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News & Special Offers  Articles Online  Analytical Quick Tip  Joke of the Month  Container Transpiration Study

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When using HCl as the matrix acid for solutions containing Ag⁺, minimize the exposure of the solution to light. The AgCl_x^-(x-1) complex is photosensitive (photo reduction to the metal) and will produce Ag⁰ on the container walls.

Transpiration is defined as the passage of vapor from within a container to the outside. This loss of vapor can occur through the container walls or between the cap and threads, resulting in an increase in concentration.

Figure 6.1 shows the rate of transpiration for 125 mL and 500 mL LDPE bottles with conventional PP caps. This study, which was conducted over a five year period, showed a significant transpiration rate difference between the two bottles. Initially, it was thought that transpiration was occurring through the container walls. However, no correlation could be found that would explain the difference of the slopes. Surprisingly, it was discovered that there was a direct correlation between the transpiration rate and the circumference of the opening.

Fig. 6.1: Transpiration - 125 and 500 mL LDPE Bottles

The transpiration rate for the study shown in Figure 6.1 was found to be directly proportional to the ratio of the circumference of the bottle opening to the surface area of the solution. No correlation of the transpiration rate to the bottle surface area could be found. These findings suggest that transpiration is occurring around the cap/bottle opening and not through the container walls.

The above passage was taken from the 'Container Transpiration' section of our Reliable Measurements guide. Read the full article here.

Articles Online  more articles

Elemental Analysis of Zeolites
Complete application notes that describe a quick sample preparation procedure for the determination of major and minor elements in zeolites.

Method Validation
Part 17 of our Reliable Measurements guide concludes the guide, focusing on method validation.

Measurement Uncertainty
Dr. Gaines offers his advice on the measurement uncertainty associated with ICP-OES data calculations.

Joke of the Month  more humor

Two chemists met for the first time at a symposium. One was American, the other was British.

"So what do you do for research?" asked the British chemist.
"I work with arsoles," replied the American.
"Yes, sometimes my colleagues annoy me too," said the British chemist.