| This survey aimed to assess the roles of pipette tip’s contamination and usage of one second-hand tip in the loading of all
samples in the electrophoresis procedure, and use of second-hand tubes in PCR procedure. Three genes with different band
sizes were amplified with the PCR method. Three dilutions of 1x, 0.5x and 0.1x were made for all three PCR products. After
loading of each PCR products in its first well, pipette tip has not replaced and washed in 5 μl distilled water. Then, 5 μl of the
washed water was loaded in the second well. Two kinds of staining methods were done, including safe stains and Ethidium-
Bromide. At the same time, Non-sterile and second-hand vials were washed with 6% NaOCl and used for PCR method, again.
Results showed that among all three dilutions (1x, 0.5x and 0.1x), only 1x dilutions had bands in first wells for each gene. In
addition, none of them has presented bands in the second wells (which was done without replacing the pipette tips). In
addition, 6% NaOCl had the ability to eliminate contamination from second-hand vials among PCR and vials could be reused
for second times. We conclude that it is not necessary to replace the pipette tips among the loading of products in
electrophoresis and second-hand tubes are usable after washing with NaOCl (6%-10%) for PCR. |