Electronic analytical balance

The Conical Vial As Vial Packaging Oops Tare to the Analytical Balance Electronic Analytical Balance Heating These Vials... 

For many laboratory operations it is necessary to weigh objects or materials which are far heavier than the upper weight limit of a macro analytical balance, or small amounts of material for which it is not necessary to weigh to the limit of sensitivity of such a balance this type of weighing is often referred to as a rough weighing . A wide range of electronic balances is available for such purposes with characteristics such as, for example,... 

No matter what type of analytical balance is employed, due attention must be paid to the manner in which it is used. The following remarks apply particularly to electronic balances. 

Electronic analytical balance Volumetric flasks 100- to 1000-mL Volumetric glass pipets, various sizes Pasteur pipets, 5.75- and 9-in lengths Refrigerated centrifuge Nalgene centrifuge bottle, 250-mL Disposable syringes, 5-cm ... 

If it is established that a measuring device provides a value for a known sample that is in agreement with the known value to within established limits of precision, that device is said to be calibrated. Thus, calibration refers to a procedure that checks the device to confirm that it provides the known value. An example is an analytical balance, as discussed above. Sometimes the device can be electronically adjusted to give the known value, such as in the case of a pH meter that is calibrated with solutions of known pH. However, calibration can also refer to the procedure by which the measurement value obtained on a device for a known sample becomes known. An example of this is a spectrophotometer, in which the absorbance values for known concentrations of solutions become known. We will encounter all of these calibration types in our studies. 

Wet methods are those that involve physical separation and classical chemical reaction stoichiometry, but no instrumentation beyond an analytical balance. Instrumental methods are those that involve additional high-tech electronic instrumentation, often complex hardware and software. Common analytical strategy operations include sampling, sampling preparation, data analysis, and calculations. Also, weight or volume data are required for almost all methods as part of the analysis method itself. 

In the case of an analytical balance, the standard is a known weight. This weight is measured and if this result and the known value are the same, the balance is calibrated. If they are not the same, the balance is taken out of service and repaired. In the case of a pH meter, the standard is a buffer solution. The pH of this buffer solution is measured and if the known pH and the measured pH are the same, the meter is calibrated. If they are not the same, the readout is electronically tweaked until it gives the correct result. It is then said to be calibrated. 

An electronic balance uses an electromagnet to balance the load on the pan. Figure 2-3a shows a typical analytical balance with a capacity of 100-200 g and a sensitivity of 0.01-0.1 mg. Sensitivity is the smallest increment of mass that can be measured. A microbalance weighs milligram quantities with a sensitivity of 0.1 p,g. 

Figure 2-3 (a) Electronic analytical balance measures mass down to 0.1 mg. [Courtesy Fisher Scientific, Pittsburgh, PA]... 

Analytical Methods. Loss on Ignition. Wet density, dry mass density, organic content, and carbonate content were determined by the method of Dean (33). Volumetric samples (1.0 cm 3) were dried overnight at 100 °C and ignited at 550 and 1000 °C for 1 h. Mass measurements were made on the wet sample and after each heating on an electronic analytical balance. 

In addition to the applications mentioned so far, the radiation from radionuclides may also be used for ionization and excitation of luminescence. Ionization is desired to remove electric charges (e.g. on analytical balances) or to trigger electric discharge (e.g. in electron valves). Tl, for example, has been applied in analytical balances. For excitation of luminescence (e.g. in luminescent substances in watches or in fluorescent screens), Ra has been used. However, Th causes relatively high activity of the luminescent substances and of watches, and to-day T is preferred for excitation of luminescence, because its low-energy f radiation is absorbed within the watch. 

Although the classic form of the balance is of great antiquity, modern balances—both mechanical and electronic— continue to apply the principle of equilibrium in a variety of ingenious ways. More than one type of balance is required for a clinical laboratory because there is a necessity to weigh, for example, 3 kg of timed urine output and microgram amounts of drug for a reference solution. Coarse balances of large capacity (up to 5 kg) have a detection limit of 0.1 g. The typical analytical balance has a capacity of 200 g and a detection limit of about 10 pg. Microbalances may have a maximum capacity of as little as 5 g and detection limit of 0.1 pg. 

Figure 2-2 Electronic analytical balance, (a) Block diagram, (b) Photo of electronic balance. 1(a) Reprinted from. R. M. Schoonover, Anal. Chem., 1982, 54, 973A. Published 1982 American Chemical Society. ...

Figure 2-3 shows the configurations for two electronic analytical balances. In each, the pan is tethered to a system of constraints known collectively as a cell. The cell incorporates several flexures that permit limited movement of the pan and prevent torsional forces (resulting from off-eenter loading) from disturbing the alignment of the balance mechanism. At null, the beam is parallel to the gravitational horizon and each flexure pivot is in a relaxed position. 

A modern electronic analytical balance provides unprecedented speed and ease of use. For example, one instrument is controlled by touching a single bar at various positions along its length. One position on the bar turns the instrument on or off, another automatically calibrates the balance again.st a standard mass or pair of masses, and a third zeros the display, either with or without an object on the pan. Reliable mass measurements are obtainable with little or no instruction or practice. 

Figure 2-3 Electronic analytical balances, (a) Classical configuration with pan beneath the cell, (b) A top-loading design. Note that the mechanism is enclosed in a windowed case.

Figure 1-11 Three types of laboratory balances, (a) A triple-beam balance used for determining mass to about 0.01 g. (b) A modern electronic top-loading balance that gives a direct readout of mass to 0.001 g. (c) A modem analytical balance that can be used to determine mass to 0.0001 g. Analytical balances are used when masses must be determined as precisely as possible.

Now I don t know if you have a hanging pan analytical balance with dialup weights or a fancy electronic model, and I don t care. Just keep your noxious organic products in closed containers, OK ... 

Most analytical balances used today are electronic balances. The mechanical single-pan balance is still used, though, and so we will describe its operation. Both types are based on comparison of one weight against another (the electronic one for calibration) and have in common factors such as zero-point drift and air buoyancy. We really deal with masses rather than weights. The weight of an object is the force exerted on it by the gravitational attraction. This force will differ at different locations on Earth. Mass, on the other hand, is the quantity of matter of which the object is composed and is invariant. 

Fip. 2.]. Electronic analytical balance. (Courtesy of Denver Instrument Co. Denver Instrument Company owns all images.)... 

Electronic analytical balances can be purchased with different weighing ranges and readabilities. A macrobalance will have a range on the order of 160 g, readable to 0.1 mg, and a semimicrobalance will have a range of about 30 g, readable to 0.01 mg. Microbalances weigh to 1 p,g, and ultramicrobalances are available that are sensitive to 0.1 g or less. 

R. M. Schoonover, A Look at the Electronic Analytical Balance, Anal. Chem., 54 (1982) 973A. 

K. M. Lang, Time-Saving Applications of Electronic Analytical Balances, Am. Lab., March (1983) 72. 

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