Checking the Calibration

Recorders and alarms. Continues 1 and checks the calibration of recorders and alarms. 

Check the calibration of the analytical balance you have chosen to use by weighing this standard weight on this balance. When finished, store the standard weight in the specified protected location. 

What does it mean to check the calibration of a balance ... 

For the determination of PAM, UV adsorbance at 189 nm was measured for various PAM concentrations. The nephelometric technique of Attia and Rubio (8 ) as modified by Pradip (9 ) was used to check the calibration curve obtained by the UV method. 

It is possible to check the calibration of a pipet, flask, or buret. The process involves weighing with a calibrated analytical balance. The volume of water (temperature noted) delivered or contained by the glassware is weighed. Then the analyst converts this weight to volume (using the density of water at the temperature noted), corrects the result to 20°C (the usual temperature of the factory calibration), and compares it to the factory calibration. If the difference is not tolerable, the piece of glassware is either not used for accurate work or a correction factor is applied. It should be pointed out that the thermometers used must be properly calibrated and that the timer used to measure the delivery time for the burets and pipets must also be calibrated. 

Resolution is also affected by the actual time that ions spend in the quadrupole. Ions that have higher kinetic energy have shorter residence time and lower resolution. Reducing the kinetic energy typically leads to an improvement in resolution. A dramatic change in resolution may cause a shift in the instrument calibration. After adjusting the resolution, it is necessary to check the calibration (calibration verification), and if it is noted that the difference between the predicted and actual mass values have shifted, the instrument should be recalibrated. 

The maintenance of analytical instrumentation requires trained personnel and is a time-consuming task (39,40). An additional problem is the necessity of frequently checking the calibration of the analysis instrumentation and recalibrating if required. Stand-alone data gathering instrumentation, once common in pilot plants, has been virtually replaced in all but the simplest pilot plants by a data gathering computer, usually used for process control as well. 

The reproducibility is improved if test portions are maintained at a constant volume. It is recommended to consistently check the calibration for moisture and oil contents against standards. 

Describe the detailed procedure to be followed to check the calibration of the instrument over its certified operating range and process failure limits (to ensure that it is within the tolerances specified in the manufacturer instruction manual and aligns with the requirements specified in the respective instrument specification/data sheet). 

In routine analysis, one standard may be ran in a batch to check the calibration curve. Within a linear range, the concentration of NH3-N in the sample may be determined from a single standard as follows ... 

Measuring the calibration solution in order of decreasing concentration, after the solution to be analysed has been measured, has no influence on the results for the sample solutions. It is better to calibrate in order of increasing concentration before measuring the sample solutions and to check the calibration values by measuring in order of decreasing concentration memory-effects can then be recognised when calibration points deviate. 

If a thermocouple or PRT was used, convert its readings to temperatures with an appropriate cahbration eqrration. It may be wise to check the calibration by measuring the bath temperature at atmospheric pressure. Calculate this bath temperature from Eq. (12) using the pressure determined with a barometer. If necessary, one can then apply a constant additive correction to all PRT resistance or thermocouple emf readings. 

The position of arrival, and hence the energy and angle of emission, is then calculated for each pair of electrons and the corresponding time-of-flight of each electron through the analysers is also calculated and used to correct the coincidence spectrum. The software allows the data to be displayed in a number of ways, and is also used to check the calibre of the data and to provide instrumental checks. 

Gas-phase epr studies have proved useful in the qualitative way described above, and they have been used also in quantitative kinetic studies. Low pressure discharge flow methods are eminently suitable, and the microwave cavity can be incorporated in the flow tube. Krongelb and Strandberg used the method to measure the rate of recombination of atomic oxygen. The spectrometer was calibrated using molecular oxygen that this procedure is valid was shown later by Westenberg and de Haas , who checked the calibration for both O and N by titration with NOj and NO (see Section 5). 

It is widely acknowledged that there should be some mechanism for checking the calibration equation after implementation. There are two types of triggers that would cause an equation to be checked. The first is a planned time point, similar to a scheduled calibration of a pump or detector for HPLC. 

It is important to have some validation tests when things start to (or appear to) go wrong. These validation tests can be used to check the calibration and performance of the DSC system. They should be run on a periodic basis, and the results kept as an historical log of the DSC system performance. There are three validation tests that are advisable to run on a regular basis baseline, calibration, and performance. The data from the validation tests are invaluable for assessing system performance when a strange or erroneous result presents itself. 

For most routine purposes, a solution of holmium oxide in perchloric acid will provide a convenient method for routinely checking the calibration of the wavelength scale. Figure 11 shows a typical spectrum. The values are known to within 0.2 nm and are adequate for most solution work. If wavelengths in the region below 241 nm are needed, then either atomic line sources such as a vapour discharge lamp or other rare earth solutions may be used. 

For most routine purposes, a solution of potassium dichromate in sulphuric acid will provide a convenient method of routinely checking the calibration of the absorbance... 

The transition should be reversible so that the sample can be run repetitively to optimize or check the calibration. 

Check the calibration of your thermometer by measuring the temperatures of a well-stirred bath of ice and distilled water (0.°C) and a boiling distilled water bath (100.°C). Record your measured temperatures in TABLE 11.2, and use these measurements to adjust the estimated errors in your previously measured boiling points, if necessary. 

The temperature-resistance characteristics of thermistors depend upon their method of fabrication as well as their chemical composition. One consequence of this is that they are less stable than metal resistors. This instability is a serious disadvantage if a series of measurements is to be made over an extended period of time. Stable temperature characteristics are particularly desirable when making cryoscopic studies with organic solvent systems which are readily contaminated, because a determination of the freezing temperature is often the most convenient check on the solvent purity. This problem of long term stability can be alleviated by frequently checking the calibration against a thermometer which has stable characteristics, e.g. a platinum resistance thermometer. The temperature-resistance relationship for a thermistor follows the equation... 

Check the conductivity cells. Check the calibration of conductivity analysers... 

Cahbrate flow indicators and transmitter Check the calibration of flow controller... 

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