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Expendable ampoules for oxygen determination
Marine Chemistry, 1 (1973) 323-327 © Elsevier Scientific Publishing Company, Amsterdam-Printed in The Netherlands
Short Communication
EXPENDABLE AMPOULES FOR OXYGEN DETERMINATION
BERTIL ()STROM
Fishery Board of Sweden, Institute of Marine Research, Gfteborg (Sweden) (Accepted for publication April 26, 1973)
ABSTRACT Ostrfm, B., 1973. Expendable ampoules for oxygen determination. Mar. Chem., 1 : 323--327. A new technique for adding Winkler reagents to water samples at sea has been developed. Expendable ampoules containing the reagents replace syringes or pipettes. The main features of the ampoules axe simpler handling and safer sampling with preserved accuracy.
METHODS AND RESULTS
The Winkler method is the most commonly used for determining the content of dissolved oxygen gas in water samples. The oxygen in the sample is tied up by the two reagents, manganese sulphate and alkaline sodium iodide-sodium azide solution. The composition of the two Winkler reagents used by the Fishery Board of Sweden for oxygen determination in ocean water is given in Table I. Pipettes or dosage syringes were previously used to add these reagents. The glass pipettes have obvious disadvantages. There is the risk of drawing the reagents accidentally into the mouth and they break easily when used at sea. The commonly used syringes showed a new drawback during a project of water sampling carried out with the aid of the Coast Guard patrol boats. The sampling was then performed by untrained personnel and it became obvious that the necessary removal of air bubbles from the syringes presented a serious hazard. The alkaline sodium iodidesodium azide solution is caustic and presents a risk, especially to the eyes. A new method for adding reagents through the cutting and emptying of ampoules was then tested. The ampoules are 12-cm-long plastic tubes with sealed ends, each containing 1 ml of reagent, and are manufactured by P. H. Tamm Laboratorier AB, Uppsala, Sweden. The manganese sulphate has a pink colour which might serve as a natural colour marking. This colour is, however, too weak to be visible in such a small volume; the manganese sulphate ampoules are therefore painted with a pink coating on the outside. The handling of
3 24
BERTIL OSTROM
TABLEI NaOH NaI NaN~ MnSO4(1 H20)
320 600 10 500
alkaline sodium iodide-sodium azide solution manganese sulphate solution
The figures give grams per liter solution in distilled water. ampoules is very simple. Take one colourless and one pink ampoule, cut one end of each and put the cut ends down into the sample water. Then cut the other ends and slowly raise the ampoules while the reagents are being introduced into the sample. For cutting the ampoules we use nail-scissors or scissors of stainless steel. Different types o f tongs can also be used. The photographs in F i g . I A - D show how the reagents are added to a sample in a Winkler bottle by using expendable ampoules. The results from the latest comparison between samples where the reagents were added TABLE II Sample No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Reagents added by syringes S
Reagents added by expendable ampoules A
S-A
4.79 4.79 4.78 4.78 4.78 4.78 1.92 1.94 1.95 8.77 8.73 8.70 4.74 4.71 4.74 4.74 4.72 4.98 4.73 2.76 2.77 2.76 8.97 8.97
4.78 4.78 4.77 4.77 4.75 4.77 1.90 1.88 1.93 8.79 8.75 8.72 4.70 4.69 4.73 4.73 4.70 4.69 4.68 2.72 2.77 2.77 9.04 8.97
O.01 0.01 0.01 0.01 0.03 0.01 0.02 0.06 0.02 0.02 -0.02 -0.02 0.04 0.02 0.01 0.01 0.02 over-titration 0.05 0.04 0.00 -0.01 -0.07 0.00
Figures give oxygen gas content in ml/l.
Difference
EXPENDABLE AMPOULES FOR OXYGEN DETERMINATION
Fig.l. Method of adding reagents to a sample in a Winkler bottle using expendable ampoules. A. Cut one end. B. Insert. C. Cut other end. D. Pull out.
325
326
Fig.lC (for legend see p.325).
Fig.lD (for legend see p.325).
BERTIL ()STROM
EXPENDABLE AMPOULES FOR OXYGEN DETERMINATION
327
from ampoules and from syringes are presented in Table II. The comparison was performed in the laboratory in order to assure that no systematic error was introduced by the use o f ampoules. For the laboratory test the samples were siphoned from an open tank. Sea water was used and in order to get different oxygen contents, oxygen was removed from the tank by 'stripping" with nitrogen gas. (Analysis performed Feb. 9 - 1 0 1972.) Another comparison was made by sampling water for oxygen determination at a station 5 n.m. W Vinga in Kattegatt on Feb. 18, 1972. The results are shown in Table III. The differences are for the most part within the analytical accuracy. The expendable ampoules for oxygen determination have proved to be comparable in every way to the syringes used previously. They are now used for oxygen sampling performed by the Swedish Coast Guard, under the administration of the Fishery Board o f Sweden. The use of expendable ampoules has led to safer and faster sampling with preserved accuracy. TABLE III Sample No.
1 2 3 4 5 6 7 8 9 10
Depth (m)
0 5 10 20 30 40 50 60 70 80
Reagents added by syringes
Difference
S
Reagents added by expendable ampoules A
9.48 9.42 8.68 6.88 6.78 6.75 6.48 6.49 6.17 6.20
9.43 9.41 8.46 6.87 6.81 6.68 6.52 6.47 6.18 6.20
0.05 0.01 0.22 0.01 -0.03 0.07 -0.04 0.02 0.01 0.00
The figures in the table give dissolved oxygen content in ml/1.
S-A
Short Communication
EXPENDABLE AMPOULES FOR OXYGEN DETERMINATION
BERTIL ()STROM
Fishery Board of Sweden, Institute of Marine Research, Gfteborg (Sweden) (Accepted for publication April 26, 1973)
ABSTRACT Ostrfm, B., 1973. Expendable ampoules for oxygen determination. Mar. Chem., 1 : 323--327. A new technique for adding Winkler reagents to water samples at sea has been developed. Expendable ampoules containing the reagents replace syringes or pipettes. The main features of the ampoules axe simpler handling and safer sampling with preserved accuracy.
METHODS AND RESULTS
The Winkler method is the most commonly used for determining the content of dissolved oxygen gas in water samples. The oxygen in the sample is tied up by the two reagents, manganese sulphate and alkaline sodium iodide-sodium azide solution. The composition of the two Winkler reagents used by the Fishery Board of Sweden for oxygen determination in ocean water is given in Table I. Pipettes or dosage syringes were previously used to add these reagents. The glass pipettes have obvious disadvantages. There is the risk of drawing the reagents accidentally into the mouth and they break easily when used at sea. The commonly used syringes showed a new drawback during a project of water sampling carried out with the aid of the Coast Guard patrol boats. The sampling was then performed by untrained personnel and it became obvious that the necessary removal of air bubbles from the syringes presented a serious hazard. The alkaline sodium iodidesodium azide solution is caustic and presents a risk, especially to the eyes. A new method for adding reagents through the cutting and emptying of ampoules was then tested. The ampoules are 12-cm-long plastic tubes with sealed ends, each containing 1 ml of reagent, and are manufactured by P. H. Tamm Laboratorier AB, Uppsala, Sweden. The manganese sulphate has a pink colour which might serve as a natural colour marking. This colour is, however, too weak to be visible in such a small volume; the manganese sulphate ampoules are therefore painted with a pink coating on the outside. The handling of
3 24
BERTIL OSTROM
TABLEI NaOH NaI NaN~ MnSO4(1 H20)
320 600 10 500
alkaline sodium iodide-sodium azide solution manganese sulphate solution
The figures give grams per liter solution in distilled water. ampoules is very simple. Take one colourless and one pink ampoule, cut one end of each and put the cut ends down into the sample water. Then cut the other ends and slowly raise the ampoules while the reagents are being introduced into the sample. For cutting the ampoules we use nail-scissors or scissors of stainless steel. Different types o f tongs can also be used. The photographs in F i g . I A - D show how the reagents are added to a sample in a Winkler bottle by using expendable ampoules. The results from the latest comparison between samples where the reagents were added TABLE II Sample No.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Reagents added by syringes S
Reagents added by expendable ampoules A
S-A
4.79 4.79 4.78 4.78 4.78 4.78 1.92 1.94 1.95 8.77 8.73 8.70 4.74 4.71 4.74 4.74 4.72 4.98 4.73 2.76 2.77 2.76 8.97 8.97
4.78 4.78 4.77 4.77 4.75 4.77 1.90 1.88 1.93 8.79 8.75 8.72 4.70 4.69 4.73 4.73 4.70 4.69 4.68 2.72 2.77 2.77 9.04 8.97
O.01 0.01 0.01 0.01 0.03 0.01 0.02 0.06 0.02 0.02 -0.02 -0.02 0.04 0.02 0.01 0.01 0.02 over-titration 0.05 0.04 0.00 -0.01 -0.07 0.00
Figures give oxygen gas content in ml/l.
Difference
EXPENDABLE AMPOULES FOR OXYGEN DETERMINATION
Fig.l. Method of adding reagents to a sample in a Winkler bottle using expendable ampoules. A. Cut one end. B. Insert. C. Cut other end. D. Pull out.
325
326
Fig.lC (for legend see p.325).
Fig.lD (for legend see p.325).
BERTIL ()STROM
EXPENDABLE AMPOULES FOR OXYGEN DETERMINATION
327
from ampoules and from syringes are presented in Table II. The comparison was performed in the laboratory in order to assure that no systematic error was introduced by the use o f ampoules. For the laboratory test the samples were siphoned from an open tank. Sea water was used and in order to get different oxygen contents, oxygen was removed from the tank by 'stripping" with nitrogen gas. (Analysis performed Feb. 9 - 1 0 1972.) Another comparison was made by sampling water for oxygen determination at a station 5 n.m. W Vinga in Kattegatt on Feb. 18, 1972. The results are shown in Table III. The differences are for the most part within the analytical accuracy. The expendable ampoules for oxygen determination have proved to be comparable in every way to the syringes used previously. They are now used for oxygen sampling performed by the Swedish Coast Guard, under the administration of the Fishery Board o f Sweden. The use of expendable ampoules has led to safer and faster sampling with preserved accuracy. TABLE III Sample No.
1 2 3 4 5 6 7 8 9 10
Depth (m)
0 5 10 20 30 40 50 60 70 80
Reagents added by syringes
Difference
S
Reagents added by expendable ampoules A
9.48 9.42 8.68 6.88 6.78 6.75 6.48 6.49 6.17 6.20
9.43 9.41 8.46 6.87 6.81 6.68 6.52 6.47 6.18 6.20
0.05 0.01 0.22 0.01 -0.03 0.07 -0.04 0.02 0.01 0.00
The figures in the table give dissolved oxygen content in ml/1.
S-A