Pipetting procedure

By this procedure about 80-85% of the mineral oil was removed. Because some sodium hydride is lost in the pipetting procedure, an excess is initially employed. 

Information on automatic pipets, procedures for use, and helpful hints. http //ehs.clemson.edu/bsm-spil.html Biological Safety Manual. http //www.hendrix.edu/chemistry/chemsafe.htm... 

A clean 25.00 mL pipette (p. 10) is required together with a suitable pipette filler. Various designs of pipette filler are available. The most common type is based on a rubber-bulb suction device. It is best to evaluate a range of pipette fillers, if available in the laboratory, for ease of use and performance. The pipetting procedure is as follows ... 

Plates from other vendors have also been used successfully. Plates should be chosen for optimal performance in accordance with pipetting procedures, samples mixing, and the chosen instrumentation used to measure microtiter plates. However, chosen plates should be colored black for the best assay performance. 

Additional hazards of exposure to aerosols are created when liquid drops from a pipet to a work surface (474), when cultures are mixed by alternate suction and expulsion (209, 350, 499), when an inoculum is forcefully ejected onto a culture dish, or when the last drop is blown out (113, 209). It has been demonstrated by high-speed photography that an aerosol of approximately 15,000 droplets, most under ten micrometers in diameter, is produced when the last drop of fluid in the tip of a pipet is blown out with moderate force (Figure 1.1). While the aerosol hazard associated with pipetting procedures can only be reduced by use of safe techniques and use of biological safety cabinets (240), the potential hazards associated with oral ingestion can be eliminated by use of mechanical pipetting aids (426, 428). 

A 10-mL volumetric pipet was calibrated following the procedure just outlined, using a balance calibrated with brass weights having a density of 8.40 g/cm. At 25 °C the pipet was found to dispense 9.9736 g of water. What is the actual volume dispensed by the pipet ... 

Procedure. Prepare a set of external standards containing 0.5 g/L to 3.0 g/L creatinine (in 5 mM H2SO4) using a stock solution of 10.00 g/L creatinine in 5 mM H2SO4. In addition, prepare a solution of 1.00 x 10 M sodium picrate. Pipet 25.00 mL of 0.20 M NaOH, adjusted to an ionic strength of 1.00 M using Na2S04, into a thermostated reaction cell at 25 °C. Add 0.500 mL of the 1.00 x 10 M picrate solution to the reaction cell. Suspend a picrate ion-selective electrode in the solution, and monitor the potential until it stabilizes. When the potential is stable, add 2.00 mL of a... 

Procedure. Pipette 25.0 mL standard (0.05M) iodine solution into a 500 mL conical flask and add 5 mL 2M hydrochloric acid and 150 mL distilled water. Weigh accurately sufficient solid sulphite to react with about 20 mL 0.05M iodine solution and add this to the contents of the flask swirl the liquid until all the solid has dissolved and then titrate the excess iodine with standard (0.1M) sodium thiosulphate using starch indicator. If the sulphite is in solution, then a volume of this equivalent to about 20 mL of 0.05M iodine should be pipetted into the contents of the flask in place of the weighed amount of solid. 

Even inside the controlled conditions of a research laboratory, analyzing clean and standardized test samples PCR procedures requires careful quality control, taking into consideration differences in sample preparation, variation in pipetting, differences in reaction tube thickness, poor calibration or instability of the thermal cycler, and reagent quality. 

One alternative method for preparing field fortifications solutions/suspensions is to prepare each fortification sample of each matrix in a separate mini-vial in the analytical laboratory and ship the vials to the field for use. This procedure precludes the use of pipets in the field and may be useful when Field Scientists not experienced in the use of pipets are involved in the field fortification process. One disadvantage of this procedure is that the mini-vials, if not designed correctly, will be hard to handle in the field, and surface tension of the suspension or fortification solution will tend to leave unacceptable amounts of the solution/suspension in the vial or at the lip of the vial and not on the matrix in question. This procedure may lead to cross-contamination of samples as the field fortification liquid is forced from the top... 

Quantitation is performed by the calibration technique. A standard solution containing 0.1 mgkg of both M.A3 and M.A4 is prepared and 1, 2.5, 5 and 7.5mL of this solution are pipetted into around-bottom flask separately and evaporated. Each sample is converted into the fluorescent anhydride derivative according to the procedures described above. Each sample is dissolved in lOmL of methanol for injection into the HPLC system. The calibration curves are obtained by plotting the peak heights against the amounts of M.A3 and M.A4. The derivatives for preparing the calibration curve should be freshly prepared on a daily basis prior to quantitation. 

Procedure. Five aliquots of the triazole stock solution of 5, 10, 15, 20, and 25 ml. are introduced into 50-ml. volumetric flasks. Each aliquot is diluted to 50 ml. with hexane, making working standards equivalent to 10, 20, 30, 40, and 50 micrograms of triazole per ml., respectively. Using a volumetric pipet, 1 ml. of each working standard is... 

Figure 1 Schematic diagrams illustrating the patch-clamp technique. (A) Overall setup for isolating single ionic channels in an intact patch of cell membrane. P = patch pipet R = reference microelectrode I = intracellular microelectrode Vp = applied patch potential Em = membrane potential Vm = Em — Vp = potential across the patch A = patch-clamp amplifier. (From Ref. 90.) (B) Five different recording configurations, and procedures used to establish them, (i) Cell attached or intact patch (ii) open cell attached patch (iii) whole cell recording (iv) excised outside-out patch (v) excised inside-out patch. Key i = inside of the cell o = outside of the cell. (Adapted from Ref. 283.)...

Procedure. Ten tests are done in series 0.1ml of horse Hb solution is pipetted into each beaker 0.020 ml serum is added to nine of the beakers. The content of the remaining one is used as a blank. Three ml 0.1 M KI is added to each beaker. A mixture of 100 ml acetate buffer, 10 ml ethyl hydroperoxide solution and 10ml iodine solution (8) is then prepared. (This mixture is only fit for use for 20 minutes.) At 60-second intervals 10 ml of this mixture is added to the beakers. Nine minutes and 15 seconds after the addition, 2 drops of starch solution are added, and titration with 0.01 N Na2SaOa is started after 9 minutes and 30 seconds. The titration should last, as closely as possible, 30 seconds. The temperature is measured in the reaction mixture. 

Some volumetric glassware products have a large A imprint on the label. This designates the item as a class A item, meaning that more stringent calibration procedures were undertaken when it was manufactured. Class A glassware is thus more expensive, but it is most appropriate when highly precise work is important. This imprint may be found on both flasks and pipets. 

Some pipets are calibrated TC. Such pipets are used to transfer unusually viscous solutions such as syrups, blood, etc. With such solutions, the wetness remaining inside after delivery is a portion of the sample and would represent a significant nontransferred volume, which translates into a significant error by normal TD standards. With TC pipets, the calibration line is affixed at the factory so that every trace of solution contained within is transferred by flushing the solution out with a suitable solvent. Thus, the pipetted volume is contained within and then quantitatively flushed out. Such a procedure would actually be acceptable with any TC glassware, including the volumetric flask. Obviously, diluting the solution in the transfer process must not adversely affect the experiment. 

In order to determine chemical elements in soil, samples of the soil must undergo a solid-liquid extraction. Sometimes the extracts resulting from this procedure have analyte concentrations that are too high to be measured accurately by the chosen method. Therefore, they must be diluted. At the Natural Resources Conservation Service (NRCS) Soil Survey Laboratory in Lincoln, Nebraska, an automated diluting device is used. Using this device, the analyst accurately transfers aliquots of the extract and a certain volume of extraction solution to the same container. This dilutor may also be used to pipet standards and prepare serial dilutions. 

The increased demand for analyses has led to the introduction of machines that will perform all or part of an analytical procedure. Many of the manipulations in laboratory methods are common to a variety of different tests (e.g. pipetting) and lend themselves readily to mechanization. 

The first so-called automated analysers were developed to carry out analyses by replacing manual pipetting by the mechanical transfer of fixed volumes of sample and reagents. They were designed to mimic the manipulations of a convential manual procedure and sometimes had the capacity to measure the amount of reaction product, usually spectrophotometrically. The... 

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