Question

Flame Atomic Absorption of Calcium In Milk

2. Record the atomic absorption data for the calcium standard curve and the diluted milk. Sample Ca? Concentration No. Absorbance 1 mg/L 5 mg/L 10 mg/L Milk, diluted 200 times 07 4. Calculating Ca2+ concentration in milk. a) Slope of the Ca2standard curve: _ graph.) (Show work if using hand-generated b) Concentration of Ca2+ in 200x diluted milk: (Show work.) c) Concentration of Ca2+ in milk: - (Show work.)

Answer 1

a) Standard curve $\left ( \text {Absorbance vs }[Ca^{2+}] \right )$ is shown below.

Absorbance (Ca2+] mg/L 0.034 0.17 5 0.332 10 Absorbance vs [Ca2+] mg/L y = 0.033x + 0.002 R2 = 0.999 Absorbance ол ел к п о л Absorbance vs [Ca2+] mg/L o 2 4 6 8 10 12 [Ca2+] mg/L

Slope is $m= 0.03308 \ L/mg$

b)

For milk diluted 200 times.

$[Ca^{2+}]=\frac{ \text { absorbance}}{m}$

$[Ca^{2+}]=\frac{ \text { 0.207}}{ 0.03308 \ L/mg}$

$[Ca^{2+}]=6.26 \ mg/L$

c)

For undiluted milk,

$[Ca^{2+}]=6.26 \ mg/L \times 200=1251 mg/L \simeq 1.3 g/L$

$\left ( \because 1 \ g = 1000 \ mg \right )$