Using the passive sampler system for nitrate and phosphate monitoring

7/25/2019 Using the passive sampler system for nitrate and phosphate monitoring

1/22

Chalmers University of Technology

Using the passive sampler systemfor nitrate and phosphate

monitoring

- calibration, factor variation analysis

and field trialKatarina Svensson, Greg Morrison and Jesper Knutsson



2/22


Properties of the Empore anion-SR

extraction DiskProperties Empore Anion-SR disk

Average pore size 80 Average particle size 12 mSurface area 350 m2/gCapacity per disk 0!20 me"

R1

R1

R1

R1CHCH

CH

CH2

CH2

CH2

CHCHCH

CH2

CH2

CH2

N+

R1

HHH

Poly (styrene-divinylbenzene)

copolymer

Quatenary Ammonium

functional group


3/22


Split view of the passive sampler

1. Protective mesh

2. Diffusion limiting membrane

(0.45 m CA)

3. Receiving disk (EmporeAnion SR)

4. Disk support

5. Sampler housing

6. Sampler housing

(Bjrklund, 2002)


4/22


Diffusional path of a passive sampler

c#i

Diffusional path

Aueous !iffusion layer

csi

cs

concentration

cmi

cmoc#

$%3&

$%3&

$%3&

'(%)2&

Diffusion limiting mem"rane

Acceptor phase


5/22


Calibration

w

s

c

BR =

The sampling rate (Rs) is substance

specific and is expressed as the

volume of cleared sample per time:

WhereBis the slope of the uptake

curve, and cwis the average

concentration of the substanceduring the calibration period.

tR

MMc

s

s

w0

=

The time averaged concentration in

the waterphase can then be

calculated:


6/22


Calibration resultsPhosphate calibration curve

y # $%1&'() * '%(($

R2# '%,$(,

'

2''

&''

(''

''

1'''

12''

1&''

1(''

' -' 1'' 1-' 2'' 2-' $'' $-' &'' &-'

time (h)

Accum

ulationfactor(mL)

Nitrate calibration curve

y # -%.(21) + (&%&$

R2# '%(2(

'

-''

1'''

1-''

2'''

2-''

$'''

$-''

' -' 1'' 1-' 2'' 2-' $'' $-' &'' &-'

t (h)

Accum

ulationfactor(mL)

Rs = 138.5 mL day-1 Rs = 75.7 mL day

-1

Calibration

parameters

Temperature 14 C

pH 7.0


7/22


Factor variation test

'%'

1%'

2%'

$%'

&%'

-%'

(%'

1 2 $ & - ( . ,

Trial set

Amount(m

g)

Nitrate

/hosphate

Factoral expriment design to

examine the influence of pH,

temperature and turbulence

ANOVA analysis of results

3 factors and 3 levels of variation

pH 5,7 and 9

temperature 7, 14 and 21 C

turbulence 50, 200 and 400

rpm


8/22


Factor variation testpH influence

'%'

'%-1%'

1%-

2%'

2%-

$%'

$%-

&%'

&%-

-%'

- . ,

pH

amount0mg1

phosphatenitrate

Temperature influence

'%'

'%-

1%'

1%-

2%'

2%-

$%'

$%-

&%'

&%-

-%'

. 1& 21

tempearature 0C

amount0mg1

phosphateNitrate

tur"ulence influence

'%'

'%-

1%'

1%-

2%'

2%-$%'

$%-

&%'

&%-

-%'

-' 2'' &''

rpm

!is2amount0mg1

phosphate

nitrate


9/22


Factor variation testTemperature is a major factor

influencing the uptake rate,

which could indicate that the

diffusion rate is controlled

mainly by the boundry layer

Phosphate is also significantlydependant on pH. See below.

Turbulence is not significant

at the variation levels chosen.

===

3

)

)!122

)

2!*

)2

1!2

)3 POHPOPOHPOH aaa pKpKpK

Influence of factors

*2'3

'3

2'3

&'3

('3

'3

1''3

Nitrate /hosphate

4ther

Tur"ulence

Temperature

pH


10/22


Rya water treatment plant trial

'

'%2

'%&

'%(

'%

1

1%2

1%&

1%(

1*2- Aug ,*1( sept 1(*2$ sept

mg(nitrate)

'

'%'2

'%'&

'%'(

'%'

'%1

'%12

'%1&

'%1(

mg(phosphate)

nitrate

phosphate


11/22


Water treatment plant resultsCalculation of results

'

'%-

1

1%-

2

2%-

$

$%-

&

&%-

5T/ 1 5T/ 2 5T/ $

trial

c(m

g/L)

6ampler C7 0mg89

5T/ !ata c 0mg89

Calculation of results

'

'%'-

'%1

'%1-

'%2

'%2-

5T/ 1 5T/ 2 5T/ $

trial

c(m

g/L)

6ampler C7 0mg89

5T/ !ata c 0mg89

Calibration Field

Temperature 14 C 19.6-19.0 C

pH 7.0 6.9-6.6


12/22


Further work and development

:Redo the nitrate calibration curveFind and develop an internal or external standardPerform further field trialsPerform further factor variation analysis


13/22


Calibration of passive samplersfor selected target metals

(Cu, Cd, Pb and Zn)

Katarina Svensson, Greg Morrison and Jesper KnutssonChalmers University of Technology


14/22


Cali+ratio, -ata+ase

for metallic (olluta,ts. etals Cu Cd (+ , a,d $i

. Co,ce,tratio, ra,ge 1 10 a,d 50 g/l

. 4emperature ra,ge ) 11 a,d 18C

. Co,vectio, ,o,e )0 a,d *0 rpm

. p' *

. 6uffer 0!01 (%)3&

. -iffusio, em+ra,e Cellulose Acetate 0!)5m

. 7eceivi,g (ase 3 9mpore Celati,g e:tractio, disk


15/22


;lo#&troug system for Co,sta,t

Co,ce,tratio,sconstant bulk concentration setup (flowrate

>> Rs x n)

termostate controlled bulk temperature

rotating turntable for homogenous

convection


16/22



17/22


Properties of the Empore Chelating

extraction DiskProperties of te Empore !elating disk

Sor+e,t (oly=styre,edivi,yl+e,ze,e>Average particle size 10m

p' sta+ility 0&1);u,ctio,al group Sodium salt of imi,odiacetic acid

R1

R1

R1

R1CHCH

CH

CH2

CH2

CH2

CHCHCH

CH2

CH2

CH2

Poly (styrene-divinylbenzene)

copolymer

At pH = 2, the carboxylate groups are ionized and exist

as neutral species; however, the nitrogen will have a net

positive charge and the molecule behaves as a weak anion

exchanger.

Increasing the pH > 5 ionizes the carboxylate groups and

both are negatively charged.

As the pH approaches neutral, the molecule functions as a

cation exchanger or metal cation chelator


18/22


Conditioning and elution


19/22


Conditioning and elution

Conditioning the chelating disk

Wet the disk with 20 mL of

reagent water under vacuum.

Wash the disk with 20 mL of

3.0M nitric acid or 3.0Mhydrochloric acid followed by two

50 mL water washes. Let the disk

go dry between each wash.

To put the disk in the ammonium

form (its most active form), wash

with 50 mL of 0.1M ammoniumacetate buffer at pH 5.3 followed

by several reagent water washes.

lution

Two elutions with 10 mL of 3.0 M nitric

aicd

Note: some metals might be difficult to elute

(e.g. Chromium)

Anal!sis

Perkin-Elmer ELAN 6000 ICP-MS

instrument and commercial calibration

standards.

Instrument is optimized to meet

manufacturer specifications


20/22


Sampling rates

y # 2%1,-) + $.%'(

R2# '%,(,,

'

2''

&''

(''

''

1'''

12''

' 1'' 2'' $'' &''

time 0h

accumulationfactor0m91

Cu ($

y # $%(,&-) + '%2(1$

R2# '%,.&

'

2''

&''

(''

''

1'''

12''

' 1'' 2'' $'' &''

time (h)

accumulationfactor(mL)

C!

y # $%2..&) * &&%&($

R2# '%,$$

'

2''

&''

(''

''

1'''

12''

' 1'' 2'' $'' &''

time (h)

accumulationfactor(mL)

/"

y # 2%&) + (,%..

R2# '%,(

'

2''

&''

(''

''

1'''

12''

' 1'' 2'' $'' &''

time 0h

accumulationfactor0m91

;n (&

Rs = 59.5 mL day-1

Rs = 89 mL day-1

Rs = 78.8 mL day-1

Rs = 52.6 mL day-1


21/22


Considerations for field use

Possible contamination of sampler during transport/handling - use a procedural blank

sampler

Sampler mounting - dependant on the sampling situation

Physical interferace from human activity if possible choose sampling spot in restricted

access areas Other physical interference (debris like branches, leafs etc)

Bio fouling bio inhibitors, internal/external standard correction


22/22


Internal standard for chelating

disks? Preloading the disk using for example Cu

Saturating the disk vs. limited amount

Triggered release applying small amount of acid to the disk before deployment

Documents

Using the passive sampler system for nitrate and phosphate monitoring