Biological fluids, samples

Under normal circumstances blood should be the biological fluid sampled to measure the concentrations of the API. In most cases the API or its metabolites are measured in serum or plasma. If the API is excreted predominantly unchanged in the urine, urine can be sampled. The volume of each sample must be measured at the study centre, where possible immediately after collection, and included in the report. The number of samples should be suf-... 

Some of the methods for determining selenium in biological materials have been compared within the same laboratory for accuracy and precision. Macpherson et al. (1988) compared the accuracy of three methods for the determination of selenium in biological fluid samples from biological materials with... 

Automated sample preparation is commonplace in the drug discovery laboratory with biological fluid samples such as plasma, serum, bile, or urine [26,31], The primary goal for sample preparation with LC-MS-based methods in drug discovery is to separate the drug and/or metabolites from the endogenous materials in the sample matrix (e.g., proteins, salts, and metabolic by-products). 

Cassiano NM, Lima VV, Oliveria RV, Pietro AC, Cass QB, Development of restricted-access media supports and their application to the direct analysis of biological fluid samples via high-performance liquid chromatography. Anal. Bioanal. Chem. 2006 384 1462-1469. 

With the empowerment of proteomics and lipidomics of tissue and biological fluid samples, investigators are able to detect low levels of ideal biomarkers for neurotraumatic and neurodegenerative diseases. Proteomics and lipidomics have... 

Liquid-liquid extraction (LLE) LLE is the classical method used for herbicide isolation, especially from water and biological fluid samples. Ethyl acetate, dichloromethane, and their mixtures are among the preferred extraction solvents for phenylureas, triazoles, amides, carbamates, benzimidazoles, and chlorotriazines. The extraction efficiency is modified by adjustment of pEI and ionic strength in the aqueous phase. In situ derivatization of the target analytes is also used as an effective tool (e.g., chlorophenoxy acidic herbicides are derivatized with dimethyl sulfate prior to their extraction by n-hexane). The classical way of performing LLE is the separation funnel extraction. Some continuous LLE extractors or steam distillers are also available. 

Many of these electrochemical methods were dedicated towards the determination of pharmaceutical drugs. The electroanalytical determination of pharmaceutical drugs has been widely explored, and the methods need to present high sensitivity, especially for the determination of active ingredients in biological fluid samples. The work reported by... 

Becanse of the differences in the matrix components of samples such as urine, blood, or serum, simple external calibration can often produce erroneous results. For that reason, it is common to use other calibration methods such as standard additions or addition calibration to achieve accurate data. These methods have been described in detail in Chapter 13, but they are required because of the matrix suppression effects caused by large variations in patients biological fluid samples. The sample preparation method used will often dictate the type of calibration curve to use, but all three... 

Rock digests containing calcium, magnesium, iron, and aluminum at a few hundred ppm, with maybe some alkaline peroxide/borate fusion mixtures Biological fluid samples such as blood or urine, containing carbonaceous, organic, and saline components... 

Polyphenolic compounds are determined mainly in the plasma, rather than in whole blood and in urine. The research, in the majority of cases, relate to samples from patients who take dietary supplements containing polyphenols or are on a diet rich in such compounds. Biological fluid samples are collected at different time intervals after the administration of the herbal preparation (e.g., Hippophae rhamnoides (20), Hawthorn leaves flavonoids (21), GegenQinlian decoction (22), Flos Lonicerae japonicae (23)) containing different amounts of polyphenols. The isolation and preconcentration of analytes of these samples usually precedes the enzymatic hydrolysis (24—28) or acid hydrolysis (20), which is based on the conversion of glucuronide and sulfate derivatives of polyphenolic compounds formed in phase II metabolism to the basic forms of polyphenols. To carry out the enzymatic hydrolysis there are... 

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