Laboratory analyses, suspect

The key word in any case is representative. A laboratory analysis sample must be representative of the whole so that the final result of the chemical analysis represents the entire system that it is intended to represent. If there are variations in composition, such as with the coal example above, or at least suspected variations, small samples must be taken from all suspect locations. If results for the entire system are to be reported, these small samples are then mixed and made homogeneous to give the final sample to be tested. Such a sample is called a composite sample. In some cases, analysis on the individual samples may be more appropriate. Such samples are called selective samples. 

The tests are designed to predict which of seven categories of drug the suspect may have used (1) CNS depressants, (2) CNS stimulants, (3) cannabinoids, (4) phencyclidine, (5) opioids, (6) hallucinogens, and (7) inhalants. The combination of results from the laboratory analysis of the blood or urine sample and from the 12-step evaluation test will help decide whetherthe defendant was impaired at the time of the stop. 

Whenever a new well is completed, the abstracted aquifer should be studied in detail, including water table and temperature measurements and complete laboratory analysis of dissolved ions and gases, stable isotopes, and age indicators such as tritium, 14C, and 36Cl. Analysis for suspected pollutants, for example, fertilizers, pesticides, pollutants from local industries, and domestic sewage, should be carried out as well. This wealth of data is needed to provide answers to the questions raised in section 1.4. 

In suspected subclinical hepatic encephalopathy, psychometric tests are extremely important for the diagnosis and cannot be substituted by other examination procedures (e.g. anamnesis, inspection, laboratory analysis, imaging). 

Published Reports (1995-2006) of Laboratory Analysis of Human Urine Samples for Hydrolysis Metabolites Following a Suspected Exposure to Sulfur Mustard... 

Application to Human Exposure (Blood Samples). Blood samples following a suspected human exposure to sulfur mustard have only rarely become available for laboratory analysis. Three of the five known reports involve the analysis of samples that were taken from casualties of the Iran-Iraq War, frozen for several years and then analyzed to verify exposure as methods were developed. The other two published reports are on the analysis of blood samples obtained from three individuals that were casualties of accidental exposures to WWI munitions. 

A feedstock may contain an unexpected chemical which shows up as one of the normal components in the routine laboratory analysis. Similarly, one of the feed components may be present in an unexpected molecular form. In either case, the volatility and solubility characteristics of the unexpected compound may cause it to distill toward the wrong end of the column. The routine lab analysis will indicate poor column separation. In one case (338), hydrogen fluoride (HF) was present mainly as carbonyl fluoride in a feed to an aqueous wash column. While HF can readily be absorbed, carbonyl fluoride could not the apparent symptom was poor absorption of HF. If an adverse reaction is suspected, routine lab analyses should be checked against comprehensive chemical assays, and attention should be paid to concisely defining the components entering and leaving the column. 

Poor performance is often suspected due to misleading laboratory analysis, even when the column performs well. Some classic distillation (2066, 268) and nondistillation (131) experiences illustrating this have reported. The author recalls several such experiences. Malfunctioning instruments can lead to similar suspicions. A thorough check of the analjd ical procedure and analytical calculations, and complication of mass, component, and energy balances can determine whether performance is really poor. This is discussed further in Sec. 14.3. 

AR 50-6 also defines requirements for management of RCWM. The regulation specifies that emergency on-site destruction of chemical munitions may be considered an option to reduce risk and that non-emergency on-site destruction is subject to CERCLA or RCRA. Also, AR 50-6 indicates that soil suspected of contamination by chemical agents or industrial chemicals is presumed hazardous until confirmed otherwise by laboratory analysis and is required to be managed in accordance with environmental laws and regulations. 

Any item or debris suspected of containing accelerant residue should be collected in a tightly sealed, clean, and previously unused paint can, a special evidence bag, or a clean glass jar to prevent further evaporation. The container should be of size similar to the amount of debris but should be no more than three-fourths full, leaving sufficient headspace volume for subsequent laboratory analysis. Care should be taken to avoid contamination as this will compromise the value of the evidence. The container should be labeled with the investigator s name as well as the date, department, location, area from which the sample was taken, case numbei and description of the item or contents. The chain of custody must be maintained if the evidence is to be used in court. 

The analysis of materials suspected to be or to contain controlled substances represents the largest portion of the workload in most forensic laboratories. When suspected controlled substances are submitted as physical evidence (exhibits), the forensic chemist must identify and, in some cases, quantify the controlled substances present. The most common forms of drug evidence seen can be summarized as the "five P s" powders, plant matter, pills, precursors, and paraphernalia. Powders include colored powders from crystalline white to resinous brown, and many, such as heroin and cocaine, are derived directly or indirectly from plants. Many powders are oily and odiferous, while some can be described (unofficially and informally) as goo. Hashish, a concentrated form of marijuana, lies between plant and powder. Typical plant matter exhibits are marijuana, mushrooms, and cactus buttons. As biological evidence, plant matter must be stored properly to prevent rotting and degradation prior to analysis failure to do so can generate the aforementioned goo. 

Definitive information must be obtained about a munition before it can be dispatched to its storage location. Neutron activation analysis and tomography equipment must be available on site, for purposes as discussed above. In some cases, samples of liquid munition contents are taken by drilling into it with a hollow drill. It is necessary that conventional chemical laboratory analysis facilities (mass spectrometer, chromatography, data base, etc.) be available so that any suspect material can be identified. The chosen dismantling techniques will be all the more effective if they are applied to well defined families of objects. 

Agency. A second example of an external method of quality assessment is the voluntary participation of the laboratory in a collaborative test (Chapter 14) sponsored by a professional organization such as the Association of Official Analytical Chemists. Finally, individuals contracting with a laboratory can perform their own external quality assessment by submitting blind duplicate samples and blind standard samples to the laboratory for analysis. If the results for the quality assessment samples are unacceptable, then there is good reason to consider the results suspect for other samples provided by the laboratory. 

Collector (collects samples of the suspect aerosol for analysis by the JBPDS, and for confirmatory analysis by supporting laboratories in the Communications Zone and the continental United States). 

Instrumentation for revealing the presence of bulk quantities of concealed drugs will differ from those developed to find evidence of minute quantities on surfaces. Bulk detection is concerned with amounts ranging from grams to kilograms [4], Bulk detection is done by manual inspection, X-ray, CT scans, and acoustic inspection. X-ray or CT scanners used as bulk detectors have sensitivity of 2-10 g, and suspect items are subsequently confirmed by chemical analysis. Hand-held acoustic inspection instruments such as the Acoustic Inspection Device (AID) and the Ultrasonic Pulse Echo (UPE) developed by Pacific Northwest National Laboratories/Battelle, can be used for analysis of cargo liquids in sealed containers of various sizes within seconds [5]. The acoustical velocity and attenuation of multiple echoes returned to the instrument is evaluated by software which compares the data to the shipping manifest. 

Drug Levels in Plasma. Drug levels may also be measured in a clinical trial. Such levels are usually part of a pharmacokinetic analysis but also provide important safety data. This information would be particularly relevant in cases of suspected or actual drug overdosage, drug interactions, to correlate medicine levels with toxic events, or in other situations. It must be clarified whether free levels of the drug and/or the protein bound will be measured by the laboratory. 

Some inhibitors interact very slowly with the enzyme protein, and onset of inhibition thus exhibits time-dependence. These inhibitors are generally referred to as slow-binding inhibitors, and as slow tight-binding inhihitors if the potency of inhibition is extremely high. Analysis of these inhibitory mechanisms is complex because binding and dissociation rate constants may be determined in addition to values. Indeed, a complete analysis may require extensive use of specialized computer software, and the complexities of such analyses preclude their discussion in this chapter. However, the reader is directed to several publications from Morrison s laboratory if a slow-binding mechanism is suspected for an inhibitor of interest (Morrison, 1982 Morrison and Stone, 1985 Sculley and Morrison, 1986 Morrison and Walsh, 1988). 

Color reactions have been extensively used in the field of explosives analysis [1-3]. Their application is easy and the equipment required is simple and inexpensive. Their sensitivities are often in the sub-microgram range. They enable rapid, on-site diagnostic detection of explosive materials, and are also used for preliminary laboratory tests of materials suspected of being explosive. Moreover, these tests can help in diagnosing impurities and degradation products of explosives. 

Field tests based on color reactions are carried out on the hands of the apprehended persons as ehmination tests swabs of the suspects hands are sent to the laboratory for further analysis only in case of a positive result. 

As noted in the last section, the correct answer to an analysis is usually not known in advance. So the key question becomes How can a laboratory be absolutely sure that the result it is reporting is accurate First, the bias, if any, of a method must be determined and the method must be validated as mentioned in the last section (see also Section 5.6). Besides periodically checking to be sure that all instruments and measuring devices are calibrated and functioning properly, and besides assuring that the sample on which the work was performed truly represents the entire bulk system (in other words, besides making certain the work performed is free of avoidable error), the analyst relies on the precision of a series of measurements or analysis results to be the indicator of accuracy. If a series of tests all provide the same or nearly the same result, and that result is free of bias or compensated for bias, it is taken to be an accurate answer. Obviously, what degree of precision is required and how to deal with the data in order to have the confidence that is needed or wanted are important questions. The answer lies in the use of statistics. Statistical methods take a look at the series of measurements that are the data, provide some mathematical indication of the precision, and reject or retain outliers, or suspect data values, based on predetermined limits. 

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