GB2427467A

GB2427467A - Solid phase extraction apparatus

Info

Publication number: GB2427467A
Application number: GB0425135A
Authority: GB
Inventors: Hossein Salar Amoli; Zeynalabedin Bashiri Sadr
Original assignee: Individual
Current assignee: Individual
Priority date: 2004-11-13
Filing date: 2004-11-13
Publication date: 2006-12-27
Also published as: GB0425135D0

Abstract

A solid phase extraction workstation for extracting a plurality of samples simultaneously, the workstation comprising a number of glass manifold chambers 2, each chamber being attached to a vacuum source and having an access opening sealable by a removable cap 3; and valve means 8 allowing each manifold to be detached from the vacuum source independently. Each manifold will preferably hold one extraction syringe, and are independently controllable. The manifolds may also have drains 4 with stopcock controlled valves 5.

Description

EASY USE MULTI CHANNEL SOLID PHASE EXTRACTION DEVICE

Technical Field of the invention: The present invention relates to separation/preconcentration techniques, generally named solid phase extraction (SPE). The suggested multi channels device is useful for processing simultaneously several samples.The running of a plurality of liquid samples in parallel may be done using the same SPE procedure, but also by using different ones. Background and prior art: Liquid sample preparation using SPE is a well known process in which targeted substances are selectively retained or evacuated through the sorbent bed used. SPE is a mean of cleaning and concentrating liquid samples prior to chromatographic analysis. The sorbent bed usually consists of a silica-based material in bead or powder form. The extraction procedure usually consists of four to six steps during which different elution solvents are used. The elution may be more readily accomplished under the influence of a vacuum, which increases the solvents flow rate through the solid packing material. It is known in the art to construct a manifold device allowing processing simultaneously several liquid samples. In a prior art device of this type, a vacuum chamber is provided whereby the vacuum acts to simultaneously elute a plurality of samples. The vacuum chamber, which in the prior art has generally been constructed of either stainless steel or an opaque plastic material, is provided with a plurality of fittings in the lid or cover. The fittings may be used directly to support and drain an SPE syringe, or may have had interposed in the flow path a stopcockcontrolled valve. The SPE syringes consist of packed columns containing said silica material, and having a luer connection to be placed into each of the valve fittings and supported thereby on the lid of the vacuum chamber.Liquid samples poured into the SPE syringes pass through the packed SPE syringes and are drawn through the silica material by the vacuum force into the vacuum manifold. Collection tubes or other collection vessels are provided in the vacuum chamber to collect the eluent from each of the valves. Transparent material, such as clear plastic, has been used for the housing of the vacuum chamber, so that the operator can observe the collection of eluent in the collection tubes inside the chamber, and monitor the progress of the sample preparation. In other prior art device, a vacuum manifold equipped with coaxial screw-type valve means providing precise and gradual control of the flow, was described. To the extent that vacuum manifolds known in the prior arts have been provided with a plurality of fittings in the lid (or cover), they have been difficult to use because SPE procedures usually consists of several steps during which different elution solvents are used and in many cases the operator has to stop the procedure, and remove the lid to introduce or change the collection tubes. In case different extraction procedure are to be simultaneously conducted, it will be difficult to the operator to take care of all the SPE syringes fitted in the lid (generally 10 fittings) and there is a possibility of contamination due to aerosols in the common chamber. The conventional SPE apparatus have other disadvantage. In some procedures, due to the small volumes of elution solvent and sample plurality, it is difficult to control the solvent flow and avoid sorbent drying. All these problems and difficulties have been considered and solved in this invention.

Summary of the invention: The present invention provides a mean for sample preparation, in order to get convenient samples (sample cleaning) for further analysis. It is also a method of preconcentration thus providing samples, which can be analyzed even by instrument with relatively low detection limit. A collection funnel is provided for receiving liquid samples. The method further includes a step of positioning the solid phase extraction syringe over the collection funnel. A pipette array over the syringe could be designed for automatically and directly transferring liquid samples and solvents. The system is directed to an original glass vacuum manifold chamber. The vacuum chambers made in accordance with the invention are useful in reducing the sealing area thus providing both easy access and better sealing of the vacuum chamber. In preferred embodiments of the invention, the vacuum chamber is made of glass for viewing the progress of the SPE procedure within the vacuum chamber. The use of glass lends itself to easy cleaning, and the transparency of the vacuum chamber is not altered by age or exposure to staining or corrosive substances. It will be understood by those skilled in the art that, from a functional standpoint, the shape and relative dimensions of the glass vacuum manifold chamber, as well as the varying types of materials from which the vacuum chamber and its cap are made, are preferred for esthetic reasons but forms no part of the functioning of the present invention. Description of the drawings: For a better description of the SPE workstation related to the invention, reference is made to the accompanying drawings in which: Fig.l- is a front view of an SPE workstation made in accordance with the invention; Fig.2- is an enlarged prospective view of one glass vacuum manifold chamber unit; Fig.3- is an enlarged sectional view showing the sealing element; Fig.4- is a back view (cover removed) of the support device showing the vacuum pipes inside the body of the support device.

Detailed description of the invention: Each glass vacuum manifold chamber (totally four) is useful for solid phase extraction to clean or prepare chromatography samples. The liquid sample can be, for example, an aqueous sample or biological sample. As an example of an aqueous sample, a sea water sample extracted to remove PAHs molecules from the eluent. Referring now to Fig. 1, a support device is designated generally at 1. The support device holds four 250ml glass vacuum manifold chambers 2. In the preferred embodiment of the invention four cylindrical glass chambers 2 with removable caps 3 at the top and drains 4, equipped with stopcock-controlled valves 5, at the bottom. It will be understood that the particular shape or appearance and the number of glass vacuum manifold chambers 2 is immaterial. A glass vacuum manifold chamber of any other size, shape, wall thickness, or design features is functionally satisfactory and is intended to be within the scope of the invention. However, use of glass of whatever shape or form is desirable because it allows the operator to monitor, inside the chamber, the progress of the extraction process.Also, glass is durable, and may be easily cleaned and is not damaged in the event that the glass is exposed to chemicals. Each glass vacuum manifold chamber is provided with a conforming access portion or removable cap 3 (Fig.2). Cap 3 includes a sealing element 6 (Fig. 3), which overlies the top edge of the glass vacuum manifold chamber 2. The sealing element forms a vacuum tight seal between the glass vacuum manifold chamber and removable cap 3. The cap may be of whatever size and shape needed, in particular, embodiment to close and seal the vacuum chamber after the SPE syringe 7 body has been engaged through it and may have various design features. In the preferred embodiment, removable cap 3 is formed of a durable plastic material, such as polypropylene, while the sealing element 6 is formed of a more resilient material, such as foamed polyethylene. It is noted that the plastic for the removable cap and the foamed polyethylene for the sealing element, are selected, in part, on the basis of their solvent resistance. A vacuum outlet 8 equipped with stopcock - controlled valve extends through the upper lateral part of the wall of each glass vacuum manifold chamber and joins the vacuum pipes 16 inside the support device (Fig.4). On the outside part of the support device, the vacuum pipes outlet 16 is provided with a gauge 9 to register the vacuum or reduced air pressure within each glass vacuum manifold chamber. Extending through the removable cap 3, is the solid phase extraction syringe body 7 (Fig. 3). Solid phase extraction syringes contain a suitable adsorptive material. Solid phase extraction syringes are engaged through the removable cap until their male luer outlet 10 becomes positioned below the level of the vacuum outlet 8 as shown in Fig. 3. A vacuum control inlet 11 enters the glass vacuum manifold chamber wall at the opposite upper lateral part of the vacuum outlet 8. A graduated button 12 provides more reliable control and reproducible vacuum inside each glass vacuum manifold chamber. The stopcock-controlled valve drains 4 at the bottom of the glass vacuum manifold chambers have many important uses: 1- evacuation of washing liquids 2- retention of elution liquids 3- evacuation of high volume samples (> 250ml up to 1 liter) in the sample loading step. The 250 ml glass vacuum manifold chamber 2 can easily be washed by opening the removable cap 3. If necessary, in some application, a collection tube may be inserted inside the chamber to recover the elution liquid directly into it. If more efficient cleaning of the glass vacuum manifold chambers is required, the operator may process as follows to separate it from the support device: 1- open the glass vacuum manifold chamber holder 13 2- while holding the glass vacuum manifold chamber in one hand, open by turning opposite clockwise with the other hand caps 14 and 15 3- gently remove the glass vacuum manifold chamber To put back the glass vacuum manifold chamber on the support device use the reverse procedure. Solid phase extraction involves a multiple step process. Generally a conditioning step follower! . r act by :in equilibration step, than a sample loading step, one or more washing steps and finally the elution step. The many possible variations of solid phase extraction that can be performed with a device made in accordance with the invention, using different SPE procedures, are too numerous to mention and the individual solid phase sorbents used and processes are not material. It would be obvious to those skilled in the art to perform any type of SPE procedure using the manifold of the present invention.

Claims

We claim: 1 .An SPE workstation for use in simultaneous solid phase extraction of a plurality of liquid samples, comprising: several glass vacuum manifold chambers (at least four) having means defining an access opening; removable caps (covers) for the access opening of said glass vacuum manifold chambers, which are capable of sealing vacuum tight thereto; means for attaching a vacuum source to said glass vacuum manifold chambers to create a vacuum therein. means for removing each glass vacuum manifold chamber unit in case efficient cleaning is required buttons for adjusting residual air pressure inside each glass vacuum manifold chamber independently. valve means which are capable of isolating each glass vacuum manifold chamber from the vacuum source, thus allowing to evacuate elution solvents. drain valve means which are useful to evacuate solvents used for the different steps of the SPE procedure.
2. The glass vacuum manifold chambers set forth in claim 1 in which each cap (cover) is tightly sealed to the body of the glass vacuum manifold chamber by a resilient sealing.
3.The resilient sealing set forth in claim 2 provides a contact surface corresponding to the outer surface of the SPE syringe body engaged through it, thus providing complete sealing.
4.The resilient sealing set forth in claim 3 in comparison with prior arts is more advantageous because of its small size and pressure exercised on it by the cap (cover) in closed position, thus providing a complete sealing.
5.The plurality of glass vacuum manifold chambers set forth in claim 1, holding only one SPE syringe each are advantageous for the operator in comparison with prior arts, because when the operator removes the cap (i.e., for washing, evacuation of matrix or elution solvents, introduction of a collection tube) the procedure of only one SPE syringe is stopped.
6.The eluting liquids drop directly into the glass vacuum manifold chamber, which is advantageous in comparison with prior arts, that use different flow paths through valves, because risks of contamination are reduced to their lowest level.
7.Simple vacuum pipe system isolated from liquid path flows, which is advantageous in comparison with prior arts, because it avoids any risk of vacuum pump contamination with eluting solvents.
8.The glass vacuum manifold chambers of the SPE workstation set forth in claim 1, are presented in the form of independently controlled units allowing simultaneous processing of a plurality of liquid samples by SPE, especially in case different SPE procedures are carried out in parallel, and in comparison with prior arts is easier to control by the operator.