Recording analytical results

Output of the detector may be recorded by a strip-chart recorder or by an integrator. Strip-chart recorders are difficult to work with when analysing mixtures of compounds because of the need to manually change attenuation and record retention times whilst compounds of different concentrations are rapidly eluted. Peak heights or areas must also be measured or computed manually. 

Integrators are manufactured by many companies (for example Hewlett-Packard, Spectro Physics, Varian). Many integrators plot the chromatography mn, record the retention times of peaks, calculate the areas under the peaks automatically and print this data at the end of the mn. 

Recorders alone are adequate for total sulphur analysis, where the relative retention times of multiple peaks are not recorded. However, an integrator is necessary for detection and measurement of concentrations of sulphur species in a mixture. 

The case history section of this chapter is severely limited by the absence of well-documented reports of the use of sulphur gases in mineral exploration. The case histories that follow are demonstrations of the ways in which sulphur gases delineate known mineral 

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A chemical analysis is not only the recording of a detector signal but a very complex matter. In Table II, the extent of total residue analysis is sketched, and at each step errors can be made which will infiuence the analytical result. When serious, these errors will convert the recorded analytical result into nonsense. When less important, these errors will only lower the over-all sensitivity of the analysis. Thus, the sensitivity limit obtainable by the detector alone is in reach only when the entire scheme of the analysis is successfully performed. 

Once the best method of dealing with interferences has been decided upon and the most appropriate method of determination chosen, the analysis should be carried out in duplicate and preferably in triplicate. For simple classical determinations the experimental results must be recorded in the analyst s notebook. However, many modern instruments employed in instrumental methods of analysis are interfaced with computers and the analytical results may be displayed on a visual display unit, whilst a printer will provide a printout of the pertinent data which can be used as a permanent record. 

When a sample is received it should have a unique identification, i.e. a number or code. All details about the sample should be recorded. This will include storage conditions and, if it is necessary to transfer the sample from person to person, this should be fully documented. Details of the container and closures should also be recorded. These may have been inappropriate and influence the analytical result. The appearance of the sample on receipt should also be documented. 

Sets of parameters such as burette volume, reagent strength, increment size and time interval, end-point potential, format of results, etc., can be stored and recalled from memory as standard methods for routine analyses. An alphanumeric keyboard is used to enter or change the parameters, to take individual pX or mV readings and to control the rinsing and the refilling of the automatic burette. Raw titration data and computed analytical results can be printed out as a permanent record, and titration curves can be produced on a chart recorder or VDU. 

Experimental system. To validate the analytical results some experimental cars, shown in Figure 6, have been equipped with a radar network. These test cars are used for data acquisition and recording to optimize the signal processing algorithms. In section 3.5 experimental results are presented to illustrate the theoretical results of developed and applied algorithms. 

The saturation concentration is calculated by the software. The signal from the Merhn shows a transient peak which is measured by peak height. In addition, the time of the peak maximum is recorded, providing further identification of the mercury present. A Hnear cahbration is obtained from which analytical results are calculated. The software is also available to couple this system directly to a process control computer. 

Reduction by zinc amalgam of a dry and oxygen-free THF solution containing [VC12(TPTP)] (TPTP = raeso-tetra-p-tolylporphyrinato) and addition of elemental sulfur yields [VS(TPTP)].659 Similar thiovanadyl complexes were prepared with OEP, TPP and TMTP (TMTP = meso-tetra-ra-tolylporphyrinato). Analytical results and mass spectra agree with the formulation [VS(por)], and v(V=S) was at 550-565 cm-1 (see Section 33.5.6.1). FT-EXAFS of [VO(OEP)] and [VS(OEP)] were recorded and the difference FT spectrum yielded... 

How do we access the qualitative and quantitative components of total error for data sets that consist of analytical results and an assortment of field and laboratory records And how do we define a standard appropriate for the intended data use ... 

The raw data and the hardcopy analytical results for original analysis and all reanalyses become part of the sample file. They are maintained as a permanent analytical record and may become part of a data package deliverable to the client. The sample and laboratory QC sample results are transferred into the LIMS for the generation of final analytical reports. 

Inadequate record keeping practices make impossible the reproduction of analytical results at a later date. Data validity cannot be established if laboratory reports are not supported with documentation that allows the tracking of every step in the analytical process for the recalculation of sample results. 

Changes should also be correlated with the statistical data available from stability, inprocess, and finished-product testing. The statistical data should be examined for trends in specification test results. Where trends are found (e.g., increases or decreases in potency, decreases in stability) the change control records should be evaluated to determine whether or not changes have occurred that might be responsible for the shifts in QC trends and analytical results. 

Current procedures emphasise the importance of storing the laboratory recorded data ( raw data ) and the XRFS analyses are now direcdy transferred via a Laboratory Information Management System (LIMS) to data tables in the BGS corporate geochemistry database. Conditioned data is loaded to different data tables and importantly every analyte result has an accompanying qualifier field that can be provided to the user to explain any data quality issues. 

Another common need is to compare two independent types of measurements. Consider recording die results of a taste panel for a type of food. Their scores relate to the underlying chemical or manufacturing process. A separate measurement could be chemical, such as a chromatographic or spectroscopic profile. Ideally the chemical measurements will relate to the taste can each type of measurement give similar information and, so, can we predict the taste by using analytical chemical techniques ... 

The majority of flame analyses in water and effluents presents few problems. A pretreatment on the sample is performed only when necessary, as described earlier. Standards are prepared in the linear range of the analytical curve and blank solutions are also made up. It is preferable to acidify blanks, standards and samples to 1% with hydrochloric acid. Apart from acting as a preservative, it promotes atomisation of the analyte by forming volatile metal chlorides. The atomic absorption instrument is then set up and flame conditions and absorbances are optimised for the analyte. Following this, blanks, standards and samples are aspirated into the flame absorbances are recorded and results calculated. 

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