glossary of common terms

Question 1

accuracy

Answer 1

closeness of the experimental result to the accepted value

Question 2

analyte

Answer 2

constituent of sample targeted for analysis

Question 3

assay

Answer 3

accurate determination of valuable or active constituent e.g. of ore or pharmaceutical product

Question 4

background

Answer 4

proportion of measurement that arises from sources other than the analyte

Question 5

blank

Answer 5

measurement in which the sample is replaced by a simulated matrix to correct for background effects

Question 6

calibration

Answer 6

procedure in which the response of the instrument is related to mass, volume or concentration of analyte. achieved by first measuring a standard of know composition or known amount of analyte

Question 7

calibration curves

Answer 7

plots of instrument response versus varying amount of analyte

Question 8

concentration

Answer 8

the amount of analyte present in a given volume or mass of sample

Question 9

constituent

Answer 9

a component of a sample. broadly classified as:
major >10% 
minor 0.01 to 10% 
trace 0.0001 to 0.01% (i.e. 1-100 ppm)
ultratrace <1ppm

Question 10

detection limit

Answer 10

the lowest concentration or amount of analyte that can be detected by a given analytical procedure

Question 11

determination

Answer 11

a quantitative measure of an analyte with an accuracy of >10%

Question 12

estimation

Answer 12

a semi-quantitative measure of the amount of analyte present in a sample where accuracy is <10%

Question 13

interference

Answer 13

an effect which alters or obscures the response of the analyte

Question 14

internal standard

Answer 14

a compound or element added to all calibration standards and samples in a constant known amount

Question 15

matrix

Answer 15

the remainder of the sample of which the analyte is a constituent

Question 16

precision

Answer 16

random or indeterminate error associate with measurement. represented statistically as standard deviation

Question 17

protocol or procedure

Answer 17

the practical steps of an analysis

Question 18

sample

Answer 18

a substance or proportion of a substance about which analytical information is required. must accurately represent the bulk of the material analysed

Question 19

sensitivity

Answer 19

i) response due to small variation in the amount of the analyte being determined = slope of calibration curve
ii) the ability of a method to detect or determine an anayte

Question 20

standard

Answer 20

a pure substance of known property, e.g. concentration, which is used to calibrate an analytical method or instrument

Question 21

validation of methods

Answer 21

analysis of standards to ensure that results produced by a method are of the required accuracy. it is essential that standards have similar analyte contents and matrix to that of the sample