Atomic Absorption Spectrometer Varian Spectr AA Model 220

Atomic Absorption Spectrometer Varian Spectr. AA Model 220 FS

The Instrument The instrument consists of: 1. A flame 2. Lamps to produce the correct wavelength of light 3. A detector 4. A system to aspirate solutions into the flame 5. A computer to control the experiment

The Instrument On the left is the flame (behind the grid) and the spectrometer. The two bottles contain water used for flushing the tubing and for diluting solutions that are too concentrated. The round object is a pump. On the right is a cabinet containing the lamps shown on the next slide. The flame, like all large burners, is vented at the top.

The Lamps From bottom to top, the lamps are for Mg, Ca, K, and a combination of Fe, Co, Ni, Mn, Cu, and Cr. Each element uses a specific wavelength of light.

The Flame The flame is with only water being aspirated. The two holes, left and right, are where the light beam enters and leaves after passing through the flame. The dark place at the top is a stain from the heat of the flame.

The Instrument Current spectrometers use a PC Computer to control the experment. There needs to be standards (solutions of known concentration) to calibrate the instrument. The experiment must be setup in the program controlling the experiment with • Ions to be analyzed • Concentration of the standards • Number of points to be measured • Wavelength of light • Lamp Position

Measurement - Standards A set of standards ready to be aspirated into the flame. This instrument automatically dilutes the solution.

Aspiration of the Solution Being Measured A sample of maple syrup ready to be aspirated into the flame.

The PC Screen The solution being measured has an absorbance of 0. 068 which corresponds to a concentration of 10. 2 ppm

Colors Produced by Different Ions The following slides show the colors of different ions in the flame. The differences in intensity of the colors is, in part, due to differences in concentration.

The Calcium Flame The calcium flame is red. This is intensely red because the calcium content is high.

The Copper Flame

The Potassium Flame

The Manganese Flame

The Cobalt Flame

Results The computer stores the data which can be printed. The experiment can be set up to show the calibration curve and the concentrations on the screen. To get reliable concentrations, the program must be told what fitting algorithm to use. As can be seen on the screen shown previously, the calibration data are not linear in that instance.

Manganese Content of Maple Syrup

Manganese An Example The maple syrup used was from Highland Sugarworks in Websterville, VT labeled as Pure New England Maple Syrup. Different concentrations of maple syrup and different concentrations of the standards were used in order to stay within the sensitive range of the light detector.

Manganese Standards 0. 35 0. 3 R 2 = 0. 9994 0. 25 Mean A 0. 2 0. 15 0. 1 0. 05 0 0. 00 0. 50 -0. 05 Std. Conc. /mg L-1 0. 000 0. 500 1. 000 1. 500 2. 000 1. 50 Mn Conc in mg/L Sample Absorbance -0. 0008 0. 0806 0. 1514 0. 2229 0. 2990 2. 00 2. 50

Manganese Standards Graph of A of standards vs. Concentration Linear Least Squares Fit (R 2 = 0. 9994): A = 0. 1484 C + 0. 0022 Or C = A/0. 1484 - 0. 0022/0. 1484 = 6. 738 A – 0. 01482 Use this equation to convert Absorbance to Concentration

Maple Syrup Solution 10. 066 g of syrup dissolved in water to make 100. 0 m. L of solution. That is 10. 066 x 106 mg of maple syrup per 100 m. L or 100. 66 x 106 mg per liter. Note that 1 L of water weighs 1 x 106 mg so mg/L is the same as ppm (parts per million).

Manganese Concentration in Solution Absorbance Concentration/mg of Mn per L 0. 2028 1. 3518 0. 2043 1. 3619 0. 2037 1. 3578 0. 2044 1. 3625 Mean = 1. 3585 ± 0. 005

Manganese Concentration in Maple Syrup Per liter: 1. 3518 mg of Mn 100. 66 g of maple syrup C = (mg Mn/mg syrup) x 106 = (1. 3518 mg Mn/100. 66 x 103 mg syrup) x 106 = 13. 52 ppm

Daily Value The daily value for manganese is 2 mg. 1. How much manganese is in one daily serving? One daily serving is ¼ cup or 60 m. L or 79. 8 g We calculated that there was 13. 52 mg of Mn in 1 x 106 mg of maple syrup. How much is in 79. 8 x 103 mg of maple syrup? (13. 52 mg Mn/1 x 106 mg syrup) x 79. 8 x 103 mg syrup = 1. 08 mg Mn. %DV = (1. 08/2) x 100 = 54%

Results Summary of results. Not all metals present were analyzed for. Meta Mass per l Serving/mg % DV Mn 1. 08 54 Zn 6. 40 43 Cu 0. 328 16 Ca 936 94 K 1524 44