Comparative study of different methods of packaging liquid reagents

Abstract

Figure 3. Dependence of differential pulsed stripping peak current on the reciprocal of the added uncompensated resistance Solution: 8 ppb Pb in 1.70 acetic acid/1.25F potassium acetate. Instrumental conditions: same as for Figure 1 Similar experiments of O'Dom (8) using the hanging mercury drop electrode indicate that a similar effect of uncompensated resistance obtains at this electrode, but that an added uncompensated resistance of ~50 ki2 is (8) G. O'Dom, Princeton Applied Research Corporation, Princeton, N.J., private communication, 1973. necessary for the effect to show clearly. That a higher resistance is necessary to demonstrate the effect is clearly due to the smaller area of the drop as compared with the thin film; the smaller area manifests itself in a smaller interfacial capacitance and a smaller stripping current, both of which require a larger uncompensated resistance to exhibit the effect seen at lower resistance values with the thin-film electrode.A complete theoretical and experimental study of pulse anodic stripping voltammetry is under way in our laboratory. Until results of this complete parametric study are available, we suggest that pulsed stripping voltammetry and other voltammetric techniques be used with caution in high resistance solutions. The response depends strongly on the resistance of the test solution which may not be under the analyst's control unless he adds additional supporting electrolyte to swamp the effects of the variable amount of electrolyte naturally present in his sample.

Selection and cleaning of plastic containers for storage of trace element samples

“…None of the observed loss rates should be construed as permeability data since the closure may have been responsible for a significant portion of the total water loss. The results obtained in this work for CPE are similar to those observed by Curtis et al (11). IDMS Studies.…”

Collection, processing and storage of specimens for biological monitoring of occupational exposure to toxic chemicals

“…such losses may become significant. Annual losses of water from polyethylene, polypropylene, high density polypropylene, Teflon-FEP, and glass containers were less than 0.5% (36,104). Losses from polyvinyl chloride was appr.…”

Evaluation of serum volume losses during long-term storage

“…We were concerned about evaporation/sublimation during storage because a loss of water would have concentrated the analytes. Other workers have reported losses from polypropylene bottles to be 0.26% [ 3 ] and 0.27% [ 4 ] per year at room temperature. This low percentage can be of significance when very small initial sample volumes are involved.…”