14. At the time of measurements, prepare suitable working solutions of silicon (0–10000 μg Si/l) for calibration by diluting
the standard stock solution (see step 11) with ultrapure water.
15. Pipette 0.5 ml calibration solution in a plastic screw-capped
plastic bottle.
16. Pipette 10 ml 0.2 mol/l NaOH to the vial and close the cap
loosely.
17. Place in water bath at 100
C for 15 min and then cool to room
temperature.
18. Add 10 ml 0.2 mol/l HCl, close the cap, and mix by swirling.
19. Prepare analyzer for analyses according to the operation manual (see Note 4). Dilute the reagents 1:10 for analyzer.
20. Place standards in the autosampler of an analyzer or measure
the standards manually by a spectrophotometer for a calibration curve and linearity test (see Note 5).
21. For manual analyses, add 600 μl Reagent I, wait for 10 min,
and then add 600 μl each of Reagents II and III and wait for
30 min (mix gently after each addition).
22. Measure the absorbance of standards and blanks in a 1 cm
cuvette at 810 nm for a calibration curve and linearity test
(see Note 5).
23. When measuring samples, start by adding 10 ml 0.2 mol/
l NaOH and close the cap loosely.
24. Place in water bath at 100
C for 15 min and then cool to room
temperature.
25. Add 10 ml 0.2 mol/l HCl, close the cap, and mix by swirling.
26. Place samples in the autosampler of an analyzer or perform
manual analyses with a spectrophotometer. Verify proper operation of the instrument with certified reference material and
include ultrapure water blanks in the run (see Note 6).
27. For manual analyses, add 600 μl Reagent I, wait for 10 min,
and then add 600 μl each of Reagents II and III and wait for
30 min (mix gently after each addition).
28. Measure the absorbance of samples in a 1 cm cuvette at 810 nm
(if the absorbance is greater than that of the highest standard,
prepare diluted sample) and calculate the silicon concentration
by the calibration curve (see Note 7).
4 Notes
1. Glass contains silica and samples/standards should not allowed
to come into contact with glass to avoid contamination.
2. Do this very carefully as a lot of heat is produced in this process.
100
Jaana Koistinen et al.
the standard stock solution (see step 11) with ultrapure water.
15. Pipette 0.5 ml calibration solution in a plastic screw-capped
plastic bottle.
16. Pipette 10 ml 0.2 mol/l NaOH to the vial and close the cap
loosely.
17. Place in water bath at 100
C for 15 min and then cool to room
temperature.
18. Add 10 ml 0.2 mol/l HCl, close the cap, and mix by swirling.
19. Prepare analyzer for analyses according to the operation manual (see Note 4). Dilute the reagents 1:10 for analyzer.
20. Place standards in the autosampler of an analyzer or measure
the standards manually by a spectrophotometer for a calibration curve and linearity test (see Note 5).
21. For manual analyses, add 600 μl Reagent I, wait for 10 min,
and then add 600 μl each of Reagents II and III and wait for
30 min (mix gently after each addition).
22. Measure the absorbance of standards and blanks in a 1 cm
cuvette at 810 nm for a calibration curve and linearity test
(see Note 5).
23. When measuring samples, start by adding 10 ml 0.2 mol/
l NaOH and close the cap loosely.
24. Place in water bath at 100
C for 15 min and then cool to room
temperature.
25. Add 10 ml 0.2 mol/l HCl, close the cap, and mix by swirling.
26. Place samples in the autosampler of an analyzer or perform
manual analyses with a spectrophotometer. Verify proper operation of the instrument with certified reference material and
include ultrapure water blanks in the run (see Note 6).
27. For manual analyses, add 600 μl Reagent I, wait for 10 min,
and then add 600 μl each of Reagents II and III and wait for
30 min (mix gently after each addition).
28. Measure the absorbance of samples in a 1 cm cuvette at 810 nm
(if the absorbance is greater than that of the highest standard,
prepare diluted sample) and calculate the silicon concentration
by the calibration curve (see Note 7).
4 Notes
1. Glass contains silica and samples/standards should not allowed
to come into contact with glass to avoid contamination.
2. Do this very carefully as a lot of heat is produced in this process.
100
Jaana Koistinen et al.