Sample preparation matrix solid-phase dispersion

Beef kidney samples were analyzed for atrazine by dispersing 0.5-g portions of kidney with 2-g portions of XAD-7 HP resin for matrix solid-phase dispersion. " By using a mortar and pestle, a powder-like mixture was prepared that was subjected to subcritical extraction using ethanol-modified water at 100 °C and 50 atm. The ethanol-water extract was sampled using a CW-DVB SPME fiber for direct analysis using ion-trap GC/MS, and the recoveries were quantitative for atrazine at the 0.2 mg kg fortification level. 

When liquid samples such as serum, plasma, milk, or honey are not to be extracted using direct liquid-liquid partitions with organic solvents but through use of solid-phase extraction or matrix solid-phase dispersion techniques, dilution with water (323, 324), phosphate buffer saline (325), or phosphoric acid (326, 327) is often the only sample preparation procedure applied. Milk analysis sometimes requires further pretreatment for fat removal (328). Centrifugation at about 7000g at 4-10 C for 20 min is the usually applied procedure for making the fat floating on top of milk readily eliminated. 

Starting with a description of the analytical challenge in Chapter 19, the third part, which is devoted to analytical attitudes, proceeds with a detailed description in Chapter 20 of modern sample preparation procedures including solid-phase extraction, matrix solid-phase dispersion, use of restricted-access media, supercritical fluid extraction, and immunoaffinity cleanup. Flexible derivatization techniques including fluorescence, ultraviolet-visible, enzymatic, and photochemical derivatization procedures are presented in Chapter 21. 

A multiresidue technique—matrix solid-phase dispersion (MSPD)—was used to purify the meat samples. The prewashed Cl8 bulk material was gently ground with the blended sample. The resultant C18/tissue matrix mixture was transferred to a 10-ml syringe barrel. The precolumn prepared in this way was washed with hexane, and FZD residues were eluted with dichloromethane, with 13 other veterinary drugs assayed. The recoveries varied from 44% to 87%, depending on the concentration level, and the LOD was established at 2.5 ng/kg (20). 

Figure 5.1.2 Matrix solid-phase dispersion (MSPD) extraction as a micro-preparative extraction technique for an on-flow LC-NMR-MS screening. Since the latter requires only sample amounts in the 0.5-2 mg range, the sample preparation can be achieved by fast small-scale extraction procedures, such as MSPD. This is a sample preparation technique that combines both sample homogenisation and extraction of compounds of interest in one single step starting from the intact sample material. Thus, it simplifies the extraction and clean-up steps, reduces the sample manipulation and is much faster than conventional techniques. It is therefore very well suited for a rough separation of extracts into classes of compounds of similar polarities, which can then be submitted to LC-NMR-MS analysis...

Karasova G. Brandsteterova E. Lachova M. 2003. Matrix solid phase dispersion as an effective preparation method for food samples and plants before HPLC analysis. Czech J. Food Sci. 21 219-234. 

Before any sample can be subjected to chromatography, some type of sample preparation is required, which can be as simple as filtration or an involved solid-phase extraction protocol. Sample preparation is that activity or those activities necessary to prepare a sample for analysis. The ultimate goal of sample preparation is to provide the component of interest in solution, free from interferences and at a concentration appropriate for detection. This entry will briefly discuss seven topic areas included in sample preparation standard methods, solid-phase extraction (SPE), matrix solid-phase dispersion (MSPD), solid-phase microextraction (SPME), microdialysis, ultraliltration (UF), and automated systems. 

Baker, S. A., Preparation of nfllk samples for immunoassay and liquid chromatographic screening using matrix solid-phase dispersion, JAOACInt. 77 848 (1994). 

Lagana, A. et al., Sample preparation for determination of macrocyclic lactone myco-toxins in fish tissue, based on on-line matrix solid-phase dispersion and solid-phase extraction cleanup followed by liquid chromatography/tandem mass spectrometry, J. AOACInt., 86(4), 729, 2003. 

Barker, S.A. Long, A.R. Preparation of milk samples for immunoassay and liquid chromatographic screening using matrix solid-phase dispersion. J.AOAC Int, 1994, 77, 848-854 [MSPD infant formula also albendazole, chloramphenicol, chlorsulon, chlortetracycline, fenbendazole, furazolidone, mebendazole, oxfendazole, oxytetracycUne, sulfadiazine, sulfadimethoxine, sulfamerazine, sulfa-... 

Matrix solid phase dispersion (MSPD) is an effective sample preparation technique that combines extraction and purification in one step. Barker et al. defined MSPD procedures as those that use dispersing sorbents with chemical modification of the silica surface (e.g.. Cl8, C8). Samples are blended and dispersed on particles (diameters of 40-100 p.m) using a glass or agate mortar and pestle (Pig. 4.3). The use of ceramic or clay mortars and pestles can result in loss of analytes. A disadvantage of the method is the traditionally high sorbent sample ratios... 

Solid-phase extraction (SPE) using small, disposable cartridges, columns, or disks is employed for isolation and cleanup of pesticides from water and other samples prior to TLC analysis, especially using reversed-phase (RP) octa-decyl (C-18) bonded silica gel phases. Microwave-assisted extraction (MAE) is a time- and solvent-saving method for removing residues from samples such as soils. Supercritical fluid extraction (SEE) has been used for sample preparation in the screening of pesticide-contaminated soil by conventional TLC and automated multiple development (AMD). Ultrasonic solvent extraction (USE) and videodensitometry have been combined for quantification of pesticides in sod. Matrix solid-phase dispersion (MSPD) with TLC and GC has been used to determine diazinon and ethion in nuts. 

For many years, the traditional sample preparation methods, such as the Soxhlet extraction, were applied. Most of these methods have been used for more than 100 years, and they mostly require large amounts of organic solvents. These methods were tested during those times, and the analysts were familiar with the processes and protocols required. However, the trends in recent years are automation, short extraction times, and reduced organic solvent consumption. Modern approaches in solid sample preparation include microwave-assisted solvent extraction (MASE), pressurized liquid extraction, accelerated solvent extraction (ASE), matrix solid-phase dispersion (MSPD), automated Soxhlet extraction, supercritical fluid extraction (SEE), gas-phase extraction, etc. 

Today, sample preparation is maybe the step that most influences the accuracy of the whole analytic method, with the extraction of pesticide residues from environmental matrices the key factor for achieving it. There is no question that in the first decade of the century, SPE technique [72] is the most employed alternative to the classical solid-liquid [13] and liquid-liquid [14] extractions. These classical techniques present multiple disadvantages such as the low recovery of polar pesticides and transformation products (in the case of liquid-liquid extractions) and use of large volumes of solvents. Furthermore, several variants emerged based on the SPE technique solid-phase microextraction (SPME) [72-74], in-tube solid-phase microextraction [72,75,76], matrix solid-phase dispersion [72,77,78], and stir-bar sorptive extraction [72,79]. 

Margarine is an example of a solid sample where the materials of interest are soluble in one solvent (in this case methanol) whereas the matrix materials, largely triglycerides, are not. As a consequence, the sample preparation procedure is relatively simple. The chromatographic separation is achieved by using the dispersive interactions between the hydrocarbon chains of the fatty acids and the hydrocarbon chains of a reversed phase. 

This sample preparation involved, firstly, an extraction and the elimination of the solid matrix by filtration and, secondly, a concentration procedure employing a solid phase extraction cartridge. The compounds of interest were separated solely by dispersive interactions with the reversed phase. In the example given, the corn meal was spiked with the aflatoxins. 

There is also a new form of SPE, called matrix dispersion solid-phase extraction, which uses the solid phase (silica and C-18) to grind the samples and prepare the analyte for extraction. The food product is incorporated into the pores of the 40-pm packing material in the grinding process, which is done in a mortar and pestle, and the packing material is then packed into a... 

Solid-phase microextraction (SPME) was developed to address the need to facilitate rapid sample preparation both in the laboratory and onsite where the investigated system is located. In this technique, a small amount of extracting phase dispersed on a solid support is exposed to the sample for a well-defined period of time. In one approach, a partitioning equilibrium between the sample matrix and extraction phase is reached. In this case, convection conditions do not affect the amount extracted. In the second approach utilizing short time pre-equilibrium extraction, if convection/agitation is constant, the amount of analyte extracted is related to extraction time. Quantification can then be performed based on timed... 

Sample Preparation Methods for Solid Matrices. Sample preparation is critical to MALDI using solid matrices. The presumption is that the polymer and the salt must be well dispersed in the final matrix mixture to achieve a one-to-one representation of the polymer MMD in the solution to the polymer MMD in the gas phase. Yet, the matrix is commonly crystalline and the polymer may be either semicrystalline, like PEO, or glassy, like atactic polystyrene. Kinetic processes occurring during the loss of solvent from the solution of the mixture of matrix, salt, and polymer must occur either to co-crystallize the polymer with the matrix and salt or to embed the polymer in the defect structure of the organic matrix. To obtain the correct representation of the MMD in the ms, each n-mer in the MMD must occur in the ms in proportion to its appearance in the original MMD. 

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