Matrix solid phase dispersion MSPD

A technique that attempts to combine the extraction and SPE into a single step is matrix solid-phase dispersion (MSPD). In this technique, a nonpolar (such as Cig) SPE sorbent is blended directly into tissue matrix, the mixture is packaged into an SPE cartridge, and the cartridge is eluted like a typical SPE cartridge. The advantage of MSPD is reduced sample size and increased efficiency due to a reduced number of steps. 

Solid-phase sorbents are also used in a technique known as matrix solid-phase dispersion (MSPD). MSPD is a patented process first reported in 1989 for conducting the simultaneous disruption and extraction of solid and semi-solid samples. The technique is rapid and requires low volumes (ca. 10 mL) of solvents. One problem that has hindered further progress in pesticide residues analysis is the high ratio of sorbent to sample, typically 0.5-2 g of sorbent per 0.5 g of sample. This limits the sample size and creates problems with representative sub-sampling. It permits complete fractionation of the sample matrix components and also the ability to elute selectively a single compound or class of compounds from the same sample. Excellent reviews of the practical and theoretical aspects of MSPD " and applications in food analysis were presented by Barker.Torres et reported the use of MSPD for the... 

Long AR, Crouch MD, Barker SA. 1991b. Multiresidue matrix solid phase dispersion (MSPD) extraction and gas chromatographic screening of nine chlorinated pesticides in catfish (Ictalurus punctatus) muscle tissue. J Assoc Off Anal Chem 74 667-670. 

In matrix solid-phase dispersion (MSPD) the sample is mixed with a suitable powdered solid-phase until a homogeneous dry, free flowing powder is obtained with the sample dispersed over the entire material. A wide variety of solid-phase materials can be used, but for the non-ionic surfactants usually a reversed-phase C18 type of sorbent is applied. The mixture is subsequently (usually dry) packed into a glass column. Next, the analytes of interest are eluted with a suitable solvent or solvent mixture. The competition between reversed-phase hydrophobic chains in the dispersed solid-phase and the solvents results in separation of lipids from analytes. Separation of analytes and interfering substances can also be achieved if polarity differences are present. The MSPD technique has been proven to be successful for a variety of matrices and a wide range of compounds [43], thanks to its sequential extraction matrices analysed include fish tissues [44,45] as well as other diverse materials [46,47]. 

Examples of Matrix Solid-Phase Dispersion (MSPD) for the Analysis of Drug Residues in Edible Animal... 

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). 

In our laboratory, an on-flow LC-NMR-MS screening (Figure 5.1.1) was applied to both saponin fractions which were not separated into pure compounds by classical column chromatography and further to total asterosaponin fractions obtained by the micropreparative technique, matrix solid-phase dispersion (MSPD) extraction [45] (see Figure 5.1.2). The LC-NMR-MS hyphenation is set up in the widely used parallel configuration of NMR and mass spectrometer (Figure 5.1.3). Typically, absolute amounts of asterosaponin mixtures of about 500 xg - 1 mg are injected onto the column. 

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...

Matrix solid-phase dispersion (MSPD) is the extraction method of choice for the analysis of solid samples, such as plant material, foodstuffs or tissue samples [26]. This method has been developed especially for solid or viscous matrices. MSPD is preferable to other extraction techniques, because the solid or viscous sample can be directly mixed with the sorbent material of the stationary phase [27]. As the carotenoid stereoisomers stay bound in their biological matrix until the elution step, they are protected against isomerisation and oxidation [28]. The extraction scheme of MSPD is shown in Figure 5.2.1. 

Figure 5.2.1 Scheme for the extraction of geometrical carotenoid isomers from solid biological samples employing matrix solid phase dispersion (MSPD)... 

Development of matrix solid-phase dispersion (MSPD) concerning New sorbents Temperature and pressure of extraction Cleanup of extracts Miniaturization Extraction of organic xenobiotics from a variety of solid, semisolid, and viscous environmental and biological matrices 70-75... 

A variety of solvent extraction techniques have been used to extract antioxidants from food matrices. The most commonly used is maceration or homogenization of the sample with an extraction solvent however, alternative procedures have been developed including pressurized fluid extraction (PFE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and matrix solid-phase dispersion (MSPD), among others. The principles of each extraction technique will be briefly discussed. 

Table 2.5 Examples of extraction of antioxidant phytochemicals from various plant materials by matrix solid phase dispersion. (MSPD). 

Barker, S.A. 2007. Matrix solid phase dispersion (MSPD). J. Biochem. Biophys. Meth. 70 151-162. 

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. 

Matrix solid-phase dispersion (MSPD) is an SPE variant where samples are ground and mixed with a Cjg support. This is placed in a disposable column previously packed with Florisil that traps the fat from the... 

Figure 9.4. Matrix solid-phase dispersion (MSPD).

Matrix solid-phase dispersion (MSPD) was developed by researchers at Louisiana State University s School of Veterinary Medicine in order to isolate, identify, and quantify veterinary drug residues in livestock (Barker and Hawley, 1992). Compared to traditional methods, MSPD reduces solvent use by 98% and turnaround time by as much as 90%. The method involves the mechanical blending of a sample matrix with bulk C-18 sorbent. The C-18 hydrophobic phase has the ability to incorporate the lipids in meat and other food products into its matrix. Mechanical shearing forces initially disrupt the sample structure and disperse the sample over the surface of the C-18 bonded silica. The process causes the sample and polymer phase to become semidry, which then allow the material to be packed into a column (see Fig. 9.4). 

The LC/MS positive-ion mode analysis of grape carbamates reported in Fig. 9.11 (carbaryl, carbofuran, diethofencarb, ethiofencarb, fenobu-carb, fenoxycarb, isoprocarb, methiocarb, metholcarb, oxamyl, pirimi-carb, propoxur, and thiobencarb) was performed by matrix solid-phase dispersion (MSPD) extraction using either atmospheric pressure-chemical ionization (APCI) or electrospray ionization (ESI) (Fernandez et al., 2000). 

Long, A.R. Hsieh, L.C. Malbrough, M.S. Short, C.R. Barker, S.A. Matrix solid-phase dispersion (MSPD) isolation and liquid chromatographic determination of oxytetracycline, tetracycline, and chlortetracycline in milk. J.Assoc.Off.Anal.Chem., 1990, 73, 379-384... 

The procedure to be used to extract carbamate pesticides from environmental samples depends on their polarity and on the type of sample matrix involved. Various choices exist for the extraction of pesticides ranging from conventional procedures (e.g., Soxhlet extraction, liquid-liquid extraction (LLE), evaporation, steam distillation) to new methodologies including solid-phase extraction (SPE), solid-phase microextraction (SPME), supercritical fluid extraction (SEE), matrix solid-phase dispersion (MSPD), accelerated solvent extraction (ASE) and microwave-assisted extraction. " ... 

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... 

Figure 4.3 Matrix solid phase dispersion (MSPD) procedure. Main steps of MSPD (I) the sample is blended with the dispersant material in a mortar with a pestle (II) the homogenized powder is transferred in a solid phase extraction cartridge, and compressed (III) elution with a suitable solvent or solvent mixture is performed by the aid of a vacuum pump. (Adapted from Capriotti et al. and with permission from Elsevier copyright 2010.)...

GC-ECD after selective extraction of CAP from muscle by means of matrix solid-phase dispersion (MSPD) and subsequent conversion into the trimethylsilyl derivative. Although the method is rapid and uses only a few millilitres of organic solvent, the LCDs of 2-4 (xg/kg found for cattle, pig, and horse muscle tissue do not permit CAP monitoring at the MRPL of 0.3 (xg/kg. 

Matrix solid-phase dispersion (MSPD) integrates extraction and clean-up in a single step, and greatly speeds-up sample throughput. It has also been proposed for the isolation of several organophosphate esters, mainly flame retardants and plasticizers in indoor dust samples (Garcia et al. 2007). 

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