the evanescent wave is equal in the contact area and the non-contact area. can do.
The infrared absorption spectrum A ₁ measured in the above (1) can be expressed by the following formula (8).

In formula (8),
A ₁ is an infrared absorption spectrum (infrared absorption spectrum measured in the above (1)) obtained by measuring by pressing the skin against the ATR prism to which oil-immersed oil was dropped,
A ₂ is the infrared absorption spectrum of the skin obtained by measuring the skin directly against the ATR prism.
A ₃ represents the infrared absorption spectrum of the oil-immersed oil, respectively.
In the formula (8), B and d _p are represented by the formulas (4) and (5), respectively.

As the pattern of the above equation the synthesis infrared absorption spectrum of skin obtained using a relational expression is consistent with the infrared absorption spectrum A ₂ of the pattern of the skin obtained by measuring by pressing the skin directly ATR prism The degree of contact x at the measurement site and the thickness d (mm) of the air layer at the non-contact part were determined. Specifically, in the infrared absorption spectrum A ₁ , peaks derived from oil immersion oil (1487 cm ⁻¹ , 1237 cm ⁻¹ , 748 cm ⁻¹ , 690 cm ^−1, etc.) are minimized, and the infrared absorption spectrum A ₂ The values of x and d were determined to match the pattern. As a result, x = 0.29 and d = 2.2 (mm).
The synthetic infrared absorption spectrum of the skin prepared based on these values is shown in FIG. Incidentally, the (1) Infrared absorption spectrum as measured in (A _1), infrared absorption spectra of the skin itself (A _2), and infrared absorption spectrum of only the oil immersion oil (A _3), respectively Figure 3 Shown in ~ 5.

And Figure 2 shows the synthesis infrared absorption spectrum obtained by the method of the present invention using the spectrum shown in FIG. 3, comparing FIG. 4 shows an infrared absorption spectrum A ₂ of the skin itself, very spectrum pattern It was consistent. Specifically, in the spectrum shown in FIG. 2, the peak shape and peak intensity (peak area) in the wavenumber regions of 500 to 1750 cm ⁻¹ , 2800 to 3000 cm ⁻¹ and 3000 to 3700 cm ⁻¹ are shown in FIG. And very similar.
From these results, it is clear that the infrared absorption spectrum of the skin can be accurately measured by the method of the present invention without being influenced by the degree of skin adhesion at the sample contact portion in the infrared absorption spectrum measuring apparatus. became.

Comparative example Assuming that the air layer is very thick in the non-contact part (oil-immersed oil part), there is no absorption of infrared light by the skin, and infrared light is absorbed only by oil-immersed oil. Correction was performed.
For the infrared absorption spectrum measured in (1) of Example 1, when the contact area ratio (contact degree) at the measurement site is x ′ (0 <x ′ ≦ 1), (1) of Example 1 The measured infrared absorption spectrum A ₁ can be expressed by the following formula (9).

Wherein (9), A _1, A ₂ and A ₃ have the same meaning as A _1, A ₂ and A ₃ in the formula (8).

As the pattern of the above equation the synthesis infrared absorption spectrum of skin obtained using a relational expression is consistent with the infrared absorption spectrum A ₂ of the pattern of the skin obtained by measuring by pressing the skin directly ATR prism The degree of contact x ′ at the measurement site was determined. As a result, x ′ = 0.3. The synthetic infrared absorption spectrum of the skin calculated from this value is shown in FIG.
Comparing FIG. 6 showing the synthetic infrared absorption spectrum obtained by using the above formula (9) with the spectrum shown in FIG. 3 and the infrared absorption spectrum of the skin itself, FIG. 4 shows either the peak shape or the peak area. It can be seen that they are also very different.

Example 2
An infrared absorption spectrum was measured in the same manner as in Example 1 except that the measurement was performed by directly pressing the skin (wrist) of a 20-year-old man against the ATR prism.
The infrared absorption spectrum shown in FIG. 2 is defined as the standard spectrum of the skin, and in the wave number regions of 650 to 1000 cm ⁻¹ and 1480 to 1580 cm ⁻¹ , the above formulas (4) and (8) X) and d) were determined, and a synthetic spectrum was prepared.

Example 3
Infrared absorption spectra were measured 6 times continuously with the skin (inner forearm) of a 40-year-old man pressed against the ATR prism (immediately after the start of measurement, as well as 2 minutes and 4 minutes after the start of measurement). 6 minutes, 8 minutes and 10 minutes, the required time is about 10 minutes). The measurement was performed under the following measurement conditions using an infrared spectroscopic measurement apparatus Exoscan (trade name, manufactured by A2 Technologies).
<Measurement conditions>
Resolution: 4cm ^-1
Integration count: 32 times Light source: Infrared light source (A2 TECHNOLOGIES)
Detector: Temperature stable DTGS (Deuterated TriGlycine Sulfate) detector (A2 TECHNOLOGIES)
Measurement range: 650-4000cm ^-1
ATR condition: Reflected infrared light incident angle: 45 degrees
ATR prism: germanium applied pressure: about 130,000 Pa FIG. 7 shows the infrared absorption spectrum obtained in this manner normalized by the peak intensity of amide II (1550 cm ⁻¹ ).

The infrared absorption spectrum shown in FIG. 7 was corrected as shown below.
The spectrum shown in FIG. 2 obtained in Example 1 is a standard spectrum of human skin, and the infrared absorption spectrum A _skin observed in the wave number regions of 650 to 1000 cm ⁻¹ and 1480 to 1580 cm ⁻¹ , The degree of contact x at the measurement site and the thickness d (mm) of the air layer at the non-contact portion were determined so as to match the standard spectrum, and an infrared absorption spectrum after correction processing was created. The result is shown in FIG.

In the infrared absorption spectrum, water-derived peaks appear mainly in the wave number region near 3300 cm ⁻¹ . In FIG. 7, an increase in absorbance was observed in the vicinity of 3300 cm ⁻¹ over time. This is because moisture evaporates from the inside of the skin over time. However, in the wave number region of 1000-1500 cm ⁻¹ , the absorbance decreased with time. This phenomenon is thought to be due to an increase in the degree of contact (contact area) between the skin and the ATR prism due to an increase in the amount of water. The peak in the wave number region of 1000 to 1500 cm ⁻¹ is mainly derived from protein, and unlike skin moisture, protein does not decrease in protein amount over time. Accordingly, the results shown in FIG. 7 do not accurately indicate changes with time of the skin.

On the other hand, in FIG. 8, an increase in absorbance near 3300 cm ^−1, which is considered to be caused by an increase in water content with time, was observed. Furthermore, the relative decrease in absorbance in the wave number region of 1000-1500 cm ⁻¹ seen in the spectrum shown in FIG. 7 was hardly confirmed in the spectrum shown in FIG. 8.

  From these results, it can be seen that according to the measurement method of the present invention, it is possible to measure an infrared absorption spectrum that is hardly influenced by a change in the degree of adhesion between the skin and the sample contact portion of the infrared absorption spectrum measuring apparatus.

DESCRIPTION OF SYMBOLS 1 Infrared absorption spectrum measuring part 2 Infrared light irradiation part 3 Sample contact part 4 Sample stand 5 Sample 6 Detection part 7 Infrared absorption spectrum calculation part 8 Calculation means 9 Infrared light 10 Infrared absorption spectrum measuring apparatus

Claims (8)

Irradiating the human skin surface with infrared light from the infrared light irradiation part through the sample contact part,
A step of detecting infrared light reflected from the human skin surface and transmitted through the sample contact portion; and infrared absorption by the skin of the contact portion where the skin surface and the sample contact portion contact in the detected infrared light. A step of performing correction processing by a calculation means for correcting the contribution and the contribution of infrared absorption by the skin of the non-contact portion where the skin surface and the sample contact portion do not contact,
A method for measuring an infrared absorption spectrum, comprising:   Infrared absorption spectrum is measured in a state where a liquid having a refractive index of 1.3 to 1.6 is arranged between the human skin surface and the sample contact portion, and the skin of the contact portion where the skin surface and the sample contact portion are in contact with each other A standard spectrum of human skin is created by performing a correction process on the contribution of infrared absorption by and the contribution of infrared absorption by the liquid present in the non-contact part where the skin surface and the sample contact part do not contact, The infrared absorption spectrum measurement method according to claim 1, wherein correction processing is performed in the calculation means based on the standard spectrum.   Infrared absorption spectrum measured by irradiating the human skin surface with infrared light from the infrared light irradiation part through the sample contact part and detecting the infrared light reflected from the human skin surface and transmitted through the sample contact part. In the detected infrared light, the contribution of infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion contact, and the non-contact portion where the skin surface and the sample contact portion do not contact A method for correcting an infrared absorption spectrum, in which correction processing is performed by a calculation means that corrects the contribution of infrared absorption by the skin.   Infrared absorption spectrum is measured in a state where a liquid having a refractive index of 1.3 to 1.6 is arranged between the human skin surface and the sample contact portion, and the skin of the contact portion where the skin surface and the sample contact portion are in contact with each other A standard spectrum of human skin is created by performing a correction process on the contribution of infrared absorption by and the contribution of infrared absorption by the liquid present in the non-contact part where the skin surface and the sample contact part do not contact, The infrared absorption spectrum correction method according to claim 3, wherein the calculation means performs correction processing based on the standard spectrum. Irradiating the human skin surface with infrared light from the infrared light irradiation part through the sample contact part,
Detecting infrared light reflected from the human skin surface and transmitted through the sample contact portion;
In the detected infrared light, the contribution of infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion contact, and the infrared absorption by the skin at the non-contact portion where the skin surface and the sample contact portion do not contact each other A step of performing correction processing by a calculation means for correcting the contribution, and a step of analyzing the skin composition based on the infrared absorption spectrum obtained by the correction processing;
A method for analyzing skin composition, comprising:   Infrared absorption spectrum is measured in a state where a liquid having a refractive index of 1.3 to 1.6 is arranged between the human skin surface and the sample contact portion, and the skin of the contact portion where the skin surface and the sample contact portion are in contact with each other A standard spectrum of human skin is created by performing a correction process on the contribution of infrared absorption by and the contribution of infrared absorption by the liquid present in the non-contact part where the skin surface and the sample contact part do not contact, The skin composition analysis method according to claim 5, wherein correction processing is performed in the calculation means based on the standard spectrum. A sample contact portion that contacts the human skin surface;
An infrared irradiation unit that irradiates the human skin surface with infrared light through the sample contact unit;
Infrared light detection means for detecting infrared light reflected from the human skin surface and transmitted through the sample contact portion;
In the detected infrared light, the contribution of infrared absorption by the skin at the contact portion where the skin surface and the sample contact portion contact, and the infrared absorption by the skin at the non-contact portion where the skin surface and the sample contact portion do not contact each other Arithmetic means for correcting the contribution,
An infrared absorption spectrum measuring apparatus. Infrared absorption spectrum is measured in a state where a liquid having a refractive index of 1.3 to 1.6 is arranged between the human skin surface and the sample contact portion, and the skin of the contact portion where the skin surface and the sample contact portion are in contact with each other A standard spectrum of human skin is created by performing a correction process on the contribution of infrared absorption by and the contribution of infrared absorption by the liquid present in the non-contact part where the skin surface and the sample contact part do not contact, The infrared absorption spectrum measuring apparatus according to claim 7, wherein correction processing is performed in the calculation means based on the standard spectrum.