Calibration separation

The isopiestic and manometric methods (units A2j A2.4) for determination of water activity have the limitation of being dependent on fixed laboratory equipment. The electronic-type sensors have advantages of portability, speed, and simplicity of measurement. The characteristics of a sensor depend upon the manufacturer and each instrument must be calibrated separately. The anodized sensors have advantages of ruggedness, small dimensions, and fast response, as well as freedom from large temperature coefficients and less susceptibility to contamination of the lithium chloride conductivity sensors (Smith, 1971). 

Cell cycle activity of the active compounds was investigated. Propidium iodine (the marker for DNA content) was used as a marker of the cell cycle. This cytometric determination was calibrated separately and calculated for a related program to evaluate the percentage of cells in each phase of the cell cycle. The treated cells were compared with that of control HL-60 cancer cells for the percentage of cells in each cell cycle compartment over a period of 24 h. HL-60 cells treated with 10 pg... 

The way in which 243 nm radiation was produced - specifically, the distinction between pulsed and cw experiments - represents the most obvious subdivision of work reported so far, and we shall discuss these categories separately. However, future cw experiments are likely to be primarily distinguished by the methods adopted to detect and calibrate the two-photon signals. We consider calibration separately at the outset. 

Calibration / Separation techniques Detectors response +1 Work outside linear range Saturation/under detection limit Contamination of detector Lower/increase sample intakes or concentrate Dilute sample or/and calibration samples Run blanks... 

Nitrate concentration can then be calculated by difference. Note, however, that each peak position must be calibrated separately, since the second peak travels a greater distance causing additional dispersion. 

The chamber should be calibrated per SOP. Some firms may elect to perform the calibration separately from the qualification. 

The NMR of Ih in IhAs and IhSb powders was determined by means of an autod3nie detector with a stabilized frequency. The line shift was measured relative to the resonance line of In in an aqueous solution of In (0104)3. When both substances were in the same holder, the shift could be found directly from the calibrated separation between the lines. At low temperatures, the magnetic field was determined using one of the samples as the standard. The stability of the apparatus ensured that the error did not exceed 2 10 at frequencies starting from 200 Hz. 

Conductimetry Conductivity meter material must be calibrated separately Requires the presence of a low concentration of a... 

The absorbance can be expressed in terms of absorbance peak height or area (area was used in the expressions above). Each species has to be calibrated separately. Normally, there are no detectable blanks for arsenite and the methylarsenic species. The linearity of the calibration curve is dependent on the optical characteristics of the instrument and the intensity of the light source. It needs to be evaluated for each instrument and checked occasionally. The analytical curve should not be extrapolated beyond the highest standard concentration. 

In Older to be able to perform effective characterization it is crucial to use appropriate interaction potentials. Parameters for fluid-fluid interaction potentials have been studied extensively and in the present work were taken from the literature. The solid-fluid interaction potential i rameters were calibrated separately for each material ttonsidered. The calibration procedure consists of the following steps [8] ... 

Warm the solution from (a) or (b) to about 40°, add 2 ml of thio-glycollic acid solution (12 g of 90 per cent v/v thioglycollic acid diluted to 100 ml with water), mix well and set aside to cool for fifteen minutes. Then cool the solution more rapidly (e.g, in a bath of ice and water) to room temperature, add 1 ml of potassium iodide-ascorbic acid solution (15 g of potassium iodide and 2 5 g of ascorbic acid dissolved in sufficient water to produce 100 ml), wash down the sides of the flask with a few millilitres of water, and mix carefully. Transfer the solution to a 100-ml calibrated separating funnel containing a few millilitres of chloroform, washing out the flask with several small portions of water. The volume of the solution at this stage should be 45 to 50 ml. 

The weakest spot of empirical intermolecular potentials is perhaps the repulsive branch, which is always ill-determined since the repulsive regime is seldom accessed in equilibrium crystal stmctures at room pressure. The case is different in liquids, where the high molecular mobility occasionally brings molecules into collision. Atom-atom intermolecular energy curves for liquids are usually calibrated separately from those for crystals. 

In principle, mass scale calibration is independent from the ionization technique. For many years we have routinely calibrated by the use of a combination of corona discharge and controlled cluster formation in the free-jet expansion. Corona discharge of the headspace of an aqueous ammonia solution creates NH4 (H20) with n = 0-4 after passage through the gas curtain. If the curtain gas flow is reduced but not cut off completely, one can tune the gas flow to allow a controlled amount of moisture into the free-jet expansion so that a complete series of NH4 (H20) ions is formed that extends all the way up to mIz 2000. The calibration mass series starts at miz 54 and one out of every live clusters can be used, giving a calibration separation of 90 on the miz scale. The relatively low abundance of deuterium and O, along with the higher abundance of 0 in the cluster ions, makes this caUbrant suitable for resolution adjustment on isotope peaks. 

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