JPH09243563A - Analysis of organic matter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the Raman spectal analysis of org. matter with high sensitivity by using a Raman spectral analyser having a laser light source of specific capacity, a spectroscope and a detector. SOLUTION: As a laser light supply to be used, any one with output of 40-150mW may be used and, in the case of 40mW or less, sufficient sensitivity is not obtained and, in the case of 150mW or more, a sample is damaged. The wavelength of the laser light supply is pref. within a visible light region of 450-800nm in order to prevent the damage of org. matter and to enhance spatial resolving power in the measurement of a minute part and, for example, argon ion laser is used. As a spectroscope, a spectral system using one with throughput of 15% or more, for example, a Rayleigh's cut filter and a spectral monochrometer is used. As a detector, one with quantum efficiency of 50% or more, for example, a back thinned MPP type CCP detector taking out a signal from the rear of a light detection surface is used. By this constitution, the damage of the sample is reduced and the Raman spectral analysis of org. matter with high spatial resolving power and high sensitivity becomes possible.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for analyzing Raman active groups in an organic substance using a Raman spectroscope. More specifically, the present invention relates to a method for analyzing a trace amount of organic matter or a minute portion of organic matter by using a Raman spectroscopic apparatus in which a laser having a specific output is used as an excitation light source, a spectroscope having a specific throughput and a detector having a specific quantum efficiency are combined.

[0002]

2. Description of the Related Art Raman spectroscopy is generally used as a method for analyzing a chemical structure from its natural vibration using Raman scattering from a substance. Infrared spectroscopy is currently the most popular method of analysis using natural vibrations, but Raman spectroscopy can detect infrared-inert natural vibrations, and it can be used to analyze chemical structures. Play complementary roles. However, Raman scattering is extremely weak in intensity as compared with Rayleigh scattering that occurs at the same time, and its detection was extremely difficult until the first half of the 20th century.

However, since the latter half of the 1960s, the development of a Raman spectroscope using a laser as an excitation light source and a double or triple spectroscope and a photomultiplier tube has made Raman spectroscopy a practical analysis method. The above laser has high output and good directivity, and is an ideal light source for Raman scattering. In addition, in a Raman spectroscope using a double or triple spectroscope, about 10% of the Raman scattering generated in the measurement sample reaches the detector while eliminating Rayleigh scattering.

However, when the sample to be analyzed is an organic substance, the Raman scattering intensity is weak as described above and the sample is easily thermally or optically damaged. The analysis could not be performed accurately. That is, when the sample is an inorganic substance, it is possible to increase the laser output in order to increase the sensitivity, but when the sample is an organic substance, the sample is burned or subjected to thermal denaturation, and If the laser output is weakened in order to avoid this, a long time measurement of several hours is required, which causes defocusing, and measurement with high spatial resolution is virtually impossible.

[0005]

From the above points, it has been desired to develop a method for analyzing a Raman active group of a trace amount of an organic matter or a minute portion of an organic matter with a high spatial resolution without damaging the sample.

[0006]

The inventors of the present invention have conducted extensive studies to overcome the above-mentioned problems, and as a result, have detected a laser light source having a specific output range, a spectroscope having a specific throughput and a specific quantum efficiency. By combining the vessels,
The inventors have found that it is possible to carry out Raman analysis of a trace amount of organic substances or minute portions of organic substances without damaging the sample, and completed the present invention.

That is, the present invention has an output of 40 mW to 150 m.
W laser light source, spectrometer with throughput of 15% or more,
A Raman spectroscopic analyzer having a detector with a quantum efficiency of 50% or more is used to measure the Raman active group in the organic matter, which is an organic matter analysis method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The laser light source used in the present invention has an output of 40 mW to at a wavelength used for measurement.
There is no particular limitation as long as it is 150 mW, and a general one can be used. That is, the output of the laser light source is 40
If it is smaller than mW, sufficient sensitivity cannot be obtained even if the other constitutions of the present invention are satisfied, and the object of the present invention cannot be achieved. Depending on the size of the sample spot to be irradiated, such output is 40 mW or more, preferably 60 mW.
The above is suitable. Further, when the output exceeds 150 mW, damage to the sample is unavoidable.

The wavelength of the laser light source is not particularly limited, but a visible light region of 450 to 800 nm is preferable for the purpose of preventing damage to organic substances and improving the spatial resolution in the measurement of minute parts, for example, an argon ion laser. And helium neon laser are listed.

The spectrometer of the present invention has a throughput of 15%.
As described above, if it is preferably 20% or more, there is no particular limitation, and a known spectroscope can be adopted. The throughput is a numerical value indicating what percentage of Raman scattering generated in the measurement sample reaches the detector, and indicates the brightness of the spectroscopic system existing from the sample to the detector.

If the throughput is less than 15%,
Sufficient sensitivity is not obtained even if the other configurations of the present invention are satisfied,
The object of the present invention cannot be achieved.

As a spectroscope having a throughput of 15% or more, a spectroscopic system using a Rayleigh cut filter and a monochromator for spectroscopy can be mentioned in order to remove a strong Rayleigh line.

The detector used in the present invention is not particularly limited as long as the quantum efficiency is 50% or more, but a spectroscope having a quantum efficiency of 70% or more can be preferably used. As an example of such a detector, there is a backsind-MPP type CCD detector that takes out a signal from the back side of the light receiving surface, instead of the usual front illuminated type.

The method of the present invention is characterized by measuring a Raman active group in an organic substance by using the Raman spectroscopic analyzer having the above-mentioned specific performance, but the effect of the present invention is more remarkable. The measurement time is an example of the measurement condition suitable for exerting the above effect.

That is, according to the present invention, it is possible to set the measurement time to a short time, and in particular, the measurement time is 2 seconds to 2 minutes, preferably 5 seconds to 1 per pixel.
By setting the number of minutes, defocus of the measurement can be eliminated, extremely high spatial resolution can be achieved, and the Raman active group in the organic substance can be measured with high sensitivity. Also, 50 to 100 ° C
The measurement time required for an organic substance having a low melting point of about 60 ° C. and a polymer having a low softening temperature of about 50 to 150 ° C. is effective,
It enables Raman spectroscopic analysis of these substances, which was impossible in the past.

In this case, the beam spot diameter of the laser light source used is 2 μm or less, preferably about 1 μm, which is suitable for achieving high spatial resolution and high sensitivity.

Further, the measurement temperature is not particularly limited,
It is also possible to measure at room temperature when measuring the low-melting point organic matter and the low-softening temperature polymer.

The organic substance to be measured in the present invention is not particularly limited, and its shape can be any of lump, film, powder and liquid. Furthermore, a mixture of an organic substance and an inorganic substance can also be a measurement target. The amount of the organic substance in the mixture of the organic substance and the inorganic substance is not particularly limited, but when the content of the organic substance is 10% by weight or more, preferably 20% by weight or more,
In particular, highly sensitive analysis according to the present invention is possible.

The Raman active group that can be analyzed by the method of the present invention is a functional group that generates Raman scattering at a specific position from the wavelength of the light (Rayleigh scattering) when the light for excitation is irradiated. That is, for example, saturated or unsaturated aliphatic hydrocarbon groups, saturated or unsaturated aromatic hydrocarbon groups, oxygen-containing groups such as hydroxyl groups, oxy groups, formyl groups, alkoxycarbonyl groups, carboxyl groups, amino groups, Nitrogen-containing groups such as imino groups, carbonitrile groups and nitrilo groups, sulfur-containing groups such as mercapto groups, thio groups, alkylsulfone groups and sulfonic acid groups, phosphorus-containing groups such as phosnico groups and phosphonos,
Examples thereof include silicon-containing groups such as silyl groups and siloxy groups, halogen-containing groups, and the like.

According to the method of the present invention, high sensitivity is achieved for Raman spectroscopic analysis of an organic sample, and as described above, it is possible to analyze a trace amount of organic component.

Therefore, it is possible to apply such an analysis method to an application field where Raman spectroscopic analysis with a small beam spot diameter could not be performed conventionally. For example, it becomes possible to quantitatively analyze the residual double bond derived from unreacted monomer present in a trace amount in the polymer, the residual double bond amount and the strength of the polymer, and in the case of a polymer having adhesiveness, It is possible to investigate the correlation between the residual double bond of the polymer and the physical properties and applied physical properties of the polymer such as the residual double bond and the adhesiveness. It is also possible to evaluate.

In the quantitative analysis of the residual double bond, a calibration curve of the intensity of Raman spectrum at a specific wavelength and the amount of double bond is prepared in advance, and the double bond of The quantity can be calculated.

Further, in the above application, in the case of applying to the evaluation of the physical properties of the polymer obtained by photopolymerization, the laser light acts on the photopolymerization initiator remaining in the polymer to polymerize the unreacted monomer. May progress, and the amount of double bonds remaining during analysis may change. In such a case, in order to eliminate the influence of the laser as the laser light source, it is preferable to irradiate a wavelength away from the absorption end of the photopolymerization initiator. For example, when a camphorquinone compound having an absorption end of 380 to 520 nm is used as a photopolymerization initiator, the absorbance is 0.002 or less, and the wavelength is 632 nm, which is 10 nm or more away from 520 nm.
It is preferable to use the helium-neon laser as a light source.

[0024]

According to the method of the present invention, it is possible to perform Raman spectroscopic analysis of an organic substance with high sensitivity in a state where a sample is less damaged and a high spatial resolution. In particular, it is advantageous in Raman spectroscopic analysis by so-called microscopic Raman spectroscopy, which has a small laser spot diameter.

As a result, for example, it becomes possible to analyze the microcrystalline structure of polyethylene or the like, the structural analysis of the multilayer structure, and the analysis of minute foreign substances, which are carried out by the above-mentioned micro Raman spectroscopy.

Further, by measuring various Raman active groups existing in the adhesive at the interface between the adhesive and the adherend, it is possible to clarify the permeation state of the adhesive into the adherend, and It can also be used as a method for evaluating agents.

Further, the analysis method of the present invention is suitable for the analysis of organic substances that are easily affected by temperature, because the heat generation of the sample due to laser light irradiation is small.

That is, by using the method of the present invention, it is possible to perform Raman spectroscopic analysis of a trace amount of an organic substance or a minute portion of an organic substance while the sample is less damaged.

Further, it becomes possible to perform Raman spectroscopic analysis of organic substances having a low melting point and polymers having a low softening temperature, which have been difficult to measure conventionally.

[0030]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

The spectroscopic analyzer used in the examples is a micro Raman spectroscopic device SYS manufactured by Renishaw Co., Ltd. in England.
TEM-2000 type, helium-neon laser manufactured by NEC Corporation and Bucksind manufactured by WRIGHT in the US
It was equipped with an MPP type CCD detector, and a Rayleigh cut filter was used for the spectroscopic system, whereby the throughput was 25% or more, and the laser output was 75 mW at 632 nm. The quantum efficiency is 60% or more in the measurement wavelength region.

Example 1 FIG. 1 is a Raman spectrum of a polyethylene film containing 0.7% of a phthalate-based additive, measured by this method. The laser output is 75 mW and the measurement time is 20 seconds per pixel.

As a result, in addition to the strong peak derived from polyethylene, 617, 1580, 1598 due to the aromatic ring
cm ^-1 peak and 17 of the alkoxycarbonyl group
A peak at 25 cm ^-1 was clearly confirmed, and it was found that a phthalate ester-based additive was contained. In this measurement, no abnormality was found on the sample surface, and it was confirmed that there was no damage.

Example 2 FIG. 2 shows the spatial resolution (measurement area on the sample surface) of 1 μm × 1.
The analysis result of the dentin joint interface of the dental adhesive when it is set to μm is shown. The measurement time is 50 seconds per pixel. The sample is bonded with bovine tooth dentin and restoration composite resin "Palfique Esterite (trade name: manufactured by Tokuyama Co., Ltd.)" bonded with an adhesive "Tokuso Mac Bond (trade name: manufactured by Tokuyama Co., Ltd.)". It cut | disconnected by the surface perpendicular | vertical to an interface, and the cut surface was mirror-polished and used. The adhesive contains camphorquinone (absorption end: 520 nm) as a photopolymerization initiator.

As a result, as shown in FIG. 2, 637 cm.
^-1 was the adhesive component, 960 cm ^-1 was the dentin hydroxyapatite, and 1638 cm ^-1 was the peak due to the remaining double bonds. In this way, the behavior of the adhesive penetrating into the adherend and polymerizing and curing can be analyzed, which is also effective as an evaluation method of the adhesive.

Example 3 The same sample used in Example 2 was used as a laser light source with an argon ion laser having an output of 100 mW and a wavelength of 515 nm, and the same Raman spectroscopic apparatus as in Example 2 was used under the same conditions as in Example 2. It was measured at.

As a result, a spectrum similar to that of Example 2 was obtained except that only the peak showing the remaining double bond at 1638 cm ⁻¹ was detected at 80% of the corresponding peak area of Example 2 in that peak area. was gotten.

Comparative Example 1 FIG. 3 shows the same sample as used in Example 1 with an output of 20 mW.
Helium-neon laser and C with a quantum efficiency of 35%
It is a Raman spectrum measured by a Raman spectroscope equipped with a CD detector (throughput: 25%).

As shown in FIG. 3, the peak of the additive confirmed in Example 1 is buried in noise and is not clear.

[Brief description of drawings]

FIG. 1 is a Raman spectrum obtained in Example 1.

FIG. 2 is a Raman spectrum obtained in Example 2.

FIG. 3 is a Raman spectrum obtained in Comparative Example 1.

Claims (1)

[Claims] 1. A laser light source having an output of 40 mW to 150 mW, a spectrometer having a throughput of 15% or more, and a quantum efficiency of 50%.
A method for analyzing an organic substance, which comprises measuring a Raman active group in the organic substance using the Raman spectroscopic analyzer having the above detector.