Ionode IJ-Ag2S User Manual

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Page 1

User maintenance and troubleshooting

GOOD CHEMISTRY

Symptom Possible cause Remedy

Drift Junction blocked Remove and clean sleeve

Membrane unclean or contaminated

Noisy Poor connection

Inaccurate readings or poor reproducibility

to meter Junction not

immersed fully Insufcient

electrolyte or bubble

Contaminated standard(s)

Improperly made standards

Contamination from electrolyte

Remove sleeve. Gently polish membrane with P1200 “Wet & Dry”

Check connection

Lower electrode into solution below junction

Rell electrolyte

Make up fresh calibration standards and recalibrate

Recalibrate using freshly made standards

Use 1M potassium nitrate in sleeve

Warranty

IJ electrodes have a warranty of 12 months from date of purchase. Any electrode found to be faulty due to manufacture within this time will be replaced. Ionode reserves the right to limit or modify product warranty if it is deemed that the electrode has been used in unsuitable applications. Electrodes with broken stems, connectors or cables are not covered by warranty. Electrode life may be reduced in chemically aggressive or abrasive samples and at high temperatures.

Visit www.ionode.com for more information.

Images are illustrative only.

Operators Manual

Short-Form

Intermediate Junction Series

IJ-Ag2S

SILVER/SULPHIDE

ION SELECTIVE

ELECTRODE

Temperature differences between calibration and sample measurement

No ISA used Add ISA

Incorrect pH Adjust pH

Sensitivity to light Perform calibration and

Ensure calibration and sample measurements are done at the same temperature

measurements in dark beakers or away from bright light

Parameter Operating Range

Concentration range S2- 0.003 –32,100 mg/L

Temperature range 0 – 60ºC pH range S

Reference Type Double Junction Ag/AgCl/rellable Sensor materials Polycrystalline solid state

Body and sleeve Polypropylene/PEEK Overall length 150mm Barrel diameter 12mm Cable length 1m standard, longer to order.

Connector BNC standard, others on request

Ag+ 0.01 – 107,900 mg/L

12-14

Ag+ 2-8

membrane

Maximum 20m

Page 2

Introduction

This guide contains the basic information for proper use of your new Silver/Sulphide Ion-selective electrode.

Preparation

IJ series electrodes are shipped without sleeve electrolyte, and must be lled prior to use. To ll, hold the electrode by the sleeve and gently ease off the rubber wetting cap. Prepare as follows:

1. 2.

Invert the electrode. Hold the electrode just below the sleeve and with careful rotation and pulling along the axis of the electrode, remove the sleeve. DO NOT BEND.

Slide the sleeve back onto the electrode ensuring the black O-

ring is well seated within the electrode body. Do not exert sideways force. Any excess electrolyte will be expelled from the end of the electrode through the ground junction. Ensure there are no air bubbles in the sleeve.Wash off any excess electrolyte before use.

Fill the annular space with electrolyte to approximately half to three quarter full. 1M potassium nitrate is normally recommended.

Application

The Ionode IJ-Ag sulphide and silver ions (Ag The limit of detection is 0.003 ppm (Sulde), and 0.01 ppm (Silver). The electrode can also be used for low level cyanide and halide titrations.

S Ion selective electrode measures free

) in aqueous solutions.

Interfering Ions

Mercury ions should be absent. Ions that complex with measured species.

Cleaning

If the membrane is poisoned by interferences, the surface may be renewed by careful polishing with ne wet-anddry (P1200 grade). The membrane surface should have a polished metallic appearance. Always inspect the membrane before use, and clean if necessary. Organic contaminants can be removed with ethanol. DO NOT use the electrode in chlorinated hydrocarbons.Routinely remove the sleeve and replace the potassium nitrate electrolyte.

Electrolyte Replacement

The electrode has an inbuilt double junction Ag/AgCl with a replaceable sleeve electrolyte. 1M potassium nitrate is suitable for most applications. Please consult Ionode Customer Service if you wish to use a different sleeve electrolyte.

Calibration Standards

Standard solutions should preferably bracket the expected measurement range. Sulphide standards are susceptible to oxidation and are not commercially available; these are to be made fresh and the titer determined by standardisation with Lead Perchlorate or equivalent.

The need for ISA (Ionic Strength Adjuster)

It is important to use ISA, so that the Ionic Strength of standards and samples is independent of the concentration of the measured ion. It is also important for pH adjustment. Use 10M NaOH or SAOB (Sulphide Anti-Oxidant Buffer) for Sulphide determination. Sodium nitrate or similar can normally be used for silver and halide determination.

Calibration Procedure

Before use, the electrode should be calibrated by measuring a series of known standard solutions by serial dilution of stock standard. For sulphide measurement, each decade of concentration will have a theoretical difference of 29mV (@25C). Similarly, for silver determination, the theoretical difference is 59mV. In practice, the measured differences will be less than these values. Acceptable values for slope are -56±4mV for Ag

and -28±4mV for S2-.

Other measurement Techniques

An unknown concentration can be determined by adding a small known amount of a concentrated standard to a known volume of sample. Other incremental techniques include sample addition, standard subtraction and analyte subtraction. More details can be obtained from the Theory Section at www.ionode.com

Typical silver calibration curve

Typical sulphide calibration curve

Titration of Chloride

The electrode may also be used as an indicator to follow the progress of a chloride (or other halide) titration using silver nitrate. During the titration, the added silver reacts with the halide ions forming a silver halide precipitate. At the stoichiometric end point, a large potential change occurs as silver ions end up in excess. These titrations may be performed manually or automatically using an automatic titrator.