Protocols trace-metal

Similar to most Hg sampling methods, sampling sediments and soils require care in avoiding contamination artifacts due to improper sample handling. However, because Hg concentratiorrs are much higher in soUd matrices than in water, if corrrmonly accepted trace-metal protocols are used, substantial contamination artifacts should be exceedingly rare. Also, because sediment Hg concentration profiles... 

The major anions and cations in seawater have a significant influence on most analytical protocols used to determine trace metals at low concentrations, so production of reference materials in seawater is absolutely essential. The major ions interfere strongly with metal analysis using graphite furnace atomic absorption spectroscopy (GFAAS) and inductively coupled plasma mass spectroscopy (ICP-MS) and must be eliminated. Consequently, preconcentration techniques used to lower detection limits must also exclude these elements. Techniques based on solvent extraction of hydrophobic chelates and column preconcentration using Chelex 100 achieve these objectives and have been widely used with GFAAS. 

Sequential extraction is now a well-established tool in soil and sediment analysis. Although the approach is unlikely to provide precise information on the mineral phases to which trace metals are bound, it does provide useful information on potential mobilities of heavy metal contaminants which is not available from (pseudo)total metal determination. The adoption of standard protocols, such as that recommended by BCR, means that reliable and comparable data can be obtained by different laboratories. 

As described by Sedwick et al. (this issue), a semicontinuous culture of the Ross Sea P. antarctica strain was successively diluted with low-iron (<0.2 nM dissolved Fe) filtered Ross Sea seawater, over a period of several weeks, using a rigorous trace-metal-clean protocol. Using this process, we obtained an inoculum culture of colonial P. antarctica in LI medium diluted 9,140-fold with filtered, low-iron (0.17 nM dissolved Fe) Ross Sea seawater, for which we calculate dissolved Fe and EDTA concentrations of 1.42 nM and 1.25 nM, respectively. Prior to commencing... 

Eleven days before commencing the experiment, 50 ml of this culture was diluted to 1 1 with 0.2 pm-filtered station B seawater in an acid-cleaned polycarbonate bottle, using a stringent trace-metal clean protocol. A peristaltic pump was used to transfer the Station B seawater from the 125-1 polyethylene barrel (in which it had been stored since collection) through acid-cleaned silicone tubing and an acid-rinsed... 

Establishing the protocol to standardize the cleaning of containers according to the sample, type of material and chemical characterization to be effected was seen as critical. The following procedure illustrates the protocol for the cleaning of LPDE bottles for the analysis of trace metals ... 

Since both the temperature of extraction and the vigour of the mechanical shaking could be expected to affect the amount of metal extracted, limits for both of these parameters were prescribed in the detailed protocol for extraction and analysis issued to the participating laboratories along with the solid sample [193]. As a check on each laboratory s calibration, reference solutions containing the trace metals of concern (Cd, Cr, Cu, Ni, Pb and Zn) were prepared. Three types of single extractant were used EDTA (0.05 mol L" ), acetic acid (0.43 mol L ) and ammonium acetate (1 mol L ). 

The portable instrumentation and low power demands of stripping analysis satisfy many of the requirements for on-site and in situ monitoring of trace metals. Efforts in this direction have led to the replacement of conventional stripping protocols and systems with remotely deployed... 

Y. Moliner-Martmez, S. Meseguer-Lloret, L.A. Tortajada-Genaro, and P. Campins-Falco. Influence of water sample storage protocols in chemiluminescence detection of trace metals. Talanta 60 257-268, 2003. 

The IND contains information regarding the drug s composition and synthesis and lists all specifications that have been set for the drug substance. Specifications are set for many tests, which may include trace metals. All subsequent batches of the drug that will be used in clinical studies must meet these specifications before their release. The IND contains information regarding animal toxicology study data and protocols for clinical trails. The IND clinical study protocol for a new drug candidate consists of three clinical phases (Table 2). 

In the fields of environmental and exploration geochemistry, considerable use has been made of sequential extraction procedures in order to determine the bioavailability and geomobUity of trace metals (including V, Cr, As, Se, Cd and Pb). More recently, sequential extractions have been used to elucidate information relating to the speciation of metals in soils and sediments. The extraction protocol developed by Tessier " has traditionally been used (with modifications) and involves the sequential use of a variable cocktail of extractants including acetic acid, sodium acetate, magnesiumchloride, EDTA, acidified hydroxylamine hydrochloride, oxalic acid, sodium... 

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