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Instrument standard runs

Silent-hours operation, which is commonly termed hands-off analysis, requires the automatic analysis to operate to a set protocol. For a fully automatic instrument to run in this manner, it will require a feedback system comparing the results with check cahbration standards. A calibration graph can be constructed from the analytical data, and the precision of this graph is easily evaluated. As the analyses proceed, the system can be monitored by reference to the check calibration standards. Should the performance remain within specification, the analyses can safely go on. The automatic instrument can then operate within the set protocols throughout the silent hours, taking full account of any variations in the instrument and its operating parameters. [Pg.254]

Often ICP-AES instruments are run by operators who are highly knowledgeable about the intricacies of their particular instrument. Discuss with the operator what samples you are running. They will probably have suggestions of how to set up a sample run to make things run quickly and most accurately. However, ICP-AES has many analytical uses, probably least of which are biophysical measurements. This is not a problem however, it should be remembered that some of the advice from standard ICP-AES references does not transfer directly to use with biological macromolecules. [Pg.383]

Close the sample chamber and adjust the scale control knob until the display reads 100. This one-point standardization sets the machine to read the DNA concentration directly in pg/mL. However, it is advisable to run a calibration curve every few weeks to ensure that the standard has not degraded, the instrument is running properly, and that a consistent technique is being applied (see Note 18). [Pg.173]

In comparative testing the standard run is the complement of the blank run it uses a standard feed and a standard catalyst and indicates any unnoticed departures from standard procedure. Despite the reliability of modern instruments, experience shows that time is saved by frequent checking and calibration. [Pg.678]

Preparing and running QC reference standards at a frequency of once every 5 or 10 samples. This QC standard serves to monitor instrument precision and accuracy during a batch run. This assumes that both calibration and ICV criteria have been met. A mean value for the QC reference standard should be obtained over all QC standards run in the batch. The standard deviation, s, and the relative standard deviation (RSD) should be calculated. [Pg.27]

Lord Kelvin stated that to measure is to know (Unnamed 2011). In fact, it would be more precise to say that to measure is to know... better. Almost all measurements have errors with respect to their absolute value, be it temperature, pressure, flow rate, or any of several other standard measurements necessary to evaluate a phenomenon, characterize an instrument, or run a chemical plant. Error is deflned as the absolute or relative difference between the measured value and the true value as measured by a recognized standard. Note that the term recognized standard is mentioned, and not true value since the true value can rarely, if ever, be known exactly. [Pg.43]

McEwen et al. have utilized another ambient technique called atmospheric pressure solids analysis probe (ASAP) [84,85] and interfaced it with TWIM-MS [86], This source is now available commercially on the Synapt instrument. They have used m/z vi drift time plots to define compound classes in CTude oil analysis and to resolve isobaric compounds. Excellent agreement was demonstrated for drift times obtained from standards run individually and doped into the crude oil mixture. This work demonstrates the utility of mobility experiments to provide a degree of separation and classification in the study of very complex mixtures where chromatographic separation is either not possible or too time consuming. [Pg.225]

Substances separated on paper and thin-layer chromatograms are revealed or detected by derivatization to coloured or fluorescent products, and these are interpreted visually, evaluated semi-quantitatively with reference to standards run under identical conditions, or quantitated by elution of the coloured or fluorescent spots and instrumental determination by colorimetry or fluorimetry respectively. In paper chromatography the spots can be cut out with scissors or removed with a paper punch thin layers are usually scraped off the support and analysed in some appropriate way. A neat application is to analyse TLC spots directly by FAB MS [8], and this potentially provides identification as well as quantitation. It is one of the advantages of paper chromatographic and TLC methods that several samples and standards can be run under identical conditions, but the accuracy and precision of quantitation by these means are usually not nearly as good as with liquid or gas-liquid chromatographic separations. [Pg.329]

However, the physical transfer of spectra between instruments is only one step in the complex chain of the standardization in spectra. The ideal is that a given sample provides a constant spectrum for a given physical state and a defined set of recording and sampling conditions. In the past, it was considered adequate to run a simple calibration standard, such as polystyrene. This is often sufficient as a simple validation of an instrument s performance relative to a prerecorded norm. However, it is not adequate for, and does not constitute, instrument standardization. Standardization implies a unified control of parameters, such as spectral resolution and band shape, actual spectral line position (wavelength calibration), and photometric recording accuracy, and all things that can impact these parameters in a practical measurement. [Pg.88]

Figure 24.4 PTH amino acid standards run on a Procise instrument see Table 24.1 for amino acid abbreviations. Peaks marked dmptu (dimethylphenylthiourea) and dptu (diphenylthiourea) represent side-reaction products of the Edman degradation. Courtesy of Applied Biosystems.)... Figure 24.4 PTH amino acid standards run on a Procise instrument see Table 24.1 for amino acid abbreviations. Peaks marked dmptu (dimethylphenylthiourea) and dptu (diphenylthiourea) represent side-reaction products of the Edman degradation. Courtesy of Applied Biosystems.)...
These three phenomena can be corrected, to a degree, by the use of internal standardisation techniques (see Chapter 4). For matrix-induced signal drift, an external drift correction technique may also be used, whereby the drift is corrected by use of drift correction standards run at intervals during the analysis. Spectral interferences are discussed in detail in Chapters 4 and 8. The effects of most of these problems can be minimised through careful instrument set-up and/or selection of an appropriate instrument configuration or sample introduction components. [Pg.423]

The vibration characteristics, determined by use of the instrumentation, will serve as the basis for acceptance or rejection of the machine. API standards generally require that the equipment be operated at speed increments of approximately 10% from zero to the maximum continuous speed and run at the maximum continuous speed until bearings, lube-oil temperatures, and shaft vibrations have stabilized. Next, the speed should be increased to trip speed and the equipment run for a minimum of 15 minutes. Finally, the speed should be reduced to the maximum continuous speed and the equipment should be run for four hours. API does not require that the four hours be uninterrupted however, it is generally interpreted that way. The interpretation is one of the many test criteria to be discussed. It would seem that a break in the test at the midpoint is not the same as having it cut short five minutes from the end because the vendor s boiler took an upset that was not related to the compressor test. The ibration during the shop test is normally specified as the API limit of 1.0 mils peak to peak, or the value from Equation 10.1, unfiltcred. whichever is lower. [Pg.410]

Factory tests establish the pressure head, power, efficiency and NPSH over the complete flow range the pump can deliver running at design speed. British Standard, DIN standard or ANSI standard codes or national variations from such main codes lay down the manner of test procedure, and a minimum requirement is quite often defined by industry codes such as API 610. This is not the place to discuss instrument accuracy, as the codes lay down the limits possible from conventional instruments. There are two main classes of test the commercial requirements normally possible in the maker s test plant and high-accuracy tests that are only possible by using substandard instruments and very sophisticated techniques. [Pg.516]

We have found that the use of serum standards for standardizing the instrument in the laboratory is useful. However, the serum standards cannot be used for urines. In urines, one runs into other problems and needs to use aqueous standards. Therefore, at present, while atomic absorption is the instrument of choice, there is much to be desired for the determination of calcium and magnesium in the routine laboratory of clinical chemistry. [Pg.131]

Donovan and Pescatore described another fast-gradient approach with very short columns (20x4.6 mm internal diameter) packed with a porous polymer (known as ODP columns) [38]. This chromatographic support presents a high chemical stability and can be used at pH 2, 10 or 13 to analyze neutral analytes. This procedure allowed a relatively high flow rate (2mLmin ) and a gradient from 10 to 100% methanol in only 7 min. The mathematical treatment was simplified and based on the direct transformation of retention time to log P. For this purpose, two standards (toluene and triphenylene) were used to minimize retention time variations from run-to-run and instrument-to-instrument, and to facilitate the... [Pg.344]

Instrument calibration is done during the analysis of samples by interspersing standards among the samples. Following completion of the samples and standards, a linear calibration curve is estimated from the response of the standards using standard linear regression techniques. The calibration constants obtained from each run are used only for the samples quantitated in that run. Drastic changes or lack of linearity may indicate a problem with the detector. [Pg.359]


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