Bioassay samples

SPMD dialysates (extracts), rinses of the exterior membrane surface (only SPMDs exposed to air), and aliquots thereof often contain a number of classes of chemicals. Figure 6.1 shows various levels of processing and enrichment used for SPMD derived bioassay samples. We strongly recommend the use of SPMDs with triolein purified by the method of Lebo et al. (2004) for bioassays to reduce the probability of false-positive results or for controls that fail to meet quality control... 

The applicability of cinchonan carbamate CSPs for bioanalytical investigations using HPLC-ESI-MS/MS has been demonstrated by Fakt et al. [120]. The goal was the stereoselective bioanalysis of (R)-3-amino-2-fluoropropylphosphinic acid, a y-aminobutyric acid (GABA) receptor agonist, in blood plasma in order to determine whether this active enantiomer is in vivo converted to the 5-enantiomer. In this enantioselective HPLC-MS/MS bioassay, sample preparation consisted of... 

TIMS has been used for many years as the benchmark technique especially for uranium isotope analysis. Instrumental improvements have enabled ICP-MS to approach the accuracy and precision obtained by TIMS in measuring data. In addition, due to time consuming sample preparation steps and the need for a large volume of urine, the method has been replaced by the more powerful ICP-MS in many laboratories. An interlaboratory analytical exercise on the determination of natural and depleted uranium in urine was carried out by different ICP-MS instruments, by thermal ionization mass spectrometry (TIMS) and instrumental neutron activation analysis. TIMS has also been employed to determine fg quantities of Pu and °Pu in bioassay samples (such as human urine and artificial urine), ° in an interlaboratory comparison for the analysis of the Pu and Pu/ °Pu atomic ratios in synthetic urine by TIMS and AMS as reported in reference. ... 

Fig. 6.5. Schematic representation of routes of entry, metabolic pathways and possible bioassay samples...

A variety of in-vitro bioassay samples can be collected from an individual for the purpose of ascertaining whether an internal radionuclide deposition has occurred previously. Samples that may be collected and analysed for such a purpose include urine, faeces, hair, teeth, breath, tissue etc. 

Each of these samples provides an indirect measure of the internal radionuclide deposition because the organ and tissues of main concern related to the radionuclide are not being sampled. Thus, proper interpretation of these results requires knowledge of the relationships between the presence of a radionuclide in the various bioassay samples and organ radionuclide burdens of interest. 

Fig. 6.6. Schematic representation of a general approach that can be used to interpret the results of an in-vitro bioassay sample. The radionuclide quantities in (a) the whole body or (b) tissues or organs are expressed in logarithms because the retention curves, when expressed in such a manner, are often straight...

Table 9.3 Toxicity in soil samples from sewage fields near Tilburg using three bioassays. Sample A is the local reference site and sample C has the highest contamination levels.

D. Personnel who may have handled the broken tritium device should report to the health clinic for a tritium bioassay. The optimum bioassay sample time is approximately four hours after the exposure. A minimum of four hours is necessary for tritium to reach equilibrium in the human body. Only after this minimum time should a urine sample be taken. For information on bioassay procedures and to receive bioassay kits, contact the USACHPPM. 

C. In general, individuals in the vicinity of the incident should wear some type of respiratory protection, cover exposed skin, decontaminate as soon as possible, and submit bioassay samples for analysis. 

Urine is the most common bioassay sample type because it is nonintrusive and readily available, and provides some insight into radionuclide intake, retention, and excretion, but is not ideal for all radionuclides. A preservative can be added to urine samples immediately after collection. Bioassay samples are refrigerated for prompt analysis and kept frozen for extended storage. 

Urine samples are measured directly by spectral analysis for radionuclides that emit gamma rays. To measure radionuclides that emit only alpha or beta particles, a general approach for urine pretreatment is boiling to dryness and then ashing. The ash is dissolved in mineral acid to prepare the aqueous solution for analysis (Chieco 1997). Other bioassay samples are pretreated similarly. 

Recent experience at DOE sites has shown that most of the environmental samples collected today are levels C and D. Hence, the laboratory under consideration in this chapter is designed for the analysis of levels C and D samples. These are environmental or bioassay samples that contain radionuclides at low concentrations, i.e., approximating levels of naturally occurring radionuclides. Samples at levels A and B generally will be analyzed in on-site government laboratories for a variety of reasons, i.e. transportation restriction, sample assay limitations, sample security, and national security. In Table 13.1, the authors provide their suggested activity levels to match the four categories identified by the DOE. 

While many operations with chemicals must take place in a hood, rarely would glove boxes or shields be required in the radioanalytical chemistry laboratory dedicated to processing environmental or bioassay samples. A glove box or shield may... 

The bioassay had a built-in control the bulls were often let out into the yard without bioassay samples being present. 

Thorium and uranium. To study the behavior of alpha-emitting thorium and uranium isotopes in bioassay samples, ultra-sensitive measuring methods are required. 

Guidance for the collection of bioassay samples has been summarized by the U.S. National Council on Radiation Protection and Measurements (NCRP) [30]. In most occupational exposure situations, any uranium actually absorbed in the body is rapidly excreted in urine. Therefore, bioassay analyses used to estimate the occupational exposure must be collected as soon as possible and for some time after discovery and control of the exposure conditions. 

FIGURE 4.10 Outline of radiochemical separation processes used to prepare uranium bioassay samples for alpha spectroscopy. (Adapted from training manual IAEA, Determination of Uranium in Urine by Alpha Spectroscopy, IAEA, Vienna, Austria, 2000.)... 

Sawant, P.D., Prabhu, S.P., and Kalsi, PC. (2011). Application of fission track techiuque in solution media for analysis of uranium in bioassay samples, Radiat. Prot. Environ. 34, 74—76. 

Once assessment of internal exposure has commenced, as much information shonld be gathered as is practicable. For example, information will be needed on the time and nature of the incident and the radionuclides involved, and on the timing of bioassay samples and measurements of body activity. This information may be necessary not only for exposure assessment, but also to assist in medical assessment, to guide medical treatment of the victim (which may include chelation therapy or wound excision), and to assist later in reconstruction of the accident or incident itself and in long term medical follow-up of the victim [20, 21]. 

The choice of bioassay sample will depend not only on the major route of excretion, as determined from the physicochemical form of the intake and the biokinetic model for the elementfs) involved, but also on such factors as ease of coUection, analysis and interpretation. Urine samples are readily obtained and analysed and generally provide information on the intake of radionuchdes in chemical forms that are readily transferred to the blood. Intakes of insoluble material can often be reliably assessed oidy from faecal samples. 

The contractor has reported that the internal dose evaluation program for K-Reactor incorporates extensive bioassay sampling for tritium and state-of-the-art whole body counting for fission products with Fast Scan devices. The contractor has stated that it is confident that both the tritium bioassay program and the Fast Scan whole body analysis meet the requirements of the Order. 

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