User:Sanuja Mohanaraj/Notebook/Experimental Biochemistry 1 Fall 2017/2017/10/03

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ICP-OES Analysis of Gold Nanoparticle Solutions

The first ICP gold standard was prepared my measuring out 2mL of the 10mM HAuCl4 into a falcon tube, followed by the addition of 8mL of deionized water to yield a final volume of 10mL (200ppm). This process was repeated with varying volumes of the 10mM HAuCl4, to ultimately yield four other solutions at 50ppm, 100ppm, 150ppm and 200ppm. Next, both HAuCl4 stock solutions (10mM and 2.5mM), were diluted to 500ppm, using 2.25mL and 9mL of the stock solutions using deionized water to achieve a final volume of 45mL each time. 2mLs samples of the five ICP standards, the two diluted HAuCl4 stock solutions, the gold nanoparticle colloids and the gold nanoparticle fiber solution were prepared to be analyzed using the Agilent Technologies 5100 ICP-OES instrument. Each sample was analyzed both axially and radially, at wavelengths of 208.207nm, 242.794nm and 267.594nm, to determine the exact concentration of each solution, with a viewing height of 8cm.

Results

Table 2 describes the actual concentration of [Au] versus the expected concentration of [Au] in each of the three solutions. The collected data was measured axially, with a wavelength of analysis at 267.594nm. According to Table 2, there is a ~30% percent error between the expected Au-concentration and actual Au-concentration, of the 2.5mM HAuCl4 stock solution; a ~53% percent error between the expected Au-concentration and actual Au-concentration, of the AuNP colloid solution; and a ~20% percent error between the expected Au-concentration and actual Au-concentration, of the 10mM HAuCl4 stock solution.
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Calculations

Conversion ppm to μM
78.96ppm [Au] - 10mM HAuCl4 Stock Solution
(78.96mg/L)(1mol Au / 196.97g) = ~400.87μM

68.09ppm [Au] - 2.5mM HAuCl4 Stock Solution
(68.09mg/L)(1mol Au / 196.97g) = ~ 345.69μM

[Au] - AuNP Colloid Solution
Expected Concentration
[(1mL HAuCl4)(2.5 mmol/L)] / 10mL = ~250μM
Actual Concentration
(23.31mg/L)(1mol Au / 196.67g) = ~118μM

HAuCl4 Stock Solutions
M1V1=M2V2

(10mM)(V1) = (500μM)(45mL)
V1 = 2.25mL

(2.5mM)(V1) = (500μM)(45mL)
V1 = 9mL