Specimen contamination

Calcium was a contaminant in some commercially available vacuum 

There are numerous substances that are administered intravenously and have a direct effect on biochemical analysis. Obviously, glucose or electrolyte concentrations will be spuriously elevated if the specimen is taken from the same vein into which these substances are being administered. The presence of sulfobromophthalein dye (BSP) in serum or plasma will interfere with protein determined by the biuret method. The 

Serum alkaline phosphatase elevations have been reported following administration of salt-poor albumin (B5). Placenta is very rich in a heat-stable alkaline phosphatase, and albumin prepared from placental blood has a high activity of this enzyme. In one cirrhotic patient who received 1-6 units per day of albumin obtained from pooled human blood and/or human placenta, the alkaline phosphatase before infusion was 5 Bodansky units and by the thirteenth day of administration had reached a value of 160 units. The physician administering the albumin at first thought the patient was having a severe toxic liver reaction and stopped the therapy. The alkaline phosphatase then started to go down and within 10 days returned to normal levels. Analysis of the albumin indicated that it contained 470 units of alkaline phosphatase activity and was probably responsible for the observed elevations in the serum enzyme activity. Albumin prepared from venous blood did not cause an alkaline phosphatase elevation, but placenta-albumin caused elevations with a half-life of about 8 days (Ml). 

Blood transfusions can also lead to misleading laboratory values. Stored blood bank blood can appreciably increase the blood ammonia levels (PIO). Blood stored 7 days has been found to contain over 1100 /xg/ml. A case has been reported of a patient receiving massive blood transfusions whose serum contained an additional lactic dehydrogenase isoenzyme (a splitting of the LDH-1 band). The authors concluded that the extra band was not an artifact, but rather represented an abnormal H subunit present in one or more of the transfused plasmas (F6). 

---

Waste disposal of infectious specimens, contaminated materials, and chemicals must be in compliance with local, state, and federal (EPA) regulations. Flammable safety cabinets are required for storage of alcohols, xylenes, and other combustible materials. 

Energy cost for a 4-month pilot-scale test on a 2-ton kaoUnite specimen contaminated with 2000 p.g/g of lead was approximately 15 per ton. Energy costs from the U.S. Environmental Protection Agency (ERA) Superfund Innovative Technology Evaluation (SITE) Program demonstration conducted in 1994 were approximately 6 per ton per month (D12696P, p. 283). 

Specimen contamination may not be immediately apparent on visual inspection. A large peak of glycerol, especially in a female newborn or infant, should be considered an artifact at first and verified by a repeat specimen before raising the possibility of glycerol kinase deficiency. Medium- and long-chain monocarboxylic fatty acids (Cio-Ci8) could be very prominent peaks in a urine profile following contamination... 

If an analytic method lacks sufficient specificity, chemical interferences will result in an erroneously high reported concentration. If a measured chemical is introduced as an artifactual contaminant during sample collection or analysis, reported concentrations will also be overestimated. For example, credibly estimating human exposure to phthalates was hindered by the difficulties involved in avoiding specimen contamination with these ubiquitous chemicals the problem was resolved by focus on the much less prevalent metabolic product, the phthalate half-ester (Silva et al. 2004). Alternatively, a chemical measured as a marker of exogenous exposure may be identical with a chemical formed by an unrelated endogenous metabolic pathway. In each of those cases, a rigorous laboratory-method validation should detect the problem before data are reported. More subtly, the measured biomarker of exposure may be chemically identical with a dietary... 

We have developed special procedures for the avoidance of false positive results and for the accurate interpretation of positive results in terms of drug use, passive exposure to drugs or specimen contamination. This experience with workplace testing will be described along with an assessment of the efficacy and reliability of hair analysis. 

The main issue in hair testing is the avoidance of exogenous interpretive false positives, i.e., positives caused by external contamination of hair by drugs present in the environment, e.g., smoke, powder. This type of false positive is not the major issue for urinalysis where endogenous interpretive false positives are the main concern. But, the effective avoidance by urinalysis of exogenous false positives due to specimen contamination in the laboratory depends critically on the exclusion of drugusing personnel, and this can best be achieved by evasion-proof hair analysis. However, when such false positives occur, or when urinalysis labs are unable to guarantee that they have taken effective measures to exclude such contamination, then very little can be done to remedy the problem. For, in contrast to hair, the collection of a new urine specimen identical to the first one is not possible. 

Developmental Toxicity. Studies on potential developmental effects in humans exposed to asbestos are restricted to reports from one group of investigators reporting that asbestos fibers were detected in fetal and placental tissues from stillborn infants more frequently and at higher concentrations than in placental tissue from livebom infants (Haque et al. 1991, 1992, 1996, 1998). Understanding of the toxicological significance of these observations awaits confirmation and explanation from further research in other laboratories. It is presently unclear if the noted differences in fiber concentrations between stillborn and livebom tissue are due to differences in maternal exposures, differences in fetal or placental factors unrelated to asbestos exposure, or specimen contamination. 

Happily, one consequence of this vacuum-engineering approach is that one important source of specimen contamination during microanalysis, namely system-borne hydrocarbons, is eliminated. Although this does not mitigate the need for cleanliness in the introduction of samples from atmosphere via an airlock, preparative facilities attached to the latter promise, ultimately, contamination-free performance in an ultra-high vacuum instrument, with consequent benefit for microanalysis. 

Lyophilized and liquid preparations containing various enzymes are available from commercial sources, and these have a usefid function in quality control. Serum pools can also be prepared in the laboratory for quality control purposes (with care to exclude any specimens contaminated with hepatitis virus or human immunodeficiency virus), then assayed for enzyme activity and stored m a freezer in small portions for daily use. 

Several clinical outcome studies using AmnioStat have been reported. Although positive PG results are about 99% predictive of maturity, negative results are highly unpredictive (RDS develops in about 25% of cases with a negative PG, depending on the population) and are therefore not useful chnically. A positive PG result is very usefiil in low-risk pregnancies that require cesarean section. Determination of PG is also usefijl for specimens contaminated with blood or meconium. PG is not found in either blood or meconium, and therefore results are not affected by the presence of either of these contaminants. ... 

An FSI value of 0.47 or greater is interpreted as mature. In two studies, a combined total of 270 fetuses with an FSI of 0.47 or greater was reported, two of which developed RDS. In 110 fetuses with an FSI of 0.46 or less, 44 (40%) developed RDS. Thus the test appears to have more false predictions of immaturity than the L/S ratio or sur-factant/albiimin ratio. Tubes and stoppers must be clean and free of detergents to prevent false-positive readings. The final concentration of the ethanol is critical. Ethanol is hygroscopic therefore careful attention must he paid to its preparation and storage. The test should be conducted at 20 C to 25 Specimens contaminated with either blood or meconium tend to give a falsely mature result. 

We typically view grids in a JEOL lOOCX transmission electron microscope operated at 80 kV with a 40-/Am objective aperture. Use of a low illumination when scanning grids helps to minimize film breakage and specimen contamination. Photographs should be taken as soon as a region of potential interest is spotted to minimize its contamination by the electron beam. 

Fajardo G, EscadeiUas G, Arhguie G (2006) Electrochemical chloride extraction (ECE) from steel-reinforced concrete specimens contaminated by artificial sea-water. Corros Sci 48(1) 110-125.doi 10.1016/j.corsci.2004.11.015... 

Hot and cold stages can easily be attached to optical, electron, and atomic force microscopes [220, 221]. Cold stages are very common in TEMs, where they may reduce specimen contamination by stopping surface diffusion. In biology, cold stages are used to keep hydrated samples frozen and stable for observation in the vacuum of the TEM or SEM (e.g., [222]),... 

Example Specimens, contaminated laundry Red bag, biohazard label)... 

---