Exam 1 Flashcards
what are the steps to analyze something meaningfully?
- ask a question
- select a method
- find your samples
- sample preparation
- analysis
- interpretation
- conclusions
when asking a question…
be specific, be reasonable, think small
when selecting a method…
exploit what is known, example is using uv-vis to find conc of drug
when finding samples…
make sure sample taken is good representation of a whole
when preparing samples…
can my method handle my sample, is conc too high or low, is it dirty, be careful
when doing analysis…
actually take the data, diff for every instrument
when interpreting…
does my data mean anything, what is drug conc, does it all agree
when concluding…
do i trust my data enough to report out/act
what can go wrong with analytical process?
complex matrix, balances, glassware
what is a blank?
matrix without analyte
what is a sample?
matrix and analyte
what is analyte?
the drug
what is matrix?
everything else
what are the types of balances?
mechanical and analytical
what is readability
lowest amount that balance can measure accurately
what can mechanical balance read to
0.1 g
what can analytical balance read to
0.001 g
what can microanalytical balance read to
0.000001 g or 1 ug
what is range
lowest –> highest
what balance has largest range
mechanical balance
what is tolerance
acceptable performance when calibrated
what is buoyancy
upward force exerted on an object
what are the types of error
random, gross, systematic
what is gross error
human error, calculation problems
what is systematic error
reproducible, either + or -, possible to detect and correct, why blanks are imp
what is random error
not reproducible, always present, + or -, follow a guassian distribution, cant correct
what do calibration curves do
measure how an instrument responds to analyte
ways to describe method
linearity, specificity, robustness, sensitivity
specificity
chromatography, can method distinguish analyte from other things in sample
robustness
how resistant is method to small changes, temp or humidity
sensitivty
how low can you go,limited by “noise”
linearity
r2
explain how an analytical balance works
- analyte is put on pan which moves the pan down and the wire up and trips null sensor
- when sensor is tripped, the current is sent to magnet through circuit
- current strengthens magnet
- wire is pulled down until sensor is no longer tripped
- amount of current measured through precision register
- current gets converted to digital by ADC
- digital signal gets displayed on readout
is number is below LOQ what does that mean
too close to noise and cant quantify it
