SPE disks

In analyses at fortification levels of 1 and lOmgkg of chlornitrofen, nitrofen and chlomethoxyfen in soil, the recoveries varied from 96 to 103% for GC/ECD (2 m x 3-mm i.d. spiral glass column packed with 1.5% silicone GE SE-30 temperature of column, injector and detector, 220, 230 and 220 °C, respectively) the LOD was 0.1 mgkg. In the method reported by Bao et a/. using a combination of disk SPE with GC/ITDMS, the recovery of oxyfluorfen at fortification levels ranging from 0.01 to 0.4mgkg was between 100 and 102% the LOD was 0.004mgkg. ... 

Other extraction methods use an SPE disk and SPME. The analysis of water samples using SPE disks (SPE-Cig disk) was performed according to the methodology described by Albanis and Hela. Generally, the SPME method is a more reliable technique than SPE for trace analysis that can shorten the analytical procedure. 

Significant improvements in the isolation of pharmaceutical compounds from plasma, serum and urine, have been achieved using ultra low mass sorbent bed and thin disk solid-phase extraction (SPE) material. The use of low sorbent masses or disk SPE material has allowed a significant reduction in solvent usage and extraction times. Several SPE RP-HPLC methods have been developed using these materials, including... 

Figure 6.39 Parallel extraction of 96 samples with an Empore 96 individual disk SPE plate (A) and vacuum manifold system, including an acrylic vacuum manifold top (.B), a polypropylene deep-well collection plate (C), two shims (D) for height adjustment of the collection plate, and a Delrin vacuum manifold (E) bottom. (Reprinted with permission from Simpson et al., 1998. Copyright 1998 John Wiley Sons.)...

Unfortunately, ASPEC procedures are rather slow. Therefore, SPE procedures in 96-well plate format were developed [95-96], Again, both cartridge and disk SPE systems have been used. An example of a 96-well plate SPE procedure is discussed in detail in Ch. 1.5.3. In this application, the use of the 96-well plate SPE procedure reduced sample work-up time for the determination of fentanyl in plasma from 3.5 hr to 2 hr [105]. 

Another example of a direct method is the on-line SPE approach embodied by a novel commercial device known as the SPE Card . This apparatus, originally developed by Olech and co-workers, couples 96-well disk SPE in a format that allows direct, serial elution into the mass spectrometer [109], Note that this method should not be confused with the Prospekt system described earlier for on-line SPE. Sample preparation occurs off-Une with the SPE-Card, and the card is placed in an on-Une device that performs serial elution into the MS. This method is considered direct, since it avoids the use of LC columns and removes the various sample transfer steps that normally follow SPE. 

The most widely used solvents in water extraction are n-hexane, ° isooctane, dichloromethane, " or pentane, or a mixture of them. SPE and elution with different mixtures of solvents are also very common. XAD-2, and CIS-bonded silica are the most widely used adsorbing resins. The adsorbing material is generally supported inside a column or fixed on a membrane disk. SPE has several advantages, i.e., use in field applications, easy automation. 

Figure 5.34 Infusion chromatograms covering the LC/MS assay time (2.5 minutes), obtained using the post-column infusion method shown in Figure 5.33, comparing the ability of different sample preparation methods to remove endogenous sample matrix components that interfere with the ionization of phenacetin. Panels (a) - (f) show the variation with time of the MS signed specific for the infused standard (phenacitin) following on-column injection of 10 p,L of a blank plasma sample prepared by one of the tested sample preparation methods, (a) Protein precipitation, (b) Oasis SPE. (c) Methyl-tertbutyl ether (MTBE) hquid-liquid extraction, (d) Empore C2 disk SPE. (e) Empore C8 disk SPE. (f) Empore Cl 8 disk SPE. Reproduced from Bonfigho, Rapid Commun. Mass Spectrom. 13,1175 (1999), with permission of John Wiley Sons, Ltd.

A variety of on line sample pretreatment procedures have been described for the coupling to on-line capillary zone electrophoresis (CZE)-MS, including capillary isotachophoresis, electrodialysis, liquid-liquid electroextraction and SPE on Empore disks. The latter system was applied to the analysis of the neuroleptic drug haloperidol in patients urine by on-line Empore-disk SPE-CZE-MS. 

The stationary phase in SPE comes in the form of a packed syringe-shaped cartridge, a 96-well plate [153], or a flat disk. These devices can be mounted on commercially available extraction manifold which allow many samples to be processed simultaneously. Up to 24 cartridges can be placed in a typical cartridge SPE manifold, while 6 disks can be placed in a typical disk SPE manifold. These SPE manifolds are usually equipped with a vacuum port to speed up the extraction process. The analytes are collected in sample tubes inside or below the manifold after they pass through the sorbent. 

Recently, SPE cartridges and disks have been widely and successfully used in preconcentration processes [1-3]. They reduce solvent usage, disposal costs, and extraction time for sample preparation and obtain large enrichment factors. 

Schmidt, L. B., et al., Injection Molding of Polycarbonate Compact Disks Relationship between Process Conditions, Birefringence, Block Error Rate, SPE-ANTEC, 1992. 

To determine secondary alkanesulfonates in sewage wastewaters, solid phase extraction (SPE) and a single-step procedure which combines elution and injection port derivatization for analysis with GC-MS were developed [36]. Again a tetrabutylammonium ion pair reagent was employed both to elute the secondary alkanesulfonates as their ion pairs from CI8-bonded silica disks and to derivatize sulfonate ion pairs under GC injection port conditions. Secondary alkanesulfonates were effectively recovered from samples of raw sewage (>92%) and from primary (>98%) and secondary (>85%) effluents. No... 

One field study on the mass flow of secondary alkanesulfonates was conducted in the Zurich-Glatt municipal wastewater treatment plant [37]. The concentration of alkanesulfonates in samples of raw sewage and primary and secondary effluents was analyzed using the above-described SPE with C18 Empore disks and injection port derivatization with GC-MS detection. The con-... 

Several extraction methods for water samples are applicable, such as solvent extraction, SPE using a cartridge and disk and solid-phase microextraction (SPME). 

A multi-residue method for 25 selected pesticides including propanil using an SPE disk has also been developed as a rapid screening method for organic contaminants in river, lake and seawater samples. Cig SPE disks are conditioned with 10 mL of acetone for 3 h. Water samples (1L) are allowed to percolate through the disks in order to trap the residues at a fiow rate of 50 mL min under vacuum. Residues trapped in the disks are extracted twice by eluting with 5 mL of dichloromethane-ethyl acetate (1 1, v/v). The more hydrophobic compounds (log/fow>3) seem to show no... 

SPE in cartridge or disk form is a rugged and reliable technique used in water analysis and is applicable to numerous classes of organic compounds including the... 

Solid phase extraction (SPE) is a very simple, rapid and reproducible cleanup technique that is now widely accepted as an alternative to the time-consuming liquid-liquid extractions. Additionally, SPE uses relatively small volumes of solvents, and is easy to automate. It is available in a number of different formats, including cartridges, disks, loose material, well plates or SPME using film-coated capillaries. SPE can be considered as an extraction technique when used for isolation and concentration or a cleanup technique when used to remove co-extractives from solvent extracts. The use of SPE for cleanup is discussed later. 

The use of SPE disks represents a relatively new SPE approach for the rapid and efficient isolation of pesticides from aqueous samples. Empore extraction disks have approximately 10 times the cross-sectional area of conventional SPE cartridges with comparable solvent mass (500 mg). The dense packing and uniform particle... 

The most common and diverse approach to cleanup (and extraction of water samples) in pesticide residue analysis is SPE. Over the last 20 years, improvements and diversifications in SPE formats, sorbent types, and apparatus have made SPE a widely used approach for a variety of applications, including the analysis of pesticide residues. SPE cartridges or disks can be likened to low-resolution HPLC columns in that similar stationary and mobile phases are used. A typical particle size in SPE is 40 pm, and the plastic cartridges are generally packed with 0.1-1 g of sorbent in plastic tubes. The choice of reversed-phase, normal-phase, and ion-exchange media in SPE is very diverse, and Table 2 lists some of the more popular SPE applications for the cleanup of pesticides. 

In summary, the development of materials for the extraction of pesticides from water samples has progressed from simple liquid-liquid extraction for the principal active compound to sophisticated SPE media capable of exclusively trapping the target pesticide and metabolites selectively. The development of alkyl bonded phase silica cartridges and extraction disks combined with on-line extraction techniques is currently the principal means used for the extraction and trace enrichment of pesticides and metabolites from water. 

The sorbents used for SPE are available in three basic formats, namely disks, prepacked cartridges, and syringe barrels, each with certain advantages. Solid media employed in SPE may be classified as nonpolar, polar and ion-exchange phases with mixed retention mechanisms (Table 3.41). The large sorbent selection ranges also... 

SPE is a useful device for working up of polymer additive dissolutions the apolar polymer is retained on the Cj 8 sorbent, while analytes may be eluted. In the fractionation of dissolutions it is advantageous to make use of the differences in polarity and affinity of the components with the sorbent. SPE of applied samples may be done with cartridges or disks, either off- or on-line. A flow-chart for the use of SPE has been published [3], Applications of SPE have been described in several monographs [511,512]. 

Yoshimura, A.S. Prud homme, R.K. "Viscosity Measurements in the Presence of Wall Slip in Capillary, Couette, and Parallel-Disk Geometries," SPE Reservoir Engineering, May 1988, 735-742. 

Analysis was performed on an ES-Ovomucoid column for stereoselectivity assessment, and for MS/MS, an X-Terra MS C18 column (2.1 x 100mm, 5 fan) was used. Figure 1.17 shows the wash and elution fractions from the SPE in a 384-well plate. The SPE conditions evaluated are listed in the table below the figure. The binding of the drug to the affinity sorbent in a 96-well plate was less efficient than the 384-well plate because the sorbent formed a disk on the former and a column on the latter. The efficiency is reflected in the >95% recoveries achieved with the 384-well format. 

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