User:Melissa Novy/Notebook/CHEM-572/2013/03/26

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Objectives

  • Continue silver ISE studies for the determination of Ag+ in solution.
  • Filter more 100Ag-LMT, made on ??? for future use.


Calibration Curve of [Ag+] for Silver ISE

  • The calibration curve for [Ag+] was redone in polypropylene containers to account for the adsorption of Ag+ on glassware. AgNO3 solutions made on 2013/03/19 were used and at concentrations according to the table below. Note that the solution of concentration 1 μM AgNO3 was discarded from the calibration curve, because the detection limit of the silver ISE is around 10 μM Ag+.
  • The protocol for calibration is as follows:
    1. Using an automated pipetter, add 3 mL of AgNO3 into a 15-mL polypropylene Falcon tube.
    2. Then using the same method, add 0.060 mL of 5 M KNO3 to the solution as an ionic strength adjustor.
    3. Rinse the silver ISE with deionized water and dry gently with KimWipes.
    4. Place the silver ISE into the AgNO3 solution and allow it to equilibrate.
    5. Record the conductivity value in mV.
    6. Repeat the measurement twice more for each solution to be tested.


Initial [Ag+] [M] Final [Ag+] [M] log [Ag+] [] Conductivity [mV] ' ' Average Conductivity [mV] Standard Deviation [mV] Corrected Conductivity [mV]
Trial 1Trial 2Trial 3
00---341.9340.2335.6339.23333333.2593455380
0.0000019.80392E-07-6.008600172328.3329.6331329.63333331.350308607-9.6
0.000019.80392E-06-5.008600172328.5330.6329.4329.51.053565375-9.733333333
0.00019.80392E-05-4.008600172357.2359.2359.5358.63333331.25033328919.4
0.0010.000980392-3.008600172417.6417.1416.6417.10.577.86666667
0.010.009803922-2.008600172472.8473.3473.6473.23333330.404145188134
0.10.098039216-1.008600172527.2527.5528527.56666670.404145188188.3333333

Image:Ag+_Calibration_Curve_3-26-2013.jpg

Analysis of Silver ISE Data

  • Conductivity and [Ag+] of PLA2002D + 5wt% LMT Solutions
Time [min] Conductivity [mV] Corrected Conductivity [mV] Positive Error Negative Error Calculated [Ag+] [M]
0283.533333345.333333339.265167744-9.2651677440.000187943
3028544.9333333316.35878969-16.358789690.000184584
60258.133333317.866666675.159780357-5.1597803575.44796E-05
90246.59.9666666674.257933771-4.2579337713.81552E-05
120231.1-4.3666666678.190238092-8.1902380921.99944E-05
1380225.3666667-100.06666675.822656896-5.8226568962.67375E-07


  • Conductivity and [Ag+] of PLA2002D + 5wt% 100AgLMT Solutions
Time [min] Conductivity [mV] Corrected Conductivity [mV] Positive Error Negative Error Calculated [Ag+] [M]
0233.5333333-4.6666666675.257692777-5.2576927771.97258E-05
30233.5333333-6.5333333339.250045045-9.2500450451.81337E-05
60230.4666667-9.84.00666112-4.006661121.56504E-05
90233.4333333-3.14.645786622-4.6457866222.11695E-05
120229.8333333-5.6333333336.553116307-6.5531163071.88846E-05
1800319.6333333-5.87.779674372-7.7796743721.87432E-05
  • Based on the nonlinearity of the data, it must be assumed that any results obtained from this study are unusable. Either silver does not leach out of films of PLA2002D + 5wt% 100AgLMT, or the concentration of silver that leaches into solution is below the detection limit of the silver ISE.



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