Radiant energy – Ionic separation or analysis – With sample supply means
Reexamination Certificate
2003-06-10
2004-08-03
Nguyen, Kiet T. (Department: 2881)
Radiant energy
Ionic separation or analysis
With sample supply means
Reexamination Certificate
active
06770877
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method for analyzing vapors generated from explosives, and an analysis apparatus for use in the method. More specifically, it relates to an analysis method and an analysis apparatus each preferably used for the stability test of an old explosive.
Deterioration of explosives due to secular changes and the like affects the aspect of performances, for example, in such a manner as to make a prescribed explosion power unobtainable. In addition, it increases the fear of causing spontaneous ignition or an incidental explosion accident. The explosives are affected by temperature, humidity, and light, and the speed of deterioration varies according to the storage state. Therefore, for explosives, it is difficult to understand the degree of its deterioration only by the length of time elapsed after manufacturing.
Conventionally, at the site of manufacturing and storage of explosives, examination of deterioration of explosives is carried out by the Abel heat test method. Below, a description will be given to the Abel heat test method adopting an explosive containing nitrate ester as an example by reference to
FIGS. 9 and 10
.
FIG. 9
is a schematic diagram of an apparatus
90
for carrying out the Abel heat test. A reference numeral
91
denotes a container for containing therein prescribed-temperature hot water. The container
91
includes a test tube
92
for filling therein an analysis sample, and a thermometer
93
for determining the bath hot water temperature. On the other hand,
FIG. 10
is a schematic diagram for illustrating the test tube
92
. The upper part of the test tube
92
is attached with a rubber stopper
94
including a glass rod
94
a
. The lower end of the glass rod
94
a
is provided with a potassium iodide starch paper
94
c
suspended from a platinum wire
94
b
in the form of key.
The Abel heat test method is carried out by means of the apparatus shown in
FIGS. 9 and 10
in the following manner. First, a proper amount of the sample is collected into the test tube
92
as it is when the explosive containing nitrate ester of the sample is in granular form, or in small pieces when it is a large-size explosive in square, band, or string form or other form (not shown). When the sample has taken up moisture, previously, it is sufficiently dried by vacuum drying or the like at ordinary temperature, and then collected into the test tube
92
. Subsequently, the test tube
92
is stopped by the rubber stopper
94
including the glass rod
94
a
having the test paper
94
c
. At this step, the upper half part of the test paper
94
c
is dampened with a half-and-half mixed solution of distilled water and glycerin. Subsequently, the test tube
92
is set in the apparatus
90
as shown in FIG.
9
. Herein, a marked line
92
a
given on the test tube
92
in
FIG. 10
denotes the critical position of the hot water bath upper surface when the test tube
92
is set in the apparatus
90
, a marked line
92
b
denotes the actual hot water bath upper surface position, and a marked line
92
c
denotes the position at a height ⅓ of the height of the test tube
92
. Whereas, in the container
91
, a prescribed amount of prescribed-temperature, generally 65° C. bath hot water is previously charged.
The analysis is carried out in the following manner. The test tube
92
is mounted at a prescribed position of the apparatus
90
, and then, the length of time elapsed until the color tone with the same density as that of a standard paper occurs at the dry-wet boundary portion of the test paper
94
c
is determined. This determined time is taken as the heat resistant time, so that the deterioration states of explosives are determined according to this time.
Such a prior-art Abel heat test method has the following problems.
First, in the deterioration processes of explosives, predictably, there are present a process in which the explosives decompose while releasing nitrogen monoxide (NO) and a process in which the explosives decompose while releasing nitrogen dioxide (NO
2
). However, with the Abel heat test method, the amount of NO
2
is determined, and hence sufficient attention has not been paid to NO. Further, in the determination of NO
2
in the Abel heat test method, the criterion for deterioration is the value as very high as 200 ppm, so that the sensitivity is too low to examine the stability of the explosive in details. Still further, the analysis is carried out by a sensory test in which the color of the test paper in the test tube is visually judged. For this reason, another problem is unfavorably encountered that the differences in experience, color and temperature of the laboratory light source, and the like cause differences in results.
On the other hand, various methods have been used for general-purpose analysis of a chemical substance Among them, the mass spectrometry is known as an analysis method excellent in sensitivity and selectivity. With the mass spectrometry, ionization of a sample is required-for achieving the separation depending upon the mass to charge ratio (m/z). As the general-purpose ionization processes, mention may be made of: (a) a process by electron impact in a vacuum; (b) a process by the chemical reaction of primary ions and sample molecules; (c) a process utilizing the tunnel effect of electrons by an electric field; and (d) a process by impacts of neutral atoms at a solid phase interface.
The process (a) is excellent in ease of use and also in reproducibility. With the process (b), a difference in sensitivity is caused from one kind to another of samples according to the reactivity with the primary ions. With the process (c), a large amount of a sample is required, and further, the apparatus increases in size. With the process (d), a sample is easy to prepare, which enables the analysis of a high boiling sample.
However, these processes (a) to (d) are not necessarily sufficient for ionizing a vapor sample generated from explosives in a general manner.
In general, in order to identify a specific substance in a vapor mixture, the specific substance is required to be separated from the vapor mixture. As such a separation process, for example, gas chromatography/mass spectrometry (below, abbreviated as GC/MS) is known. This process is a system in which a specific substance is separated from a vapor mixture by GC, and analyzed by MS. However, with this process, a long time is taken for analysis, and hence it is difficult to continuously monitor the state of deterioration with time. In addition, operation and maintenance are required to be performed using a reference material at all times. Other analysis processes also present the same problems when using a separation means.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for analyzing vapors generated from explosives, capable of collecting a sample with ease, and stably analyzing the vapors generated from explosives in a short time and with high accuracy.
It is another object of the present invention to provide an apparatus for analyzing vapors generated from explosives, capable of analyzing the vapors generated from explosives in a short time and with high accuracy, and also capable of being reduced in size.
In accordance with the present invention, there is provided a method for analyzing vapors generated from explosives, which comprises: a step (1) of generating vapors from explosives; a step (2) of generating primary ions and neutral molecules from air; a step (3) of allowing the primary ions generated in the step (2) and an analysis target sample contained in the vapors generated in the step (1) to react with each other in an area inhibited or prevented from being penetrated by the neutral molecules generated in the step (2), and ionizing the sample; and a step (4) of subjecting the sample ionized in the step (3) to mass spectrometry.
In the step (1), as a process for generating vapors from explosives, for example, mention may be made of a process in which the explosives are heated to a desired
Kusumoto Kenji
Nagano Hisashi
Ohta Toshihiko
Takada Yasuaki
Antonelli Terry Stout & Kraus LLP
Hitachi , Ltd.
Nguyen Kiet T.
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