Several chemical analysis instruments utilize a direct sample introduction (DSI) attachment for gas chromatography (GC) and mass spectrometry (MS). Standard DSI techniques for GC and MS instruments involve placing a sample material into a microvial which is subsequently positioned in a modified inlet. Due to their size, loading these microvials with solid samples, such as trace residue and powders, can be difficult without contaminating the instrument. The standard approach for transferring these types of samples to a microvial involves collecting the sample with a Pasteur pipette and subsequently shaking or tapping the sample into the microvial. Another transfer method involves folding a piece of paper, adding the sample to the paper, and then sliding the microvial through the sample. These approaches often result in contamination of neighboring surfaces including the DSI probe. Accordingly, a device and sampling method is needed to alleviate the contamination issues associated with these current transfer techniques.
A contamination-free sample transfer device and method is provided. The device comprises an elongated member having an internal cavity and a pressure-sensitive region. The internal cavity is in communication with a first end of the elongated member such that sample can be received into the internal cavity by contacting the sample with the first end. The internal cavity can extend through only a portion of the elongated member or alternatively, can extend to and communicate with a second end of the elongated member. The pressure sensitive region is positioned at a first distance from the first end such that the portion of the elongated member between the first end and pressure sensitive region forms the separable sampling portion. A handling portion is positioned between the second end of the elongated member and the pressure-sensitive region.
The elongated member can be formed of an inert material that does not out gas between 180 degrees Celsius and 300 degrees Celsius. In one instance, the elongated member is formed of glass. The elongated member is of a size sufficient to permit stable handling and placement of the sampling portion into a receiving container, such as a microvial for a DSI probe. For example, the elongated member has a length from about 65 millimeters (2.5 inches) to about 25.4 centimeters (10 inches), and more preferably about 10.2 centimeters (4 inches). The outer diameter of the elongated member should be of a size sufficient to permit insertion into a sample receiving container used with a standard chemical analysis instrument. For example, the outer diameter of the elongated member is from about 0.1mm (0.0004 inches) to about 1 5 millimeters (0.059 inches) and is preferably 1.18 millimeters (0.0465 inches). Alternatively, the elongated member can be completely solid with a quadrilateral cross-section such that the device may not include an internal cavity. In this instance, sample is retained on an edge or wall of the sampling portion of the device. Moreover, perforations can be used with solid devices to form a pressure-sensitive region.
The internal cavity is preferably of a diameter and length sufficient to receive the desired quantity of sample. In some instances, the diameter of the internal cavity will be dependent on the diameter of the elongated member. For example, an elongated member having a diameter of 1.18 millimeters preferably comprises an internal cavity with a diameter of about 0.546 millimeters (0.02151 inches). The internal cavity may be of a length that extends from the first end of the elongated member to immediately below the pressure-sensitive region. Alternatively, the internal cavity can extend from the first end to the second end of the elongated member such that both ends are in communication with the internal cavity. In instances where the elongated member is a hollow tube, the internal cavity is characterized by the hollow internal space of the elongated member such that the diameter of the internal cavity is the inner diameter of the elongated member.
The pressure-sensitive region provides a stress concentration on the elongated member such that this region is more susceptible to breaking than the remainder of the elongated member when a pressure or force is applied. For example, the pressure-sensitive region can be a scored or perforated segment on the elongated member. Alternatively, the pressure-sensitive region can be a partial cut in a wall of the elongated member. More generally, the pressure-sensitive region can comprise any means that provides a stress concentration on the device thereby causing an increased susceptibility to breaking as compared to the remainder of the elongated member when pressure or force is applied to the sampling portion of the elongated member. The means can include any of the aforementioned structural modifications listed above including a scored segment, a perforated segment, or a partial cut in the wall of the elongated member.
The pressure-sensitive region is positioned on the elongated member at a first distance from the first end of the elongated member. In one instance, the first distance provides the length of the separable sampling portion of the elongated member and should be sufficient to retain a desired amount of sample in the internal cavity of the sampling portion below the pressure-sensitive region. For example, the first distance is from about 5 millimeters to about 17 millimeters, and preferably is about 13 millimeters.
In another instance, the device may comprise multiple pressure-sensitive regions thereby creating multiple separable sampling portions. For example, the device may comprise a second pressure-sensitive region positioned at a second distance from the first end of the elongated member. The second distance may be from about 10 millimeters to about 34 millimeters and is preferably about 26 millimeters.
A method for contamination-free loading of a sample into a receiving container of a chemical analysis instrument using the present device is also provided. The method involves contacting the sample with a first end of a sampling device, the first end being in communication with an internal cavity of the sampling device such that a portion of the sample is received by the internal cavity, retained on an edge of the first end, or retained on a side wall of the device near the first end. A first portion of the sampling device containing the sample is then inserted into a receiving container where the first portion extends from the first end to a first pressure-sensitive region on the sampling device. Pressure is then applied to the sampling device against an internal wall of the receiving container thereby causing the first portion to separate from the sampling device at the first pressure-sensitive region such that the first portion containing the sample is retained in the receiving container. The portion of the sampling device above the pressure-sensitive region is then discarded and the sample is analyzed without removing the first portion from the receiving container.
This method can further include repeating these steps where the sampling device comprises a second pressure-sensitive region located in the device portion above the first pressure-sensitive region. This permits multiple samples to be obtained and transferred with a single device. Additionally, the steps can be repeated without performing the contacting step for a second time. In this instance, the step of contacting the sample resulted in the sample extending in the internal cavity to a point between the first pressure-sensitive region and the second pressure-sensitive region. This method will typically be employed where quantification of the level of analyte at varying depths of the sample are desired.
A method for contamination-free loading of a liquid sample into a receiving container of a chemical analysis instrument using the present device is also provided. The first step of the method involves applying a blockade to a first open end of a sampling device. Second, a second open end of the sampling device is placed into the liquid sample. In this method, the sampling device comprises an internal cavity that is in communication with the first and second open ends. Third, the blockade to the first open end is removed thereby causing a portion of the liquid sample to be received by the internal cavity via the second open end. Fourth, the blockade to the first open end is re-applied upon receipt of sufficient liquid sample into the internal cavity. Fifth, and while maintaining the blockade of the first open end, a portion of the sampling device is inserted into the receiving container. The inserted portion comprises a portion below a first pressure-sensitive region and contains the portion of liquid sample received by the internal cavity via the second open end. Sixth, pressure is applied to the first pressure-sensitive region against the receiving container in a manner sufficient to cause the sampling device to separate into two portions, the portion below the first pressure-sensitive region and a portion above the first pressure-sensitive region. In this instance, the portion below the first pressure-sensitive region is retained in the receiving container. Seventh and finally, the portion of liquid sample is analyzed without removing the portion of the sampling device below the first pressure-sensitive region from the receiving container.
The current invention is directed to a device and method for contamination-free transfer of material. For example, the device and method can be used in conjunction with a variety of DSI attachments for gas chromatography and/or mass spectrometry sample analysis and other chemical analysis requiring high temperature pyrolysis. More generally, the present device and method can be used for many laboratory and field applications where contamination-free transfer of small amounts of material is required. As used herein, the term “direct sample introduction attachment” is a device used with a GC and/or MS instrument that permits introduction of samples beyond gases and liquids that are not readily able to be introduced into said instrument without further processing.
The device comprises an elongated member having an internal cavity in communication with at least one end of the elongated member and a pressure-sensitive region. The internal cavity receives a portion of the target sample via an open end of the elongated member that is in communication with the internal cavity. Additionally, sample may be contained on the outer walls of the elongated member near the open end. The pressure-sensitive region allows the portion of the elongated member containing the sample (sampling portion) to be separated from the remaining device by applying pressure or force to the device against the receiving container. Thus, the sample is retained in the sampling portion throughout the transfer process and subsequent analysis thereby reducing or eliminating contamination of the assay equipment and surrounding areas or surfaces.
One embodiment of the device 10 is depicted in
Referring now to
Referring now to
In any of the above described embodiments, device 10 may be formed of glass or any inert material that does not out gas between 180° and 300° C. Examples of appropriate material include, but are not limited to ceramics, plastics such as polytetrafluoroethylene (Teflon), PAI, PEEK, PEAK, polyetherimide (Ultem), and metals such as aluminum, copper, stainless steel, nickel, steel, titanium, brass, and alloys thereof. The shape of device 10 is preferably an elongated, cylindrical member with a circular cross-section. However, device 10 can have a variety of cross-sectional shapes including, but not limited to oval, figure eight, dumbbell shape, and any polygon convex or concave such as quadrilaterals, pentagons, heptagons, octagon, nonagon and decagon. Regardless, the shape and size of device 10 should permit efficient handling and include a sampling portion 30 that allows for a sufficient quantity of sample to be received or retained on a surface thereof while of a size to fit within the appropriate receiving container.
In one instance, device 10 comprises an elongated member 12 formed of a 4-inch (101.6 millimeters) glass capillary tube having an outside diameter (OD) of 1.18 millimeters (0.0465 inches) and an inner diameter (ID) of 0.546 millimeters (0.02151 inches), such as depicted in
The OD of elongated member 12 can be selected to conform to the size of the ID of the receiving container being used to receive sampling portion 30. Generally, the OD of elongated member 12 is from about 0.1 mm (0.0004 inches) to about 1.5 mm (0.059 inches) and is preferably 1.18 mm (0.0465 inches). The ID of elongated member 12 depends generally on the OD, the desired strength of member 12, the materials used to form member 12, and the desired capacity of inner cavity 14 in sampling portion 30. When a glass capillary tube is used as the elongated member 12 as discussed above, the ID is from about 1% to about 95% of the OD of the tube and preferably about 46% of the OD. Alternatively, a solid rod having a zero percent ID/OD ratio could be used in sampling substances that would adhere to the outside or edges of the rod such as gels, slurries, powders, or liquids. In other words, device 10 does not necessarily require internal cavity 14, 15 since, for some applications, the sample can adhere to the edge of an end of the sampling portion 30 or a surface thereof. The length of device 10 is generally related to the desired size of sampling portion 30 and handling portion 32 and is from about 26 mm (1 inch) to about 25.4 cm (10 inches), and more preferably from about 65 millimeters (2.5 inches) to about 130 millimeters (5⅛ inches). Sampling portion 30 (portion of elongated member 12 between pressure-sensitive region 16 and first end 18) should be of length that will permit it to be completely retained in the receiving container and furthermore, allows for receipt of a suitable quantity of sample. In one instance, sampling portion 30 is about 5 millimeters (0.197 inches) to about 17 millimeters (0.669 inches) and is preferably 13 millimeters (0.51 inches). These dimensions are applicable to a device 10 having one sampling portion 30 or multiple sampling portions 30a and 30b as in
Pressure-sensitive region 16 forms a stress concentration thereby causing an increased sensitivity to pressure or force in this region of elongated member 12. In one instance, as depicted in
As discussed specifically above with respect to
Device 10 can be used in methods for contamination-free transfer of sample to a receiving container for use in a variety of chemical analysis instruments. For example, the receiving container can include a microvial (standard size—15 mm×2.5 mm OD×1.9 mm ID) for a DSI used with a GC/MS instrument, a TD tube for pyrolysis, or a graphite tube used in atomic absorption. Samples can include both underivatized or raw materials as well as those that have been chemically modified to facilitate their separation via chromatography.
Referring now to
Referring now to
In methods using a device with multiple pressure-sensitive regions 16 (multiple sampling portions 30), for example device 10 of
Device 10 can also be used for contamination-free transfer of liquids. For example, in the identification of raw starting materials for methamphetamine production, law enforcement personnel will interact with and seize potentially dangerous liquid agents. By utilizing device 10, small liquid volumes may be collected and quickly analyzed with onsite instrumentation providing rapid identification of potentially illegal or dangerous substances. A device 10 comprising an elongated member 12 having an OD of 1.18 millimeters (0.0465 inches), an internal cavity 14 diameter of 0.546 millimeters (0.02151 inches), and a sampling portion 30 length of 13 millimeters possesses 3 microliters of total internal volume, which is a suitable volume for split-based GC/MS and other common industry analysis instruments.
A method of liquid-based sampling using device 10 of
The inventive device can be used with a variety of solid materials. For example, fruits and vegetables may be subject to excessive pesticide exposure, with potentially fatal consequences. The present device 10 presents a unique approach to the analysis of pesticides and other environmentally persistent pollutants that may be introduced into the food chain. The technique for analysis of surface level contaminants involves sampling the outer surface of the fruit/vegetable with the present device 10 by dragging or pushing first open end 18 across the surface of the prospective food item. This will result in either rind being received into internal cavity 14 of sampling portion 30, or residue collecting to the edges of first opening 18. Additionally, sampling portion 30 may be physically inserted into the outer epidermis of the fruit/vegetable and removed likewise, collecting the outer skin of the material into internal cavity 14 of sampling portion 30. Sampling portion 30 is then separated from the remaining device 10 as described above.
The present device 10 may also be used with biological and synthetic plant materials including alkaloids, terpenoids, cannabinoids and other potentially psychoactive agents. Naturally occurring plants such as Salvia Divinorum contain low concentrations of psychoactive agents such as Salvinorin A. New generation “herbal incense” or synthetic cannabis contains residues of synthetic cannabinoids which have been sprayed onto plant material to produce a legal high. Due to the difficulties and labor associated with extraction of psychoactive chemicals within these plant materials—including low concentration components and unknown solubilities of the chemicals of interest—the present device 10 offers an excellent alternative for collection of the plant material for subsequent GC and/or MS analysis.
In methods involving use of device 10 with plant material, a user first isolates a section of plant material, either whole or cut into pieces for ease of handling, and repeatedly contacts the plant material with first end 18 of sampling portion 30 until visual residue is present on either the first end 18 and/or inner cavity 14 of sampling portion 30. The remaining steps are the same as set forth above. Use of the present device 10 in this method reduces sample preparation time from potentially hours (1-4) to an average of 1 minute.
In methods involving device 10 without an internal cavity 14, 15, such as that depicted in
In the Examples below, a device similar to that described in reference to
A sample of canine gastric contents from an animal previously suffering from seizures with subsequent vomiting was obtained and transferred to a microvial using the device and methods described herein. The microvial was then transferred to a DSI probe and inserted into the GC/MS analysis instrument. The results of the GC (top panel)/MS (bottom panel) analysis of the gastric content sampled using the present device and methods are depicted in
An orange peel sample was analyzed for surface level contaminants using GC/MS. The sample was obtained and transferred to a microvial for a DSI probe using the methods described herein for sampling fruits and vegetables. The results of the GC (top panel)/MS (bottom panel) analysis of the orange peel sample obtained using the present device and methods are depicted in
A plant material was sampled and transferred to a microvial for a DSI probe using the inventive device according to the methods described above for sampling plant material. The plant sample was subjected to GC analysis and the results depicted in
A powdery substance was sampled and transferred to a microvial for a DSI probe using the inventive device according to the general method described above. The powdery was subjected to GC analysis and the results depicted in
Other embodiments of the presently described device and methods will be apparent to those skilled in the art from a consideration of this specification, including the examples, or practice of the invention disclosed herein. However, the foregoing specification is considered merely exemplary of the present invention with the true scope and spirit of the invention being indicated by the following claims.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US12/56073 | 9/19/2012 | WO | 00 | 3/19/2014 |
Number | Date | Country | |
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61536462 | Sep 2011 | US |