Laboratory notebook calculations

TECHNIQUE 2 The Laboratory Notebook, Calculations, and Laboratory Records... 

Forensic analysis is usually required for the collection of data in the course of determining whether legislation has been infringed. The customer requires that, above all, there is an unbroken chain of evidence from the time the samples were taken to the presentation of evidence in courts of law. In the laboratory this will include documentation and authorization for sample receipt, sample transfer, sub-sampling, laboratory notebooks, analytical procedures, calculations and observations, witness statements and sample disposal. All of these aspects can be called as evidence in court. 

Repeat the experiment (any quantitative determination must be repeated at least twice until similar results are obtained) as indicated above. Enter the results of your observations and calculations in your laboratory notebook, using Form 1,... 

Bring the pressure of the air in the eudiometer to atmospheric. How can this be done Calculate the molecular mass of the liquid being tested and enter the results in your laboratory notebook, using Form 3 for this purpose. 

Calculate the equivalent of zinc. Determine the magnitude of the error in computing it in per cent. Enter the results of your calculations and observations into your laboratory notebook as in the preceding experiment, using Form 5. Proceeding from the known valence of magnesium and zinc and your results, calculate the atomic masses of these elements. Compare the values obtained with tabulated data. 

In a modern laboratory, automated computer software for data acquisition and processing performs most of data reduction. Raw data for organic compound and trace element analyses comprise standardized calibration and quantitation reports from various instruments, mass spectra, and chromatograms. Laboratory data reduction for these instrumental analytical methods is computerized. Contrary to instrumental analyses, most general chemistry analyses and sample preparation methods are not sufficiently automated, and their data are recorded and reduced manually in laboratory notebooks and bench sheets. The SOP for every analytical method performed by the laboratory should contain a section that details calculations used in the method s data reduction. 

Because analytical results can be accumulated over long periods on easily accessible disks — a big improvement on laboratory notebooks — it is easier to evaluate the performance of a method or process over a period of time. It is easy to determine the frequency of defects in performance, both by inspection and by more formal methods. One of these which is being used more widely is the cusum procedure. A reference value, k, is selected typically it is the mean value of the expected result. Then sequentially the cumulative sum, Si is calculated... 

The tare of a container is its weight when empty. Throughout this laboratory course it will be necessary to know the tares of containers so that the weights of the compounds within can be calculated. If identifying marks can be placed on the containers (e.g., with a diamond stylus) you may want to record tares for frequently used containers in your laboratory notebook. 

The recommended initial formulation is displayed, including final tablet weight, recommended tablet diameter calculated compression properties, and all relevant data (Table 7). This is normally printed for inclusion in a laboratory notebook, file, etc. If required, the data may be stored in a database for future reference, necessary if the formulation optimization route is used. 

Daily use without LIMS concerns much time spent on writing (and often also finding) the laboratory notebooks and logbooks, performing calculations, writing results, controlling results and other items, and transfer of the data from one medium to the other, finally the certificate of analysis. 

The basic components of the notebook were identified as Date, Tide, Objective, Data Tables, Equations and Calculations, and Procedure and Observations. Time is spent examining each component. For example, students are taught that the laboratory notebook represents what they did and what they obseized while in the laboratory and therefore the Procedure and Observations section is to be written while they are doing the experiment, not before, and should be in the past tense. With respect to audience, as outlined above, entries are to include enough detail for a student of similar chemistry background to repeat the experiment based on the laboratory notes. 

Laboratory records are kept very carefully in order to follow the progress of any study and to be able to repeat any steps that are necessary. Detailed records include all the information about samples, preparation methods, analysis results, and storage. These records provide the documentation necessary to prove that the research was done and how it was completed. All of this information together is data and there are two major places these data are kept a notebook and computer database. The Laboratory Notebook is an essential part of lab activities and the first record of all information. A laboratory notebook is needed to explain lab procediues, write down all lab data, show how calculations are made, and discuss the results of an experiment. A record of lab work is an important document, which will show the quantity and quality of the lab work that you have done. The laboratory database is the digital archive of information from the activities, experiments, and measurements of the laboratory. 

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