Transporting samples

Other volatile compounds of elements can be used to transport samples into the plasma flame. For example, hydride reduction of mercury compounds gives the element (Hg), which is very volatile. Osmium can be oxidized to its volatile tetroxide (OSO4), and some elements can be measured as their volatile acetylacetonate (acac) derivatives, as with Zn(acac)2. 

Good rules to adopt when transporting samples are as follows ... 

Cross-flow FFF or, as it was known in the past, FIFFF draws its name from the field type used to transport sample components across the channel thickness to the accumulation wall [3,8]. The... 

Cross-flow FFF (F1FFF) utilizes a second fluid flow to transport sample components across the channel thickness to the accumulation wall, and the position of individual species in the laminar carrier profile corresponds to their ordinary (Fick s) diffusion coefficient. As the particle size increases, the diffusion coefficient (decreases until it becomes a relatively insignificant transport process. For micron-size particles, the extent of protrusion into the channel becomes the decisive factor in determining the order of elution. 

Experimental variables (sampling times, volumes and donor compartment concentrations) were varied appropriately for the different solutes and temperatures due to the large variation in permeability values to insure steady state conditions. As an example of experimental variables, the diffusion cell was equilibrated at 37°C in the water bath, then 100 pi were taken from the donor and receiver compartments. The removed solutions were replaced with 100 pi of one of the radiolabelled solute solutions in PBS in the donor compartments and 100 pi PBS in the receiver compartments. EDTA (ethylene-dinitrilo-tetraacetic acid, 0.05%) was added to both solutions for permeability studies involving hydrocortisone as the solute for temperatures up to 90°C. The EDTA was necessary to insure less than 5% degradation of hydrocortisone and did not affect hydrocortisone transport. Samples were taken from the donor compartments (3 pi for hydrocortisone, 10 pi for... 

Plastic bags and containers for transporting samples Miscellaneous plastic bags are required to place samples for transport to prevent leakages. Also rigid plastic containers are useful to protect samples in the rucksack... 

This is almost impossible to do satisfactorily because of the major segregation in the filling and vibrations in transport. Sampling should not be carried out in the top 30 cm to avoid the segregation in the surface layer that will have occurred as a result of vibration. When removing the samples, no surfaces on which particles can slide should be introduced. This can be achieved using a sample thief. ... 

Filter-Tape Method. A filter-tape system may be envisaged for automating even the 50-fxL method. An automatic tape system for collection of aerosols on filter paper was discussed earlier. The concept could be used here to transport samples to a drying chamber and then to an electrochemical cell where the sample is remoistened with a known volume of ionic-strength adjuster and measured by pressing the opposed electrodes together as shown in Figure 5. The paper must be pretreated by addition of hydro-phobic barriers to confine the sample to the desired area of the paper. All of these steps could be automated under control of the microprocessor. 

The Freeh two-step furnace, with separate control of the vaporization and atomization functions, represents a substantial improvement on commercial Massmann-type and THGA furnaces for interference-free analyses by ETA-AAS. However, it has the disadvantage that it relies on diffusion and convection to transport sample vapours from the cup vaporizer to the tube atomizer. Transport by purging is one solution to this shortcoming. For this purpose, the Massmann-type atomizer is heated to a steady-state atomization temperature and the THGA vaporizer is pulse-heated to have the purge gas drive the analyte from the vaporizer to the atomizer [21],... 

Other volatile compounds of elements can be used to transport samples into the plasma flame. For example, hydride reduction of mercury compounds gives the element (Hg), which is very volatile. 

In the development of lab-on-a-chip technology, a key is to develop the ability to pump the liquids and transport sample/reagent molecules as well as biological cells in a microchannel network. This can be achieved by using the electroosmotic flow and electrophoresis. Mixing of different solutions and dispensing a specified amount of one solution from one microchannel into another microchannel are important to many microfluidic chips. There are extensive research works done in these areas [1]. Furthermore, precise control of temperature is often critical to on-chip biochemical reactions. In the following the PCR lab-on-a-chip, flow cytometer lab-on-a-chip and immunoassay lab-on-a-chip will be reviewed. 

It should be noted that within the UK, the transportation of samples containing asbestos for analysis is only subject to the Carriage of Dangerous Substances Regulations, if the samples are contained in a receptacle of a capacity of 5 litres or more. However, it is not necessary to hold a waste transfer licence whilst transporting samples containing asbestos, but it should be noted that the testing... 

There is a defined need for point-of-care analysis for certain tests, those for which results are needed quickly. For example, the length of time between symptom onset and initiation of treatment is critical for minimizing cardiac injury during a heart attack. The emergency care unit (ECU) is very dependent on quick blood test results to confirm a heart attack and render the appropriate care. Transporting samples to a laboratory to obtain results can be very inefficient. So ECUs may have a bedside enzyme analyzer requiring minimal operation. A blood sample may be inserted, a button pushed, and results obtained in less than one minute. 

Biological samples including blood and urine may present health risks to the personnel collecting and analyzing the samples. When diverse blood samples are transported, received, or analyzed, every effort should be made to reduce the biohazards for laboratory staff (Truchaud et al. 1994 WHO 2003). Suitable containers or bags should be used to transport samples from the animal care buildings to the laboratory. Allergies to laboratory animals and their samples remain a risk for laboratory workers, and efforts should be made to minimize exposure to animal dander, etc. (Venables et al. 1988 Hunskaar and Fosse 1990 Cullinan et al. 1994 Wood and Smith 1999). 

Modern continuous flow analysers arc generally mechanically simpler and less expensive than their discrete counterparts. Indeed, in many continuous flow systems, the only moving parts arc pumps and switching valves. Both of these componem.s arc inexpensive and reliable. In contrast, discrete systems often have a number of moving parts such as syringes, valves, and mechanical devices for transporting samples or packets of reagents from one part of the system to another. In the most sophisticated discrete systems, unit operations are performed hy versatile computerized robots, in much the same way human operators would. 

Screening in response to emergencies is particularly subject to problems due to the unexpected situation and the possibly unprepared persons who collect and transport samples. In the laboratory, problems can arise due to large differences in radionuclide contents among samples, unexpected radionuclide mixtures, unusual modes of detector operation, and the pressure to report analytical results immediately. Problematic actions that need to be prevented because they adversely affect results include ... 

SPME affords a means of enhancing selectivity and specificity as well as increasing sensitivity by preconcentration of vapors or dissolved compounds. SPME can also serve to transport samples that were collected in the field to the laboratory, where the analysis may take place. 

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