JP2012088242A - Quantitative method for fatty acid on surface of metal microparticle - Google Patents
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本発明は、金属微粒子の表面に存在する脂肪酸の定量方法、特に表面処理によって金属微粒子に付着した脂肪酸を定量する方法に関する。 The present invention relates to a method for quantifying fatty acids present on the surface of metal fine particles, and more particularly to a method for quantifying fatty acids attached to metal fine particles by surface treatment.
金や銅などの各種金属微粒子は、有機・無機複合材料である導電性接着剤や導電性ペーストなどの電子材料に幅広く利用されている。これらの金属微粒子は粒子径が１０〜１０００ｎｍ程度のナノ粒子であり、表面が活性なため、粒子同士が凝集しないように脂肪酸で表面処理されている場合が多い。そのため、表面処理された金属微粒子を導電性接着剤や導電性ペーストに適用した場合には、表面処理剤である脂肪酸の残留によって抵抗値が上昇する場合がある。従って、表面処理した金属微粒子に付着残留している脂肪酸を定量的に把握することが重要である。 Various metal fine particles such as gold and copper are widely used in electronic materials such as conductive adhesives and conductive pastes, which are organic / inorganic composite materials. Since these metal fine particles are nanoparticles having a particle diameter of about 10 to 1000 nm and the surface is active, they are often surface-treated with a fatty acid so that the particles do not aggregate. Therefore, when the surface-treated metal fine particles are applied to a conductive adhesive or a conductive paste, the resistance value may increase due to the residual fatty acid as the surface treatment agent. Therefore, it is important to quantitatively grasp the fatty acid remaining on the surface-treated metal fine particles.
金属微粒子に付着している脂肪酸を定量する方法としては、金属微粒子を硝酸で溶かしてフーリエ変換核磁気共鳴分光法を用いる方法を適用することが考えられる（特許文献１参照）。しかし、この方法では、例えば脂肪酸が非水溶性の高級脂肪酸の場合には溶液と分離してしまうため、定量することができないという問題を有している。他の方法として金属微粒子中の全炭素量を分析する燃焼法の利用も考えられるが、脂肪酸以外の有機成分が存在した場合には、両者を分離できないという問題がある。 As a method for quantifying the fatty acid adhering to the metal fine particles, a method using Fourier transform nuclear magnetic resonance spectroscopy after dissolving the metal fine particles with nitric acid can be considered (see Patent Document 1). However, this method has a problem that, for example, when the fatty acid is a water-insoluble higher fatty acid, it is separated from the solution and cannot be quantified. As another method, the use of a combustion method for analyzing the total amount of carbon in the metal fine particles is also conceivable, but there is a problem that when organic components other than fatty acids are present, the two cannot be separated.
一方、人の皮膚の構成成分である脂肪酸を定量する方法として、人の皮膚に有機アルカリ溶液を添加してパイロホイルに包埋した後、誘導加熱して皮膚中の脂肪酸を脂肪酸アルキルエステルに変え、ガスクロマトグラフまたはガスクロマトグラフ質量分析計で定量する方法が知られている（特許文献２および特許文献３参照）。 On the other hand, as a method of quantifying fatty acids that are constituents of human skin, after adding organic alkaline solution to human skin and embedding in pyrofoil, induction heating converts fatty acid in the skin to fatty acid alkyl ester, A method of quantifying with a gas chromatograph or a gas chromatograph mass spectrometer is known (see Patent Document 2 and Patent Document 3).
上記特許文献２および特許文献３に記載された熱分解ガスクロマトグラフィーを利用する脂肪酸の定量方法は、人の皮膚の脂肪酸を定量する場合は有効な方法であるが、金属微粒子表面の脂肪酸の定量に利用すると、誘導加熱により脂肪酸から生成された脂肪酸アルキルエステルの測定値が測定ごとに変動してしまい、金属微粒子の脂肪酸を正確に定量することは困難であった。 The method for quantifying fatty acids using pyrolysis gas chromatography described in Patent Document 2 and Patent Document 3 is an effective method for quantifying fatty acids in human skin. When used for the above, the measured value of the fatty acid alkyl ester generated from the fatty acid by induction heating varies from measurement to measurement, and it is difficult to accurately determine the fatty acid of the metal fine particles.
本発明は、上記した従来技術の問題点に鑑み、表面処理などにより金属微粒子の表面に付着残留している脂肪酸の量を、液体クロマトグラフ分析装置を利用して正確に定量する方法を提供することを目的とする。 The present invention provides a method for accurately quantifying the amount of fatty acid remaining on the surface of metal fine particles by surface treatment or the like using a liquid chromatographic analyzer in view of the above-described problems of the prior art. For the purpose.
本発明者は、液体クロマトグラフ分析装置を利用して金属微粒子に付着している脂肪酸を定量する方法について鋭意研究を重ねた結果、有機溶媒と酸性水溶液とを用いて金属微粒子から脂肪酸を効率的に抽出できる事を見出し、本発明を完成するに至ったものである。 As a result of extensive research on a method for quantifying fatty acids adhering to metal fine particles using a liquid chromatographic analyzer, the present inventor has found that fatty acids are efficiently extracted from metal fine particles using an organic solvent and an acidic aqueous solution. As a result, the inventors have found that it can be extracted, and have completed the present invention.
すなわち、本発明が提供する金属微粒子表面の脂肪酸の定量方法は、金属微粒子表面に付着している脂肪酸を定量する際に、有機溶媒と酸性水溶液とを用いて金属微粒子から脂肪酸を抽出し、得られた抽出液を液体クロマトグラフ分析装置へ導入して脂肪酸を定量分析することを特徴としている。 That is, the method for quantifying fatty acid on the surface of metal fine particles provided by the present invention is obtained by extracting fatty acid from metal fine particles using an organic solvent and an acidic aqueous solution when quantifying the fatty acid adhering to the surface of metal fine particles. The extracted liquid is introduced into a liquid chromatograph analyzer and the fatty acid is quantitatively analyzed.
上記本発明による金属微粒子表面の脂肪酸の定量方法においては、前記有機溶媒が、メタノール、アセトニトリル、テトラヒドロフラン、Ｎ，Ｎ−ジメチルホルムアミドから選ばれる少なくとも１種であることが好ましい。また、前記酸性水溶液で使用する酸が、塩酸、硝酸、硫酸、りん酸、蟻酸、酢酸から選ばれる少なくとも１種であることが好ましい。 In the method for quantifying fatty acids on the surface of metal fine particles according to the present invention, the organic solvent is preferably at least one selected from methanol, acetonitrile, tetrahydrofuran, and N, N-dimethylformamide. The acid used in the acidic aqueous solution is preferably at least one selected from hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, formic acid, and acetic acid.
さらに、上記本発明による金属微粒子表面の脂肪酸の定量方法において、前記抽出は、金属微粒子に有機溶媒を添加した後、酸性水溶液を添加することが好ましく、前記金属微粒子が、金、銀、銅、白金、パラジウム、ロジウム、ルテニウム、亜鉛から選ばれる少なくとも１種からなる。 Furthermore, in the method for quantifying fatty acids on the surface of metal fine particles according to the present invention, the extraction is preferably performed by adding an organic solvent to the metal fine particles, and then adding an acidic aqueous solution, and the metal fine particles include gold, silver, copper, It consists of at least one selected from platinum, palladium, rhodium, ruthenium and zinc.
本発明によれば、有機溶媒と酸性水溶液とによってほぼ完全に金属微粒子から脂肪酸を抽出することができ、得られた抽出液を液体クロマトグラフ分析法で測定することによって脂肪酸を正確に定量分析することができる。よって、表面処理により金属微粒子表面に付着した脂肪酸の量を高い再現性で定量することができる。 According to the present invention, fatty acids can be extracted from metal fine particles almost completely with an organic solvent and an acidic aqueous solution, and fatty acids are accurately quantitatively analyzed by measuring the obtained extract with a liquid chromatographic analysis method. be able to. Therefore, the amount of fatty acid attached to the surface of the metal fine particles by the surface treatment can be quantified with high reproducibility.
本発明による金属微粒子表面に付着している脂肪酸の定量方法は、例えば以下の（１）〜（６）の操作手順に従って行うことができる。
（１）脂肪酸で表面処理された金属微粒子から所定量を重量で量り取って容器に採取する。
（２）この容器内に所定量の有機溶媒を入れて振とうし、有機溶媒と金属微粒子とを混合する。
（３）さらに、この容器内に所定の濃度の酸性水溶液を所定量添加し、所定の時間攪拌・混合して脂肪酸を抽出する。
（４）上記（３）の抽出処理完了後、容器を静置して固液分離し、上澄み液を採取する。得られた上澄み液を１段目の抽出液とする。
（５）上記（４）で上澄み液を採取した後に残る残渣分に対して、上記（２）〜（４）と同様の操作を繰り返し、得られた上澄み液を２段目の抽出液とする。
（６）上記（４）および（５）で得られた１段目と２段目の抽出液を別々に液体クロマトグラフ分析装置へ導入し、脂肪酸を検出する。
The method for quantifying fatty acids adhering to the surface of the metal fine particles according to the present invention can be performed, for example, according to the following operation procedures (1) to (6).
(1) A predetermined amount is weighed out from metal fine particles surface-treated with a fatty acid and collected in a container.
(2) A predetermined amount of an organic solvent is placed in the container and shaken to mix the organic solvent and the metal fine particles.
(3) Further, a predetermined amount of an acidic aqueous solution having a predetermined concentration is added to the container, and the fatty acid is extracted by stirring and mixing for a predetermined time.
(4) After completion of the extraction process of (3) above, the container is allowed to stand to separate into solid and liquid, and the supernatant is collected. The obtained supernatant is used as the first stage extract.
(5) The same operation as in (2) to (4) above is repeated for the residue remaining after collecting the supernatant in (4) above, and the resulting supernatant is used as the second stage extract. .
(6) The first-stage and second-stage extracts obtained in (4) and (5) above are separately introduced into a liquid chromatograph analyzer, and fatty acids are detected.
本発明で用いる有機溶媒は、脂肪酸を溶解する事ができ、水と容易に混合し得るものであれば種々のものを使用することができる。例えば、メタノール、エタノール、１−プロパノール、２−プロパノールなどのアルコール系溶媒、アセトンなどのケトン系溶媒、エチレングリコールモノメチルエーテル、エチレングリコールモノエチルエーテル、エチレングリコールモノブチルエーテル、エチレングリコールモノメチルエーテルアセテート、プロピレングリコールメチルエーテル、ジエチレングリコールモノメチルエーテル、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノブチルエーテル、ジエチレングリコールジメチルエーテル、ジエチレングリコールジエチルエーテルなどのグリコール誘導体、ホルムアミド、Ｎ−メチルホルムアミド、Ｎ，Ｎ−ジメチルホルムアミド、ジメチルアセトアミド、ジメチルスルフォキシド、Ｎ−メチル−２−ピロリドン、４−ブチロラクトン、エチレングリコール、ジエチレングリコール、アセトニトリル、テトラヒドロフラン等を挙げることができるが、これらに限定されるものではない。また、有機溶媒にはこれらを２種類以上混合して用いてもかまわない。 Various organic solvents can be used as long as they can dissolve fatty acids and can be easily mixed with water. For example, alcohol solvents such as methanol, ethanol, 1-propanol, 2-propanol, ketone solvents such as acetone, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, propylene glycol Glycol derivatives such as methyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, formamide, N-methylformamide, N, N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N -Methyl-2-pi Pyrrolidone, 4-butyrolactone, ethylene glycol, diethylene glycol, acetonitrile, although and tetrahydrofuran, but is not limited thereto. In addition, two or more of these may be used as the organic solvent.
但し、本発明では、液体クロマトグラフ(以下、「ＨＰＬＣ」とも称する)で測定する際に、有機溶媒と脂肪酸の保持時間が重ならない事が望まれる。したがって、有機溶媒としては、ＨＰＬＣの溶離液として汎用的に用いられるメタノール、アセトニトリル、テトラヒドロフラン、Ｎ，Ｎ−ジメチルホルムアミドから選ばれる少なくとも１種が特に望ましい。これらの有機溶媒を用いれば、有機溶媒由来のピーク強度を抑制でき、なお且つ、有機溶媒と脂肪酸との保持時間の重なりを軽減できる。 However, in the present invention, it is desirable that the retention times of the organic solvent and the fatty acid do not overlap when measured by a liquid chromatograph (hereinafter also referred to as “HPLC”). Therefore, the organic solvent is particularly preferably at least one selected from methanol, acetonitrile, tetrahydrofuran, and N, N-dimethylformamide, which are generally used as an eluent for HPLC. If these organic solvents are used, the peak intensity derived from the organic solvent can be suppressed, and the overlap of the retention times of the organic solvent and the fatty acid can be reduced.
さらに、脂肪酸の炭素数が長くなる、すなわち、高級脂肪酸になるにつれて極性溶媒への溶解度が低下していくため、脂肪酸中に高級脂肪酸が含まれる場合は、非プロトン性極性溶媒であるアセトニトリル、テトラヒドロフラン、Ｎ，Ｎ−ジメチルホルムアミドを有機溶媒に用いることが特に望ましい。 Furthermore, since the number of carbon atoms of the fatty acid becomes longer, that is, the solubility in the polar solvent decreases as the fatty acid becomes higher, when the fatty acid is contained in the fatty acid, acetonitrile, tetrahydrofuran, which are aprotic polar solvents It is particularly desirable to use N, N-dimethylformamide as the organic solvent.
本発明で用いる酸性水溶液は、上記有機溶媒で抽出しきれなかった金属微粒子最表面の脂肪酸を、金属微粒子表面を酸によって僅かに溶解することで完全に抽出するために添加するものである。これにより、脂肪酸の抽出率を上げることができる。ここで使用する酸は、金属微粒子を溶解することができるのであれば様々なものを使用することができる。 The acidic aqueous solution used in the present invention is added in order to completely extract the fatty acid on the outermost surface of the metal fine particles that could not be extracted with the organic solvent by slightly dissolving the surface of the metal fine particles with an acid. Thereby, the extraction rate of a fatty acid can be raised. Various acids can be used as long as they can dissolve metal fine particles.
例えば、塩酸、硝酸、硫酸、りん酸、蟻酸および酢酸などを挙げることができるが、これらに限定されるものではない。また、酸はこれらの２種以上を使用してもかまわない。酸性水溶液の濃度は、金属微粒子を僅かに溶解する事ができれば良く、通常はＨＰＬＣ法で使用するカラムの適正ｐＨ範囲内にあれば特に問題になることはない。 For example, hydrochloric acid, nitric acid, sulfuric acid, phosphoric acid, formic acid, acetic acid and the like can be mentioned, but are not limited thereto. Two or more of these acids may be used. The concentration of the acidic aqueous solution is not particularly limited as long as the metal fine particles can be slightly dissolved, and is usually within the proper pH range of the column used in the HPLC method.
本発明では、金属微粒子に上記有機溶媒と酸性水溶液とを添加して脂肪酸の抽出を行う。その際、初めに有機溶媒を添加してから酸性水溶液を添加する事が望ましい。これは、前述したように酸性水溶液の添加の目的が金属微粒子表面の溶解であり、この順序で添加することで酸と金属微粒子との接触効率がより向上するためである。ちなみに、酸を先に加えた場合は、金属微粒子表面の一部が過度に溶解して活性面が露出し、金属微粒子同士が凝集し易くなるため、脂肪酸が金属微粒子の凝集体中に取り込まれて抽出効率が低下するおそれがある。 In the present invention, the fatty acid is extracted by adding the organic solvent and the acidic aqueous solution to the metal fine particles. At that time, it is desirable to add the organic solvent first and then the acidic aqueous solution. This is because, as described above, the purpose of adding the acidic aqueous solution is to dissolve the surface of the metal fine particles, and the contact efficiency between the acid and the metal fine particles is further improved by adding in this order. By the way, when the acid is added first, a part of the surface of the metal fine particles is excessively dissolved to expose the active surface, and the metal fine particles are likely to aggregate, so that the fatty acid is taken into the aggregate of the metal fine particles. This may reduce the extraction efficiency.
なお、有機溶媒と酸性水溶液とを予め混合し、得られた混合液を金属微粒子に添加して抽出を行う場合は、酸を先に加えた場合と同じ状況となって抽出効率が低下するおそれがある。 In addition, when an organic solvent and an acidic aqueous solution are mixed in advance and extraction is performed by adding the obtained mixed liquid to metal fine particles, the extraction situation may be reduced in the same situation as when acid is added first. There is.
上記操作手順では、２段目の抽出液を得るとき、上澄み液を採取した後の残渣分にそのまま有機溶媒と酸性水溶液とを添加したが、残渣分を水洗すると、付着している脂肪酸が水洗水に移行する可能性があるので水洗は好ましくない。水洗水として溶離液を用いこれを抽出液に混ぜれば脂肪酸が回収されるのでこのような手法で洗浄を行っても良い。また、抽出液を残渣分から分離する方法は、静置に限定されるものではなく、遠心分離やろ過などの一般的な固液分離法を使用してもよい。 In the above operation procedure, when obtaining the second stage extract, the organic solvent and the acidic aqueous solution were added to the residue after collecting the supernatant, but when the residue was washed with water, the attached fatty acid was washed with water. Washing with water is not preferred because it may migrate to water. Since the fatty acid is recovered by using an eluent as washing water and mixing this with the extract, washing may be performed by such a method. Further, the method for separating the extract from the residue is not limited to standing, and a general solid-liquid separation method such as centrifugation or filtration may be used.
本発明による定量方法が測定対象としている金属微粒子は、金、銀、銅、白金、パラジウム、ロジウム、ルテニウム、亜鉛から選ばれる１種の金属、または２種以上からなる合金であるが、これらに限定されるものではない。 The metal fine particles to be measured by the determination method according to the present invention are one kind of metal selected from gold, silver, copper, platinum, palladium, rhodium, ruthenium and zinc, or an alloy composed of two or more kinds. It is not limited.
本発明では、有機溶媒と酸性水溶液とを用いて抽出して得た抽出液に対してＨＰＬＣ法を適用し、脂肪酸の定量分析を行う。ＨＰＬＣ法とは、試料を分離カラムへ導入し、試料中に含まれる複数の分析対象成分を、それらの分離カラム中の充填剤との相互作用の差異を利用して互いに分離した後、紫外可視分光光度計や示差屈折率計等によって分析するものである。 In the present invention, the HPLC method is applied to the extract obtained by extraction using an organic solvent and an acidic aqueous solution, and the fatty acid is quantitatively analyzed. In the HPLC method, a sample is introduced into a separation column, a plurality of components to be analyzed contained in the sample are separated from each other by utilizing the difference in interaction with the packing material in the separation column, and then UV-visible. Analysis is performed using a spectrophotometer, a differential refractometer, or the like.
１段目と２段目の抽出液を用いて脂肪酸の定量分析を行う場合は、１段目と２段目の抽出液を別々にＨＰＬＣ装置に導入して脂肪酸のピーク面積をそれぞれ算出し、それらの総和を、同じ条件で予め測定した脂肪酸のピーク面積から作成した検量線を用いて定量する。なお、１段目と２段目の抽出液のそれぞれの分析結果に大きな差がない場合は、これらに大きな差異が認められるまで、３段目以降の抽出処理を繰り返すのが望ましい。 When the fatty acid quantitative analysis is performed using the first and second stage extracts, the first and second stage extracts are separately introduced into the HPLC apparatus to calculate the fatty acid peak areas, These sums are quantified using a calibration curve created from the peak areas of fatty acids measured in advance under the same conditions. In addition, when there is no big difference in each analysis result of the 1st stage and the 2nd stage extract, it is desirable to repeat the extraction process after the 3rd stage until a big difference is recognized in these.
上記した本発明の定量方法によれば、金属微粒子表面に付着残留している脂肪酸の全てを確実に離脱させて、液体クロマトグラフ分析装置で正確に定量することができる。実際に、既知量の脂肪酸が付着している金属微粒子を用い、上記した定量方法に基づいて脂肪酸の定量を行い、脂肪酸の回収率を確認したところ１０４％であった。この結果から、金属微粒子から脂肪酸が完全に脱離することが確認された。 According to the above-described quantification method of the present invention, it is possible to reliably detach all the fatty acids adhering and remaining on the surface of the metal fine particles and accurately quantify them with a liquid chromatograph analyzer. Actually, fatty acid was quantified based on the above-described quantification method using metal fine particles to which a known amount of fatty acid was adhered, and the fatty acid recovery rate was confirmed to be 104%. From this result, it was confirmed that the fatty acid was completely detached from the metal fine particles.
脂肪酸で表面処理された各種金属微粒子について、上記した本発明の定量方法に従って金属微粒子表面に付着残留している脂肪酸の量を測定した。なお、ＨＰＬＣ分析装置は（株）島津製作所製のものを用い、分離カラムはＳｈｏｄｅｘ製のＲＳｐａｋ ＲＰ１８−４１３（１５０ｍｍ×４.６ｍｍｉ.ｄ.、粒径３.５μｍ）を２本使用し、恒温槽：４０℃、流速：１ｍｌ／ｍｉｎ、溶離液：水／アセトニトリル（容量比）＝１／９の条件で測定した。ここで、水／アセトニトリル＝１／９とした理由は、水／アセトニトリル＝２／８の場合は、脂肪酸が溶けきらない状況となったからである。また、検出器には示差屈折率計を用いた。 About the various metal fine particles surface-treated with the fatty acid, the amount of the fatty acid remaining on the surface of the metal fine particles was measured according to the above-described quantitative method of the present invention. The HPLC analyzer used was manufactured by Shimadzu Corporation, and two separation columns, RSpak RP18-413 (150 mm × 4.6 mmid, particle size 3.5 μm) manufactured by Shodex, were used at a constant temperature. Measurement was performed under the conditions of a bath: 40 ° C., a flow rate: 1 ml / min, and an eluent: water / acetonitrile (volume ratio) = 1/9. Here, the reason why water / acetonitrile = 1/9 is that when water / acetonitrile = 2/8, the fatty acid is not completely dissolved. A differential refractometer was used as the detector.
［実施例１］
脂肪酸で表面処理した銀微粒子を１ｇ量り取って容器に入れ、この容器内にアセトニトリルを９ｍｌ添加して数秒間振とうし、さらに濃度０.３６質量％の塩酸水溶液（３６質量％の試薬塩酸を容量比で１００倍希釈したもの）を１ｍｌ添加して数秒間振とうし、次にガス抜きを行った後、超音波洗浄器を用いて３０分間攪拌・混合して脂肪酸の抽出を行なった。抽出処理完了後、スラリー液を含む容器を静置して固液分離した後、上澄み液をメスピペットで採取した。
[Example 1]
1 g of silver fine particles surface-treated with a fatty acid are weighed and placed in a container, 9 ml of acetonitrile is added to the container and shaken for a few seconds, and further a 0.36 mass% hydrochloric acid aqueous solution (36 mass% reagent hydrochloric acid is added). 1 ml of a solution diluted 100-fold by volume ratio) was added and shaken for several seconds. Next, after degassing, the mixture was stirred and mixed for 30 minutes using an ultrasonic cleaner to extract fatty acids. After completion of the extraction process, the container containing the slurry liquid was allowed to stand and solid-liquid separation was performed, and then the supernatant liquid was collected with a measuring pipette.
上澄み液を採取した後に残る残渣分に対して、上記したアセトニトリルと塩酸水溶液の添加、振とう、ガス抜き、超音波洗浄器による脂肪酸の抽出までの操作をもう一回繰り返した。このようにして、１段目および２段目の上澄み液（試料１）を得た。これら上澄み液を別々にＨＰＬＣ装置へ導入して脂肪酸をそれぞれ測定した。得られた脂肪酸が与えるピーク面積を総和し、予め作成した検量線を用いて定量した。なお、２段目の上澄み液の定量値は、１段目の上澄み液の定量値に比較して１／１０以下であったため、３段目以降の抽出処理は行わなかった。 For the residue remaining after collecting the supernatant, the above-described operations from addition of acetonitrile and aqueous hydrochloric acid, shaking, degassing, and extraction of fatty acid by an ultrasonic cleaner were repeated once more. In this way, first and second supernatant liquids (sample 1) were obtained. These supernatants were separately introduced into the HPLC apparatus and the fatty acids were measured. The peak areas given by the obtained fatty acids were summed and quantified using a calibration curve prepared in advance. In addition, since the quantitative value of the supernatant liquid in the second stage was 1/10 or less as compared with the quantitative value of the supernatant liquid in the first stage, the third and subsequent extraction processes were not performed.
また、脂肪酸で表面処理された金属微粒子を、銀微粒子に代えて亜鉛微粒子としたこと以外は上記試料１と同様にして試料２の１段目および２段目の上澄み液を得た。さらに、脂肪酸で表面処理された金属微粒子を、それぞれ金微粒子、銅微粒子、白金微粒子、パラジウム微粒子、および金−銀合金微粒子とし、酸性水溶液には塩酸と硝酸の混合液を使用したこと以外は上記試料１と同様にして、試料３〜７の１段目および２段目の上澄み液を得た。 Further, the first and second supernatant liquids of Sample 2 were obtained in the same manner as Sample 1 except that the metal fine particles surface-treated with fatty acids were replaced with zinc fine particles instead of silver fine particles. Further, the metal fine particles surface-treated with fatty acid are gold fine particles, copper fine particles, platinum fine particles, palladium fine particles, and gold-silver alloy fine particles, respectively, except that a mixed liquid of hydrochloric acid and nitric acid is used as the acidic aqueous solution. In the same manner as Sample 1, the first and second supernatant liquids of Samples 3 to 7 were obtained.
さらに、脂肪酸で表面処理された金属微粒子に、Ｃ１８以上の炭素鎖を持つ高級脂肪酸を含む脂肪酸で表面処理した銀微粒子を用いたこと以外は試料１と同様にして、試料８の１段目および２段目の上澄み液を得た。そして、比較例として、酸性水溶液を使用せずにアセトニトリルのみで抽出したこと以外は試料１と同様にして、試料９の１段目および２段目の上澄み液を得た。これら試料２〜９についても、試料１と同様にしてＨＰＬＣ装置を用いた脂肪酸の分析を行った。これら試料１〜９の分析結果を下記の表１に示す。なお、表１中の脂肪酸の定量値は、金属微粒子の重量（ｇ）当たりの脂肪酸の重量（μｇ）で示した（下記表２も同じ）。 Further, in the same manner as Sample 1 except that silver fine particles surface-treated with a fatty acid containing a higher fatty acid having a C18 or higher carbon chain were used as the metal fine particles surface-treated with a fatty acid. A second supernatant liquid was obtained. As a comparative example, the first and second supernatant liquids of Sample 9 were obtained in the same manner as Sample 1 except that the extraction was performed only with acetonitrile without using an acidic aqueous solution. For Samples 2 to 9, fatty acids were analyzed in the same manner as Sample 1 using an HPLC apparatus. The analysis results of these samples 1 to 9 are shown in Table 1 below. In addition, the quantitative value of the fatty acid in Table 1 was shown by the weight (μg) of the fatty acid per weight (g) of the metal fine particles (the same applies to Table 2 below).
上記表１の結果から、本発明に係る定量方法に従って測定を行った試料１では、表面処理された銀微粒子の脂肪酸を高い再現性で定量分析できることが分かった。これは、有機溶媒と酸性水溶液とをこの順序で添加することによって金属微粒子から脂肪酸を効率的に抽出できたことによるものと考えられる。 From the results of Table 1 above, it was found that Sample 1 measured according to the quantification method of the present invention can quantitatively analyze the fatty acid of the surface-treated silver fine particles with high reproducibility. This is considered to be because the fatty acid was efficiently extracted from the metal fine particles by adding the organic solvent and the acidic aqueous solution in this order.
また、金属微粒子の種類を変えた試料２、および金属微粒子の種類と酸性水溶液の種類の両方を変えた試料３〜７においても、本発明に係る定量方法に従えば脂肪酸を定量的に把握できることが分かった。さらに、Ｃ１８以上の炭素鎖を持つ高級脂肪酸を含む脂肪酸で表面処理した試料８においても、本発明に係る定量方法に従えば脂肪酸を定量的に把握できることが分かった。なお、金属微粒子の種類によって脂肪酸の定量値が異なるのは、それぞれの微粒子の粒度分布、表面積あるいは酸・塩基度の違いなどにより脂肪酸が付着する度合いが異なるためである。 Further, in Sample 2 in which the type of metal fine particles is changed, and also in Samples 3 to 7 in which both the type of metal fine particles and the type of acidic aqueous solution are changed, the fatty acid can be quantitatively grasped according to the quantitative method according to the present invention. I understood. Furthermore, it was found that even in the sample 8 surface-treated with a fatty acid containing a higher fatty acid having a C18 or higher carbon chain, the fatty acid can be quantitatively grasped according to the quantification method according to the present invention. The reason why the fatty acid quantitative value differs depending on the type of metal fine particles is that the degree of adhesion of fatty acids varies depending on the particle size distribution, surface area, or acid / basicity of each fine particle.
これに対して、酸性水溶液を使用せずにアセトニトリルのみで抽出した試料９では、試料１に比べて定量値が大きく低下して正確な定量ができなかった。これは金属微粒子最表面の脂肪酸が抽出できなかったことによると考えられる。 On the other hand, the sample 9 extracted with only acetonitrile without using the acidic aqueous solution had a lower quantitative value than the sample 1 and could not be accurately quantified. This is probably because the fatty acid on the outermost surface of the metal fine particles could not be extracted.
［実施例２］
この実施例２では、上記実施例１の試料１と同じ銀微粒子に対して試料１とは異なる条件で抽出し、その脂肪酸の定量値に与える影響を調べた。すなわち、有機溶媒と酸性水溶液の添加順序が脂肪酸の定量値に与える影響を調べるため、塩酸水溶液を最初に添加した後にアセトニトリルを添加したこと以外は試料１と同様にして、試料１０の１段目および２段目の上澄み液を得た。
[Example 2]
In Example 2, the same silver fine particles as in Sample 1 of Example 1 were extracted under conditions different from those of Sample 1, and the influence on the fatty acid quantitative value was examined. That is, in order to investigate the effect of the addition order of the organic solvent and the acidic aqueous solution on the quantitative value of the fatty acid, the first step of the sample 10 was performed in the same manner as the sample 1 except that acetonitrile was added after the hydrochloric acid aqueous solution was first added. And the second supernatant liquid was obtained.
また、有機溶媒の種類が脂肪酸の定量値に与える影響を調べるため、アセトニトリルに代えてメタノールを使用したこと以外は試料１と同様にして、試料１２の１段目および２段目の上澄み液を得た。 Moreover, in order to investigate the influence which the kind of organic solvent has on the quantitative value of fatty acid, the supernatant liquids of the first and second stages of the sample 12 were obtained in the same manner as in the sample 1 except that methanol was used instead of acetonitrile. Obtained.
さらに、酸性水溶液の種類が脂肪酸の定量値に与える影響を調べるため、塩酸水溶液に代えてりん酸水溶液を用いたこと以外は試料１と同様にして、試料１１の１段目および２段目の上澄み液を得た。りん酸水溶液の濃度は０.０８５質量％（８５質量％の試薬りん酸を容量比で１０００倍希釈したもの）である。これら試料１０〜１２の上澄み液についても、実施例１と同様にしてＨＰＬＣ装置を用いて脂肪酸の分析を行った。なお、試料１１については、溶離液に水／メタノール（容量比）＝１／９を用いた。得られた結果を、上記実施例１の試料１の結果と共に下記の表２に示す。 Furthermore, in order to investigate the influence of the kind of the acidic aqueous solution on the quantitative value of the fatty acid, the first and second steps of the sample 11 were performed in the same manner as the sample 1 except that a phosphoric acid aqueous solution was used instead of the hydrochloric acid aqueous solution. A supernatant was obtained. The concentration of the aqueous phosphoric acid solution is 0.085% by mass (85% by mass of reagent phosphoric acid diluted 1000 times by volume). The supernatants of Samples 10 to 12 were also analyzed for fatty acids using an HPLC apparatus in the same manner as in Example 1. For sample 11, water / methanol (volume ratio) = 1/9 was used as the eluent. The obtained results are shown in Table 2 below together with the results of Sample 1 of Example 1 above.
上記表２から分かるように、試料１０〜１２においては、脂肪酸の定量値が実施例１の試料１と比較して大きく低下している。この定量値の低下の理由は、試料１０では金属微粒子表面の一部が溶解して活性面が露出し、金属微粒子同士が凝集しため、脂肪酸が金属微粒子の凝集体中に取り込まれたためと考えられる。また、試料１１では、高級脂肪酸のメタノールへの溶解度が低いためと考えられる。さらに、試料１２では、りん酸によって溶解できない金属微粒子であったため、金属微粒子最表面の脂肪酸が抽出できなかったためと考えられる。 As can be seen from Table 2 above, in Samples 10 to 12, the quantitative value of the fatty acid is greatly reduced as compared to Sample 1 of Example 1. The reason for the decrease in the quantitative value is considered to be that, in Sample 10, a part of the surface of the metal fine particles was dissolved to expose the active surface, and the metal fine particles were aggregated together, so that the fatty acid was taken into the aggregate of the metal fine particles. It is done. In Sample 11, it is considered that the higher fatty acid has low solubility in methanol. Furthermore, in Sample 12, it was considered that the fatty acid on the outermost surface of the metal fine particle could not be extracted because it was a metal fine particle that could not be dissolved by phosphoric acid.
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| WO2017170023A1 (en) | 2016-03-28 | 2017-10-05 | 協立化学産業株式会社 | Coated silver particle, production method therefor, conductive composition, and conductive body |
| JP2017187475A (en) * | 2016-04-01 | 2017-10-12 | 住友金属鉱山株式会社 | Method for evaluating amount of oligomer in polyimide resin |
| CN109387585A (en) * | 2018-10-23 | 2019-02-26 | 江汉大学 | The method of content of fatty acid in gas-chromatography, mass spectrometric hyphenated technique detection nematode |
| WO2020059461A1 (en) | 2018-09-20 | 2020-03-26 | 協立化学産業株式会社 | Composition for sealing |
| CN112748196A (en) * | 2020-12-23 | 2021-05-04 | 上海微谱化工技术服务有限公司 | Method for determining content of fatty acid by derivatization |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2017170023A1 (en) | 2016-03-28 | 2017-10-05 | 協立化学産業株式会社 | Coated silver particle, production method therefor, conductive composition, and conductive body |
| JP2017187475A (en) * | 2016-04-01 | 2017-10-12 | 住友金属鉱山株式会社 | Method for evaluating amount of oligomer in polyimide resin |
| WO2020059461A1 (en) | 2018-09-20 | 2020-03-26 | 協立化学産業株式会社 | Composition for sealing |
| CN109387585A (en) * | 2018-10-23 | 2019-02-26 | 江汉大学 | The method of content of fatty acid in gas-chromatography, mass spectrometric hyphenated technique detection nematode |
| CN112748196A (en) * | 2020-12-23 | 2021-05-04 | 上海微谱化工技术服务有限公司 | Method for determining content of fatty acid by derivatization |
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