The measured area of the analyte in the environmental sample is converted
to absolute amount of analyte in the 1 μL aliquot by applying the calibration
function. Thereafter, it is multiplied with 50 to obtain the total extracted
amount of the analyte:
Concentration of analyte in 1 μL ¼
5:57 þ 0:0831
0:2508
¼ 22:54 ng=μL
Total extracted amount of analyte ¼ 22:54 ng=μL Á 50 μL ¼ 1122:5 ng
% 1120 ng
A comparison with the blank value showed a neglectable contribution by
laboratory contamination (at around 0.15 ng), hence the detected value is
assumed to be reliable.
The total amount of the analyte already corrected by the surrogate standard
is now normalized to the sample amount by division with 9.5 g (see above) to
obtain the concentration in soil:
Concentration of analyte in soil sample ¼ 1120 ng=9:5 g soil ¼ 117:9 ng=g
% 118 ng=g
Finally, this value is corrected by the recovery rate of approx. 83% resulting
in the final value of 142.2 ng/g. Since the recovery experiments revealed a rel.
deviation of around 10%, the result will be given as 140 ng/g.
General Note
Quantitative analysis needs a quality control by checking the sensitivity as
well as the precision. This implies additional measurements and calculations
but are essential for obtaining reliable quantitative data.
134
6 Analytical Quality Control
to absolute amount of analyte in the 1 μL aliquot by applying the calibration
function. Thereafter, it is multiplied with 50 to obtain the total extracted
amount of the analyte:
Concentration of analyte in 1 μL ¼
5:57 þ 0:0831
0:2508
¼ 22:54 ng=μL
Total extracted amount of analyte ¼ 22:54 ng=μL Á 50 μL ¼ 1122:5 ng
% 1120 ng
A comparison with the blank value showed a neglectable contribution by
laboratory contamination (at around 0.15 ng), hence the detected value is
assumed to be reliable.
The total amount of the analyte already corrected by the surrogate standard
is now normalized to the sample amount by division with 9.5 g (see above) to
obtain the concentration in soil:
Concentration of analyte in soil sample ¼ 1120 ng=9:5 g soil ¼ 117:9 ng=g
% 118 ng=g
Finally, this value is corrected by the recovery rate of approx. 83% resulting
in the final value of 142.2 ng/g. Since the recovery experiments revealed a rel.
deviation of around 10%, the result will be given as 140 ng/g.
General Note
Quantitative analysis needs a quality control by checking the sensitivity as
well as the precision. This implies additional measurements and calculations
but are essential for obtaining reliable quantitative data.
134
6 Analytical Quality Control