Alternate matrix

Defining Ax as the column vector with elements (x —x0) and (y — y0), an alternative matrix formulation is... 

Polarization propagators or linear response functions are normally not calculated from their spectral representation but from an alternative matrix representation [25,46-48] which avoids the explicit calculation of the excited states. 

Alternatively, matrix effects can be evaluated using postcolumn infusion methods described in detail in this chapter and elsewhere (King et al., 2000 Weng and Halls, 2002 Mei, 2005). 

FIGURE 9.3 Alternative matrix and reservoir patch designs. (Modified from Rathbone, M.J., Oral Mucosal Drug Delivery, Marcel Dekker, New York, 1996.)... 

The common biological matrixes for bioanalysis are various tissues, body fluid, whole blood, plasma, serum, and urine. More recently, dried-blood spot sample as alternative matrix has gained popularity in the industry [8], Prior to LC-MS/MS... 

Alternative Fblymer Matrices. The prospect for alternative matrix materials (Table II) for calcium ISEs has been examined in conjunction with the model liquid calciun ion-exchanger/DOPP cocktail (2). Evidently functional electrodes can be fabricated with poly(2-methyl propyl methacrylate) (P2-MFMA) but not with the corresponding poly(butyl methacrylate) (PBMA), poly(methyl methacrylate ) (PMMA) or... 

Each storage condition should be treated separately under its own matrixing design. Matrixing should not be performed across test attributes. However, alternative matrixing designs for different test attributes can be applied if justified. 

As alternative matrix additives for FCC catalysts, several silico-alinninates with controlled structural properties were prepared and characterized. These silico-aluminates have the potential to crack high molecular weight hydrocarbons without a loss of selectivity. In this... 

Arendt, R.H. Alternate matrix materials for molten carbonate fuel cell electrolyte structures. J. Electrochem. Soc. 1982, 129 (5), 979-983. 

Tanimoto, K. Miyazaki, Y. Yanagida, M. Tanase, S. Kojima, T. Okuyama, H. Kodama, T. Alternative matrix materials for molten carbonate fuel cell. Denki Kagaku 1990, 41 (2), 51-55. 

The alternative matrix (C or S) is then estimated (C or S), followed by applying the constraints to that specific matrix (C or S)... 

Standard penetrator material [6.29]. Nevertheless, recent environmental considerations have put a strong emphasis on substituting depleted uranium by heavy metals because of its radioactivity. Efforts to improve the ballistic performance through proper processing and compositional modifications have failed [6.29,6.39]. Recent research has therefore focused on alternative matrix alloys, such as tungsten-hafhium, tungsten-uranium composites [6.29], or heavy metal alloys with a spiculating core of WC [6.41]. 

Keywords Cannabinoids Pharmacokinetics Tetrahydrocannabinol Cannabidiol Absorption Distribution Metabolism Excretion Interpretation Oral fluid Sweat Hair Plasma Urine Alternate matrix Marijuana... 

For a majority of biomarker assays, standard calibrators are prepared in an analyte-free alternative matrix instead of the de facto sample matrix of patient samples. For such methods, it is crucial to demonstrate that the concentration response relationship in the sample matrix is similar to that of the alternate matrix. Spike-recovery experiments with the reference standard may be inadequate to evaluate the matrix effect, as the reference standard may not fully represent the endogenous analyte. Instead, parallelism experiments are performed through serial dilutions of a high-concentration sample with the calibrator matrix. Multiple individual matrix lots (>3 lots) should be tested to compare lot-to-lot consistency. In the instance that the limited amounts of sample are available, apooled matrix strategy can be used with caution as discussed by Lee et al. [15]. The samples can be serially diluted with the standard matrix (standard... 

Fig. 6. Electron micrograph of a portion of nucleolar core isolated from Tritunis viridescens oocyte, showing alternating matrix units (M) and spacer segments (S). (By courtesy of Dr. O. L. Miller, Jr., reprinted from J. Cell Physiol. Suppl. 1 74, 225 (1969).]...

For reasons such as cost and availabibty, it may be necessary to use a matrix with a composition differnt from that of the samples which are to be analyzed. The choice of an appropriate alternate matrix may be as simple as using... 

Despite the universal adoption of PVC, some investigations have centred on the prospect of alternative matrix materials. Except for poly(vinylisobutyl ether) (71), poly(methyl methyl acrylate) (72), poly(methyl acrylate) (39) and poly(vinyl chloride/alcohol) copolymer (73), practically no functional calcium ISEs were realized with poly(vinylidene chloride) (19), cellulose acetate, ethyl cellulose, collodion or pyroxylin (11). Photocured sensor membranes based on acrylates are considered in section 3.4.4. 

Modulation of the Discriminatory Power Using an Alternative Matrix Solntion... 

In order to eliminate this unconvenient feature various procedures were proposed of which the simplest is probably the topological approximation arising from the philosophy of the overlap determinant method with its assigning tables. Rewriting these tables in the alternative matrix form (140), the problem of the multicenter integrals can be substantially simplified. 

Other alternative matrix in forensic analysis by GC is sweat. For this matrix, drug detection windows may be longer (up to 1-2 weeks) and sweat testing offers... 

The extremely large excess of matrix ions renders the analysis of anionic impurities very difficult. Concentration differences between matrix and analyte ions of 10 1 are not unusual. (Example chloride contamination in the range of 100 pg/L in 24.5% (v/v) HF) Although the matrix problem can be solved by diluting the acids, the sample then falls below the detection limits for the analyte ions. Siriraks et al. [142], for example, obtained detection limits between 0.04 and 0.08 mg/L for chloride, bromide, orthophosphate, and sulfate in 0.25 % HF by direct injection. Utilizing an alternative matrix elimination technique — methanol/water rinse of the concentrator column after pre-concentration of HF — the tolerable HF concentration could be increased to 5 %, while maintaining the detection limit. However,... 

C. Alternative matrix application Solvent-free and matrix-free methods. Sublimation of matrix was successfully developed for matrix application [23, 61, 62], This approach provided a homogeneous coating of matrix for high-resolution IMS of GPL species from tissue sections. The apparatus used for the method is relatively simple and commercially available. The advantages of sublimation include the elimination of diffusion of the lipid molecules because no solvent is used during the matrix application, the increased purity of the matrix, and the reduction of the crystal size. 

Much has been written about the progress and development of the use of oral fluid as an alternative matrix for DUID testing. Similarly, oral fluid as an alternative matrix is finding application in workplace drug testing. 

Analysis of oral fluid as an alternative matrix to blood and urine in DUID testing offers many advantages. Developments in LC—tandem MS systems have permitted the practical realization of these advantages. The current limitations of ionization source technology means that the robustness of the associated methodology is greatly influenced by matrix effects, and it is essential that this is adequately investigated as part of the method validation. 

---