Post Experimental Cleaning
After the experiment has been completed, the equipment should be thoroughly cleaned. It is important to remember that the solutions used to provide isolated organ or tissue preparations with nutrients will also provide an ideal environment for bacteria and fungal growth. Standard cleaning procedures will depend on:
• The types of chemicals and biological materials used in the experimental protocols.
• The types of measurements that have been made and the use of substances that could interfere with those measurements.
• The frequency of equipment use and the number of operators.
Non-phosphate soaps are preferred, since insoluble phosphates can form from calcium and magnesium in the physiological salt solutions. Note that bactericidal soaps may contain iodine or other materials that can affect isolated tissues and cells. Rinsing after using any of these products is therefore important.
Accessories and Procedures
It is recommended that cleaning supplies and equipment, such as brushes, should be used only for cleaning a single piece of equipment and not used for other lab cleaning procedures.
To maintain and care for the equipment properly, the following procedure could be implemented:
• One individual is assigned responsibility of maintenance and equipment.
• The laboratory has clearly written cleaning protocols posted with the equipment.
• The laboratory has a logbook where cleaning dates, as well as notification of problems, suggestions, etc., can be recorded.
Often overlooked as a source of contamination is the water circulator. This should be kept clean and the bath rinsed and solution changed to reduce precipitate build up. A small quantity of Liquid Bleach or Copper Sulfate can be added to the distilled, deionized water used in the water circulator to prevent bacterial or fungal growth in the system's water jacket system.
Covering equipment to reduce air borne contamination from microbes and spores is useful. If the equipment is not going to be used on a regular basis, or is put into storage, then it is important that the apparatus is cleaned, rinsed and dried thoroughly before storage.
If the equipment has not been used for some time, then it is recommended that the system be properly cleaned and rinsed before any experiments. If two consecutive experimental failures (using a protocol that has previously been reliable) cannot be explained by an obviously damaged sample, poor dissection technique or solution problems, then the system may be contaminated and thorough cleaning is recommended.
Cleaning Radnoti Glassware
Radnoti apparatus is manufactured of borosilicate glass and can be easily cleaned using a wide range of soaps, ethyl alcohol, dilute HCl or HNO3 (0.1 M) or other cleaning solvents. After washing with any cleaning agents, it is important to thoroughly rinse all of the components multiple times with distilled, deionized water, thereby removing all traces of any cleaning agents and salts. Large glassware, such as reservoirs or assemblies, can be flushed whilst placed within the system; however, care must be taken to thoroughly clean aerators, stopcocks and associated parts. Aerators should be carefully blown dry using gas or air after the final water rinse. If acid is used for cleaning, a test to ensure that the acid has been completely removed is to check that the runoff water is less acidic than the normal water pH. As with the use of any chemicals, proper protective gear and training are essential to reduce personnel hazards and experimental and environmental contamination. The use of heated acid or chromic acid is not recommended due to potential hazards and possible heavy metal contamination of the system.
If very lipophilic substances (prostaglandins, ionophores, certain dyes, etc.) are used in the system, rinsing with ethyl alcohol or the most appropriate organic solvents should be performed first. After cleaning with organic solvents, it is important to thoroughly rinse the glassware. Use of toxins, biohazardous materials and radiochemicals can present considerable complications to a generalized cleaning procedure. Having the correct cleaning apparatus and a containment area that is dedicated only for such cleaning procedures reduces potential risks. Diluted bleach can also be used on glassware, but must be rinsed thoroughly.
The glass aerators can be cleaned with water, or dilute acid if blocked. The use of water or gas under high pressure can result in damage to the glassware and personnel and therefore is not recommended. After a general soap and water rinse to remove soluble materials, cleaning with 0.1M HCl or 0.1 M HNO3 for several hours or overnight, followed by multiple water rinses, will usually remove most contaminants. If this does not work, 1 M acid can be used for a shorter period of time. Because the glass frit filaments are thin, high concentrations of acids, or especially alkalis, can destroy them and are not recommended.
Glassware can be sterilized but any plastic fixtures, such as aerators, stopcocks caps, etc., should be removed prior to sterilization.
Cleaning Non-glass Items Included in the Radnoti Systems
The initial cleaning of non-glass items should be with aqueous soap solutions. Depending upon the chemical resistance of the materials, the use of other solvents, cleaning procedures or sterilization may be possible. It is advisable to consult a material data sheet on the material to be cleaned to ensure any chemical agents within the cleaning or sterilization solutions will not cause damage. Areas and items to be especially well cleaned are the aerator, tubing, syringe ports, cannulae, pressure transducer fittings, septa, balloon and other catheters and electrodes (oxygen, pacing, ion selective, etc.).
Tubing should be inspected at the pump head for normal wear. Note that the interior of the tubing can gradually be roughened through normal use and the abraded areas will form sites for bacterial growth. Tubing should be of a high grade with low plasticizer leaching. Note that silicone tubing is permeable to gases, so it should not be generally used to transport gassed solutions.