Automatic pipette

Automatic pipettes. The Dafert pipette (Fig. 3.2) is an automatic version of a transfer pipette. One side of the two-way tap is connected to a reservoir containing the solution to be dispensed. When the tap is in the appropriate position, solution fills the pipette completely, excess solution draining away... 

Besides counting equipment, automatic pipettes and dilutors are also needed in doing competitive protein binding assays. 

Before measuring the mass spectra, it is appropriate to concentrate and refine the peptides that are released into the solution by trypsin-catalysed hydrolysis of proteins. The reverse phase Cig in the 10 pi tip of the automatic pipette (commercially available ZIP-TIP, Millipore Corporation, Bedford, MA, USA) was used. The peptides that are rather... 

Figure 12.6 illustrates the outline of such an analysis. An automatic pipette extracts a preset volume of the liquid sample (or solution) from a cup presented to it on a turntable. The measured sample is mixed with the reagents in the appropriate proportions, and propelled through the instrument by the peristaltic proportioning pump. This pump operates by means of moving bars, attached to a chain drive, which sequentially compress the plastic sample and reagent tubes to drive the liquids forward through the instrument. The incorporation of a succession of air bubbles at... 

Automatic Pipettes (Transfer Pipettes) Automatic pipettes are always preferred to ordinary transfer pipettes because of their ability to handle corrosive and toxic liquids in routine analytical laboratories, e.g., determination of Iodine Value in edible oils by iodine-monochloride (IC1) solution. 

The automatic pipette (Figure 2.1) dispenses a stated volume of liquid when filled with liquid used in the assay from tip (B) to tip (C) and is allowed to drain out in the normal manner. D is connected to an aspirator which is placed above the pipette so as to enable the solution to flow under gravity. 

Operation of the Automatic Pipette The automatic pipette may be operated by observing the following steps in a sequential manner ... 

As the amt of w collected in the moisture tube usually will be too small to form two distinct menisci, add 1.00 ml of distd w from an automatic pipette, allowing it to run down the side of the tube and unite with the w collected from the sample. Read the vol of w in the moist tube, correct for the amt added, and calc the %-age of moist (Ref 8, pp 3-4) B)Ether Soluble Material. Transfer a weighed portion of ca 25 g of the sample to an extractor (Soxhlet or other) and extract with anh ether Evaporate the eth from the extract, dry at 100° to const wt, cool and weigh. 

Mix the stock enzyme solution with the polymer in a 1 2 PP2A PVA-AWP ratio on a Vortex mixer (an automatic pipette special for viscous solutions is used for PVA-AWP). 

A different application of SPE which needs 100-200 pi of sample has recently been successfully applied to plasma. Micro SPE (pSPE) followed by HPLC-MS/ MS was used by Napoletano et al. [67] to determinate amphetamine, methamphet-amine, MDA, MDE, MDMA, cocaine, BEG, mescaline, ketamine, PCP, psilocy-bine in plasma. In this method 180 pi of plasma were submitted to slight PPT with 20 pi of methanol containing ISTD, 100 pi of supernatant were then collected and passed through C18 tips, adapted to automatic pipettes. Validation results showed pSPE allows to reduce matrix effect (<10 %) keeping satisfactory recoveries. pSPE represent a simple, fast and reliable procedure with extremely reduced solvent consumption it will be discussed in more detail below in its other applications. 

Use automatic pipettes (e.g. Finnpipette, Gilson, Oxford) and sterile tips for small volumes. Repeating versions and eight place... 

Any functional set of pipettes can be used. However, the student should be familiar with the two main types of pipettes glass lambda pipettes and automatic pipettes. 

The charcoal tube samples were desorbed with 2 ml. of chrcanatoquality carbon disulfide (CS2), dispensed with an automatic pipette, in vials with Teflon-lined septum caps. Vials were agitated for 30 minutes on an SKC developing vibrator equipped with an automatic timer. Standards and spiked charcoal tubes with known amounts of solvent were prepared with Hamilton syringes. A Varian Model 1800 Gas Chromatograph equipped with a flame ionization detector was used to analyze the CS2-desorbed samples. Two GC colums were used ... 

Biopipette Automatic Pipette 23 Pumpett 18 27 Analytic Products Safety Bulb... 

Automatic analysis consists essentially of the same steps as the corresponding manual method (p. 4). In some cases this may be simple, the requirements amounting to a mechanical device for presenting the sample to the detector, a timer to control the time of measurement and a data recorder. However, if sample pretreatment and separations are necessary a variety of wet chemical stages needs to be automated. Such automated steps may be included in what remains essentially as an operator procedure. For example, an automatic pipette may be used for sampling a fraction collector in a chromatographic separation or an automatic sequence for making a measurement and... 

Figure 12.7 illustrates the outline of such an analysis. An automatic pipette extracts a preset volume of the liquid sample (or solution) from a cup presented to it on a turntable. The measured sample is mixed with the reagents in the... 

A calibration schedule details the calibration of balances, volumetric glassware, automatic pipettes, thermometers, pH and conductivity meters, wavelength and photometric scales etc. The schedule consists of periodic external checks, employing a suitably accredited calibration service, supported by more regular in-house performance checks. 

Different operators, using the same instrument, may obtain different results due to variations in technique which, for example, markedly affects the precision of some automatic pipettes (B19). Manufacturers instructions may give little or no information on how to obtain the best results. The optimal absorbance required to obtain maximum precision varies for different types of spectrophotometer from 0.43-0.88 (H26) the user may not know this if it is not stated in the instructions. Inadequate maintenance is undoubtedly a major source of error, and includes such simple faults as greasy spectrophotometer cuvettes and pipettes and dirty tubing in continuous-flow systems, resulting in excessive sample interaction. Errors of spectrophotometers, arising from poor technique and faults in wavelength accuracy, photometric linearity, and photometric accuracy, are discussed in Section 4.5. 

Ektachem DT-60 II is the basic instrument (further extensions are the DTE module for electrolytes and the DTSC module for enzymes) the course of the analysis is monitored from the Ektachem DT-6011, the dialogue with the user is effected via a keyboard and display and the result is computed and printed out. The user selects the slide required for the desired analysis, removes it from the packing and inserts it into the sample receiver unit. The undiluted serum is applied to the slide by means of an automatic pipette (Fig. 16). Pipetting of the sample is monitored via an optical detector. Subsequently, the time cycle for the period of incubation and measurement is started. Incubation for 5 minutes is effected at 37°C in the incubator to which the slide has been transported automatically. 

Fig. 16. Automatic pipette of the Ektachem DT-60 II system with pipette tips.

To the fullest extent practical, toxin should be handled by mechanical means (e.g., automatic pipettes). Care should be taken to avoid creation of aerosols, and the toxin must not be allowed to come into contact with the mouth or broken skin. 

Pipetting must be done by means of pipette fillers or automatic pipettes never by mouth. 

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