Analyses plan module 19
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Analyses plan Module 19. Major base cations to be determined by ICP-AES Conductivity and temperature {H + } determined using pH electrode Al fractionation Major anions to be determined by IC Use of auto-pipettes Total organic carbon UV and Vis absorption. Conductivity.

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Analyses plan Module 19

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Analyses plan module 19

Analyses planModule 19

  • Major base cations to be determined by ICP-AES

  • Conductivity and temperature

  • {H+} determined using pH electrode

  • Al fractionation

  • Major anions to be determined by IC

    • Use of auto-pipettes

  • Total organic carbon

    • UV and Vis absorption


Conductivity

Conductivity

  • Master student lab V160

  • Ecoscan Con5 (Eutech instruments) conductivity meter.

    • The instrument is calibrated using 1000 and 1433 µS calibration solutions

  • The measurements are done for quality control purposes in order to compare measured and calculated conductivity


H determined using ph electrode

{H+} determined using pH electrode

  • Analytical Chemistry lab Ø109

  • Thermo Orion model 720 pH-meter with a Blueline 11-pH electrode.

    • The pH-meter is calibrated with pH = 4.00 and 7.01 buffer solutions


Major base cations to be determined by icp aes

Major base cations to be determined by ICP-AES

  • Ca2+, Mg2+, Na+, K+

    • Method will be demonstrated in Module 24

      • Appropriate calibration solutions are prepared by Masha

      • Conducted by Anne-Marie Skramstad


Major anions to be determined by ion chromathograph ic

Major anions to be determined by Ion Chromathograph (IC)

  • Analytical Chemistry lab Ø109

  • Tot-F, Cl-, NO3-, SO42-

    • Principle

      • The sample is injected in a flow of eluent

      • The analyte ions are separated by different degree of binding to the active sites on the ion exchange material

      • Ions with opposite charge of the analyte is exchanged with H+ or OH-

      • The activity of the analyte is and accompanied H+ or OH- in the eluent stream is measured by means of a conductometer

    • Presented by Hege Lynne et al


Total organic carbon

Total organic carbon

  • Analytical chemistry lab Ø 104

  • High temperature (680C) catalytic combustion analysis on a Shimadzu TOC-5000A instrument

  • Principle:

    • The organic carbon is combusted to CO2 by high temperature and catalysis. The amount of CO2 produced is measured using av IR detector

  • Presented by Hege Lynne et al.

    • Analytes measured may include: TC, IC, TOC, NPOC, and POC


Al fractionation

Al fractionation

  • Master student lab V160

  • Method presented as example in Lecture 1 (slide 15)

  • Download manual from

    • http://folk.uio.no/rvogt/KJM_MEF_4010/


Qc of data

QC of data

  • After the analysis the data must be compiled and quality controlled by ion balance and agreement between measured and calculated conductivity

  • For this purpose you may use the Data compilation and QC worksheet available at http://folk.uio.no/rvogt/KJM_MEF_4010/


Species in natural freshwater central equilibriums in natural water samples

Speciesin natural freshwaterCentral equilibriums in natural water samples

KJM MEF 4010

Module 19


Inorganic complexes

Inorganic complexes

  • Major cations in natural waters

    • H+, Ca2+, Mg2+, Na+, K+

  • Common ligands in natural systems:

    • OH-, HCO3-, CO32-, Cl-, SO42-, F- & organic anions

    • In anoxic environment: HS- & S2-

  • Dominating species in aerobic freshwater at pH 8 are:


Hydrolysis

Hydrolysis

  • In aqueous systems, hydrolysis reactions are important

    • Hydrolysis reactions are controlled by {H+}

      • The higher the pH, the stronger the hydrolysis of metal cations

      • E.g. Aluminium

        • Al3+aq denotes Al(H2O)63+


Concentrations of dissolved fe 3 species two total fe concentrations fe t 10 4 m and fe t 10 2 m

Concentrations of dissolved Fe3+ speciesTwo total Fe concentrations, FeT = 10-4M and FeT = 10-2M


Dissolved organic matter

Dissolved Organic Matter

  • Low molecular weight (LMW)

    • < 1000Da (e.g. C32H80O33N5P0.3)

    • E.g.:

  • High molecular weight

    • 1000 - > 100 000Da

    • Humic substance

      • Very complex and coloured substances

  • Enhances weathering

    • The protolyzation of weak organic acids

    • Complexation of Al and Fe

      • Total congruent dissolution


Concentrations and activities

Concentrations and activities


Activity

Activity

  • {X}=X · [X]

    • {X} is the activity to X

    • [X] is the concentration to X

    • X is the activity coefficient to X

      • X are dimensionless

      • It is determined by:

        • The diameter (å) of the hydrated X

        • Its valence (nX)

        • The ionic strength (I)

Not possible to calculate further than I=0.1

n=1

n=2

n=3

n=4

  •   when I  0 1 when I<10-5M

Anions + cations


Debye huckel dh equation

Debye Huckel(DH) equation

  • For ionic strengths (I) < 0.1M the X can be calculated by means of e.g. the Debye Huckel equation:

    I < 0.1

    I < 0.005

    • 0.5 & 0.33 are temperature dependent table values

      • Presented values are for 25°C

    • åX is a table value for the specie in question


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