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Good Laboratory Practice (GLP)

 Labeling |  Solutions & Measuring  |  Error  |  Lab Notebook

Good Laboratory Practice (GLP) is an international system of practices used to maintain the quality of results in a research laboratory. The goal of the practices is to produce uniform, consistent, reliable, and reproducible results. We will focus on the most basic aspects of GLP.

Establishing Good Laboratory Practice at Small Colleges and Universities

Good laboratory practice for nonclinical laboratory studies

Labeling

• Lids - We usually do not label lids as lids can be switched, lost, or broken. Instead, the container (tube, microfuge tube, specimen vial, slide, box) should be labeled.
• Labeling Before - In many fields of science, you label the container for a chemical, solution, or specimen before you dispense the material into the container. Every stock solution you aliquot should go into a labeled container.  Every solution you make should be made in a labeled container. That way, if your beakers or flasks are moved, or several are put in the same area, you will know exactly what each one is.
• Labeling After - In the health sciences, there are specific specimen labeling guidelines and requirements. The Journal Of Clinical Laboratory Analysis reports that a common reason for rejecting a specimen is mislabeling.  In general, specimen containers should be labeled in the presence of the patient after the specimen is collected. It is also important that the label is placed on the container in the correct position. Once the label has been placed on the container it should be visually compared to the ID band or the patient should confirm the labeling information.

Solutions & Measuring

Solution - a liquid that contains one or more dissolved solutes.

Solute - a substance dissolved in a liquid.

Stock solutions - concentrated solutions of known, accurate concentrations that will be diluted for future laboratory use.

Aliquot - a portion of a larger whole, especially a sample taken for chemical analysis or other treatment.

Error

Experimental design - the laying out of a detailed experimental plan in advance of experimenting. Well-chosen experimental designs maximize the amount of “information” that can be obtained for a given amount of experimental effort and reduce experimental error.

Observational / measurement / experimental error – the difference between a measured value of a quantity and its true value and can be the result of systematic error and random error. Systematic error always occurs, with the same value, when we use the instrument in the same way and the same case, and can be reduced with standardized procedures. The random error varies from one observation to another:
A. Accuracy - how close or far off a given set of measurements (observations or readings) are to their true value, accurate if their average (mean) is close to the true value.
B. Precision - how close or dispersed the measurements are to each other describes random errors; standard deviation is relatively small.

Investigator error - is a type of systematic error caused by the technical skills of the investigator and can result from measuring solutions inaccurately, not labeling correctly, not rinsing equipment well enough between tests (contamination), etc.

Controlled experiment groupings:
A. Control - the group that does not receive the new treatment being studied. This group is compared to the group that receives the new treatment, to see if the new treatment works.
B. Experimental - the sample in an experiment that is subjected to some type of variation that does not occur naturally.

Controls - constant and unchanging standards of comparison in scientific experimentation:
A. Negative - is not exposed to any treatment (experimental or otherwise) that is known to produce the expected effect.
B. Positive - is exposed to some other treatment that is known to produce the expected effect but not the experimental treatment.

Lab Notebook

Although, the majority of research labs require the use of lab notebooks we will not use them in our introductory courses in the GLP format. Instead, it is expected that you use 3-ring binders, the assigned task sheets, and other lab materials to make up the lab notebook and you will need to use pencils not pens for your introductory course. See the directions listed in Moodle.

GLP Format of a Lab Notebook

1. General:
   • Entries should be made in black pen, not pencil.
   • Incorrect entries should never be erased but should be struck through with a single line.
   • Blank sections of pages should be drawn through with a single diagonal line.
   • The date should be entered on each page.
   • Pages should be consecutively numbered.
   • All non-standard terms and abbreviations should be defined in the notebook.
   • The labeling system of reagents, samples, etc. should be clearly defined.
2. Name the notebook - use a bound notebook that is clearly labeled on the front with the following:
   • Your name.
   • Project name.
   • The beginning date and the end date that the notebook was used.
   • Multiple lab notebooks may be used, identify each one with either Roman Numerals or numbers. 
   • Address of the laboratory or office of the researcher.
3. Table of Contents - inside cover or cover page and help you and present and future researchers quickly find previous experiments.
   • If there is no space provided for a table of contents, make your own within the first few pages of the notebook
   • Write down the date and title of the experiment
   • If completing an experiment that is multi-page, record the entry on the first page used, then use arrows to show the number of pages devoted to that entry.
4. Experimental records - entries should be made directly in the notebook as the experiment is carried out and results should be entered immediately as they are obtained.
   • Dates and titles of experiments.
   • New ideas and plans for experiments.
   • The purpose of each experiment should be indicated along with the hypothesis/goals/specific aims.
   • Background information.
   • Each experiment performed should be described in detail in the past tense.
   • Protocols, calculations, reagents, and equipment used during experiments.
   • Observations - anything planned or unplanned, raw data, permanently affixed information with reference to data location.
   • Some results may be difficult to enter directly into the notebook. Photographs, graphs etc should be stuck in, and signed and dated across the border to show that they have not been added later. Bulky results such as large computer printouts, may need to be kept separately. Some laboratories keep separate catalogs of signed and dated printouts numbered by consecutive catalog numbers, with a description of the results and a cross-reference to the catalog number entered in the notebook.
   • Conclusions