ACS Analytical Chemistry questions
and answers
standard deviation (s) ✔✔the square root of the variance
% relative standard deviation (%RSD) ✔✔Standard deviation divided by mean times
100
Grubbs test (Gcalc) ✔✔|Questionable value - mean/ std dev|
If that is larger than the Gtable value then the value is thrown out. Locate Gtable value
based on number of values in data set.
Used to define outliers
z score ✔✔(x- xavg)/s
F Test ✔✔used to compare precision
(s2)^2/(s1)^2 (should always be >1)
Use n-1 to find on table.
Fcalc> Ftable -- There is some noise or error
External standard ✔✔use standard solutions spanning a range of conc, measure
response
Internal standard ✔✔substance similar to analyte (ie deuterated); used to normalize
signal by reducing random error
Standard Addition ✔✔ideal for analyzing sample in a complex matrix; add known
standard to constant amount of sample; x-int =[sample]
Box car average ✔✔minimizes distance between data points and best fit line/
minimizes standard deviation
Limit of detection (LOD) ✔✔3*std dev
Limit of quantitation (LOQ) ✔✔10* std dev
and answers
standard deviation (s) ✔✔the square root of the variance
% relative standard deviation (%RSD) ✔✔Standard deviation divided by mean times
100
Grubbs test (Gcalc) ✔✔|Questionable value - mean/ std dev|
If that is larger than the Gtable value then the value is thrown out. Locate Gtable value
based on number of values in data set.
Used to define outliers
z score ✔✔(x- xavg)/s
F Test ✔✔used to compare precision
(s2)^2/(s1)^2 (should always be >1)
Use n-1 to find on table.
Fcalc> Ftable -- There is some noise or error
External standard ✔✔use standard solutions spanning a range of conc, measure
response
Internal standard ✔✔substance similar to analyte (ie deuterated); used to normalize
signal by reducing random error
Standard Addition ✔✔ideal for analyzing sample in a complex matrix; add known
standard to constant amount of sample; x-int =[sample]
Box car average ✔✔minimizes distance between data points and best fit line/
minimizes standard deviation
Limit of detection (LOD) ✔✔3*std dev
Limit of quantitation (LOQ) ✔✔10* std dev
