Biomedical Sampling

Mass spectrometry is a highly selective analytical technique, which can provide reliable information about the molecular composition of a biological sample. The 

In bioanalytical studies it is always necessary to collect appropriate blank samples. These blank samples are the matrices that have no measurable amount of the analyte of interest. The ideal blank will be collected from the same source as the samples, but will be free of analyte. All the conditions related to the collection of the blank sample—storage, pretreatment, extraction, concentration, and analysis— have to be the same as for the actual samples. Such an ideal blank sample is not always available, so often a compromise is necessary. For example, when an 

In most cases, standards are also needed for analysis, and these should be added to the sample as soon as possible, preferably at the time of sampling. The standard is often an isotope-labeled compound. A big advantage of mass spectrometry-based methods is that they can detect stable isotope labels and are not radioactive therefore, they do not pose a health hazard and can be freely used. Stable isotope labeling is also called isotope labeled affinity tags, especially in the field of proteomics. 

Biological matrices may be liquid or solid, and contain a variety of different molecules and particles. Various biological samples are used for chemical analysis. Most commonly blood and urine are used, but saliva, milk, sweat, feces, and various tissues (liver, kidney, brain, etc.) are also studied. The properties of these matrices for sampling and sample preparation are described in books [3,4] and reviews [5] here only a brief description is given. 

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. 

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BIOMEDICAL SAMPLING FOLLOWING A CHEMICAL WARFARE AGENT TERRORIST EVENT - AN OPCW PERSPECTIVE... 

Keywords biomarkers biomedical sampling chemical warfare agents chemical weapons convention invstigation of alleged use terrorism... 

A comprehensive approach to a states response to a chemical terrorism includes having a plan not only for the crisis and consequence management phases of the incident, but also for all elements required for complete resolution of the event. This may include the necessity to definitively establish whether chemical agents were used, to provide supporting evidence to confirm other analyses, or to provide the forensic proof required to support a criminal prosecution. The collection and analysis of biomedical samples - blood, urine or other tissue from affected humans or animals - is one of the means for providing such information. Although current capabilities such as urinary thiodyglycol excretion or plasma cholinesterase activity can be performed, there is scope for far more sensitive and specific assessments that overcome the limitations of these approaches. 

Biomedical Sampling Following a Chemical Warfare Agent... 

Draft Report - Temporary working Group on Biomedical Samples... 

If these methods do prove inconclusive, biomedical sample analysis may provide a unique method for establishing exposure. Due to both the complex technical requirements and the strict forensic approach used it is unlikely that this information will be available in the early phases of response to such an incident. Biomedical sample analysis does however offer another method by which proof of the use of chemical agents can be provided, and thus has a potentially significant role in the overall preparation of a capability for the response to a terrorist chemical agent attack. 

Biomedical sample analysis relies on appropriate sample collection. Although any result is unlikely to guide the response phase of the incident, the emergency response should include consideration of the collection of these samples. The best results are expected to be generated from samples taken as early as possible, and from patients considered to have had the greatest exposure. There is however little clear data available on the urgency of analysis in relation to the stability of markers, and on the effects of lag-times for bringing samples to the laboratory. 

Draft Working Instruction for the collection of biomedical samples during an investigation of alleged use. 

BIOMEDICAL SAMPLE ANALYSIS COMPARED TO ENVIRONMENTAL SAMPLE ANALYSIS... 

The OPCW expert group found however that the procedures for environmental sample analysis were too inflexible to achieve the desired outcome. A separate approach would be needed to enable a system that would provide the necessary level and quality of information, but be practical and also recognise the very infrequent likelihood of a requirement for this capability. Compared to the current OPCW approach to environmental samples, that for biomedical samples would likely use a laboratory with a research rather than a routine focus, the accreditation procedures would be less stringent, and the methods used would focus on high quality results at the lowest limits of detection, rather than high throughput. It is not expected that more than a few laboratories will wish to maintain all or some of the necessary expertise to perform these tasks. 

As the OPCW biomedical sampling requirement is of the lowest level of detection possible, the samples would be presented to the lab with as much relevant information as possible, to enable the most appropriate... 

Although not yet a mature science, the development of a practical biomedical sampling capability is underway. At present, the OPCW does not have such a capability, and the capability in Member States in this field is also still very limited. Despite a number of practical and technical challenges, biomedical sample analysis has the potential however to be an extremely sensitive and specific method of establishing credible forensic information on the alleged use of chemical agents. 

Table 1. Sampling and Analysis of Biomedical Samples for the Presence of Chemical Agents ...

Standing Operating Procedure for Obtaining, Shipping, Receipt and Storage of Biomedical Samples. U.S. Army Medical Research Institute of Chemical Defense (USAMRICD), Aberdeen Proving Ground, MD. Undated. 

A third type of detector, required for some environmental and biomedical applications, is the electron capture detector (ECD). This detector is especially useful for large halogenated hydrocarbon molecules since it is the only one that has an acceptable sensitivity for such molecules. Thus, it finds special utility in the analysis of halogenated pesticide residues found in environmental and biomedical samples. 

DeJong G, Kwakman P. Chemi-luminescence detection for high-performance liquid-chromatography of biomedical samples. Journal of Chromatography. Biomedical Applications 492, 319-343, 1989. 

Pulsed THz radiation is typically non-ionizing hence, it is suitable for medical imaging [2], Various biomedical samples were imaged using 0.15 ps THz pulses generated from 775 nm laser pulses directed onto either a ZnTe crystal or a GaAs antenna. The samples were also successfully classified. 

Samples of importance in the investigation of alleged use include toxic chemicals, munitions and devices, remnants of munitions and devices, environmental samples (air, soil, vegetation, water, snow, etc.) and biomedical samples from human or animal sources (blood, urine, excreta, tissue etc.). 

GAS CHROMATOGRAPHY/MASS SPECTROMETRY ANALYSIS PROCEDURES FOR BIOMEDICAL SAMPLES... 

The development of procedures in this field poses the greatest challenge to the analytical chemist. Although GC/MS(/MS) still plays a major role in the analysis of biomedical samples, the role of LC/ES/MS(/MS) is increasing, because this latter method allows direct determination of the mostly polar and, sometimes, high MW metabolites. 

The development of procedures for the identification of CW agents in biomedical samples is ongoing and existing procedures are continuously improved. Quantization is also an important factor, and an isotope dilution GC/MS/MS method was developed for the quantitative determination of five organophosphorus acids derived from the nerve agents VX, tabun, sarin, soman, and cyclohexyl sarin in urine samples. The acids were isolated and converted into their methyl esters by diazomethane. Detection limits in the low p,g I. 1 were obtained using CID of the protonated molecular ion peaks obtained with isobutane Cl(58). 

Column Diameter and Flow 7.3 Biomedical Sample Analysis. 307... 

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