JPS6235621B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the concentration of aromatic hydrocarbons contained in gasoline, and particularly relates to a method for measuring the concentration of aromatic hydrocarbons contained in gasoline. This relates to a simple measuring method that can determine the concentration of aromatic hydrocarbons.

It has long been known that when the concentration of aromatic hydrocarbons contained in gasoline is abnormally high, it has an adverse effect on the fuel piping systems of automobiles, etc., and for this reason, even gas stations have been disposing of aromatic hydrocarbons in gasoline. It is desirable to measure and understand the hydrocarbon concentration as necessary.

Generally, the concentration of aromatic hydrocarbons in gasoline is measured by gas chromatography, fluorescence analysis, mass spectrometry, etc., but all of these methods require expensive and large-scale equipment. Not only are these methods necessary, but they also require a high degree of training in analytical operations, but these methods are difficult for people who are not proficient in analytical operations, such as gas station attendants, to adopt. .

The present invention was developed against the background of the above, and its purpose is to enable people without specialized knowledge in analysis, such as gas station personnel, dealer service personnel, and owner-drivers, to easily analyze gasoline. An object of the present invention is to provide an analysis method that can easily, quickly, and inexpensively measure the concentration of aromatic hydrocarbons in a sample. In order to achieve this object, the present invention involves immersing a plate for thin layer chromatography on which an indicator that can be moved by aromatic hydrocarbons is immersed in gasoline as an analytical sample. The distance traveled by the indicator on the plate is measured by developing the indicator using a developing solution, and then, based on the measured value, the relationship between the aromatic hydrocarbon concentration and the distance traveled by the indicator determined in advance is calculated. This method is characterized in that the concentration of aromatic hydrocarbons in gasoline is determined.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A more detailed explanation will be given below based on the drawings showing an apparatus suitable for carrying out the present invention.

FIG. 1 is a sectional view showing a state in which a thin layer plate is loaded into a measuring device configured to carry out the present invention.
First, the configuration of this device will be explained.

In the figure, reference numeral 1 denotes a container for containing a thin layer plate 2 and a sample gasoline, and is composed of a cylindrical portion 4 that is open at both ends, and a bottom lid portion 5. The cylindrical portion 4 includes an elongated neck portion 6 and a container portion 7 extending downward from the neck portion 6. The content of the neck 6 is larger than the width of the laminar plate, and the container part 7 has a larger inner diameter than the neck 6, making it suitable for accommodating the laminar plate 2 and gasoline, respectively.

The bottom lid part 5 consists of a container part 7, a fitting part 8 to be fitted on the outer circumferential surface of the container part 7, and a bottom part 9 with a flat back surface. , a constant volume section 12 recessed on the base section 11 and capable of accommodating only a fixed volume of gasoline is formed. This constant volume section 12 is configured to accommodate a predetermined volume of gasoline by means of a wall 13 erected along the outer peripheral edge of the base section 11 . In addition, in this example device, so that 5 ml of gasoline can be stored,
The height of the wall 13 and the top area of the platform 11 are selected.

In general, it is desirable that the container 1, which further comprises the cylinder part 4 and the bottom lid part 5, be made of a transparent material such as glass. Of course, it is also possible to form it from material.

Further, 14 is fitted to the upper end of the neck portion 6 and is inserted into the container 1.
It is a cap and holder that seals the thin layer plate 2 and holds the thin layer plate 2, and is made of an elastic material such as rubber. In the center of the cap and holder 14,
A rectangular through hole is provided into which the thin layer plate 2 can be inserted under a predetermined elastic force.

As the thin layer plate used in this method, a permanent plate whose surface is coated with an adsorbent such as silica gel that does not easily peel off is preferably used. A coloring indicator such as an aldehyde derivative of 2.4 DNPH (dinitrophenylhydrazine) is spotted on the thin layer plate 2 at a predetermined position (position A in the figure) determined from the bottom end. This indicator may be anything that can be moved by aromatic hydrocarbons, in other words, in proportion to the concentration of aromatic hydrocarbons in gasoline, and is limited to only the aldehyde derivatives of 2,4DNPH mentioned above. It's not a thing.

A method for measuring the aromatic hydrocarbon concentration in a sample gasoline using the apparatus configured as described above will be described below.

First, the container 1 consisting of the cylindrical part 4 fitted into the bottom lid part 5 is placed on a horizontal table, and the thin plate 2 is inserted into the through hole of the cap/holder 14 to hold it. At this time, the thin plate 2 is inserted to a position where the lower end of the thin plate 2 does not touch the gasoline in the fixed container 12 when the cap/holder 14 is fitted into the neck as described later. Next, about 10 ml of sample gasoline is collected using a dropper or the like, and this is discharged into the constant volume section 12. The constant volume section 12 stores a predetermined amount of gasoline, here 5 ml, and the remainder overflows and is stored in the container section 7.

Next, after fitting the cap/holder 14 that holds the thin plate 2 into the neck part 4, push the thin plate 2 in until its lower end reaches the top surface of the base part 11, and then Gently immerse in gasoline. At the same time, gasoline rises above the thin layer plate 2 due to capillarity. When the gasoline reaches the spot point of the indicator (ie, point A in FIG. 1), the indicator also starts to rise as the gasoline rises. This increase in the indicator is based on the affinity for aromatic hydrocarbons in gasoline, and the rate and distance of increase depend on the concentration of aromatic components in the sample gasoline.

When the gasoline reaches a predetermined position B (marked) on the thin layer plate 2, the cap/holder 14 holding the thin layer plate 2 is quickly pulled out to complete the unfolding operation. Then, the thin layer plate 2 is taken out from the cap/holder 14, and the rising distance of the indicator is measured. Comparing the measured values obtained in this way with the calibration curve separately obtained in advance shown in Figure 2, that is, the calibration curve showing the relationship between the aromatic hydrocarbon content and the distance traveled by the indicator, it is found that Aromatic hydrocarbon content (%)
can be found extremely easily. In addition, the second
The calibration curve shown in the figure plots the distance traveled by the indicator against the aromatic hydrocarbon content when the indicator is deployed with gasoline of known concentration containing aromatic hydrocarbons at various concentrations. The horizontal axis shows the aromatic hydrocarbon content (%), and the vertical axis shows the distance traveled by the indicator (mm). Therefore, by reading the value on the horizontal axis at one point on the calibration curve that corresponds to the above-mentioned measured value of the sample gasoline, it is possible to determine the desired aromatic hydrocarbon.
This means the content. As a result of experiments, it has been confirmed that the measurement accuracy of this method is about ±5% in the aromatic hydrocarbon content range of 15 to 50%.

As is well known, gasoline contains several types of aromatic hydrocarbons, the typical components of which are toluene, xylene, and benzene. When we examine the moving distance (Rf value) when changing it within a range of %, we get the results shown in Figure 5. However, the measurement conditions are as follows.

Thin layer plate: Yamato Replate50 (manufactured by Yamato Scientific Co., Ltd.) Deployment distance: 80mm Spot component: Decanal 2.4DNPH Temperature: 20±5℃ Therefore, as is clear from Figure 5, even if the aromatic component changes, it will move. The difference in distance is extremely small, and its effect on quantitative values can be ignored.

As mentioned above, the concentration of aromatic hydrocarbons in gasoline can be measured by using the method described above. Moreover, in this method, after supplying an appropriate amount of gasoline into the container 1, the thin layer plate 2
The operation is extremely simple, and the aromatic hydrocarbon content can be measured with high precision in a very short time because the measurement can be performed by simply loading and extracting the aromatic hydrocarbon into a container.

In particular, one of the things we have achieved with this Act is that
Although the thin layer chromatography method, which is relatively easy to operate, was skillfully utilized, the major feature of this method is that it goes even further by using the sample to be measured as the developing solution. It is possible to omit operations such as adjusting, spotting a sample, or spraying an indicator after deployment, simplifying measurement operations,
Along with this, errors in the spot position of the sample, errors in adjusting the developing solution due to two or more components often used in thin layer chromatography, and changes in the concentration of the developing solution due to volatilization of specific components after adjustment, etc. Factors that would cause measurement errors could be eliminated, and a method could be provided that would allow even those who are not proficient in analytical operations to perform measurements with desired accuracy.

The device used in this embodiment includes a cylinder part 4, a bottom lid part 5, and a cap/holder 14 that can be disassembled and assembled.
It is easy to handle, and it is also easy to drain the gasoline and clean the container after measurement. Further, since the bottom cover part 5 is provided with the stand part 11 and the constant volume part 12, the volume of the sample to be collected does not require strictness, contributing to accuracy and ease of work. It should be noted that it is not essential that such a device be disassembled, and it is also possible to use an integrated container as shown in FIG.

Next, other embodiments of the present invention will be described.

FIG. 4 shows a thin layer plate 21 used in this embodiment, and a numerical value 22 indicating the aromatic hydrocarbon concentration corresponding to a predetermined height position on the thin layer plate 21 is graduated.

Therefore, when the indicator is raised using the thin plate 21 in the same manner as described above, the aroma in the gasoline will change from the position of the indicator when the gasoline reaches position B in FIG. Group hydrocarbon content can be read immediately. Therefore, this embodiment has the advantage that operations such as removing the thin layer plate 21, measuring the moving distance of the indicator, and converting the calibration curve to the aromatic hydrocarbon content are omitted, further simplifying the measurement operation. be.

As described in detail above, the present invention involves immersing a plate for thin layer chromatography on which an indicator is spotted in gasoline, and measuring the aromatic hydrocarbon content in the gasoline from the distance the indicator is raised by the gasoline. By using such a method, even those who do not have specialized knowledge of analysis can check aromatic components in gasoline, and the measurement operation is facilitated.
This simplifies the process and has excellent effects such as reducing the cost required for measurement.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of an apparatus suitable for implementing the method of the present invention, FIG. 2 is a diagram showing a calibration curve, and FIG. 3 is a cross-sectional perspective view showing another example of the apparatus for implementing the present invention.
FIG. 4 is a front view of a thin layer plate used in another embodiment of the invention. FIG. 5 is a graph showing the relationship between aromatic component concentration and migration distance (Rf value). 1: Container, 2, 21: Thin layer plate, 4: Cylinder part, 5: Bottom cover part, 12: Fixed volume part, 22: Scale. 〓〓〓〓

Claims (1)

[Claims] 1. A plate for thin layer chromatography on which an indicator that can be moved by aromatic hydrocarbons is spotted is immersed in gasoline as an analysis sample, and the indicator is developed using the gasoline as a developing liquid. to measure the distance traveled by the indicator on the plate, and then based on such measurements,
A measuring method characterized in that the aromatic hydrocarbon concentration in the gasoline is determined from the relationship between the aromatic hydrocarbon concentration and the indicator travel distance determined in advance.