determination of total phosphorus using sodium persulfate › fileadmin › tvrl › files ›...

Professor: Jian Ma

Research assistant: Yuan Yuan and Shu Wang

Students: Fangrui Liu and Manuela Stierna Fernandez

International Summer Water Resources Research SchoolDept. of

Water Resources Engineering, Lund University

Determination of Total Phosphorus

using Sodium Persulfate

Manuela Stierna Fernandez

7/17/2015

Figure 1 From right Wang Shu, Yuan Yuan , Fangrui Liu and Manuela Stierna Fernandez

VVRF05 Manuela Stierna Fernandez

International Water Summer Resources Research School 2015

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1. Abstract

This project focuses on the determination of Total Phosphorus (TP) using sodium persulfate

as the oxidative reagent. The determination of TP is an important issue for environmental

science and engineering as it is directly related to eutrophication and algal bloom. Potassium

persulfate is the oxidative regent used in the current method for the determination of TP.

However sodium persulfate is more soluble and less expensive than potassium persulfate and

therefore it has been tested as the substitute of potassium persulfate in this project.

In order to derive this hypothesis the concentration of TP was determined for 30 different

samples using both reagents. Both phosphorus samples and water samples were studied

coming from different locations, time periods and temperatures. A COD digester was used to

convert the TP to inorganic phosphorus. Then this inorganic phosphorus was transformed

using the phosphomolybdenum blue method into heteropoly compound. The absorbance of

this compound was measured using a spectrophotometer. Finally comparing the results in a

calibration curve the concentration of TP was determined. All results were summarized in a

1:1 diagram comparing sodium persulfate and potassium persulfate. The accuracy of this

diagram was calculated using a student t- test and determining the relative standard deviation.

The results using both reagents had non-significant difference. Therefore the conclusion was

that the determination of TP could be performed using sodium persulfate as the oxidative

reagent, in other words the hypothesis was correct. Nevertheless these results would have

been more accurate if more data would have been studied.

2. Keywords Total Phosphorus, sodium persulfate, potassium persulfate, phosphomolybdenum blue

method, eutrophication and algal bloom.



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Table of Contents

1. Abstract .............................................................................................................................. 1

2. Keywords ........................................................................................................................... 1

3. Introduction and Hypothesis .............................................................................................. 3

4. Methodology and Theory ................................................................................................... 3

4.1 Apparatus ..................................................................................................................... 3

4.1.1. Phosphomolybdenum blue method .......................................................................... 3

4.1.2. Digestion .................................................................................................................. 4

4.1.3. Spectrophotometer ................................................................................................... 4

4.1.4Calibration curve ........................................................................................................ 5

4.1.5 Test of Significance ................................................................................................... 5

4.1.6 Relative standard deviation (RSD) ............................................................................ 6

4.2 Reagents and standards .................................................................................................... 7

4.2.1. Phosphorus ............................................................................................................... 7

4.2.2. Potassium persulfate ................................................................................................. 7

4.2.3. Sodium persulfate ..................................................................................................... 8

4.3 Procedure ..................................................................................................................... 8

5 Results .............................................................................................................................. 10

5.1 Phosphorus samples ................................................................................................... 10

5.2 Water samples ............................................................................................................ 10

5.3 Calibration curves inclinations .................................................................................. 11

5.4 Relation between TP concentrations determined using sodium and potassium persulfate.

.............................................................................................................................................. 12

5.5 Test of Significance ........................................................................................................ 12

5.6 Relative standard deviation (RSD) ................................................................................. 13

6 Discussion ........................................................................................................................ 13

7 Conclusion ........................................................................................................................ 15

7.1Future recommendations ................................................................................................. 15

8. Acknowledgements .............................................................................................................. 16

9. References ............................................................................................................................ 17

10. Appendix ............................................................................................................................ 18



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3. Introduction and Hypothesis

Eutrophication and algal bloom are both worldwide problems. These issues are related to the

concentration of Total Phosphorus (TP) present in both terrestrial and aquatic environments.

Therefore the determination of TP is an important analysis that can be performed for several

reasons: water pollution, biological and chemical studies and eutrophication.

The current method used for the determination of TP utilizes potassium persulfate in order to

oxidize TP to phosphate. This project was performed with the hypothesis that sodium

persulfate could be used as the oxidative reagent in the determination of TP. This hypothesis

was formulated after comprehensive evaluation of sodium persulfate. If the hypothesis is

correct the determination of TP could be performed more convenient and cheaper since

sodium persulfate is more soluble and less expensive than potassium persulfate.

The determination of TP was performed with the classical phosphomolybdenum blue method

and the usage of a calibration curve. ACOD digester utilizing conventional heating was used

in order to convert the TP to inorganic phosphorus. This chemical process was necessary in

order to determine the absorbance of the phosphorus in a spectrophotometer. The accuracy of

the results was determined with the test of significance and the relative standard deviation

(RSD).

4. Methodology and Theory

4.1 Apparatus

4.1.1. Phosphomolybdenum blue method

The concentration of TP was determined with the phosphomolybdenum blue method, which is

the most widely used. The chemistry is based on the reaction of orthophosphate with

molybdenum under acidic condition to form 12-molybdophosphoric acid, which is usually

then reduced to a blue heteropoly compound (Burton, 1973). The blue heteropoly compound

is further used to determine the absorbance of the TP present in a sample utilizing a

spectrophotometer.

Ascorbic acid, C6H8O6, was the reductant used to reduce12-molybdophosphoric acid. The

following acid has been shown to possess both theoretical and practical advantages in the

presence of antimonyl ions according to Burton, 1973. Ammonium molybdate mixture was

then used to create the blue color in the sample. In order to reach a minimum reaction time



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the molybdate mixture had to be higher than 25% of the stock mixed reagent and the ascorbic

acid concentration had to be higher than 25 g/L as stated by Ma et.al, 2014.

4.1.2. Digestion

In order to determine the absorbance of TP a COD digester was utilized. This apparatus

breakdowns the organic phosphorus and convert it to inorganic phosphorus, most likely

orthophosphate. The digestion reaction followed by the phosphomolybdenum blue method is

determined by the following equation (Mather et.al, 1998):

𝑃𝑂3− + 12𝑀𝑜𝑂4

2− → 𝑃𝑀𝑜12𝑂403− + 12𝑂2− → 𝑃𝑆𝑏2𝑀𝑜𝑂10𝑂40

3− 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 1

The conventional heating was the type of COD digester used

for this experiment. The digestion was therefore obtained with

high pressure inside the digestion tubes which increased with

higher temperature. The temperature in the digestion was 150

℃ and the reaction time was 15 minutes.

A disadvantage with the conventional heating is that

precipitation of salts may occur which causes problems when

analyzing phosphorus with the phosphomolybdenum blue

method, as studied by Huang et.al, 2008.

4.1.3. Spectrophotometer

A spectrophotometer was used to determine the absorption of the diluted inorganic

phosphorus which is related to its concentration. Since the spectrophotometer only analyzes

the wavelengths of inorganic phosphorus digestion was needed to convert TP to inorganic

phosphorus.

This apparatus is composed by a spectrometer

which produces light of any selected color

dependent on its wavelength and a photometer

which measures the intensity of the light. This

reaction is described by Beers law as following:

𝐼

𝐼0= 10 ∗ 𝑘 ∗ 𝑐 = 𝑇 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 2

Figure 2 COD digester used during the

laboratory experiments

Figure 3 Spectrophotometer used during the laboratory

experiments



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I0=the intensity of the transmitted light

I= the intensity of the transmitted light when the colored compound is added

c = the concentration of the colored compound, phosphorus

k= constant relate to the distance the light passes through the solution

T = the transmittance of the solution.

The Logarithmic equation for the above equation studies the optical density which is

proportional to the phosphorus concentration and is measured in absorbance units:

− 𝑙𝑜𝑔(𝑇) =𝑙𝑜𝑔(1)

𝑇= 𝑘𝑐 = 𝑜𝑝𝑡𝑖𝑐𝑎𝑙 𝑑𝑒𝑛𝑠𝑖𝑡𝑦 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 3

The absorbance used in this research was 700 nm with a 1 cm cuvette under the condition of

wavelength 1 cm using water as reference solution.

Since the colorimetric method used was the phosphomolybdenum blue method the samples

were blue. Therefore the wavelength for the red color was the one studied by the

spectrophotometer which was proportional to the concentration of the inorganic phosphorus

present in the analyzed sample.

4.1.4Calibration curve

A calibration curve was calculated in order to determine the relation between different

concentration of TP and its absorbance. The phosphomolybdenum blue method and a

spectrophotometer were used to determine the absorbance of the known concentrations. The

results were then linearized and the accuracy was determined by R2 which had to be higher

than 0.99.

The purpose of the calibration curve was to

determine the final concentration of the TP present

in the different samples by knowing its absorbance.

To achieve accurate results a new calibration curve

was performed for each laboratory experiment.

4.1.5 Test of Significance

The Student t- test was utilized to analyze the difference between the TP concentration results

obtained using potassium persulfate or sodium persulfate. The hypothesis was that both

methods were identical. With other words we compared the results of a new analytical method

with an accepted method in order to determine its accuracy.

Figure 4 Calibration cuvettes used during the

laboratory experiments



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The calculations were based on a statistical t- value that was compared with a tabulated value

for the given results. If the t-value was lower than the tabulated value the methods did not

have any significant error and were therefore identical.

The equation used to calculate the t-value when comparing the means of two methods was the

following (Garry et.al, 2014):

𝑡𝑐𝑎𝑙𝑐 =𝑥1̅̅ ̅ − 𝑥2̅̅ ̅

𝑠𝑝

√𝑁1𝑁2

𝑁1 + 𝑁2 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 4

Where 𝑥1̅̅ ̅ and 𝑥2̅̅ ̅ were the means of the results, N1 and N2 were the number of samples

measured in each method and sp was the pooled standard deviation.

The pooled standard deviation, sp, was determined with the following equation (Garry et.al,

2014):

𝑠𝑝 = √∑(𝑥𝑖 − 𝑥1)

2+ ∑(𝑥𝑖2 − 𝑥2)

2+ ⋯ + ∑(𝑥𝑖𝑘 − 𝑥𝑘)

2

𝑁 − 𝑘 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 5

Where x1,x2,xk were the means of each set of analysis, xi1,xi2,xik were the individual values of

each set and N was the total value of measurements.

The student t- test was performed in Excel with a 95% confident. In Excel, to acquire a non-

significant difference in the result the tcalc had to be lower than the critical two tailed value.

4.1.6 Relative standard deviation (RSD)

During the laboratory experiments each phosphorus sample and water sample was analyzed

three times. Therefore the relative standard deviation was calculated in order to study the

probable error of the results. The equation used was the following:

𝑅𝑆𝐷 =𝑠

𝑥∗ 100 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 6

Where x was the mean of the three results and s was the estimated standard deviation

calculated with the below equation:



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𝑠 = √∑(𝑥𝑖 − 𝑥)

2

𝑁 − 1 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 7

4.2 Reagents and standards

4.2.1. Phosphorus

Phosphorus is an important nutrient for living organisms in both terrestrial and aquatic

environments. It could be presented as the limiting nutrient in marine environment

compromising photosynthesis. Nevertheless phosphorus can be an excessive nutrient, related

to water pollution, causing eutrophication and algal bloom.

Phosphorus compounds present in natural water are classified into four groups according to

Mather et.al, 1998. These compounds may contain PO43−, P-O-P, C-O-P and C-P bonds:

Orthophosphates

Condensed Phosphates

Organically bound Phosphates

Phosphonates

The majority of the inorganic phosphorus is dominated by ortophosphoric acid which has an

important effect on the phosphorus cycling. This effect has been highly studied in many

papers.

On the other hand, papers studying the role of organic phosphorus in aquatic biogeochemical

and ecological processes are far less advanced as stated by Baldwin, 2013.However it has

been studied that organic phosphorus is an important pool of phosphorus in many aquatic

environments and its effect on the phosphorus cycling globally is also significant. There are

seven types of organic phosphorus as studied by Worsfold et.al, 2008: nucleic acids,

phospholipids, inositol phosphates, phosphoamides, phosphoproteins, sugar phosphates,

amino phosphoric acids and organic condensed Phosphorus species.

4.2.2. Potassium persulfate

Potassium persulfate is a white solid inorganic compound with the chemical formulaK2 S2O8.

It has been extensively used for the determination of TP as it has proved suitable for a wide

range of samples as stated by Burton, 1973. On the other hand potassium persulfate has lower

solubility and a higher price than sodium persulfate. Therefore in this experiment sodium

persulfate has also been used for the determination of TP concentration.



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4.2.3. Sodium persulfate

Sodium persulfate is an inorganic compound with the chemical formula Na2S2O3. It is a white

solid with a higher solubility and a lower price compared to potassium persulfate. It has not

been used before for the determination of TP.

4.3 Procedure

The aim of this experiment was to compare the concentration of TP present in different

phosphorus and water samples using sodium persulfate and potassium persulfate. The

following procedure was performed for 30 samples in order to reach accurate results. The

different phosphorus and water samples are presented in table 2 and 3 respectively.

1. During each laboratory day a new calibration curve was performed for several

concentrations of phosphorus. The concentrations were diluted into 25 mL distillated water.

Then 0.5 mL of ascorbic acid and 1 mL of ammonium molybdate mixture were added to

create a blue color to the diluted volumes. As the color was blue the spectrophotometer

studied the absorbance of the red light. The absorbance was calculated with a 1 cm cuvette

under the condition of wavelength 1 cm, 700 nm, and using distillated water as reference

solution.

An example of a calibration curve calculated is presented below:

Table 1Example Calibration curve for phosphorus concentrations

Concentration(𝛍mol/L) 0 1 2 4 8 16 32

Absorbance 0 0.025 0.05 0.086 0.155 0.306 0.635

Figure 5 Example Calibration curve

y = 0,0196x + 0,0035 R² = 0,9992

0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

0 5 10 15 20 25 30 35

Ab

sorb

ance

(A

)

Concentration TP (umol/L)



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2. The digestion was then performed to transform the TP, present in the samples, into

inorganic phosphorus. When studying phosphorus samples 0.5 mL of three phosphorus types

were mixed three times with 2 mL sodium persulfate and three times with 2 mL potassium

persulfate, in total 18 tubes. When using water samples, 5 mL of two samples were mixed

three times with 5 mL sodium persulfate and three times with 5 mL potassium persulfate, in

total 12 tubes.

These tubes were then digested for 15 min in a COD digester with a temperature of 150 ℃.

After taking them out and cool, 2.5 mL of each solution was transferred to a 25 mL

colorimetric tube.

Then 0.5 mL of ascorbic acid and 1 mL of ammonium molybdate were added to each tube

and the absorbance was calculated with a 1 cm cuvette under the condition of wavelength 1

cm, 700 nm, and using distillated water as reference solution.

3. After calculating the absorbance, the concentration of the TP was calculated using the

equation of the calibration curve. This procedure was performed assuming that all TP had

transformed to inorganic phosphorus during the digestion.

Example calibration curve equation: y = 0.0196x + 0.0035

y= absorbance of the TP using potassium persulfate/ sodium persulfate.

x=concentration of the TP using potassium persulfate/ sodium persulfate

4. Different sources of error appear during the experiment:

The digestion tubes were not perfectly closed when entering the COD digester. As a

consequence some of the solutions had evaporated with the high temperature.

When utilizing the phosphomolybdenum blue method the absorbance was too fast

determined even though the blue color did not totally develop.



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5 Results

5.1 Phosphorus samples

The following table studies fifteen different phosphorus samples analyzed during the

laboratory experiment. Each phosphorus sample is presented with its name, chemical formula

and concentration.

Table 2 Phosphorus samples information

Phosphorus samples

Sodium Phosphonoformate hexahydrate

CH12Na2O11P ,0.305 g/L

Riboflavin-5-phosphate sodium salt dehydrate

0.45 g/L

Phenyl phosphate disodium salt dehydrate

C6H5Na2O4P, 1mmol/L

Adenosine-5-monophosphoric acid

C10H14N5O7P 980 mol/L

Sodium peryphosphate Na4P2O7, 0.05g/L Sodium trypolyphosphate Na5P3O10 946 mol/L

2-deoxyadenosine 5-dihydrogen phosphate

C10H14N5O6P, 0.153 g/L

Glycerol phosphate disodium salt

hydrate C3H7Na2O6P, 0.212 g/L

Glycerophosphoric acid C3H9O6P 0.66 g/L 4-nitrophonyl phosphate disodium salt hexahydrate

O2NC6H4OP(O)(ONa)2, 0.342 g/L

Phosphonoacetic acid C2H5O5P, 0.132 g/L 5-ciuanylic acid, 0.410 g/L

α-sodium Glycerophosphate C3H7Na2O6P ,0.216

g/L

Beta-D-glucose 6-phosphate sodium salt anhydrous

C6H12NaO9P, 0.268 g/L

Adenosine triphosphate C10H16N5O13P3, 1395

mol/L

5.2 Water samples

Table 3 shows fifteen water samples analyzed during the laboratory experiments. These

samples were taken from different locations (lake, river water, industry, irrigation, seawater

and tap water) at different time and temperature. All samples were located in the Xiamen area.



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Table 3 Water samples information

Water samples

Lake, Xiamen University

River water

M5 24.8℃

2015/06/27

River water

M6 24.5℃

2015/06/27

River water

M7 25.5℃

2015/06/27

River water M8

25.1℃

2015/06/27

River water

M9 26℃

2015/06/27

River water

M11

25.1℃

2015/06/27

Industry pesticide filtered Xiamen 0,5 ml Industry pesticide filtered Xiamen 2 ml

Irrigation water, Xiamen University

Coastal Area in Xiamen S5 Coastal Area in Xiamen S6 Coastal Area in Xiamen S4

Tap water 1 Tap water 2

5.3 Calibration curves inclinations

The diagram below presents the inclinations of nine different calibration curves performed

during nine laboratory days. The lowest inclination was 0.138 and the highest was 0.197.

With other words, the largest difference between the inclinations of the different calibration

curves was 0.059.

Figure 6 Calibrations curves in different days.

0

0,005

0,01

0,015

0,02

1 2 3 4 5 6 7 8 9

Incl

inat

ion

Daily Calibration Curve

Calibration curve incline

Calibration curve incline



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5.4 Relation between TP concentrations determined using sodium and potassium

persulfate.

The following diagram presents the TP concentration presented in the phosphorus samples

and the water samples using sodium persulfate or potassium persulfate. These results were

presented in a 1:1 line where the TP concentrations using sodium persulfate equals the TP

concentrations using potassium persulfate.

Seven different kinds of samples were described in the legend. The lowest TP concentration

was 3.13 μmol/L and the highest concentration was 2192 μmol/L. All the data for the

following diagram is presented in table 7 and 8 located in the appendix.

Figure 7 Relation between TP concentrations determined using sodium and potassium persulfate.

5.5 Test of Significance

Table 4 and 5 shows the t statistic and the t critical two-tailed value obtained when

performing the test of significance for the phosphorus samples and the water samples. The

calculations were performed in excel.

0

500

1000

1500

2000

2500

3000

3500

0 500 1000 1500 2000 2500 3000 3500

Tota

l Ph

osp

ho

rus

con

cen

trat

ion

usi

ng

sod

ium

p

ersu

lfat

e (u

mo

l/L)

Total Phosphorus concentration using potassium persulfate (umol/L)

Phosphorus samples

Spring Lake

Irrigation water

River water

Industry water

Costal area water

Tap water

Linear (K=Na 1:1)



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Table 4 T- test for the phosphorus samples

Test of Significance for phosphorus samples

t Statistic 0.1645

t Critical two-tailed 2.04

Table 5 T-test for the water samples

5.6 Relative standard deviation (RSD)

The relative standard deviation calculations are presented in table 6 situated in the appendix.

In order to calculate the RSD the standard deviation and the average were calculated for all

concentrations of TP analyzed during the laboratory experiments. The calculations were

performed in excel.

6 Discussion

The aim of this paper was to determine if the determination of TP could be performed using

sodium persulfate as the oxidative reagent instead of potassium persulfate. In order to derive

this hypothesis the concentration of TP was determined for 30 different samples using both

sodium persulfate and potassium persulfate.

The TP concentrations from the 30 samples were gather in Figure 7 around a 1:1 line where

the results using sodium persulfate equals the one using potassium persulfate. When

analyzing this Figure we can conclude that the determination of TP was very similar using the

two different oxidative reagents as nearly all concentrations were situated near or in the 1:1

line.

This statement was proved with the student t-test performed for both the phosphorus samples

and the water samples. The results were presented in table 4 and 5. In order to achieve a non-

significant difference the t-statistic had to be lower than the t-critical two tailed. This was the

Test of Significance for water samples

t Statistic 0.007972

t Critical two-tailed 2.04



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case for both the phosphorus samples where the t-statistic was 12 times lower than the t-

critical two tailed and for the water samples were the t-statistic was 255 times lower than the

t-critical two tailed. In other words, this proves that there was no significant different in the

determination of TP using sodium persulfate instead of potassium persulfate.

On the other hand when looking at Table 7 and 8, located in the appendix, we can study that

for some samples there was a higher difference between the TP concentrations calculated with

sodium persulfate and the ones calculated with potassium persulfate. The reason for this

difference could be that after digestion all the chemical compound was not pore down in the

phosphomolybdenum blue cuvettes. As a consequence the absorbance studied for these

samples was lower than expected. Another reason could be that sodium persulfate is not an

accurate oxidative reagent for all types of samples and therefore it has not been used in earlier

studies.

Since each sample was performed three times the RSD was calculated for each three samples.

These calculations were done in order to be confident about the accuracy of the results. Table

6, situated in the appendix, presents the standard deviation, the average and the RSD for each

phosphorus samples and water samples. According to Garry et.al, 2014 if the RSD is lower

than 10% the results have non-significant difference from each other. Studying Table 6 we

can conclude that all the samples despite three had non-significant difference and were

therefore accurate results. The reason why three samples had a higher RSD than 10 could be

that the TP concentrations calculated were to low making it difficult to calculate the

difference between them.

The 30 samples were taken from different locations at different temperature and time as

presented in Table 2 and 3. As explained above the results showed that the determination of

TP can be calculated using sodium persulfate instead of potassium persulfate. Nevertheless

these results would have been more accurate if more data would have been studied and if the

samples would have been taken from more locations. As an example we could have studied

samples from different soil types where the phosphorus concentration is high.

Figure 6 shows the calibration curve inclination for nine laboratory experiment. A new

calibration curve was performed each day in order to achieve the best results possible.

Studying Figure 6 we can conclude that all inclinations were closed to each other meaning

that similar results were calculated. The highest difference between the inclinations was 0.059

which can be accepted for trace analysis.



15

One assumption made during the digestion was that all TP present in the samples was

converted to inorganic phosphorus. This may not have been the case; therefore it would have

been interesting to calculate the efficiency of the digestion. Different types of digestion could

also have been studied in order to increase the accuracy.

7 Conclusion

From the results and discussion it was concluded that the determination of TP can be

performed using sodium persulfate. In other words the experiment was successful and the

hypothesis was correct. The reason why some samples matched better with the hypothesis

than others could be due to human errors during the laboratory experiments or due to the fact

that sodium persulfate do not have the same oxidative effect on all samples.

This project was the first one analyzing sodium persulfate for the determination of TP. The

reason why sodium persulfate was chosen was that it is less expensive and more soluble than

potassium persulfate. Therefore this report has given the possibility to save money in future

work related with the determination of TP.

7.1Future recommendations

These results would have been more accurate if more data would have been studied and if the

samples would have been taken from more locations. Also it would have been interesting to

calculate the efficiency of the digestion and utilize different types of digestion.



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8. Acknowledgements

First of all I would like to thank Professor Jian Ma for preparing this very well planned and

interesting project and for all the help and guidance given to me. Then I would like to thank

my two research assistants Yuan Yuan and Shu Wang for all the work performed in order to

make the laboratory experiments easy and all the kind explanations. I would also want to

thank my student partner Fangrui Liu for all work performed together. Then I would like to

thank all the persons that made this cooperation between Lund University and Xiamen

University possible such as Professor Linus Chang. I also want to thank all the Swedish and

Chinese students that have been part of the summer research school making it a wonderful

stay. Last I would like to thank our sponsor Tyréns to contributing to funding the expenses of

this stay.

Figur 8 From right Wang Shu, Fangrui Liu, Manuela Stierna, Yuan Yuan and Qipei Shangguan

Thank you



17

9. References

Baldwin D.S, (2013), Organic Phosphorus in the aquatic environment, La Trobe University,

Vol 2013, pp 439-454.

Burton J.D, ((1973), Problem in the analysis of phosphorus compounds, University of

Southampton, Vol l7, pp291-307,

Crouch S.R. & Malmstad H.V, (1967), A Mechanism Investigation of Molybdenum Blue

Method for Determination of Phosphate, University of Illinois.

Garry D.C & Purnendu K.D & Schug K.A , (2014), Analytical Chemistry, Wiley, Seventh

Edition, United Stated of America.

Huang X.L & Zhang J.Z, (2009), Neutral persulfate digestion at sub-boiling temperature in

an oven for total dissolved phosphorus determination in natural waters, Talanta, Vol 78,pp

1129-1135 .

Huang X.L & Zhang J.Z, (2008), Rate of phosphoantimonylmolybdenum blue complex

formation in acidic persulfate digested sample matrix for total dissolved phosphorus

determination: Importance of post-digestion pH adjustment, Talanta, Vol 77,pp 340-345.

Ma J & Li Q & Yuan D., (2014), Loop flow analysis of dissolved reactive phosphorus in

aqueous samples, Talanta, Vol 123, pp 218-223 .

Mather W &Woo L., (1998), Procedures for the storage and digestion of natural waters for the

determination of filterable reactive phosphorus, total filterable phosphorus and total

phosphorus, Analytica Chimica Acta, Vol 375, pp5-47 .

Nidal A.Z & Mather.A & Abdullah F, (1999), Spectrophotometric determination of nitrite

and nitrate using phosphomolybdenum blue complex Talanta, Vol 50, pp 819-826.

Statham P.J, (2012), Nutrients in estuaries — An overview and the potential impacts of

climate change. Science of the Total Eenvironment, Vol 434, pp213.227

Worsfold P.J & Monbet P& Tappin A.& Fitzsimons. M& Stiles D,&McKelvie I. , (2008),

Characterisation and quantification of organic phosphorus and organic nitrogen components

in aquatic systems, Analytica Chimica Acta, Vol 624, pp27-58.



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10. Appendix

Table 6 Relative standard deviation calculations for all the samples performed during the

experiment

TP,K Std Av Av+std RSD TP,Na

Std Av Av+Std RSD

0,31 0,35 0,03 0,33 0,36 10,02 0,30 0,30 0,31 0,0045 0,30 0,31 1,47

0,30 0,27 0,27 0,014 0,28 0,29 4,98 0,29 0,30 0,28 0,010 0,29 0,30 3,55

0,07 0,07 0,07 0,001 0,075 0,076 1,33 0,07 0,07 0,06 0,0037 0,073 0,077 5,16

0,22 0,14 0,14 0,042 0,17 0,21 25,06 0,13 0,14 0,13 0,0056 0,13 0,14 4,13

0,61 0,61 0,60 0,0083 0,61 0,61 1,37 0,61 0,59 0,6 0,0097 0,60 0,61 1,61

0,25 0,28 0,24 0,017 0,26 0,27 6,87 0,24 0,26 0,24 0,0075 0,25 0,26 3,05

0,22 0,21 0,23 0,0075 0,22 0,23 3,41 0,22 0,22 0,21 0,0049 0,22 0,22 2,26

0,26 0,26 0,24 0,0098 0,25 0,26 3,85 0,23 0,23 0,21 0,013 0,22 0,23 6,04

0,22 0,22 0,22 0,0045 0,22 0,22 2,07 0,22 0,22 0,21 0,006 0,22 0,23 2,75

0,33 0,34 0,33 0,0083 0,33 0,34 2,47 0,35 0,37 0,33 0,0210 0,35 0,37 5,92

0,26 0,26 0,27 0,0047 0,26 0,27 1,75 0,26 0,24 0,24 0,010 0,25 0,26 4,16

0,34 0,39 0,039 0,37 0,41 10,55 0,34 0,36 0,35 0,0093 0,35 0,36 2,66

0,02 0,02 0,0007 0,023 0,024 3,0089 0,02 0,02 0,02 0,0005 0,02 0,021 2,84

0,24 0,24 0,24 0,0020 0,24 0,24 0,86 0,24 0,24 0,24 0,0017 0,24 0,24 0,7

0,04 0,04 0,04 0,0015 0,0416 0,043 3,66 0,04 0,03 0,03 0,0020 0,039 0,040 5,38

0,01 0,01 0,01 0,0017 0,012 0,0137 14,43 0,01 0,01 0,01 0,001 0,01 0,014 7,69

0,03 0,02 0,02 0,0015 0,029 0,030 5,20 0,01 0,01 0,01 0,001 0,01 0,019 5,55

0,01 0,01 0,01 0,003 0,014 0,017 24,74 0,01 0,01 0,01 0,003 0,01 0,018 19,92

0,02 0,01 0,01 0,0020 0,018 0,020 11,15 0,01 0,02 0,02 0,0026 0,02 0,02264 13,23

0,02 0,02 0,02 0,0011 0,027 0,028 4,22 0,02 0,02 0,02 0,001 0,02 0,024 4,34

0,07 0,07 0,06 0,0035 0,067 0,071 5,19 0,05 0,05 0,04 0,005 0,05 0,055 10

0,02 0,03 0,03 0,002 0,026 0,028 7,69 0,02 0,03 0,03 0,0036 0,03 0,03 13,35

0,04 0,04 0,04 0,0020 0,047 0,049 4,39 0,04 0,04 0,04 0,002 0,04 0,047 4,59

0,03 0,03 0,03 0,0015 0,031 0,033 4,87 0,03 0,03 0,03 0,0005 0,03 0,034 1,71

0,02 0,02 0,02 0,0020 0,023 0,025 8,79 0,02 0,01 0,02 0,0005 0,02 0,021 2,79

0,11 0,11 0,11 0,0043 0,112 0,12 3,89 0,11 0,10 0,11 0,001 0,11 0,111 0,91

0,61 0,66 0,7 0,062 0,674 0,73 9,24 0,65 0,69 0,70 0,029 0,68 0,71 4,31



19

Table 7 Concentration of total phosphorus present in the phosphorus samples

Concentration of total phosphorus present in the phosphorus samples (umol/L)

Using Potassium persulfate Using Sodium persulfate

1104.5 1017.5

938.5 979

261 255

630.43 510.86

2206.43 2192.029

938.4 909.42

949.13 910.5

1142.39 1150.84

987.8 1021.01

719.06 719.14

727.08 727.08

1071.329 1123.909

871.92 816.36

1166.07 1109.02

Table 8 Concentration of total phosphorus present in the water samples

Water samples

Concentration of TP using

Potassium persulfate

(μmol/L)

Concentration of TP using

Sodium persulfate

(μmol/L)

Irrigation water 74.34 74.45

Spring lake

5.1 4.29

River water 9.73 8.97

2.16 2.42

6.59 3.69

2.67 3.01

3.86 4.2

6.07 4.97

Industry water 403.08 396.23

582.22 591.06

Coastal area water 25.12 19.07

5 5.26

10.67 10.14

Tap water 6.41 7.03

4.37 3.58

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