Lecture 3: Efficiency and quantification P2 (unfinished)

Question 1

whats Quantitative analysis?

Answer 1

The analysis of a substance to determine the amounts and

proportions of its chemical constituents

Question 2

whats Qualitative analysis?

Answer 2

The analysis of a substance in order to ascertain the identity of its chemical constituents

Question 3

what signal is used for quantification?

Answer 3

detector response/signal

Question 4

Name some detector response signals?

Answer 4

• Absorbance • Peak height • Peak area

Question 5

How do you quantify?

Answer 5

Compare signal of unknown with known standards

Question 6

what are the three main methods to quantify?

Answer 6

• External standard
• Internal standard
• Standard addition

Question 7

what happens in Standard Addition?

Answer 7

quantities of the same analyte is added to the solution containing the analyte of unknown quantity.

Question 8

what is standard solution also known as?

Answer 8

spiking

Question 9

when is standard addition useful?

Answer 9

Useful if the response of the analyte is affected by the matrix

Question 10

for standard addition to work what do we assume?

Answer 10

Assume that the matrix has the same effect on the added analyte than on the analyte in solution

Question 11

whats a drawback of standard addition?

Answer 11

Requires availability of the analyte to be quantified

Question 12

what is internal standards?

Answer 12

Its when a known amount of a compound (different from the analyte) is added to the sample containing the analyte of unknown concentration prior to extraction

Question 13

what is compared when doing an internal standard?

Answer 13

Detector signal from analyte is compared to signal from standard

Question 14

whats created and used when using internal standard method?

Answer 14

calibration curve is made and used, plotts the ratio of the

analyte signal to the reference

Question 15

what snot critical in the internal standard method?

Answer 15

Injection volume not critical

Question 16

In internal standard method, the compound being added depends on the ____, but should also have what?

Answer 16

1. detector

have equal chemical properties as analyte (similar response factor)

Question 17

in internal stand method the compound being used should have what retention time ?

Answer 17

Retention time should not be the same as analyte, but close to it.

Question 18

internal standard has what 2 types of calibrations?

Answer 18

One point calibration and multi point calibration

Question 19

IS

one point calibration uses what?

Answer 19

response factor (F)

Question 20

response factor (F) equation?

Answer 20

Area of analyte signal/ Concentration of analyte = F (Area of standard signal / Concentration of standard)

Question 21

whats the differences between internal standard and standard addition methods?

Answer 21

IS: diff substance then analyse
SA: same substance as analyte
IS:Used when sample
recovery is less than 100%
or when instrumental response varies from run to run
SA:Used when the sample
matrix is unknown or complex and where it might interfere with analyte