Term
| Briefly describe the four basic properties of a standard normal curve |
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Definition
-Area under the curve is equal to 1
-The curve is symmetrical about 0
-The curve expands infinity from negative infinity to positive infinity without touching the x-axis
-Most area under the curve fall between -3 to 3 |
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Term
| Define limit of decision and describe how it can be determined |
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Definition
-Point were the positive and the negative bias results meet
-Lowest concentration level at which a particular analyte can be analyzed from the background noise |
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Term
| Compare Analog and Digital analytical equipment |
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Definition
1) Power consumption -Analog consumes more power than Digital
2) Errors -Analog give considerate observational errors; Digital is free from observational errors
3) Waves -Analog gives sine wave signals; Digital gives square wave signals
4) Signal -Analog gives continuous signal; Digital gives discrete time signal
5) Data transmission -Analog subject to noise during transmission; Digital is noise immune during transmission
6) Response to noise -Analog likely to get affected; Digital less affected |
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Term
| Briefly describe Thermal or Johnson Noise |
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Definition
| Are due to the voltage fluctuations due to random electron motion in resistive devices |
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Term
| Briefly describe Short Noise |
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Definition
| Caused by current fluctuations due to random electron motion across a junction |
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Term
| Briefly describe Flicker Noise |
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Definition
- Amplitude varies with 1/f due to drift and low frequency signal fluctuation
- Any noise that is inversely proportional to signal |
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Term
| Briefly describe Environmental Noise |
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Definition
-Composite of many noise sources
1)Interference noise -Predictable; occurs at known discrete frequency
2)Impulse noise -erratic and unpredictable; difficult to detect; difficult to correct |
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Term
| Briefly describe Random sample |
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Definition
| A sample selected by a random process to eliminate problems of bias in selection |
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Term
| Briefly describe Composite sample |
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Definition
Consists of two or more portions of material obtained at the same time.
-Selected so as to represent the material being investigated.
-components are taken in proportion to the amount of the material that they represent. |
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Term
| What is good laboratory practice (GLP) in the operation of analytical labs |
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Definition
-GLP is the term used to describe how chemists and other scientists should go about their day-day work.
-It covers variety of characteristics such as tidiness, cleanliness, thoughtfulness, safety.
-A chemist with these qualities is likely to get precise and accurate results same time. |
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Term
| Discuss the importance of Blanks |
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Definition
-Used to establish which part of the measurement result is not due to characteristic being measured
-Blank should be as close as possible to the composition of analyte. |
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Term
| Discuss the importance of Quality control samples |
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Definition
| -Used as a means to study variations within and between batches of a particular analysis. They are fully characterized. |
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Term
| Discuss the importance of Blind samples |
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Definition
| -Type of a sample inserted into the analytical batch without knowledge of the analyst. |
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Term
| What is the importance of control charts |
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Definition
| It is used to verify if the process is capable of producing a minimal number of non-conformities |
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Term
| What does the acronym SOP mean? What should be included in the instrument room |
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Definition
-Standard operating procedures
-Well organized and equipped instruments |
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Term
| In brief, discuss the factors that have to be considered when choosing between types of method to be used for analyzing a sample in a chemical analysis. |
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Definition
-Type of sample
-Time
-Cost
-Equipment availability
-Limit of detection
-Limit of quantitation
-Working range
-Selectivity
-Precision |
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Term
| Describe confidence level |
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Definition
| Fixes the level of probability that the mean is within the confidence limit |
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Term
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Definition
| Test whether there is a significant difference between the precision of the two methods |
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Term
| Describe the Grubb's test |
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Definition
| Test used to test for outliers in a set of replicates |
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Term
| In which order should the statistical tools for data quality assurance be applied. |
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Definition
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Term
| Under which statistical conditions will the t-test be carried out |
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Definition
| When there is no significant difference between the precision of the methods |
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Term
| Describe the risks associated with poor sampling |
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Definition
1)Poor sampling may result in the sample being unrepresentative of the bulk material from which it was collected
2)Resulting in wrong batches of material being accepted or perfectly good batches being rejected.
3)In environmental analysis it may result in invalid decisions being made.
4)This could in turn impact the public health |
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Term
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Definition
A sample that is typical of the parent sample material for the characteristic under inspection
at least 5%m/m level. |
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