Instrument internal calibration

To minimize experiment time a very strong Co/Rh source was used, with an initial source strength of about 350 mCi at launch. Instrument internal calibration is accomplished by a second, less intense radioactive source mounted on the end of the velocity transducer opposite to the main source and in transmission measurement geometry with a reference sample. For further details, see the technical description in Sect. 3.3. 

The MS sample plate is dried under high vacuum for 5 min prior to analysis on the MALDI-TOF instrument. Internal calibration may be performed using insulin 5734.59 daltons and sinapinic acid 225.22 daltons. 

Ionizing radiation measuring instruments containing, for purposes of internal calibration or standardization, one or more sources of byproduct material—exempt quantities of 241 Am 0.05 pCi NRC 2001 g 10CFR30.15(a)(9)... 

For the analytical representation the signals have to be transformed from time functions into conventional measuring functions. These are characterized by analytical quantities on abscissa and ordinate axes where the values of them may be relativized in some cases (e.g. MS). Such a transformation of quantities is mostly carried out on the basis of instrument-internal adjustment and calibration. 

Molecular rotors with a dual emission band, such as DMABN or A/,A/-dimethyl-[4-(2-pyrimidin-4-yl-vinyl)-phenyl]-amine (DMA-2,4 38, Fig. 13) [64], allow to use the ratio between LE and TICT emission to eliminate instrument- and experiment-dependent factors analogous to (10). One example is the measurement of pH with the TICT probe p-A,A-dimethylaminobenzoic acid 39 [69]. The use of such an intensity ratio requires calibration with solvent gradients, and influences of solvent polarity may cause solvatochromic shifts and adversely influence the calibration. Probes with dual emission bands often have points in their emission spectra that are independent from the solvent properties, analogous to isosbestic points in absorption spectra. Emission at these wavelengths can be used as an internal calibration reference. 

A flour sample is weighed then mixed with water for a standard time and poured into a glass cuvette. The cuvette is inserted into the instrument, which moves into the measurement position and takes the reflectance reading. The results appear on a LED display and are printed out. The instrument is calibrated with an internal ceramic tile and standardised using a national standard flour. The normal range of flour grades is -5 to +18. 

The mass accuracy is highly dependent on the mode the instrument is operating in. In the reflector mode, with time-lag focusing, the best MALDI-TOF and oa-TOF instruments are capable of achieving <5 ppm with internal standards, provided that the isotopes are resolved. In many cases it is not possible to add internal calibrants, and then the error in mass accuracy is often increased to 50-100 ppm. Operation of an instalment in a linear mode will typically decrease the mass accuracy. 

Quadmpole analyzers have generally been considered to give poor mass accuracy. Recently, however, with better machined parts and better electronics, commercially available instruments can perform quite well. A mass accuracy <5 ppm can be obtained with internal calibrants. 

The orbitrap mass accuracy is better than all quadmpoles and TOF instruments just right after the FTICR and sector instruments, that is, around 2 ppm with internal calibration [248]. 

The RQ flex test kit (Merck) which uses specific test strips is useful for the semi-quantitative determination of several analytes. D(+) ascorbic acid can be determined in fortified food products with an accuracy of 85-115% (unpublished data), however the procedure cannot be applied to coloured food products. Added iron salts may be extracted from food products with dilute sulphuric acid and adjusted to pH2 with NaOH solution. Fe3+ is reduced to Fe2+ with ascorbic acid. Fe2+ reacts with Ferrospectral to form a red-violet complex. An internal calibration is provided on a barcode which is read by the RQ-flex reflectometer prior to any measurements. This avoids the need to calibrate the instrument with standard solutions. 

The IQ is typically followed in close succession by the OQ protocol. The OQ confirms and documents that an instrument operates in accordance with the vendor s functional specifications. Again, similar to that for the IQ, the OQ protocol is often partly, if not totally, developed by the vendor of the instrument. In some laboratories, the internal calibration tests may be incorporated as part of the OQ protocol. In most cases the protocol is typically carried out by a vendor s qualified service engineer. Since the same service engineer often performs both the IQ and the OQ, the IQ and PQ are often combined as part of an overall IQ/OQ protocol. 

Standardization The instrument response function can vary from analyzer to analyzer. If calibration transfer is to be achieved across all instrument platforms it is important that the instrument function is characterized, and preferably standardized [31]. Also, at times it is necessary to perform a local calibration while the analyzer is still on-line. In order to handle this, it is beneficial to consider an on-board calibration/standardization, integrated into the sample conditioning system. Most commercial NIR analyzers require some form of standardization and calibration transfer. Similarly, modem FTIR systems include some form of instrument standardization, usually based on an internal calibrant. This attribute is becoming an important feature for regulatory controlled analyses, where a proper audit trail has to be established, including instrument calibration. 

Purchase and control measuring equipment and reference material necessary for internal calibration certification of calibrated instruments. Label them with the date when last calibrated and also date when the next calibration is due. Write a calibration report and, if necessary, an incident report or a calibration variance report. 

Use the protocols set out in the instrument manual for a pulsed NMR unit to perform the recommended self-tests and internal calibrations. 

Emission measuring sensors also need an internal calibration source. In the case of absorption sensors, the external source most often served as the standard. In the case of emission, a reference source is usually incorporated in the instrument to certify instrument performance and provide an absolute reference. 

The photoelectron spectrum was obtained1 with a Vacuum Generator UV 63 instrument at low resolution (35 eV) using He excitation at 140° and xenon internal calibration. 

FT-Raman instruments are calibrated with an internal laser, which is used to provide the exact location of the movable mirror in the interferometer. Thus the intensity of the interferogram is known as a function of the mirror location (distance in cm), and this is converted through a fast Fourier transform to reciprocal distance or wavenumber (cm-1) in the spectral domain. 

Percentage of critical instruments or safety instrumented systems calibrated on time (e.g., within the timelines suggested by the assessment to meet the requirements of lEC (International Electrotechnical Commission Standard) 61511)... 

An important feature of modern high-performance liquid chromatography (HPLC) is its excellent quantitation capability. HPLC can be used to quantify the major components in a purified sample, the components of a reaction mixture, and trace impurities in a complex sample matrix. The quantitation is based on the detector response with respect to the concentration or mass of the analyte. In order to perform the quantitation, a standard is usually needed to calibrate the instrument. The calibration techniques include an external standard method, an internal standard method, and a standard addition method. For cases in which a standard is not available, a method using normalized peak area can be used to estimate the relative amounts of small impurities in a purified sample. 

The performance characteristics of this analyzer are quite remarkable with mass accuracies of <2 ppm at a resolving power of 60 000 using an external calibration 5 and of <1 ppm with internal calibration.76 As such, it has attracted the attention of analysts and instrument developers alike. New features have included ETD (see Section 9.10.3.2.5) and options for higher energy collisions in the C-trap or in an additional octapole collision cell.77... 

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