Chapter 10 Flashcards
What is an internal standard and why is it used?
A i s i a a a t t s i a f a. T s f t i s i u t c t d f c c.
A i s i a a a t t s i a f a. T s f t i s i u t c t d f c c.
An internal standard is an analyte added to the sample in a fixed amount. The signal from the internal standard is used to correct the data for calibration curves.
Why arc atomic emission methods with an ICP source better suited for multielement analysis than arc flame atomic absorption methods?
T p t a e o m e d t i h t. T m i e t d m e u t s c w i d w a f e s.
T p t a e o m e d t i h t. T m i e t d m e u t s c w i d w a f e s.
The plasma torch allows excitation of multiple elements due to its high temperature. This makes it easy to detect multiple elements under the same conditions
which is difficult with a flame emission spectrometer.
Why is the internal-standard method often used in plasma emission spectrometry?
I s a t u i p e s t a f c f i d.
I s a t u i p e s t a f c f i d.
Internal standards are typically used in plasma emission spectrometry to allow for correction for instrumental drift.
The chromium in a series of steel samples was determined by ICP emission spectroscopy. The spectrometer was calibrated with a series of standards
containing O.2.0, 4.0, 6.0. and 8.0 ug K2Cr2O7 per milliliter. The instrument readings for these solutions were 3.1, 21.5, 40.9, 57.1, and 77.3. respectively, in
arbitrary units.
(a) Plot the data using a spreadsheet.
(b) Find the equation for the regression line.
(c) Calculate standard deviations for the slope and the intercept of the line in (b).
(d) The following data were obtained for replicate 1.00-g samples of cement dissolved in HCI and diluted to 100.0 mL after neutralization.
Emission Readings
Blank: Sample A Sample B Sample C
Replicate 1: 5.1 28.6 40.7 73.1
Replicate 2: 4.8 28,2 41.2 72.1
Replicate 3 4.9 28,9 40.2 spilled
Calculate the percentage of Cr,03 in each sample. What are the absolute and relative standard deviations for the average of each determination?
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