Sampling and Dispensing

Clinical chemistry procedures require accurate volumetric measurements to ensure accurate results. For accurate work, only Class A glassware should be used. Class A glassware is certified to conform to the specifications outlined in NIST circular C-602.  

Pipettes are used for the transfer of a known volume of liquid from one container to anotiier. They are designed 

TABLE l-IO Standard Reference Materials (SRMs) Available from the National Institute of Standards and Technology (www.nist.gov). 

Antiepilepsy drug level. assay (phenytoin, ethosuximide, phenobarbital, and primidone) 

Electrolytes in frozen human serum Glucose in frozen human serum Toxic elements in blood 

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The sample probe s vertical stroke can be as long as 100 mm and this, with the in built hquid level sensor, allows a wide range of primary tubes and centrifuge tubes to be held on the trays. Sample racks are automatically transported in the front section of the analyser, which in turn simpHfies maintenance should the nozzle become blocked or if mechanical problems arise. The AUSOOO Series provides precise sample dispensing capabihty. Each of the two sample probes aspirates a volume sufficient for a maximum of four chemistries per sample and dispenses it into eight cuvettes on the twin reactor Hnes. The probes are constructed from water-resistant plastic which minimizes any dilution from wash solution or contamination. The built-in level sensor Hmits the immersion of the probe in the sample. The inside and outside of the probe as well as the level sensor are rinsed after each use to further prevent contamination. 

To operate the Opus analyzer, the operator selects a test and provides other information through an interactive touch screen/LCD display. When prompted, the operator inserts one assay-specific test module per test into the loading port of the instrument. The loader transports the test module to a 20 position incubated rotor where the test module is equilibrated to 37 C. The analyzer prompts for sample cup and pipette tip trays. Once these trays are supplied, the analyzer automatically picks up a new pipette tip, aspirates the sample and dispenses the sample onto the test module. For certain assays the pipettor also transports conjugate, substrate or other reagents from the test module wells to the test module dispense port. After processing, the test module is rotated to the read position where the fluorimeter takes measurements. The rotor then moves the used test module to the loader/ ejector where it is... 

To reliably perform qualitative and quantitative analyses on body fluids and tissue, the clinical laboratorian must understand the basic principles and procedures that affect the analytical process and operation of the clinical laboratory. These include the knowledge of (1) the concept of solute and solvent, (2) units of measurement, (3) chemicals and reference materials, (4) basic techniques, such as volumetric sampling and dispensing, centrifugation, measurement of radioactivity, gravimetry, thermometry, buffer solution, and processing of solutions, and (5) safety. ... 

Get new 200 pL tips and aspirate 10 100 pL of sample and dispense into the first intermediate locations. 

A very recent development of ITIES in micropipettes is the electrochemical attosyringe by Laforge et al. [243] who demonstrated electrochemical control of the fluid motion inside the pipette to sample and dispense attoliter-to-picoliter volumes, for example, in an immobilized biological cell. The movement of the interface supported at the tip of a micropipette was recently observed by Dale and Unwin using confocal fluorescence microscopy [244], This motion was found to be reversible upon cycling. 

With today s instruments the customer may specify an injector or an automatic reagent dispenser, and a choice of sample formats is available test tube, vial, microplate, Petri dish. The volumes of sample and reagent required to carry out a determination steadily decrease and are typically a few microliters. Sample temperature during the assays is generally controlled. 

In a typical extraction, 50 jiL of plasma was treated with 25 /./I. of internal standard solution and then diluted with 200 /iL of 3% ammonium hydroxide. The C18 /./-SPE tips were conditioned with 150 /iL of methanol and then 300 /./I. of 3% ammonium hydroxide. The sample was exhaustively extracted by aspirating and dispensing the plasma samples seven times from the dilution tube. For the wash, 90 /./I. of 3% ammonium hydroxide followed by 100 /./I. of methanokwater (20 80 v/v) was used. Elution was achieved with 50 /./I. of methanokwater (90 10 v/v). After evaporation of the collected eluate in the 96-well block, the residues were reconstituted in 200 fjL of mobile phase A B... 

The morphology of mesoporous structures can be investigated by TEM, as shown in Fig. 7.2 b and d. However, sample preparation for TEM is time-consuming. Fortunately the mesoporous regime can also be studied by today s most advanced SEMs. For SEM inspection no sample preparation is required, and even sputtering of the sample is dispensable, as shown by the SEM micrographs displayed in this and the next section. 

Starter packs are small packs designed to provide sufficient medicine for a primary care prescriber to initiate treatment in such circumstances as a call out in the night or in other instances where there might be some undesirable or unavoidable delay in having a prescription dispensed. It follows from this that the types of medicines for which starter packs are appropriate are limited to those where immediate commencement of treatment is necessary or desirable, such as analgesics and antibiotics. Starter packs are not samples and should not be labelled as such. The quantity of medicine in a starter pack should be modest, only being sufficient to tide a patient over until their prescription can be dispensed. 

Place Sample and Container Under Dispensing Nozzle... 

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