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Automatic sampling and analysis of organics and biomolecules by capillary action-supported contactless atmospheric pressure ionization mass spectrometry.

Hsieh CH, Meher AK, Chen YC - PLoS ONE (2013)

Bottom Line: Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells.No carryover problems are observed during the analyses.The feasibility of using this setup for quantitative analysis is also demonstrated.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan.

ABSTRACT
Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (∼1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated.

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Photograph of the automatic-sampling C-API setup.1, forceps; 2, 1 cm long capillary; 3, mass spectrometer; 4, XY movable stage; 5a and 5b, actuators; 6a and 6b, controllers; and 7a and 7b, cables to computers.
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pone-0066292-g001: Photograph of the automatic-sampling C-API setup.1, forceps; 2, 1 cm long capillary; 3, mass spectrometer; 4, XY movable stage; 5a and 5b, actuators; 6a and 6b, controllers; and 7a and 7b, cables to computers.

Mentions: The tapered capillary (1 cm) prepared above was held using a forceps, which was fixed with a clamp and an adjustable stand (Fig. 1). An aluminium sheet (3 cm×3 cm×2 mm) was used as the sample holder, whereas small round sample wells (1 mm in diameter and 0.5 mm in depth) were fabricated using a SDPL-50W (Sintec Optronics Pte, Singapore) µs-laser engraving machine. The machine was equipped with a Nd:YAG diode-pumped solid-state laser (λ = 1064 nm) and controlled using the Laser Marker software (version 3.2.3.5, Jinan DuoWei Laser Technology, Jinan, Shandong, China). Each well (1 mm in diameter) on the aluminium sample holder had a 3 mm (center-to-center) distance between each well. The aluminium sample holder was placed on a motorized XY stage regulated by motorized actuators (Z825B, Thorlabs) and controllers (TDC001, Thorlabs) and controlled with the T-cube DC servo motor driver software. Sample droplets (4 µL) were deposited in each well prior to MS analysis. During C-API automatic sampling analysis, the C-API capillary positioned in front of the orifice of an Esquire 2k ion trap mass analyzer (Bruker Daltonics, Bremen, Germany), was initially immersed into a rinse solvent [acetonitrile/deionized water (1∶1, v/v)] to conduct automatically flush for 10 s (or 30 s). Simultaneously, the MS was activated and it continually acquired the MS data. After 10 s, the aluminium plate was programmed to move quickly in x-direction for 3 mm (or 4 mm) and to allow the C-API capillary to be immersed into the next sample droplet, which consisting of sample solution. The MS continued to acquire data to monitor the changes in the ion signals. After 10 s (or 20 s), the aluminium plate was then moved 3 mm further in the x-direction and allowed the C-API capillary to sample the next well of rinse solvent for flushing through capillary action. The steps were repeated as a cycle during the auto-sampling C-API analysis. The maximum moving speed was set to 3 mm s−1 (with an average acceleration of 1 mm s−2). All movements steps were programmed using the T-cube DC servo motor driver software.


Automatic sampling and analysis of organics and biomolecules by capillary action-supported contactless atmospheric pressure ionization mass spectrometry.

Hsieh CH, Meher AK, Chen YC - PLoS ONE (2013)

Photograph of the automatic-sampling C-API setup.1, forceps; 2, 1 cm long capillary; 3, mass spectrometer; 4, XY movable stage; 5a and 5b, actuators; 6a and 6b, controllers; and 7a and 7b, cables to computers.
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3675195&req=5

pone-0066292-g001: Photograph of the automatic-sampling C-API setup.1, forceps; 2, 1 cm long capillary; 3, mass spectrometer; 4, XY movable stage; 5a and 5b, actuators; 6a and 6b, controllers; and 7a and 7b, cables to computers.
Mentions: The tapered capillary (1 cm) prepared above was held using a forceps, which was fixed with a clamp and an adjustable stand (Fig. 1). An aluminium sheet (3 cm×3 cm×2 mm) was used as the sample holder, whereas small round sample wells (1 mm in diameter and 0.5 mm in depth) were fabricated using a SDPL-50W (Sintec Optronics Pte, Singapore) µs-laser engraving machine. The machine was equipped with a Nd:YAG diode-pumped solid-state laser (λ = 1064 nm) and controlled using the Laser Marker software (version 3.2.3.5, Jinan DuoWei Laser Technology, Jinan, Shandong, China). Each well (1 mm in diameter) on the aluminium sample holder had a 3 mm (center-to-center) distance between each well. The aluminium sample holder was placed on a motorized XY stage regulated by motorized actuators (Z825B, Thorlabs) and controllers (TDC001, Thorlabs) and controlled with the T-cube DC servo motor driver software. Sample droplets (4 µL) were deposited in each well prior to MS analysis. During C-API automatic sampling analysis, the C-API capillary positioned in front of the orifice of an Esquire 2k ion trap mass analyzer (Bruker Daltonics, Bremen, Germany), was initially immersed into a rinse solvent [acetonitrile/deionized water (1∶1, v/v)] to conduct automatically flush for 10 s (or 30 s). Simultaneously, the MS was activated and it continually acquired the MS data. After 10 s, the aluminium plate was programmed to move quickly in x-direction for 3 mm (or 4 mm) and to allow the C-API capillary to be immersed into the next sample droplet, which consisting of sample solution. The MS continued to acquire data to monitor the changes in the ion signals. After 10 s (or 20 s), the aluminium plate was then moved 3 mm further in the x-direction and allowed the C-API capillary to sample the next well of rinse solvent for flushing through capillary action. The steps were repeated as a cycle during the auto-sampling C-API analysis. The maximum moving speed was set to 3 mm s−1 (with an average acceleration of 1 mm s−2). All movements steps were programmed using the T-cube DC servo motor driver software.

Bottom Line: Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells.No carryover problems are observed during the analyses.The feasibility of using this setup for quantitative analysis is also demonstrated.

View Article: PubMed Central - PubMed

Affiliation: Department of Applied Chemistry, National Chiao Tung University, Hsinchu, Taiwan.

ABSTRACT
Contactless atmospheric pressure ionization (C-API) method has been recently developed for mass spectrometric analysis. A tapered capillary is used as both the sampling tube and spray emitter in C-API. No electric contact is required on the capillary tip during C-API mass spectrometric analysis. The simple design of the ionization method enables the automation of the C-API sampling system. In this study, we propose an automatic C-API sampling system consisting of a capillary (∼1 cm), an aluminium sample holder, and a movable XY stage for the mass spectrometric analysis of organics and biomolecules. The aluminium sample holder is controlled by the movable XY stage. The outlet of the C-API capillary is placed in front of the orifice of a mass spectrometer, whereas the sample well on the sample holder is moved underneath the capillary inlet. The sample droplet on the well can be readily infused into the C-API capillary through capillary action. When the sample solution reaches the capillary outlet, the sample spray is readily formed in the proximity of the mass spectrometer applied with a high electric field. The gas phase ions generated from the spray can be readily monitored by the mass spectrometer. We demonstrate that six samples can be analyzed in sequence within 3.5 min using this automatic C-API MS setup. Furthermore, the well containing the rinsing solvent is alternately arranged between the sample wells. Therefore, the C-API capillary could be readily flushed between runs. No carryover problems are observed during the analyses. The sample volume required for the C-API MS analysis is minimal, with less than 1 nL of the sample solution being sufficient for analysis. The feasibility of using this setup for quantitative analysis is also demonstrated.

Show MeSH
Related in: MedlinePlus