JPS61225650A - Solvent analysis - Google Patents

Abstract

PURPOSE:To achieve a higher identification accuracy, by employing a connected column which has columns respectively packed with particulate material having polyethylene glycol with the average molecular weight of 6,000 and having a dimethylsiloxane polymer with 25% thereof substituted by a phenyl group adsorbed on respective carriers as stationary liquid arranged on the sample injection side and on the sample detection side thereof respectively to be connected in series. CONSTITUTION:This method employs a connected column in which a column packed with particulate material having polyethylene glycol with the average molecular weight of 6,000 adsorbed on a carrier as stationary liquid is arranged on the sample injection side and a column packed with particulate material having particulate material a dimethylsiloxane polymer with 25% thereof substituted by a phenyl group adsorbed on a carrier as stationary liquid on the sample detection side thereof to be connected in series. The carrier herein used is appropriately those made of cerrite, especially diatomaceous earth. The stationary liquids are diluted by an organic solvent to be added to a carrier and allowed to dry until the organic solvent is scattered, where the amount thereof attached to the carrier is preferably about 20wt%. The column temperature shall be about 120-150 deg.C while the flow rate of a carrier gas about 40-60ml/min and the use of helium gas is appropriate.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for analyzing solvents by gas chromatography using a connected column in which columns of different types are connected in series.

[Conventional technology]

Conventionally, when analyzing single solvents, mixed solvents, and mixtures of these solvents used in paints by gas chromatography, polyethylene glycol (hereinafter abbreviated as PEG) with an average molecular weight of 6000 was adsorbed onto a carrier as a stationary phase liquid. Attach a column packed with granules to a gas chromatograph, or attach a column packed with granules with a carrier coated with a dimethylsiloxane polymer (hereinafter abbreviated as DC) in which 25% of the particles are substituted with phenyl groups to a gas chromatograph. When an analysis is performed, it is simply a matter of which column to use.
They are appropriately selected and used depending on the polarity of the solvent, mixed solvent, and constituent solvent components of the solvent mixture.

However, recently, paints have become more diverse, the types of solvents used have increased, and their polarities have become wider.

In the analysis of solvents, the first thing that is required is to separate the solvent components contained in the mixed solvent or solution mixture. One such separation method is to connect in series multiple columns packed with particles in which the same type of stationary phase liquid is adsorbed onto a carrier to increase the length of the force ram itself (hereinafter referred to as the first method). , A method in which a column with new properties is created by mixing two or more types of stationary phase liquids and filling them with particles that are adsorbed onto a carrier (hereinafter referred to as the second method), and analysis is performed while changing the temperature of the column. method (hereinafter referred to as the third method), a method in which analysis is performed while changing the carrier gas flow rate (
(hereinafter referred to as the 4th Law), etc.

[Problem that the invention seeks to solve]

When mixed solvents or solvent mixtures are analyzed using methods 1 and 2 above, it is common for one peak to appear from one solvent component, but as the types of solvent components increase, they are not completely separated. First, several types of solvent components appeared as one peak, and a problem remained in the accuracy of solvent identification.

In particular, compared to the first method, the second method not only requires more skill in preparing the column, but also requires more complicated analysis operations. Further, the accuracy of the third method and the fourth method is extremely low compared to the solvent identification accuracy of the first method and the second method. When we examined the identification accuracy by applying the first method to a sample containing 9 types of single solvents using PEG as the stationary phase liquid, we found that the probability of 6 independent peaks appearing was 100%. On the other hand, the probability that seven independent peaks will appear has decreased to 50%, and as a result of conducting a similar test using [)C, the probability that four independent peaks will appear is 100%, but 5 The probability that two independent peaks will appear decreases rapidly to 38%.

In addition, when examining the identification accuracy of the second method, which is a sample in which PEG and DC are mixed equally, and this is used as the stationary phase liquid, and nine types of single solvents are mixed as above, the probability that five independent peaks will appear is as follows. However, the probability of six independent peaks appearing was 30%, meaning that several types of single solvents were not separated, making it difficult to identify the type of solvent.

[Means for solving problems]

As a result of various studies, the present inventors have discovered that analysis of solvents containing a large number of solvent components can be carried out by connecting in series two columns filled with particles each having a different stationary phase liquid attached to a carrier. It was discovered that the # degree was improved, and the present invention was completed.

That is, the present invention provides a method for analyzing a solvent using a gas chromatograph, in which a column filled with particles of polyethylene glycol having an average molecular weight of 6,000 attached to a carrier is placed on the sample injection side as a stationary phase liquid, and 25% of the stationary phase liquid is used as a stationary phase liquid. This is a solvent analysis method that uses a connected column in which a column filled with particles of dimethylsiloxane polymer substituted with phenyl groups adsorbed onto a carrier is connected in series to the detection side.

As the carrier used here, one made from celite, especially diatomaceous earth, is suitable. Then, the stationary phase liquid is diluted with an organic solvent, added to the carrier, and thoroughly dried at room temperature while stirring until the organic solvent is scattered, and the amount of Attachment II to the carrier is 15 to 25 Ifi%, preferably 20% by weight. .

The temperature of the column is suitably 120 DEG -150 DEG C., and the carrier gas flow rate is about 40 DEG/min - 60 d/min. As the carrier gas, known carrier gases are widely used, but helium gas is suitably used.

The solvent to be analyzed in the present invention is a solvent containing multiple solvent components.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples and Comparative Examples.

Example 1 and Comparative Examples 1 to 5 9 of sec-butyl alcohol, methyl ethyl ketone, ethyl acetate, methyl isobutyl ketone, sec-butyl acetate, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether acetate, cyclohexanone Samples were prepared by mixing equal weights of different single solvents.

The structure of the column is as follows, and in the case of two connected columns, the connection order from the sample injection side to the detection side is shown. The stationary phase liquid used was a polyethylene glycol having an average molecular weight of 6000, commercially available as PEG6000, and a dimethylcyxane polymer with 25% of phenyl groups substituted, commercially available as DC550, manufactured by PerkinElmer.

Example 1 A column made of DC550 was connected to a column whose stationary phase liquid was made of PEG6000.

Comparative Example 1 Two columns in which the stationary phase liquid was DC550 were used.
A concatenation of individual pieces.

Comparative Example 2 A column in which the stationary phase liquid was made of [)C550 was connected to a column made of PEG6000 (Example 1 was reversed).

Comparative Example 3 Two columns in which the stationary phase liquid was PEG6000 were connected.

Comparative Example 4 Two columns were connected in which the stationary phase liquid was a mixture of equal amounts of PEG6000 and DC550.

Comparative Example 5 One column in which the stationary phase liquid was DC550 was
Personally used.

Comparative Example 6 One column in which the stationary phase liquid was PEG6000 was used.

Comparative Example 7 One column was used in which the stationary phase liquid was an equal mixture of PEG6000 and DC550.

Using these columns, gas chromatograph analysis was performed under the following measurement conditions.

Measurement conditions Equipment: Shimadzu Corporation, GO-4APT type detector Temperature: 250°C Column temperature: 120°C, 150°C Sample injection part temperature: 200°C Carrier gas: Helium carrier gas flow ffi: 40 relatives/min, 60 d /min Sample injection time: 3- Column size: 3M diameter x 3m length/Carrier for adsorbing this stationary phase liquid: Diatom ± (trade name: Celite 545 manufactured by Johns Manville) Particles in which the stationary phase liquid is adsorbed on a carrier Packing into one column 1:8! IF Particle size of particles with stationary phase liquid adsorbed on carrier: 60-80
Adsorption of mesh stationary phase liquid onto carrier 1: 20% by weight From the obtained spectrum, the number of independent peaks was determined, and the effect of different columns was analyzed by the cumulative method.

As a result, the probability (%) of the number of independent peaks appearing is:
It is shown in Table 1.

Among the nine types of single solvents, the solvents whose peaks approach and overlap each other differ depending on the column temperature, carrier gas flow rate, and column type. Therefore, it is necessary to select a column that can produce many peaks even when the column temperature and carrier gas flow rate vary.

As is clear from Table 1 in Table 1 below, in Example 1 of the present invention, even if the column temperature and carrier gas flow rate were changed, 9! The probability that a solvent mixture of a single solvent I can be separated into 9 parts is 50%, indicating that at worst it can be separated into 8 or more parts,
It can be seen that the separation ability is much better than that of Comparative Examples 1 to 7.

Example 2 and Comparative Examples 8 to 10 Propyl alcohol, isobutyl alcohol, isobutyl alcohol, sec-butyl alcohol, benzene, toluene, heptane, diethyl ketone, methyl isobutyl ketone, methyl ethyl ketone, methyl propyl ketone, ethyl acetate, butyl acetate, isobutyl acetate , sec-butyl acetate were used.

The structure of the column is as follows, and in the case of two connected columns, the connection order from the sample injection side to the detection side is shown.

The stationary phase liquid used was the same as in Example 1 and Comparative Examples 1-7.

Example 2 A column in which the stationary phase liquid was made of PEG6000 was connected to a column made of DC550.

Comparative Example 8 The stationary phase liquid was P on a column consisting of DC550.
A combination of columns made of EG6000.

Comparative Example 9 One column in which the stationary phase liquid was DC550 was
Personally used.

Comparative Example 10 One column in which the stationary phase liquid was made of PEG6000 was used.

Using these columns, gas chromatograph analysis was performed under the same measurement conditions as in Example 1 and Comparative Examples 1 to 7. The absolute retention capacities obtained are shown in Table 2.

Table 2 in the margin below Absolute retention capacity is the value obtained by subtracting the time from the time the sample is injected until individual peaks appear (retention capacity) to the time it takes for air contained in the sample to come out. It is shown that the larger the spread of the holding capacity, the larger the difference in the absolute holding capacity between each single solvent. Therefore, it shows that the solvent separation ability is good.

Statistical analysis was performed using the absolute retention capacity as a characteristic value, and the S/N ratio, which is a statistical analysis method commonly used to judge the superiority of test methods, was determined as follows.

Example 2 SN ratio -37.7::db Comparative example 8
SN ratio = 25.2±:::db Comparative example 9 SN ratio = 29.2 ± 2.7 db3.8 Comparative example 10 SN ratio = 32. g+z・7db-3,
8 A quantitative comparison of analysis accuracy is obtained from the above S/N ratios, and the following is found.

That is, the separation capacity of Example 2 was about 13 times that of Comparative Example 8, about 7 times that of Comparative Example 9, and about 7 times that of Comparative Example 10. It can be seen that the separation capacity is about three times that of the previous capacity.

Example 3 and Comparative Example 11 Petroleum-based mixed solvents having a wide range of distillation ranges are often used in paints. This mixed solvent contains many components, and the types of constituent solvent components may differ not only depending on the manufacturer but also depending on the production lot.

In the analysis of paints and thinners using these petroleum-based mixed solvents, it is absolutely necessary to reduce the overlap of peaks and increase the number of peaks in order to perform analysis with excellent accuracy.

Now, referring to the results of Example 2 and Comparative Examples 8 to 10, and since the column using PEG6000 used in Comparative Example 10 is currently the most widely used column, as Example 3, the stationary phase liquid was Using a column made of PEG6000 connected to a column made of DC550, and as Comparative Example 11, using one column whose stationary phase liquid was made of PEG6000, seven types of petroleum-based mixed solvents were analyzed under the following measurement conditions. As a result, gas chromatographs shown in FIGS. 1 to 14 were obtained.

Mixed solvent A: Rubber volatile oil, manufactured by Kyodo Sekiyu Co., Ltd. B: Medium-boiling aromatic petroleum naphtha, Swasol #310,
Maruzen Sekiyu Co., Ltd. C: Mineral Spirit, Kyodo Sekiyu Co., Ltd. D: Aliphatic solvent, MK Solvent, Kyodo Sekiyu Co., Ltd. E: Gasoline W, Kyodo Sekiyu Co., Ltd. F: High-boiling aromatic oil Natsuta, Tsurpets 150 Exxon Chemical Co., Ltd. G: High boiling point solvent, Pegasol AN-45, Tonen Petrochemical Co., Ltd. Measurement conditions Column temperature = 150°C Kiselya gas flow rate: 40 d/min Recording sensitivity: Example 3 647 FLv Comparative Example 11
128 mV Recording speed: Example 3 10 darkness/min Comparative example 11 20 aaV/min Other measurement conditions are the same as in Example 1 and Comparative Examples 1 to 5.

When the number of peaks observed in FIGS. 1 to 14 was calculated, the results were as shown in Table 3.

Table 3 As is clear from Table 3, Example 3 has more peaks than Comparative Example 11.

Although the peak obtained in Example 3 does not necessarily indicate all the component solvents contained in the mixed solvent,
Two to three times as many peaks as Comparative Example 11 were obtained, which means that Example 3 had two to three times higher analytical accuracy than Comparative Example 11.

〔Effect of the invention〕

The present invention uses PEG as a stationary phase liquid, i.e., an average molecular weight of 1900
A column packed with granules with 0% polyethylene glycol adsorbed onto a carrier was placed on the sample injection side, and DC was used as the stationary phase liquid.
In other words, by using a connected column in which a column filled with particles of dimethylsiloxane polymer with 25% phenyl group adsorption adsorbed on a carrier was connected in series to the detection side, nine types of dimethylsiloxane polymers, as clarified in the examples, were used. The probability that eight independent peaks will appear for a sample mixed with a single solvent is 1
00%, the probability of 9 independent peaks appearing is 50%
In addition, in the case of a sample containing a mixture of 15 types of single solvents, PE
The separation capacity was approximately 3 times that of using one G-only column, and about 7 times that of one DC-only column. In the case of petroleum-based mixed solvents, two to three times as many peaks appear as in the case of a single column containing only PEG, so it is easy to understand that the separation ability of sample solvent components is Even if the types of solvent components increase, regardless of changes in column temperature or carrier gas flow rate, many independent peaks will appear depending on the component, making it easier to identify component solvents and improving identification accuracy for high-quality analysis. The effect of obtaining results has been recognized.

[Brief explanation of the drawing]

1 to 14 show gas chromatography of seven types of petroleum-based various mixed solvents A to G carried out in Example 3 and Comparative Example 11. Patent applicant: Nippon Oil & Fats Co., Ltd. Representative Patent Attorney Katsu Ohno Rei Ohno Figure 2 Broom 3 Figure 6 Figure 8 Figure 9 Figure 10 Figure 11 Figure 12 Figure 13 Figure 14 (public)

Claims (1)

[Claims] In a method for analyzing solvents using gas chromatography, a column filled with particles of polyethylene glycol with an average molecular weight of 6000 adsorbed onto a carrier is used as the stationary phase liquid on the sample injection side, and 25% of the stationary phase liquid is substituted with phenyl groups. 1. A method for analyzing a solvent containing multiple solvent components, characterized by using a connected column in which a column packed with particles in which a dimethylsiloxane polymer is adsorbed onto a carrier is connected in series to the detection side.