Biological matrices blood analyses

The framework for the mixed effect modeling approach to population pharmacokinetic analysis can be dehned from the same two/three-stage approach perspective. For the f = 1,. .., n individuals in a population of interest, letXy,7 = rij represent the design points on which the responses are observed. In the pharmacokinetic setting, Xij are typically the sampling time points and are the observed concentrations in the biologic matrix of interest (usually plasma or blood). Hence, the pharmacokinetic response can be described by... 

Urine is also a very commonly studied biological matrix. It is much less complex than blood, and contains only a small amount of macromolecules. It has a high salt content and both organic and inorganic constituents. Its main components include NaCl (10 g/1), K (1.5 g/1), sulfate (0.8 g/1), phosphate (0.8 g/1), Ca and Mg (0.15 g/1), urea (20 g/1), creatinine (1 g/1), and uric acid (0.5 g/1). Urine should be protected from bacterial degradation, which is mostly accomplished by freezing the samples until analysis. 

Several methods are available for the analysis of trichloroethylene in biological media. The method of choice depends on the nature of the sample matrix cost of analysis required precision, accuracy, and detection limit and turnaround time of the method. The main analytical method used to analyze for the presence of trichloroethylene and its metabolites, trichloroethanol and TCA, in biological samples is separation by gas chromatography (GC) combined with detection by mass spectrometry (MS) or electron capture detection (ECD). Trichloroethylene and/or its metabolites have been detected in exhaled air, blood, urine, breast milk, and tissues. Details on sample preparation, analytical method, and sensitivity and accuracy of selected methods are provided in Table 6-1. 

Electrothermal atomization is particularly useful when the amount of sample is very small, when very low levels of detection are required and when the matrix is dilute or volatile. These criteria often apply to clinical samples (a pin-prick sample of blood produces only 50-100 mm of whole blood, but this is sufficient for analysis using an electrothermal atomizer, hence it is not essential for an intravenous sample to be taken). For such samples, often pretreatment is not required, and body fluids and biological tissues can be ashed in situ in the furnace. This also applies to some foods, although others may need some preliminary wet ashing. 

Methods for the detemination of organobromine compounds such as PBBs and PBDEs generally consist of the following steps extraction of the analyte from the sample matrix clean-up to remove interfering compounds and analysis (separation and quantitation). The primary method of analysis is GC coupled with ECD or MS. Analytical methods have been developed for the determination of PBBs and PBDEs in blood or serum, urine, feces, adipose tissue, liver, and breast milk. The methods for determining PBB and PBDE residues in biological samples are given in Tables 7-1 and 7-2, respectively. 

Interest for the analysis of taxanes in biological fluids deals, in most cases, with the determination of the two pharmaceuticals, paclitaxel, and docetaxel, and their metabolites in blood plasma. The complexity of this matrix and the interference of endogenous compounds are, in... 

In clinical analysis, flame AAS is very useful for serum analysis. Ca and Mg can be determined directly in serum samples after a 1 50 dilution, even with microaliquots of 20-50 pL [314]. In the case of Ca, La3+ or Sr2+ are added so as to avoid phosphate interferences. Na and K are usually determined in the flame emission mode, which can be realized with almost any flame AAS instrument. The burner head is often turned to shorten the optical path so as to avoid self-reversal. For the direct determination of Fe, Zn and Cu, flame AAS can also be used but with a lower sample dilution. Determination of trace elements such as Al, Cr, Co, Mo and V with flame AAS often requires a pre-concentration stage, but in serum and other body fluids as well as in various other biological matrices some of these elements can be determined directly with furnace AAS. This also applies to toxic elements such as Ni, Cd and Pb, which often must be determined when screening for work place exposure. When aiming towards the direct determination of the latter elements in blood, urine or serum, matrix modification has found wide acceptance in working practices that are now legally accepted for work place surveillance, etc. This applies e.g. for the determination of Pb in whole blood [315] as well as for the determination of Ni in urine (see e.g. Ref. [316]). 

In the analysis of 1,1,1-trichloroethane in biological materials, a key factor in the determination is the sample matrix under consideration. In the broadest sense, this can be broken down into liquid samples (e.g., blood or urine), solid samples (which would include adipose tissue, liver samples), and expired air samples. After 1,1,1-trichloroethane has been liberated from the sample matrix, a... 

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