Dual-mode scanning optical system for capillary electrophoresis

Abstract

To provide a suitable dual mode scanning optical system for capillary electrophoresis.SOLUTION: A dual-mode capillary electrophoresis system is disclosed that includes: a plurality of capillaries for receiving a plurality of samples; a UV radiation source (120) for generating UV radiation along a first path (PB); a laser light source (110) for generating laser radiation along a second path (PA); and a galvanometric mirror (116) configured to receive radiation from the UV radiation source along the first path and light from the laser light source along the second path and direct the received UV radiation and the laser light onto a common optical path. The galvanometric mirror is configured to scan the UV radiation and the laser light sequentially across the plurality of capillaries. The system may further include a detector (190) for detecting the UV radiation, and a detector (180) for detecting fluorescent radiation via an optical fiber (185) emitted by the sample in response to laser excitation.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] (Related U.S. Application) This application claims the benefit of priority from U.S. Provisional Application No. 62 / 935,609, filed November 14, 2019, the entire contents of which are incorporated herein by reference.

[0002] (Field) The present disclosure relates generally to dual-mode capillary electrophoresis systems, and more specifically to capillary electrophoresis systems that can readily operate in at least two detection modes, for example, a UV absorption mode and a laser-induced fluorescence (LIF) mode. [Background technology]

[0003] (background) Capillary electrophoresis is often employed for rapid separation and analysis of charged species such as synthetic polynucleotides, DNA sequencing fragments, DNA restriction fragments, amino acids, optical isomers of dansyl amino acids, as well as separation of proteins, viruses, and bacteria. Micellar electrokinetic capillary chromatography, isoelectric focusing, and on-column derivatization can all be performed on CE columns.

[0004] Current instruments can typically analyze only one sample at a time, which limits the throughput of the instrument. Furthermore, changing the detection mode of a current instrument is difficult and typically requires hardware modification and revalidation of the instrument. Summary of the Invention [Means for solving the problem]

[0005] (overview) In one aspect, a dual mode capillary electrophoresis system is disclosed, the dual mode capillary electrophoresis system comprising a plurality of capillaries for receiving a plurality of samples, a UV radiation source for generating UV radiation along a first path, a laser light source for generating laser radiation along a second path, and a galvanometric mirror configured to receive radiation from the UV radiation source along the first path, receive light from the laser light source along the second path, and direct the received UV radiation and the laser light onto a common optical path, the galvanometric mirror further configured to scan the UV radiation and the laser light sequentially across the plurality of capillaries. The system may further include a first detector positioned relative to the capillaries to receive at least a portion of the UV radiation passing through each of the capillaries when each of the capillaries is illuminated with UV radiation. At least one optical fiber bundle is positioned relative to the capillaries to receive at least a portion of the fluorescent radiation emitted by a sample disposed within each of the capillaries in response to excitation of the sample within the capillary by the laser light. A second detector is optically coupled to the optical fiber for receiving at least a portion of the fluorescent radiation emitted by the capillary.

[0006] A lens may be disposed between the galvanometric mirror and the plurality of capillaries to focus the UV radiation and the laser light onto the capillaries as they are scanned across the capillaries, hi some such embodiments, the lens is configured to focus the UV radiation and the laser light substantially onto the center of each of the capillaries.

[0007] In some embodiments, the laser radiation may excite a fluorescent label(s) attached to the sample disposed in the capillary. In some embodiments, ultraviolet (UV) radiation may be employed to excite the intrinsic fluorescence of the biological sample. An optical fiber may collect the fluorescent radiation. In some embodiments, two bundles of optical fibers are employed to collect the laser-induced fluorescent or UV-induced fluorescent radiation. In some such embodiments, one bundle of optical fibers is positioned above the lens and angled downward toward the plurality of capillaries to receive at least a portion of the laser-induced or UV-induced fluorescent radiation, and another bundle of optical fibers is positioned below the lens and angled upward toward the plurality of capillaries to receive at least a portion of the laser-induced or UV-induced fluorescent radiation.

[0008] In some embodiments, the proximal ends of the optical fibers may be coupled to a plate to fix them relative to the capillary. In some such embodiments, the distal ends of the optical fibers may be coupled to a coupling element that may align their distal ends relative to a second detector so that light exiting the optical fiber may be detected by the detector. In some embodiments, the detector may measure light having multiple wavelengths in parallel or may be a detector that provides spectral separation to measure multiple wavelengths separately.

[0009] In some embodiments, the system may further include a controller for controlling the galvanometric mirror. The controller may be implemented in hardware, software and / or firmware. As an example, the controller may include a processor and one or more memory modules in communication with the processor via at least one communication bus. In some embodiments, instructions for operating the galvanometric mirror may be stored in a permanent memory module and transferred by the processor to the random access memory module during run-time to be executed to operate the galvanometric mirror. As an example, the controller may cause the galvanometric mirror to illuminate multiple capillaries in a sequential manner. In some such embodiments, the controller may communicate with the UV radiation source and the laser light source to activate the UV radiation source and the laser light source in different time intervals to transmit UV radiation or laser light to the galvanometric mirror in these time intervals. In each time interval, the mirror may scan the UV radiation or laser light across the multiple capillaries in a sequential manner.

[0010] In some embodiments, the multiple capillaries are housed in a cartridge. A mount can be provided on which the cartridge can be mounted to place the capillaries in the path of the UV radiation and laser light.

[0011] In some embodiments, the UV radiation source may include a UV lamp for generating UV radiation and a plurality of filters that may be selectively deployed to select different wavelengths of UV radiation emitted by the UV lamp. In some such embodiments, the UV lamp may generate UV radiation at a wavelength in the range of about 185 nm to about 400 nm. Additionally, in some embodiments, one or more filters may be positioned in front of a detector configured to detect the fluorescent radiation, e.g., to block excitation light and thereby increase the signal / noise level. In some embodiments, the light source may generate light having a wavelength in the range of about 372 nm to about 980 nm.

[0012] A variety of detectors can be employed to detect UV radiation and laser-induced fluorescence radiation. Some examples of suitable detectors include, but are not limited to, photodiodes and photomultiplier tubes, photomultiplier tubes and photodiode array spectrometers.

[0013] In some embodiments, the multiple capillaries are disposed within a removable cartridge that is slidably insertable into the system, and the multiple capillaries are aligned to receive the UV radiation and / or the laser light from the galvanometric mirror when the removable cartridge is in an inserted state of the system.

[0014] In another aspect, a cartridge for use with a dual mode capillary electrophoresis system is described, the cartridge comprising a plurality of capillaries adapted to receive a plurality of samples, the cartridge adapted to be insertable into the dual mode capillary electrophoresis system between an inserted state and a removed state. The dual mode capillary electrophoresis system includes a UV radiation source for generating UV radiation along a first path, a laser light source for generating laser radiation along a second path, a galvanometric mirror configured to receive radiation from the UV radiation source along the first path and light from the laser light source along the second path and direct the received UV radiation and the laser light onto a common optical path, the galvanometric mirror further configured to scan the UV radiation and the laser light sequentially across the plurality of capillaries when the cartridge is in the inserted state, and a galvanometric mirror configured to scan the UV radiation and the laser light sequentially across the plurality of capillaries when the cartridge is in the inserted state. the capillaries are irradiated with the UV radiation; at least one optical fiber bundle positioned relative to the capillaries to receive at least a portion of the fluorescent radiation emitted by a sample disposed in each of the capillaries in response to excitation of the sample in that capillary by the laser light or the UV radiation when the cartridge is in an inserted state; and a second detector optically coupled to the optical fiber for receiving at least a portion of the fluorescent radiation captured by the capillary when the cartridge is in an inserted state. The present specification also provides, for example, the following: (Item 1) 1. A dual mode capillary electrophoresis system, comprising: a plurality of capillaries for receiving a plurality of samples; a UV radiation source for generating UV radiation along a first path; a laser source for generating laser radiation along a second path; a galvanometric mirror configured to receive radiation from the UV radiation source along the first path and light from the laser light source along the second path and direct the received UV radiation and the laser light onto a common optical path, the galvanometric mirror being further configured to scan the UV radiation and the laser light sequentially across the plurality of capillaries; a first detector positioned relative to the capillaries to receive at least a portion of the UV radiation passing through each of the capillaries when each of the capillaries is irradiated with the UV radiation; at least one optical fiber bundle positioned relative to the capillaries to receive at least a portion of fluorescent radiation emitted by a sample disposed within each of the capillaries in response to excitation of the sample within the capillaries by the laser light or the UV radiation; a second detector optically coupled to the optical fiber for receiving at least a portion of the fluorescent radiation captured by the capillary; and A system comprising: (Item 2) 2. The system of claim 1, further comprising a lens disposed between the galvanometric mirror and the plurality of capillaries to focus the UV radiation and the laser light onto the capillaries as the UV radiation and the laser light are scanned across the capillaries. (Item 3) 3. The system of claim 2, wherein the lens is configured to focus the UV radiation and the laser light substantially onto a center of each of the capillaries. (Item 4) 2. The system of claim 1, wherein the at least one optical fiber bundle comprises a first optical fiber bundle positioned above the scan lens and angled toward the plurality of capillaries to receive at least a portion of the fluorescent radiation. (Item 5) 2. The system of claim 1, wherein the at least one optical fiber bundle comprises a second optical fiber bundle positioned below the scan lens and angled toward the plurality of capillaries to receive at least a portion of the fluorescent radiation. (Item 6) Item 10. The system of item 1, further comprising a controller for controlling the galvanometric mirror. (Item 7) 7. The system of claim 6, wherein the controller is configured to control the galvanometric mirror to scan the UV radiation and the laser light across the capillary for different time intervals. (Item 8) Item 1, further comprising a cartridge containing the plurality of capillaries. (Item 9) Item 1. The system of item 1, further comprising a stand on which the cartridge can be mounted. (Item 10) Item 10. The system of item 9, further comprising a bracket to which a proximal end of the at least one optical fiber bundle is coupled. (Item 11) Item 11. The system of item 10, further comprising a coupling element for receiving a proximal end of the at least one optical fiber bundle and aligning the distal end with the second detector to couple light from the optical fiber to the detector. (Item 12) Item 1. The system of item 1, wherein the UV radiation source comprises a UV lamp. (Item 13) 2. The system of claim 1, wherein the UV radiation source comprises a plurality of filters selectively deployable to select different wavelength bands of the UV light emitted by the UV lamp. (Item 14) Item 13. The system of item 12, wherein the UV lamp generates UV radiation at a wavelength in the range of about 185 nm to about 400 nm. (Item 15) Item 14. The system of item 1, further comprising at least one filter positioned in front of the second detector to filter out fluorescence excitation light generated by the laser or UV source. (Item 16) 2. The system of claim 1, wherein the laser light source generates light having a wavelength in the range of about 372 nm to about 980 nm. (Item 17) Item 10. The system of item 1, wherein the first detector comprises a photodiode. (Item 18) Item 1, wherein the second detector comprises one of a photomultiplier tube and a diode array spectrometer. (Item 19) 2. The system of claim 1, wherein the plurality of capillaries are disposed within a removable cartridge that is slidably insertable into the system, and the plurality of capillaries are aligned to receive the UV radiation and the laser light from the galvanometric mirror when the removable cartridge is in an inserted state of the system. (Item 20) 1. A cartridge for use with a dual mode capillary electrophoresis system, comprising: the cartridge comprises a plurality of capillaries adapted to receive a plurality of samples, the cartridge being adapted to be insertable into the dual-mode capillary electrophoresis system between an insertion state and a removal state; The dual mode capillary electrophoresis system comprises: a UV radiation source for generating UV radiation along a first path; a laser source for generating laser radiation along a second path; a galvanometric mirror configured to receive radiation from the UV radiation source along the first path and light from the laser light source along the second path and direct the received UV radiation and the laser light onto a common optical path, the galvanometric mirror configured to scan the UV radiation and the laser light sequentially across the plurality of capillaries when the cartridge is in the inserted state; a first detector positioned relative to the capillaries to receive at least a portion of the UV radiation passing through each of the capillaries when each of the capillaries is irradiated with the UV radiation when the cartridge is in the inserted state; at least one optical fiber bundle positioned relative to the capillaries to receive at least a portion of fluorescent radiation emitted by a sample disposed within each of the capillaries in response to excitation of the sample in the capillaries by the laser light or the UV radiation when the cartridge is in the inserted state; a second detector optically coupled to the optical fiber for receiving at least a portion of the fluorescent radiation captured by the capillary when the cartridge is in the inserted state; and A cartridge comprising: [Brief description of the drawings]

[0015] BRIEF DESCRIPTION OF THE DRAWINGS [Figure 1A] FIG. 1A diagrammatically depicts a dual-mode capillary electrophoresis system according to an embodiment.

[0016] [Figure 1B] FIG. 1B diagrammatically depicts certain components of the system shown in FIG. 1A.

[0017] [Figure 1C] FIG. 1C diagrammatically depicts certain components of the system shown in FIG. 1A.

[0018] [Figure 1D] FIG. 1D diagrammatically depicts a cartridge according to one embodiment including multiple capillaries and a cradle for receiving the cartridge.

[0019] [Figure 1E] FIG. 1E diagrammatically depicts a UV radiation source suitable for use in practicing some embodiments of the present teachings.

[0020] [Figure 1F]FIG. 1F diagrammatically depicts lenses employed in the system shown in FIG. 1A for focusing either UV radiation and laser light onto multiple sample-holding capillaries.

[0021] [Figure 1G] FIG. 1G shows multiple optical fibers for directing laser-induced fluorescence radiation to a detector, a plate for supporting the proximal ends of the optical fibers, a stand for receiving a cartridge containing the capillaries, and a translation stage for moving the stand and the plate.

[0022] [Diagram 2] FIG. 2 diagrammatically depicts an example of an implementation of a controller for operating a galvanometric mirror.

[0023] [Figure 3A] 3A and 3B show diagrammatically a capillary employed in one embodiment of the present teachings, the capillary being bonded to a tip. [Figure 3B] 3A and 3B show diagrammatically a capillary employed in one embodiment of the present teachings, the capillary being bonded to a tip.

[0024] [Figure 4] Figure 4 demonstrates the linear dynamic range in detecting caffeine concentrations from 2 μM up to 2 mM.

[0025] [Diagram 5] FIG. 5 shows a CZE separation using test matrix B samples (Sciex) performed simultaneously through eight capillaries.

[0026] [Figure 6] FIG. 6 shows the fluorescence intensity using different concentrations of sodium fluorescein.

[0027] [Figure 7]FIG. 7 shows the results of a CZE separation using a LIF test matrix sample (Sciex) performed simultaneously through eight capillaries. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] (Detailed Description) The present teachings provide a dual-mode capillary electrophoresis system that facilitates the analysis of multiple samples. In some embodiments, the system employs a galvanometric scanning mirror that can sequentially direct radiation from a laser or UV source across an array of capillaries, for example, through a single lens. In some embodiments, the array of capillaries can be implemented in a silicon chip with a window at each capillary location where the capillary is bonded to the chip. The window is configured to control the passage of light through the capillary, resulting in optimal performance of the system. As discussed in more detail below, in some such embodiments, a photodiode is positioned, for example, along the optical axis, to collect at least a portion of the UV radiation passing through the capillary to perform an absorbance measurement. The photodiode can also serve to initially align the beam position with the center of each capillary window by sweeping UV radiation or laser light across the array of capillaries and recording the center position.

[0029] During data acquisition, a galvanometric scanning mirror may step-scan UV radiation or laser light to each capillary and maintain radiation on each capillary for a preselected dwell time for data collection. In some embodiments, laser light is employed to excite fluorescent labels attached to the sample under investigation, or UV radiation is employed to excite intrinsic fluorescence (e.g., intrinsic fluorescence of a biological sample). In response to such excitation, fluorescent labels or biological samples exhibiting intrinsic fluorescence may emit fluorescent radiation, which may be detected as discussed below. By way of example, in some embodiments, for such laser-induced fluorescence detection, an array of optical fibers (e.g., 24 optical fibers) is placed at 45 degree angles above and below the optical axis of the radiation (e.g., 12 above and 12 below), with the intersection of the estimated extension lines from the tips of the fibers to the capillary located at the center of the capillary, and the radiation enters the capillary at the intersection. The fiber can collect the fluorescence radiation from the entire capillary array after passing through a laser light or UV blocking filter and a bandpass filter to block the excitation light from reaching the photomultiplier and select the desired radiation bandwidth for detection, and direct the fluorescence radiation to the photomultiplier. Alternatively, the radiation can be separated by wavelength through an optical grid onto an array of photodiodes. One advantage of the system according to the present teachings is that it eliminates the need for hardware replacement to switch from UV radiation to laser light to interrogate the sample under study. Rather, in the system according to the present teachings, switching from one detection mode to another only involves moving a galvanometric mirror from one radiation source to another. In some embodiments, the user can simply select the detection mode of interest, for example, via a graphical user interface.

[0030] 1A, 1B, 1C, 1D, 1E, and 1G, a dual-mode capillary electrophoresis system 100 according to an embodiment includes an array of capillaries 122 arranged in a cartridge 195, each of which is configured to receive a sample to be studied. The multi-capillary array 122 includes a silicon chip with a window at each capillary position where a capillary is bonded. The cartridge is insertable (slidably or otherwise) into a system as described herein and is loaded into the system when in an inserted state. When the cartridge is in an inserted state, the capillaries 122 contained within the cartridge 195 are aligned to receive UV light and / or laser light from a galvanic scanner and are also aligned with optical fibers and / or photodiodes that are part of a detection system.

[0031] 3A and 3B, by way of example, diagrammatically depict an array 122 of capillaries bonded to a chip 122a and having windows 122b through which laser light and / or UV radiation can be received or emitted. The windows control the passage of radiation through the capillaries to provide optimal performance of the system. As discussed in more detail below, the capillaries are positioned in the paths of radiation generated by multiple radiation sources.

[0032] In this embodiment, the system 100 includes an ultraviolet (UV) radiation source 131 (see FIG. 1E), an associated UV filter 130, and a laser source 110. The UV radiation source may be, for example, a UV lamp capable of generating UV radiation (e.g., radiation with a wavelength in the range of about 185 nm to about 400 nm) to perform absorbance measurements of samples disposed in the capillary 122, and the laser source 110 may be any suitable laser that generates laser radiation by inducing fluorescent radiation from one or more samples disposed in the capillary (e.g., exciting fluorescent labels attached to one or more samples disposed in the capillary 122). By way of example, the laser source 110 may generate radiation at one or more wavelengths in the range of about 372 nm to about 980 nm to perform laser-induced fluorescence studies of those samples. By way of example, as mentioned above, in some embodiments, the samples disposed in the capillary may be labeled with one or more fluorescent tags that may be excited by the laser radiation and emit fluorescent radiation in response to such excitation. In some embodiments, UV radiation may be employed to excite the intrinsic fluorescence of a biological sample.

[0033] In this embodiment, the UV radiation source 120 includes a broad spectrum UV lamp 120a. The UV source uses a single optical fiber (see fitting 202 in FIG. 1E) that runs to a fiber collimator (see fiber collimator 120b in FIG. 1). Multiple switchable UV filters 130 are provided that can be selected one at a time to filter the radiation generated by the UV radiation source 120. A stepper motor can be used to switch between the UV filters positioned along the path of the radiation generated by the UV radiation source 120, and a knob 130a is used to remove the UV filters. In this way, a wavelength of interest can be selected from the wavelengths generated by the broad spectrum UV lamp. In addition, the UV source is adjustable by use of a stepper motor to maximize the light power depending on the wavelength selected and the filter(s) utilized.

[0034] As shown in Fig. 1E, the lens pair 200 may focus the UV radiation generated by the lamp towards the UV output fitting 202. A shutter 203 may allow blocking the UV radiation generated by the lamp from exiting the source. An XY translation device 204 may be moved via a stepper motor to allow adjusting the position of the UV output fitting relative to the lens pair 200.

[0035] The dual-mode capillary electrophoresis system 100 further includes suitable optics for directing radiation emitted by the laser source 110 and the UV radiation source 120 onto the array of capillaries 122. Such optical elements may include, but are not limited to, one or more mirrors, lenses (e.g., focusing lenses), among others. In this embodiment, a galvanometric scanning mirror 116 may receive radiation emitted by the UV radiation source 120 and the laser 110 along different paths (PA) and (PB), respectively, and focus or direct the UV radiation and the laser light onto a common optical path that is directed to the scanning lens 114. As shown in FIG. 1F, the focusing lens 114 may be held in place via coupling to a holder 114a.

[0036] In this embodiment, the galvanometric mirror 116 receives the UV radiation and laser light directly from the UV and laser sources, respectively, although in other embodiments, one or more optical elements (e.g., lenses) may be positioned between either the UV radiation source or the laser source and the galvanometric mirror.

[0037] The focusing or scanning lens 114 may then focus the UV radiation and the laser light onto one of the capillaries of the capillary array 122. For example, in some embodiments, the lens 114 is configured to focus the UV radiation and the laser light at the center of a selected capillary. The galvanometric mirror 116 may be scanned to sequentially illuminate samples contained within the capillaries of the capillary array with the UV radiation and the laser light.

[0038] The system 100 may further include a number of detectors for detecting at least a portion of the UV radiation transmitted through the capillary and the fluorescent radiation emitted by fluorescent label(s) attached to the sample(s) disposed within the capillary in response to excitation by the laser light or excitation of the intrinsic fluorescence of one or more biomolecules of the biological sample by the UV radiation. The detectors may generate detection signals in response to detection of the UV radiation and / or the fluorescent radiation, which may be analyzed to obtain information regarding the sample disposed within the capillary.

[0039] More specifically, in this embodiment, a UV detector 190 (e.g., a photodiode detector) is positioned relative to the capillary to receive at least a portion of the UV radiation transmitted through a sample disposed within the capillary. In this embodiment, the photodiode detector 190 is positioned substantially along a common optical path, and the galvanometric mirror 116 directs the UV radiation and the laser light along the common optical path.

[0040] In some embodiments, the photodiode detector 190 also serves to initially align the beam position to the center of each window. For example, UV radiation can be swept across an array of capillaries and the capillary center positions can be recorded. In front of each capillary is a window. During the sweep of the UV radiation, as the light passes through the window associated with the capillary, a signal exhibiting eight peaks is detected. The midpoint between the start and end of each peak corresponds to the center of the capillary window and therefore the capillary.

[0041] In this embodiment, system 100 further includes a fluorescence detector 180 for detecting laser-induced or UV-induced fluorescence, which in this implementation is a photomultiplier tube (PMT) for detecting fluorescence radiation emitted by the sample (e.g., fluorescence radiation emitted by a fluorescent marker attached to the sample, or the intrinsic fluorescence radiation of a biological sample excited by UV radiation). As discussed in more detail below, in this embodiment, the fluorescence detector receives the emitted fluorescence radiation via a number of optical fibers 185.

[0042] More specifically, an array of optical fibers 185a is positioned above the plane of the optical axis of the radiation (i.e., the common optical path), with the fibers angled downward at about 45 degrees to receive at least a portion of the fluorescent radiation emitted by the sample(s) disposed in the capillary. Another array of optical fibers 185b is positioned below the plane of the optical axis, with the fibers of that array angled upward at about 45 degrees to receive at least a portion of the fluorescent radiation emitted by the sample(s) disposed in the capillary. In general, the upper and lower optical fibers are angled such that their estimated extensions intersect the core of the capillary through which the radiation passes.

[0043] In this embodiment, each of the upper and lower optical fiber bundles includes 12 fibers (i.e., a total of 24 optical fibers are employed), although other numbers of optical fibers may be employed in other embodiments. In this embodiment, the proximal end of the optical fiber 185 is attached to a plate 191 that is in turn attached to a mount 193 on which a cartridge 195 containing the capillary may be mounted. As shown in FIG. 1G, the mount 193 may be coupled to a translation stage 193a, which allows the height of the mount to be adjusted to align the capillary with the radiation / light beam. A number of guide rods (400) may bring the collection fibers into close proximity to the capillary.

[0044] The distal end of the optical fiber 185 is coupled to a fiber coupling element 196 that aligns the distal end of the optical fiber with the fluorescence detector for efficiently coupling the fluorescence radiation (e.g., laser-induced or UV-induced fluorescence radiation) into the fluorescence detector.

[0045] In use, the galvanometric scanning mirror 116 scans the UV radiation and laser light across the capillaries by sequentially stepping the UV and laser beams across the center locations of the capillaries 122. During data acquisition, the beams are centered on the capillaries for a selected dwell time when data (e.g., UV absorption data and / or fluorescence data) is collected. The dwell time can vary based, for example, on the number of capillaries and the type of analysis.

[0046] In some embodiments, the controller 300 may control the scanning of the galvanometric mirror 116 to direct the UV radiation or the laser light beam to the capillary. The controller 300 may be implemented in hardware, firmware and / or software. By way of example, as shown in FIG. 2, the controller 300 may include a processor 302, a random access memory RAM 304, a permanent memory ROM 306, and a communication bus 308 that allows the processor 302 to communicate with other components of the controller 300. A set of instructions for controlling the galvanometric mirror 116 may be stored in the ROM 306 and transferred to the RAM 304 during run-time to control the scanning of the galvanometric mirror 116.

[0047] Fluorescence radiation emitted by a sample placed in the capillary is collected by fiber 185, which then transmits the collected fluorescence radiation to fluorescence detector 180. In this embodiment, cartridge 135 includes a filter 135a for blocking scattered laser or UV excitation light and a bandpass filter 135b for positioning in front of fluorescence detector 180 to block scattered laser or UV excitation light from reaching the detector and allow a desired bandwidth of fluorescence radiation to reach the detector, thereby improving the signal-to-noise ratio of the detected fluorescence radiation.

[0048] In some embodiments, the capillary is illuminated with UV radiation and laser light for different time intervals, although in some embodiments, the capillary may be illuminated with UV radiation and laser light sequentially. In some embodiments, at least a portion of the UV radiation may be absorbed by the illuminated sample and a portion of the UV radiation may be transmitted through the sample. The UV radiation (or at least a portion thereof) transmitted through the sample may be detected by a photodiode detector 190. The photodiode detector may generate a detection signal that may be employed to determine the UV absorption of the illuminated sample.

[0049] 2, system 100 may further include an analysis module 1000, which communicates with photodiode 190 and photomultiplier tube 180, receives detection signals from these detectors, and acts on the signals to obtain information about the sample under test. Analysis module 1000 may be implemented in hardware, firmware, and / or software, for example, in the manner discussed above in connection with controller 300. In some embodiments, a diode array spectrometer detector may be employed.

[0050] A dual-mode capillary electrophoresis system 100 according to the present teachings may provide several advantages. For example, in such a system, switching the mode of operation from a UV absorption mode to a laser-induced fluorescence (LIF) or intrinsic fluorescence (also referred to as fluorescence spectroscopy) mode may be easily accomplished by adjusting a galvanometric scanning mirror to receive radiation from a source of interest. In other words, since the system employs common components for the two modes, there is no need to remove and replace various components to switch from one mode of operation to another.

[0051] (Example) Example 1 The UV absorption of samples of deionized (DI) water containing different concentrations of caffeine (i.e., 2 μM, 5 μM, 20 μM, 100 μM, 500 μM, 1 mM, 2 mM, and 3 mM) was measured by passing UV radiation at a wavelength of 220 nm through multiple capillaries containing the samples. The decrease in transmitted UV power was converted to UV absorbance.

[0052] Figure 4 shows the R 2 A linear dynamic range in detecting caffeine concentrations from 2 μM up to 2 mM with a linear correlation of >=0.9998 is demonstrated.

[0053] Figure 5 shows a CZE separation using a test MixB sample (Sciex) performed simultaneously through eight capillaries. The relative standard deviation of migration time was below 0.5% for step-to-step and capillary-to-capillary. The relative standard deviation of peak area was below 2% for step-to-step and below 5% for capillary-to-capillary. UV signal crosstalk from adjacent capillaries was below 0.08%.

[0054] Example 2 Laser-induced fluorescence (LIF) was measured by placing the fluorescence through a fiber array cable to a photomultiplier detector. The excitation wavelength was 488 nm for sodium fluorescein and the LIF Test Mix sample. Figure 6 shows the fluorescence intensity (relative fluorescence units RFU) using different concentrations of sodium fluorescein (i.e., 100 pM, 200 pM, 1 nM, 5 nM, 20 nM, 100 nM, 500 nM, and 1 μm) in a 50 μm core capillary array. The dynamic range was 2 = 0.9998, which is at least 10,000:1.

[0055] Figure 7 shows the results of a CZE (capillary zone electrophoresis) separation using a LIF test Mix sample (Sciex) performed simultaneously through eight capillaries. The LIF signal crosstalk from adjacent capillaries is below 0.015%.

Claims

[Claim 1] The invention described in this specification.

Images