SUBSTANCES

TECHNICAL FIELD OF THE INVENTION The invention relates to a method and arrangement for security screening and detecting harmful substances, such as explosives, drugs, narcotics and poisons.

BACKGROUND OF THE INVENTION Solutions are known from prior art to detect and screen harmful substances, such as explosives. These solutions include a method, where a sample is taken manually from the surface of the object, after which the sample is analysed e.g. chemically. Additionally, also methods for collecting air samples (including nitrocompounds of possible explosives or narcotics) are known, where the air sample or vapour is collected from a person or an object to be inspected. For example, in a method disclosed in US 4,987,767 the sample gas is concentrated chemically, whereafter it is heated and desorbed, and then examined using a detector, such as an ion mobility analyzer or a gas chromatograph having an electron capture detector. There are however some disadvantages relating to the known prior art, such as they are quite slow and not sensitive enough to quickly analyse small amounts of compounds revealing the existence of possible harmful substances. In addition, the devices according to the known prior art are typically separate apparatuses, through which the person, luggage, cargo or the like to be determined must be additionally delivered, which again makes the security screening more slower.

SUMMARY OF THE INVENTION

An object of the invention is to alleviate and eliminate the problems relating to the known prior art. Especially the object of the invention is to provide a method and arrangement for performing a security screening and detection of possible harmful substances in a fast and reliable manner so that also very small amounts of chemical components of the possible harmful substance can be detected. In addition, the object of the invention is to implement the arrangement so that no new additional arrangements are needed through which the object to be screened has to be transported e.g. at security check point.

The object of the invention can be achieved by the features of independent claims.

The invention relates to a security screening arrangement for detecting harmful substances according to claim 1. In addition, the invention relates to a security screening method for detecting harmful substances according to claim 10.

According to an embodiment of the invention an object comprising possible harmful substance is first received into a receiving chamber. The receiving may be implemented for example by used transportation systems at the screening place, such as by a conveyor belt of the used X-ray screening devices. When the object is received a carrier gas flow possibly comprising reagent component is provided. Advantageously the carrier gas flow is introduced into the vicinity of the object to be screened and determined. According to an embodiment the X-ray radiation is used to charge molecules of the harmful substance directly thereby producing target ions of said harmful substance molecules, whereupon no reagent component is even needed. However, according to an embodiment reagent component ions can be provided and used to charge the molecules of the harmful substance and thereby producing target ions of said harmful substance molecules. The target ions of the harmful substance are then introduced into a mass spectrometer for detection of possible existence of the harmful substance.

As an example the carrier gas flow comprises the reagent component either naturally and/or there is added reagent component in said carrier gas flow. The reagent component ions can be achieved advantageously by radiating the reagent component of the carrier gas flow by X-ray radiation. The reagent component ions are advantageously used to charge the molecules of the harmful substance, namely the charging of the target molecules is typically much stronger via using reagent component ions than directly radiating the target molecules by the X-ray radiation. Thus the use of the reagent component ions provides sensitivity and reliability for the detection.

According to an example the carrier gas flow is a flow of an ambient air, which naturally comprises the reagent component. Alternatively, or in addition to, the reagent component may also be an added reagent component, which may be provided into the carrier gas flow for example by spraying or in other suitable way. The reagent component is advantageously added if the original gas flow, such as the ambient air, does not comprise the reagent component at all or enough. The using of added reagent component makes the detection still more sensitive and reliable.

The reagent component chosen depends on the substances or molecules of the harmful substances to be determined. Many explosives have nitrogen or nitrates as functional group in their molecular structure and they are eagerly forming clusters or proton exchanges with nitrate ions in ambient air. The nitric acid is a very abundant strong acid and with-in milliseconds majority of negative ions under direct radiation with x-ray are converted to nitrate ions. The nitrate ions are colliding with target molecules and charge them by clustering or proton transfer. However, the target ions of the target molecules may also be generated via direct charging by x-ray. According to an example the reagent component of the carrier gas flow comprises e.g. nitric acid. In addition, according to an embodiment the carrier gas flow may be generated e.g. by a fan with suitable flow pipes or channels. Also other flow generating techniques can be used, such as vacuum pumps. The nitric acid is advantageously added to the carrier gas flow by a nitric acid spraying device, but also other types of nitric acid adding mechanisms can be used.

The carrier gas is then exposed by X-ray beams of the X-ray screening devices at the screening place, thereby producing ions of the reagent component of the carrier gas flow. The produced ions of the reagent component of the carrier gas flow are, for example and advantageously, nitrate ions. The base system of the arrangement can be a typical X-ray screening device used in the screening industry, whereupon the ions of the reagent component of the carrier gas flow are produced as by a side process of the X-ray screening typically done at the screening place, just when the suitable carrier gas with suitable reagent component is provided. The produced reagent component ions of the carrier gas are then introduced to the possible molecules of the harmful substance in order to arrange interaction between the reagent component ions and particles of the harmful substance, whereupon the molecules of the harmful substance are charged by the produced reagent component ions. The molecules of the harmful substance are gathered or taken into contact with the produced reagent component ions e.g. by diffusion and turbulent air flows. Alternatively, or in addition to, also additional facilitating means can be used to facilitate the releasing of the molecules of the harmful substance. The charged molecules of the harmful substance (chemical composition of produced ions) are then introduced into a mass spectrometer for analysis and detection of possible existence of the harmful substance, such as explosives, drugs, narcotics or poisons. If any harmful substances are present they are detected with high selectivity and sensitivity. According to an example the charged molecules of the harmful substance can be led to the mass spectrometer with the help of carrier gas flow. Also an electrical field can be used to drive the ions more efficiently to the mass spectrometer. The mass spectrometer may be any suitable mass spectrometer used in ion detecting techniques, such as a time of flight mass spectrometer operated advantageously in an atmospheric pressure interface.

Target molecules of the harmful substance are often very low in vapour pressure and thus, very low in concentration as well. High energy (e.g. 100- 200 keV) and high intensity of x-rays used in the screening devices will produce large number of ions and increase sensitivity towards very low concentration molecules. Formed ionic target molecules of the harmful substance will be sampled from the receiving chamber e.g. by sucking air (carrier gas with the formed target ions) to the mass spectrometer where ionized target molecules will be detected and identified. Utilizing the precision and accuracy of the mass spectrometer the target molecules can be detected with high certainty.

The present invention offers advantages over the known prior art, such as the possibility to analyse and detect very low concentration of the harmful substance. According to an advantageous embodiment the invention combines the existing security x-ray screening technology with the mass spectrometer to detect harmful compounds at the same time when the screening for content is being performed, whereupon the invention also offers very fast and convenient way to analyse and detect the presence of possible harmful substances or compounds. Therefore the functionality and capabilities of the current security screening devices operated for example in airports can be highly increased. Thus, also aviation security is increased.

BRIEF DESCRIPTION OF THE DRAWINGS

Next the invention will be described in greater detail with reference to exemplary embodiments in accordance with the accompanying drawings, in which: Figure 1 illustrates a principle of an exemplary security screening arrangement for detecting harmful substances according to an advantageous embodiment of the invention,

Figure 2 illustrates a principle of another exemplary security screening arrangement for detecting harmful substances according to an advantageous embodiment of the invention.

DETAILED DESCRIPTION

Figure 1 illustrates a principle of an exemplary security screening arrangement 100 for detecting harmful substances according to an advantageous embodiment of the invention. The arrangement comprises a receiving device or chamber 101 for receiving an object 102 comprising the possible harmful substances 103. The receiving device is advantageously the chamber 101 of the security x-ray screening machine 104, to where a conveyor belt 105 or the like transfers the object 102 to be screened. The arrangement comprises also a carrier gas providing device 106 with a fan 107 and/or other suitable means, like pipes and channels for providing a carrier gas flow 108. In addition, the arrangement comprises a reagent component adding device 109, which is advantageously a nitric acid spraying device 109. The nitric acid 1 10 (or other reagent component) is advantageously sprayed in a section 1 1 1 into the carrier gas flow 108, such as an air flow. The arrangement comprises also an X-ray device 1 12 for X-ray screening the object 102 or at least exposing the carrier gas flow 108 with the reagent component in the vicinity 1 13 of the object 102. When the carrier gas flow 108 with the reagent component is exposed by the X-ray radiation (in section 1 13), ions of the reagent component of the carrier gas flow, e.g. nitrate ions 1 14, are produced.

The produced reagent component ions 1 14 of the carrier gas 108 are then flown around or in the vicinity of the object 102, whereupon the produced reagent component ions, e.g. nitrate ions 1 14, collide and interact with target molecules 103 of the harmful substance and charge them e.g. by clustering or proton transfer or direct charging advantageously in a section 1 15 and thereby produce target ions 1 16. The target molecules 103 of the harmful substance are gathered or taken into contact with the nitrate ions advantageously by diffusion and turbulent carrier gas flows originated from the carrier gas providing device 106.

The arrangement advantageously also comprises, or is connected to, a mass spectrometer 1 17. The arrangement comprises also means for delivering and introducing the target ions 1 16 of the harmful substance advantageously with the help of carrier gas into the mass spectrometer 1 17 for detection and analysing of existence of the harmful substance. The arrangement comprises advantageously suitable conduits or flow channels 1 18 allowing said gas flow (including said target ions 1 16). In addition, or alternatively, the arrangement may also comprise electrodes 1 19 or the like for generating an electrical field, or vacuum pump 120, for driving the target ions 1 16 more efficiently to the mass spectrometer 1 17.

Figure 2 illustrates a principle of another exemplary security screening arrangement 100 for detecting harmful substances according to an advantageous embodiment of the invention, where the arrangement is very similar than illustrated in Figure 1. The arrangement 100 comprises the receiving device 101 for receiving an object 102 comprising the possible harmful substances 103, as well as the carrier gas providing device 106 and the X-ray device 1 12 for X-ray screening the object 102 and at the same time X-raying the object 102 and the molecules of the harmful substances 103. In the example illustrated in Figure 2 the X-ray radiation 1 12 is used to charge molecules 103 of the harmful substance directly thereby producing target ions 1 16 of said harmful substance molecules, and no reagent component is needed. The target ions 1 16 are then introduced into the mass spectrometer 1 17 for detection of the possible existence of the harmful substance.

The invention is explained in this document with reference to the aforementioned embodiments, and several advantages of the invention are demonstrated. It is clear that the invention is not only restricted to these embodiments, but comprises all possible embodiments within the spirit and scope of the inventive thought and the following patent claims. The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the description of specific embodiments when read in connection with the accompanying drawings. For example, it should be understood that according to an embodiment the target ions of the harmful substance can be generated both by direct charging and charging via ions at the same time.

The exemplary embodiments of the invention presented in this patent application are not to be interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this patent application as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated.