# User:Melissa Novy/Notebook/CHEM-572/2013/02/20

(Difference between revisions)
+ + * Protocol + *# Pour 50 mL pure H2O into a clean, dry 250-mL Erlenmeyer flask and add 1 mL of 5 M KNO3. + *# Measure the conductivity of the solution with the ISE. + *# Place a single 0.5 g piece of film into the flask, swirl, and measure the conductivity. + *# Wait 30 min, then measure the conductivity again. + *# Repeat the above step 5 more times.

## Revision as of 13:21, 20 February 2013

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## Objectives

• Calculate the amount of AgNO3 to add to LB media solutions for desired final [Ag+].
• Remove PLA films, made on 2013/02/19, from glass molds.
• Soak PLA films in pure H2O to test for Ag+ leaching with a silver ion selective electrode.

## Calculations

• Two sample calculations are given as examples. The final [Ag+] in 50-mL solutions of LB media was calculated as follows:
```  1 μM Ag+ in 50 mL of LB media
(0.0105 M Ag+) × V1 = (1×10-6 M) × (50 mL)
V1 = 0.00476 mL of 0.0105 M AgNO3
```
```  10 μM Ag+ in 50 mL of LB media
(0.1 M Ag+) × V1 = (10×10-6 M) × (50 mL)
V1 = 0.005 mL of 0.1 M AgNO3
```
• AgNO3 solutions made on 2013/02/05 and 2013/02/13 were added to the LB media solutions in the following amounts:
 Final [Ag+] Volume of AgNO3 Solution Added 1 μM 4.76 μL of 0.0105 M 10 μM 5.00 μL of 0.1 M 100 μM 50.0 μL of 0.1 M 1 mM 500 μL of 0.1 M 10 mM 5000 μL of 0.1 M
• Note that for each volume of AgNO3 added to the LB media, the same volume of LB media was first removed from the flask to maintain the final concentration of Ag+.

## ISE Study of PLA2002D + 5 wt% 100Ag-LMT

• Calculations:
• To determine maximum [Ag+] possible, assume that all Ag+ leaches out of solution.
• The solution contained 50 mL pure H2O and 1 mL ionic strength adjuster. The recommended ratio of solution to ionic strength adjuster is 50 mL to 1 mL. Then, 0.50 g of film was added to the solution.
```  (4.47 × 10-8mol Ag+0 ÷ 0.051 L = 8.76 × 10-7 M or 0.876 μM
```

• Protocol
1. Pour 50 mL pure H2O into a clean, dry 250-mL Erlenmeyer flask and add 1 mL of 5 M KNO3.
2. Measure the conductivity of the solution with the ISE.
3. Place a single 0.5 g piece of film into the flask, swirl, and measure the conductivity.
4. Wait 30 min, then measure the conductivity again.
5. Repeat the above step 5 more times.