Trace metal contamination of evacuated blood collection tubes

Storage and preservation of blood and urine for trace element analysis. A review

In any well-defined study, a sample preservation and storage scheme compatible with the information or analyte sought should be incorporated. This article emphasizes the need for preservation and storage of biological fluids collected for trace element determination; cites the major factors, such as container material, container pretreatment, storage time, storage temperature, and contamination of the laboratory environment affecting preservation; presents a historical account of the available literature studies on the preservation and storage of trace metals in whole blood, plasma, serum, and urine; and makes recommendations on the most effective storage and preservation methods.

Trace metal analysis of chromium and nickel in lung tissue fixed and stored in formalin

In an attempt to answer the question whether the determination of chromium and nickel concentration in lung tissue, fixed and stored in formalin is still tolerable despite the related sources of error, the entire system (tissue, tissue abrasion, formalin, plastic container) was analysed by means of flameless atomic absorption spectrometry. It appears that such a procedure can be justified for practical purposes. In order to reduce possible errors, well defined rules are to be observed during specimen collection and processing and specialities have to be taken into account.

The Collection and Preparation of Human Blood Plasma or Serum for Trace Element Analysis

Trace element concentrations in blood plasma or serum have been assayed by numerous investigators using a variety of analytical techniques. For several elements, figures obtained in different centers are widely disparate. Impressive evidence has accumulated that a great deal of the inconsistencies should be ascribed to unsuspected contamination of the samples with exogenous material during their collection and preparation. In this paper, a number of potential sources of extraneous additions are indicated. Methods for controlling contamination are also briefly discussed.

Analysis and evaluation of zinc and copper in human plasma and serum

Recommendations for daily dietary intakes of copper and zinc have been made by the National Academy of Sciences during the last decade. As a result there is increasing interest in analytic techniques for accurate and precise assessment of these trace elements in human tissues, including blood. In addition, the importance of standardizing techniques for the collection, preparation, and analysis of biologic samples is now recognized. The necessity for preventing contamination or losses requires careful monitoring at each step, from collection to analysis. Likewise, precision and accuracy must be established for techniques and certified reference standards employed. The selection of an ideal anticoagulant for preparing plasma for copper and zinc analyses is receiving increased attention. The discrepancy observed regarding higher concentrations (10-15%) of zinc and copper in serum than citrated plasma remains to be resolved. Following analysis and summary of the data, interpretation of the results is of paramount importance. It must be remembered that abnormal plasma or serum zinc or copper concentrations do not necessarily reflect true aberrations in metabolism, since several conditions (disease and nondisease) can also influence these indices of trace element nutriture. Immediate attention must be given to advancing the concept that trace element analysis of biological materials requires special collection, storage, and analysis precautions.

Trace elements in human body fluids and tissues

Published figures for trace element concentrations in body fluids and tissues of apparently healthy subjects are widely divergent. For a considerable time, the apparent disparities were readily ascribed to biological sources of variation such as age, sex, dietary habits, physiological conditions, environmental exposure, geographical circumstances, or similar influences. Growing evidence, however, suggests that this interpretation may be seriously questioned in numerous instances. First, values obtained in reference materials leave no doubt that some previous studies must have been subject to gross analytical inaccuracies. Second, it has now been thoroughly documented that inadequate sample collection and manipulation may drastically distort the intrinsic trace element content of biological matrices. This review scrutinizes data reported by a number of investigators. In an effort to settle the currently flourishing confusion, critically selected reference values are set forth for trace element levels in human blood plasma or serum, packed blood cells, urine, lung, liver, kidney, and skeletal muscle tissue.

Comparison of the in vivo and in vitro effects of lead on the pH-activity relationship of human erythrocytic delta-aminolaevulinic acid dehydratase

The effect of lead in vitro on the pH-activity relationship of human erythrocytic delta-aminolaevulinic acid dehydratase (delta-ALAD) and on the assessment of lead exposure with ratios of delta-ALAD activity measured at specific pH values was investigated. The addition of lead nitrate to whole blood at concentrations ranging from 0.40 to 8.1 mumole Pb2+/1, for periods of contact ranging from 16 h to 20 days at 4 degrees C, resulted in a time and dose dependent shift of the enzyme's pH optimum to a more acid value. The pH optimum shift obtained at raised lead concentrations or after long periods of contact at 4 degrees C, in both, closely approximated that observed in vivo. The loss of enzyme activity, however, was significantly less in vitro than that in vivo for similar whole blood lead concentrations. These findings indicate that the presence of trace amounts of lead in blood collection devices can seriously affect results obtained with the pH activity ratio method of assessing lead exposure.

Unsuitability of evacuated tubes for monitoring heparin therapy by activated partial thromboplastin time

Activated partial thromboplastin times (APTT) for monitoring heparin therapy for venous thromboembolism tended to be inappropriately short if blood was collected in commercially available evacuated glass tubes. Five types of evacuated tubes marketed under the trade names Vacutainer and Venoject were examined. The APTT of heparinized blood collected in these tubes correlated poorly (r = 0.04 to 4 = 0.25) with that of blood samples from the same patients collected in plastic tubes. Most of the evacuated tube APTT were shorter than that of blood collected in plastic or siliconised glass tubes, but the results were unpredictable and varied from tube to tube and from batch to batch. This effect on heparin is apparently due to an unidentified substances which is eluted from the rubber stoppers of the tubes. Heparin control according to the APTT blood collected in these evacuated tubes is hazardous.