test 1 Flashcards
measurement
a trial, replicate (specific)
determination
several trials (1 analyte) (general)
analysis
several analytes [ie blood panel]
technique
many times [with] a particular instrument
method
a way to determine an analyte using a particular technique
procedure
set of instructions that can be modified if needed
protocol
a specific set of instructions
What are the 10 Figures of Merit ?
- Accuracy
- Precision
- Sesitivity
- LOD (Limit of Detection)
- Linear Dynamic Range
- Robust/ Rugged
- Analysis time
- Selectivity
- Cost
- Sample size
sensitivity*
response vs concentration plot
the measure of the ability to establish that such differences are significant
LOD
Limit of Detection- the smallest amount of analyte that can be determined with confidence
-the minimum amount of analyte ( concen. or mass) that is “significantly different from the blank”
linear dynamic range
number of #s of orders of linearity of your calibration
robust/rugged
ability to minimize down-time
selectivity
the ability of the method to distinguish the analyte from the concomitants (forest) (needle in a haystack)
sample size
amount of sample one has to work with
Constituent Concentrations in a Sample (4)
1) major- 1-100%
2) minor- 10ppt-100ppm
3) trace- 100ppm-1ppb
4) ultratrace- = 1 ppb
Overall Sample Size (4)
1) macro- 100mg and up
2) meso/semi micro- 10-100mg
3) micro- 0.1-10mg
4) ultramicro-
replicates
(N) # of trials simulating the same conditions
mean (x-bar) (mu)
x-bar= (Sum of replicates)/ N
median
middle data point in rank order
4 Descriptors of Precision
1- range 2- standard deviation --> relative standard deviation 3- coefficient of variation (CV) 4- variance (s^2)
2 Descriptors of Accuracy
1- absolute error (E)
2- relative error
absolute error*
- descriptor of accuracy
- E = xi - xtrue
- shown with sign dependence
relative error*
- descriptor of accuracy
- %Er ={(| xi - xtrue |)/ xtrue}x 100
Types of Error
1- Systematic
2-Indeterminate
systematic error*
- type of error
- determinant
- can be corrected/avoided/minimized
- can be constant/ variable
constant systematic error** (EX)
ie. balance bias
variable systematic error** (EX)
ie. burret with varying diameter