EUTECH INSTRUMENTS AMMONIA GAS Instruction Manual

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Instruction Manual

GENERAL INSTRUCTIONS

Introduction

Eutech Instruments Ammonia Gas-Sensing Electrode is used to quickly, simply, accurately, and

economically measure dissolved ammonia in aqueous solutions. It can also be used to measure the

ammonium ion after conversion to ammonia or organic nitrogen from Kjeldahl digestion of the

sample. The measurement is not affected by sample color or turbidity and samples do not need to be

distilled. Interference from anions, cations, and dissolved species, other than volatile amines, do not

occur. With a flow-through cap, the electrode can be used in flow-through applications.

Required Equipment

A pH/mV meter or an ion meter, either line operated or portable.

Semi-logarithmic 4-cycle graph paper for preparing calibration curves when using the

meter in the mV mode.

A magnetic stirrer.

Eutech Ammonia Gas-sensing Electrode, Code No. EC-NH3-01.

Required Solutions

Deionized or distilled water for solution preparation.

Eutech Ammonia Standard, 0.1M NH

solution from your own laboratory stock, half fill a one liter volumetric flask with distilled

water and add 5.35 grams of reagent-grade NH 4 Cl. Swirl the flask gently to dissolve the

solid. Fill the flask to the mark with distilled water, cap, and upend several times to mix

the solution.

Eutech Ammonia Standard, 1,000 ppm NH

this solution from your own laboratory stock, half fill a one liter volumetric flask with

distilled water and add 3.82 grams of reagent-grade NH 4 Cl. Swirl the flask gently to

dissolve the solid. Fill the flask to the mark with distilled water, cap, and upend several

times to mix the solution.

Eutech Ammonia Standard, 100 ppm NH

this solution from your own laboratory stock, half fill a one liter volumetric flask with

distilled water and add 0.382 grams of reagent-grade NH

dissolve the solid. Fill the flask to the mark with distilled water, cap, and upend several

times to mix the solution.

EUTECH INSTRUMENTS PTE LTD.

AMMONIA GAS-SENSING ELECTRODE

INSTRUCTION MANUAL

Cl, Code No. EC-SCS-AA1-BT. To prepare this

as N, Code No. EC-SCS-AA2-BT. To prepare

as N, Code No. EC-SCS-AA3-BT. To prepare

Ammonia Gas-sensing Electrode

Cl. Swirl the flask gently to

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Summary of Contents for EUTECH INSTRUMENTS AMMONIA GAS

Page 1: General Instructions
GENERAL INSTRUCTIONS Introduction Eutech Instruments Ammonia Gas-Sensing Electrode is used to quickly, simply, accurately, and economically measure dissolved ammonia in aqueous solutions. It can also be used to measure the ammonium ion after conversion to ammonia or organic nitrogen from Kjeldahl digestion of the sample.
Page 2: General Preparation
Instruction Manual Ammonia Gas-sensing Electrode Eutech Ionic Strength Adjuster (ISA) Solution, 10 M NaOH, Code No. EC-ISA-AA1-BT. To prepare this solution from your own laboratory stock, half fill a 1,000 ml beaker with distilled water, add 400 grams of reagent-grade NaOH (sodium hydroxide). Swirl the flask gently under a hood to dissolve the solid.
Page 3: Connecting The Electrode To The Meter
Instruction Manual Ammonia Gas-sensing Electrode the electrode body up at the threads with thumb and forefinger. Place one edge of the membrane against the threads and hold in place with your thumb. Stretch new membrane lengthwise across the electrode opening so that it smoothly covers the opening. Place the other edge of the membrane against the threads and hold in place with your forefinger.
Page 4: Measurement
Instruction Manual Ammonia Gas-sensing Electrode Adjust the meter to the concentration of the standard and fix the value in the memory according to the meter manufacturer's instructions. Rinse the electrodes with distilled water and blot dry. To another 150 ml beaker, add 100 ml of the higher value standard and 2 ml of ISA. Place the beaker on the magnetic stirrer and begin stirring at a constant rate.
Page 5: Sample Requirements
Instruction Manual Ammonia Gas-sensing Electrode Sample Requirements Sodium hydroxide buffer must be added to standards and samples before measurement. When 10M NaOH is added, all standards and samples should be in the range of pH 11 to 14. In this range, all ammonium species are converted to ammonia.
Page 6: Direct Measurement Of Ammonia (Using An Ion Meter)
Instruction Manual Ammonia Gas-sensing Electrode Using the semi-logarithmic graph paper, plot the mV reading (linear axis) against the concentration (log axis). Extrapolate the calibration curve down to about 1.0 x 10 - M. A typical calibration curve can be found in Figure 1.
Page 7: Low Level Ammonia Determination (Using A Ph/Mv Meter)
Instruction Manual Ammonia Gas-sensing Electrode Place the more dilute solution on the magnetic stirrer and begin stirring at a constant rate. Assure that the meter is in the concentration mode. Lower the electrode tip into the solution. Adjust the meter to the concentration of the ammonia standard and fix the value in the memory according to the meter manufacturer's instructions after stabilization of the reading.
Page 8: Ammonia Measurements In Membrane Wetting Solutions
Instruction Manual Ammonia Gas-sensing Electrode Measure out 100 ml of a pH 4 buffer solution, add it to a 150 ml beaker, place the beaker on the magnetic stirrer, and begin stirring. Place the electrode tip in the solution for about 3 minutes.
Page 9: Electrode Characteristics
Instruction Manual Ammonia Gas-sensing Electrode Since water vapor reacts with ammonia in the gas phase, placing the ammonia electrode in a closed system containing water vapor will allow measurements of solutions above 10 - M (14 ppm) to be taken.
Page 10: Complexation
Instruction Manual Ammonia Gas-sensing Electrode Complexation Metal complexes are formed with ammonia and a number of metal ions. Complexes of mercury, copper, gold, silver, nickel, zinc, cobalt, and cadmium are removed in the form of hydroxide complexes or precipitates in basic solution. When ammonia concentration is below 10 -...
Page 11: Limits Of Detection
A gas-permeable membrane is used to separate the electrode's internal solution from the sample solution in the Eutech Ammonia Gas-Sensing Electrode. The sample diffuses dissolved ammonia through the membrane until the partial pressure of ammonia is the same on both sides of the...
Page 12: Ammonia Chemistry
Instruction Manual Ammonia Gas-sensing Electrode The ammonia that diffuses through the membrane dissolves in the internal filling solution, reacting reversibly with water in the filling solution, to a small extent: O ⇒ NH + + OH - The equilibrium equation gives rise to the equilibrium constant in the following equation: + ] [OH - ] constant = ⎯⎯⎯⎯⎯⎯⎯...
Page 13: Troubleshooting Guide
Instruction Manual Ammonia Gas-sensing Electrode It is possible to calculate the ratio of ammonia to ammonium ion, theoretically, if the pH is known. A. Martell and R. Smith in Critical Stability Constants, Plenum Press, New York, 1974, state: ⎯⎯⎯⎯ = ⎯⎯⎯⎯ K ~ 10 -9.3...
Page 14: Glassware
Instruction Manual Ammonia Gas-sensing Electrode Glassware Clean glassware is essential for good measurement. Be sure to wash the glassware well with a mild detergent and rinse very well with distilled or deionized water. Clean glassware will drain without leaving water droplets behind.
Page 15: Technique
Refer to the instruction manual GENERAL PREPARATION ELECTRODE CHARACTERISTICS. again. Reread the sections If trouble still persists, call Eutech Instruments Pte Ltd. at (65) 6778-6876 and ask for the Customer Services Department.
Page 16: Troubleshooting Hints
Instruction Manual Ammonia Gas-sensing Electrode TROUBLESHOOTING HINTS Symptom Possible Causes Next Step Out of Range defective meter perform meter checkout procedure Reading (see meter instruction manual) Checking the Electrode defective inner body refer to Inner Body electrode not unplug electrode and reset...
Page 17 Instruction Manual Ammonia Gas-sensing Electrode high temperatures membrane failure replace membrane (wet, perforation, discoloration) samples and standards allow samples and standards to come standards not at to room temperature before use constant temperature heat generated by place insulating material between...
Page 18: Checking The Electrode Inner Body
Instruction Manual Ammonia Gas-sensing Electrode value correctly incorrect standards prepare fresh standards wrong units used apply correct conversion factor: 10 - M = 17 ppm as = 14 ppm as N buffer added to add same proportions of buffer to...
Page 19: Specifications
Storage: Store electrodes in 0.1M NH ORDERING INFORMATION CODE NO. DESCRIPTION EC-NH3-01 Ammonia Gas Sensing Electrode EC-MIS-AM Ammonia Membrane Kit, bag of 20 membranes and spare o-ring EC-SCS-AA1-BT Ammonia Standard, 0.1M NH EC-SCS-AA2-BT Nitrogen Standard, 1,000 ppm NH as N...
Page 20: Table Of Contents
Instruction Manual Ammonia Gas-sensing Electrode TABLE OF CONTENTS GENERAL INSTRUCTIONS .........................1 Introduction..............................1 Required Equipment ...........................1 Required Solutions............................1 GENERAL PREPARATION ..........................2 Electrode Preparation..........................2 Checking Membrane...........................2 Changing Membrane (see Figure 4) ......................2 Connecting the Electrode to the Meter .......................3 Electrode Slope Check (with pH/mV meter) ....................3 Electrode Slope Check (with ion meter).....................3...
Page 21 Instruction Manual Ammonia Gas-sensing Electrode ORDERING INFORMATION........................19...

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Ammonia gas-sensing electrode