Exam 1

Question 1

what are the steps to analyze something meaningfully?

Answer 1

1. ask a question
2. select a method
3. find your samples
4. sample preparation
5. analysis
6. interpretation
7. conclusions

Question 2

when asking a question…

Answer 2

be specific, be reasonable, think small

Question 3

when selecting a method…

Answer 3

exploit what is known, example is using uv-vis to find conc of drug

Question 4

when finding samples…

Answer 4

make sure sample taken is good representation of a whole

Question 5

when preparing samples…

Answer 5

can my method handle my sample, is conc too high or low, is it dirty, be careful

Question 6

when doing analysis…

Answer 6

actually take the data, diff for every instrument

Question 7

when interpreting…

Answer 7

does my data mean anything, what is drug conc, does it all agree

Question 8

when concluding…

Answer 8

do i trust my data enough to report out/act

Question 9

what can go wrong with analytical process?

Answer 9

complex matrix, balances, glassware

Question 10

what is a blank?

Answer 10

matrix without analyte

Question 11

what is a sample?

Answer 11

matrix and analyte

Question 12

what is analyte?

Answer 12

the drug

Question 13

what is matrix?

Answer 13

everything else

Question 14

what are the types of balances?

Answer 14

mechanical and analytical

Question 15

what is readability

Answer 15

lowest amount that balance can measure accurately

Question 16

what can mechanical balance read to

Answer 16

0.1 g

Question 17

what can analytical balance read to

Answer 17

0.001 g

Question 18

what can microanalytical balance read to

Answer 18

0.000001 g or 1 ug

Question 19

what is range

Answer 19

lowest –> highest

Question 20

what balance has largest range

Answer 20

mechanical balance

Question 21

what is tolerance

Answer 21

acceptable performance when calibrated

Question 22

what is buoyancy

Answer 22

upward force exerted on an object

Question 23

what are the types of error

Answer 23

random, gross, systematic

Question 24

what is gross error

Answer 24

human error, calculation problems

Question 25

what is systematic error

Answer 25

reproducible, either + or -, possible to detect and correct, why blanks are imp

Question 26

what is random error

Answer 26

not reproducible, always present, + or -, follow a guassian distribution, cant correct

Question 27

what do calibration curves do

Answer 27

measure how an instrument responds to analyte

Question 28

ways to describe method

Answer 28

linearity, specificity, robustness, sensitivity

Question 29

specificity

Answer 29

chromatography, can method distinguish analyte from other things in sample

Question 30

robustness

Answer 30

how resistant is method to small changes, temp or humidity

Question 31

sensitivty

Answer 31

how low can you go,limited by "noise"

Question 32

linearity

Answer 32

r2

Question 33

explain how an analytical balance works

Answer 33

1. analyte is put on pan which moves the pan down and the wire up and trips null sensor 2. when sensor is tripped, the current is sent to magnet through circuit 3. current strengthens magnet 4. wire is pulled down until sensor is no longer tripped 5. amount of current measured through precision register 6. current gets converted to digital by ADC 7. digital signal gets displayed on readout

Question 34

is number is below LOQ what does that mean

Answer 34

too close to noise and cant quantify it