Atomic Spectrometry Quiz

When using the external calibration method to determine the concentration of an unknown sample, what two things will you implement to ensure accurate determination of the analyte concentration?

1. Careful prep of samples and standards

2. Ensure careful observation and measurements.

how do you know what experiment is more sensitive givn a linear regression result?

The plot with a smaller R2.

What are the types of instrumental noise?

Flicker, Environment, Thermal/Johnson, Instrumental, Shot

What is shot noise?

Fluctuations of electrons in semiconductors

What is thermal noise/johnson noise caused by?

Caused by electron or charge agitation which leads to voltage fluctuations

What is Flicker Noise?

1/f, slow drift in signal at low frequencies.

What are 2 methods to improve the signal-to-noise of a measurement?

Grounding/Shielding, Electronic filtering

How do you calculate signal to noise ratio?

You find the mean, and take the mean/standard deviation.

What are the three hardware signal to noise enhancement methods?

Grounding/Shielding, Electronic Filtering, Modulation

What are the three software methods of signal to noise enhancement?

Ensemble averaging, smoothing, digital filtering.

What types of noise can be reduced by a) decreasing the temperature of measurement b) increasing the frequency c) decreasing the bandwidth?

a) Thermal Noise b) Flicker Noise C) Shot noise

What are the assumptions made in using an external standard calibration method?

1. No error in conc of standards.

2. No error in measurments

3. Signal response is same for standards and samples.

What factors can cause errors in external standard method?

Contamination and systematic errors.

What is the standard addition method and what is it used to eliminate?

Used to eliminate matrix effect in samples by spiking the sample with known aliquots of a standard.

What does the internal standard method correct for?

Corrects for both measurement errors and instrument errors

What is smoothing?

Averaging successive points

What is digital filtering?

Mathematically removing selected frequencies using the signal as a function of frequency rather than time.