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SC-919
Installation Manual
51 pgs373.09 Kb0

Omega Products SC-919 Installation Manual

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2
Colorimeter
TABLE OF CONTENTS
GENERAL INFORMATION
Packaging & Delivery ······································································ 3 General Precautions ········································································ 3 Safety Precautions ··········································································· 3 Limits of Liability ············································································ 3 Specifications ·················································································· 4 Contents and Accessories ································································ 5 EPA Compliance ············································································· 5 CE Compliance················································································ 6
CHEMICAL TESTING
Water Sampling for Chemical Analysis ··········································· 7 Filtration ························································································· 8 An Introduction to Colorimetric Analysis ······································ 9 Reagent Blank ················································································· 10 Colorimeter Tubes ··········································································· 10 Selecting an Appropriate Wavelength ············································ 10 Calibration Curves ·········································································· 11 Standard Additions ········································································· 13 Sample Dilution Techniques & Volumetric Measurements ············ 14 Interferences ··················································································· 15 Stray Light Interference ·································································· 15
OPERATION OF THE SMART 2 COLORIMETER
GENERAL OPERATING PROCEDURES
TESTING
1 SMART 2 COLORIMETER OPERATOR’S MANUAL
TABLE OF CONTENTS (cont.)
EDITING MENU
PC LINK
BATTERY OPERATION
MAINTENANCE
TROUBLESHOOTING GUIDE
SMART REAGENT SYSTEMS
······································································································· 47
SMART 2 COLORIMETER TEST INSTRUCTIONS APPENDIX
SMART 2 COLORIMETER OPERATOR’S MANUAL 2
GENERAL INFORMATION
PACKAGING & DELIVERY
n
Experienced packaging personnel at LaMotte Company assure adequate protection against normal hazards encountered in transportation of shipments. After the product leaves the manufacturer, all responsibility for its safe delivery is assured by the transportation company. Damage claims must be filed immediately with the transportation company to receive compensation for damaged goods.
Should it be necessary to return the instrument for repair or servicing, pack instrument carefully in suitable container with adequate packing material. A return authorization number must be obtained from LaMotte Company by calling 1-800-344-3100. Attach a letter with the authorization number to the shipping carton which describes the kind of trouble experienced. This valuable information will enable the service department to make the required repairs more efficiently.
GENERAL PRECAUTIONS
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Before attempting to set up or operate this instrument it is important to read the instruction manual. Failure to do so could result in personal injury or damage to the equipment.
The SMART 2 Colorimeter should not be stored or used in a wet or corrosive environment. Care should be taken to prevent water or reagent chemicals from wet colorimeter tubes from entering the colorimeter chamber.
NEVER PUT WET TUBES IN COLORIMETER.
SAFETY PRECAUTIONS
n
Read the labels on all LaMotte reagent containers prior to use. Some containers include precautionary notices and first aid information. Certain reagents are considered hazardous substances and are designated with a * in the instruction manual. Material Safety Data Sheets (MSDS) are supplied for these reagents. Read the accompanying MSDS before using these reagents. Additional emergency information for all LaMotte reagents is available 24 hours a day from the Poison Control Center listed in the front of the phone book. Be prepared to supply the name and four-digit LaMotte code number found on the container label or at the top of the MSDS. LaMotte reagents are registered with a computerized poison control information system available to all local poison control centers.
Keep equipment and reagent chemicals out of the reach of young children. Protect Yourself and Equipment: Use Proper Analytical Techniques
LIMITS OF LIABILITY
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Under no circumstances shall LaMotte Company be liable for loss of life, property, profits, or other damages incurred through the use or misuse of its products.
3 SMART 2 COLORIMETER OPERATOR’S MANUAL
SPECIFICATIONS
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INSTRUMENT TYPE: Colorimeter
Readout Graphical 4 line, 16 character per line LCD Wavelengths 430nm, 520 nm, 570 nm, 620 nm Wavelength Accuracy ± 2 nm Readable Resolution Determined by reagent system Wavelength Bandwidth 10 nm typical Photometric Range −2 to +2A Photometric Precision ± 0.001Α Sample Chamber Accepts 25 mm diameter flat-bottomed test tubes, 10
mm square cuvettes, 16 mm COD test tubes
Light Sources 4 LEDs Detectors 4 silicon photodiodes with integrated interference
filters
Modes Absorbance, pre-programmed tests Pre-Programmed Tests YES, with automatic wavelength selection User Defined Tests Up to 10 user tests can be input RS232 Port 8 pin mDIN, 9600b, 8, 1, n Power Requirements Battery Operation: 9 volt alkaline
Line Operation: 120/220V, 50/60 Hz with adapter Dimensions (LxWxH) 8.5 x 16.2 x 16.7 cm, 3.4 x 6.4 x 2.6 inches Weight 312 g, 11 oz (meter only) Data Logger 350 test results stored for download to a PC
SMART 2 COLORIMETER OPERATOR’S MANUAL 4
CONTENTS AND ACCESSORIES
n
n
CONTENTS
SMART 2 Colorimeter Test Tubes, with Caps Sample Cell Holder, Universal Sample Cell Holder, 10 mm Square Power Cable Battery Charger Power Supply, 110/220V SMART 2 Colorimeter Quick Start Guide SMART 2 Colorimeter Manual
n
ACCESSORIES
Cigarette Lighter Adapter Carrying Case SMARTLink 2 Software with Cable
EPA COMPLIANCE
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The SMART 2 Colorimeter is an EPA-Accepted instrument. EPA-Accepted means that the instrument meets the requirements for instrumentation as found in test procedures that are approved for the National Primary Drinking Water Regulations (NPDWR) or National Pollutant Discharge Elimination System (NPDES) compliance monitoring programs. EPA-Accepted instruments may be used with approved test procedures without additional approval.
5 SMART 2 COLORIMETER OPERATOR’S MANUAL
CE COMPLIANCE
Standards to which Conformity Declared:
Manufacturer's Name:
Manufacturer's Address:
Type of Equipment:
Model Name:
Year of Manufacture:
Testing Performed By:
Place
Date
Signature
Name
Position
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The SMART 2 Colorimeter has earned the European CE Mark of Compliance for electromagnetic compatibility and safety.
SMART 2 COLORIMETER OPERATOR’S MANUAL 6
CHEMICAL TESTING
WATER SAMPLING FOR CHEMICAL ANALYSIS
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Taking Representative Samples
The underlying factor to be considered for any type of water sampling is whether or not the sample is truly representative of the source. To properly collect a representative sample:
l
Sample as frequently as possible.
l
Collect a large sample or at least enough to conduct whatever tests are necessary.
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Make a composite sample for the same sampling area.
l
Handle the sample in such a way as to prevent deterioration or contamination before the analysis is performed.
l
Perform analysis for dissolved gases such as dissolved oxygen, carbon dioxide, and hydrogen sulfide immediately at the site of sampling. These factors, as well as samples for pH, cannot be stored for later examination.
l
Make a list of conditions or observations which may affect the sample. Other considerations for taking representative samples are dependent upon the source of the sample. Taking samples from surface waters involves different considerations than taking samples from impounded and sub-surface waters.
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Sampling of Open Water Systems
Surface waters, such as those found in streams and rivers, are usually well mixed. The sample should be taken downstream from any tributary, industrial or sewage pollution source. For comparison purposes samples may be taken upstream and at the source of the pollution before mixing.
In ponds, lakes, and reservoirs with restricted flow, it is necessary to collect a number of samples in a cross section of the body of water, and where possible composite samples should be made to ensure representative samples.
To collect samples from surface waters, select a suitable plastic container with a tight fitting screw cap. Rinse the container several times with the sample to be tested, then immerse the container below the surface until it is filled to overflowing and replace the cap. If the sample is not to be tested immediately, pour a small part of the sample out and reseal. This will allow for any expansion. Any condition which might affect the sample should be listed.
Sub-surface sampling is required to obtain a vertical profile of streams, lakes, ponds, and reservoirs at specific depths. This type of sampling requires more sophisticated sampling equipment.
For dissolved oxygen studies, or for tests requiring small sample sizes, a Water Sampler (LaMotte Code 1060) will serve as a subsurface or in-depth sampler.
7 SMART 2 COLORIMETER OPERATOR’S MANUAL
This weighted device is lowered to the sampling depth and allowed to rest at this depth for a few minutes. The water percolates into the sample chamber displacing the air which bubbles to the surface. When the bubbles cease to rise, the device has flushed itself approximately five times and it may be raised to the surface for examination. The inner chamber of the sampling device is lifted out and portions of the water sample are carefully dispensed for subsequent chemical analysis.
A Snap-Plunger Water Sampler (LaMotte Code 1077) is another “in-depth” sampling device which is designed to collect large samples which can be used for a multitude of tests. Basically, this collection apparatus is a hollow cylinder with a spring loaded plunger attached to each end. The device is cocked above the surface of the water and lowered to the desired depth. A weighted messenger is sent down the calibrated line to trip the closing mechanism and the plungers seal the sample from mixing with intermediate layers as it is brought to the surface. A special drain outlet is provided to draw off samples for chemical analysis.
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Sampling of Closed System
To obtain representative samples from confined water systems, such as pipe lines, tanks, vats, filters, water softeners, evaporators and condensers, different considerations are required because of chemical changes which occur between the inlet and outlet water. One must have a basic understanding of the type of chemical changes which occur for the type of equipment used. Also, consideration should be given to the rate of passage and retaining time for the process water.
Temperature changes play an important part in deciding exactly what test should be performed. Process water should be allowed to come to room temperature, 20–25°C, before conducting any tests.
When drawing off samples from an outlet pipe such as a tap, allow sample to run for several minutes, rinsing the container several times before taking the final sample. Avoid splashing and introduction of any contaminating material.
FILTRATION
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When testing natural waters that contain significant turbidity due to suspended solids and algae, filtration is an option. Reagent systems, whether EPA, Standard Methods, LaMotte or any others, will generally only determine dissolved constituents. Both EPA and Standard Methods suggest filtration through a 0.45 micron filter membrane, to remove turbidity, for the determination of dissolved constituents.** To test for total constituents, organically bound and suspended or colloidal materials, a rigorous high temperature acid digestion is necessary.
**LaMotte offers a filtering apparatus: syringe assembly (Code 1050) and membrane filters, 0.45 micron, (Code 1103).
SMART 2 COLORIMETER OPERATOR’S MANUAL 8
AN INTRODUCTION TO COLORIMETRIC ANALYSIS
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Most test substances in water are colorless and undetectable to the human eye. To test for their presence we must find a way to “see” them. The SMART 2 Colorimeter can be used to measure any test substance that is itself colored or can be reacted to produce a color. In fact a simple definition of colorimetry is “the measurement of color” and a colorimetric method is “any technique used to evaluate an unknown color in reference to known colors”. In a colorimetric chemical test the intensity of the color from the reaction must be proportional to the concentration of the substance being tested. Some reactions have limitations or variances inherent to them that may give misleading results. Many such interferences are discussed with each particular test instruction. In the most basic colorimetric method the reacted test sample is visually compared to a known color standard. However, accurate and reproducible results are limited by the eyesight of the analyst, inconsistencies in the light sources, and the fading of color standards.
To avoid these sources of error, a colorimeter can be used to photoelectrically measure the amount of colored light absorbed by a colored sample in reference to a colorless sample (blank).
White light is made up of many different colors or wavelengths of light. A colored sample typically absorbs only one color or one band of wavelengths from the white light. Only a small difference would be measured between white light before it passes through a colored sample versus after it passes through a colored sample. The reason for this is that the one color absorbed by the sample is only a small portion of the total amount of light passing through the sample. However, if we could select only that one color or band of wavelengths of light to which the test sample is most sensitive, we would see a large difference between the light before it passes through the sample and after it passes through the sample.
The SMART 2 Colorimeter passes one of four colored light beams through one of four optical filters which transmits only one particular color or band of wavelengths of light to the photodectector where it is measured. The difference in the amount of colored light transmitted by a colored sample is a measurement of the amount of colored light absorbed by the sample. In most colorimetric tests the amount of colored light absorbed is directly proportional to the concentration of the test factor producing the color and the path length through the sample. However, for some tests the amount of colored light absorbed is inversely proportional to the concentration.
The choice of the correct wavelength for testing is important. It is interesting to note that the wavelength that gives the most sensitivity (lower detection limit) for a test factor is the complementary color of the test sample. For example the Nitrate-Nitrogen test produces a pink color proportional to the nitrate concentration in the sample (the greater the nitrate concentration, the darker the pink color). A wavelength in the green region should be selected to analyze this sample since a pinkish-red solution absorbs mostly green light.
9 SMART 2 COLORIMETER OPERATOR’S MANUAL
REAGENT BLANK
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Some tests will provide greater accuracy if a reagent blank is determined to compensate for any color or turbidity resulting from the reagents themselves. A reagent blank is performed by running the test procedure on 10 mL of demineralized water. Use sample water to SCAN BLANK. Insert the reagent blank in the colorimeter chamber and select SCAN SAMPLE. Note result of reagent blank. Perform the tests on the sample water as described. Subtract results of reagent blank from all subsequent test results. NOTE: Some tests require a reagent blank to be used to SCAN BLANK.
COLORIMETER TUBES
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Colorimeter tubes which have been scratched through excessive use should be discarded and replaced with new ones. Dirty tubes should be cleaned on both the inside and outside. Fingerprints on the exterior of the tubes can cause excessive light scattering and result in errors. Handle the tubes carefully, making sure the bottom half of the tube is not handled.
LaMotte Company makes every effort to provide high quality colorimeter tubes. However, wall thicknesses and diameter of tubes may still vary slightly. This may lead to slight variations in results (e.g. if a tube is turned while in the sample chamber, the reading will likely change slightly). To eliminate this error put the tubes into the sample chamber with the same orientation every time.
The tubes that are included with the colorimeter have an index mark to facilitate this. If possible, use the same tube to SCAN BLANK and SCAN SAMPLE.
SELECTING AN APPROPRIATE WAVELENGTH
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The most appropriate wavelength to use when creating a calibration curve is usually the one which gives the greatest change from the lowest reacted standard concentration to the highest reacted standard concentration. However, the absorbance of the highest reacted standard concentration should never be greater than 2.0 absorbance units. Scan the lowest and highest reacted standards at different wavelengths using the absorbance mode to find the wavelength which gives the greatest change in absorbance without exceeding
2.0 absorbance units. Use this wavelength to create a calibration curve.
SMART 2 COLORIMETER OPERATOR’S MANUAL 10
Below is a list of suggested wavelengths for the color of the reacted samples. Use these as a starting point.
Green and Blue 620
CALIBRATION CURVES
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Sample
Color
Yellow 430
Pink 520
Red 570
Wavelength
Range
The SMART 2 Colorimeter contains precalibrated tests for the LaMotte reagent systems (see Page 45). The first step in using a non-LaMotte reagent system with your SMART 2 Colorimeter is to create a calibration curve for the reagent system. To create a calibration curve, prepare standard solutions of the test factor and use the reagent system to test the standard solutions with the SMART 2 Colorimeter. Select a wavelength for the test as described above.
Plot the results (in ABS or %Transmittance) versus concentration to create a calibration curve. The calibration curve may then be used to identify the concentration of an unknown sample by testing the unknown, reading Absorbance or %T, and finding the corresponding concentration from the curve. The linear range of the reagent system can be determined and this information can be used to input a User Test into the SMART 2 Colorimeter (see EDIT USER TESTS, page 34).
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PROCEDURE
1. Prepare 5 or 6 standard solutions of the factor being tested. The concentration of these standards should be evenly distributed throughout the range of the reagent system, and should include a 0 ppm standard (distilled water). For instance, the solutions could measure 0, 10%, 30%, 50%, 70%, and 90% of the system’s maximum range.
2. Turn on the SMART 2 Colorimeter. Select the appropriate wavelength from the absorbance mode. Be sure to select the appropriate wavelength for the color produced by the reagent system.
3. Use the unreacted 0 ppm standard to standardize the colorimeter by using it to scan blank.
4. Following the individual reagent system instructions, react each standard solution beginning with 0 ppm. Continue with standards in increasing concentration. Record the reading and the standard solution concentration on a chart. Readings can be recorded as percent transmittance (%T) or absorbance (A).
11 SMART 2 COLORIMETER OPERATOR’S MANUAL
5. Plot results on graph paper or computer using any available plotting
0
1
10
100
1 2 3 4 5 6
Concentration in ppm
%T vs. Concentration
CALIBRATION CURVE
891070
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
1 2 3 4 5 6
Concentration in ppm
Absorbance vs. Concentration
CALIBRATION CURVE
89107
program. If results are as %T versus concentration, semilog graph paper must be used. Plot the standard solution concentrations on the horizontal, linear axis, and the %T on the vertical, logarithmic axis. If results are as absorbance versus standard solution concentration, simple linear graph paper can be used. Plot the standard solution concentration on the horizontal axis, and the absorbance on the vertical axis.
6. After plotting the results, draw a line, or curve, of best fit through the plotted points. The best fit may not connect the points. There should be approximately an equal number of points above the curve as below the curve. Some reagent systems will produce a straight line, while others produce a curve. Many computer spreadsheet programs can produce the curve of best fit by regression analysis of the standard solution data.
NOTE: Only reagent systems which produce a straight line can be used for a User Test.
A sample of each type of graph appears below:
SMART 2 COLORIMETER OPERATOR’S MANUAL 12
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PREPARING DILUTE STANDARD SOLUTIONS
Standard solutions should be prepared to create a calibration curve. Standard solutions can be prepared by diluting a known concentrated standard by specified amounts. A chart or computer spreadsheet can be created to determine the proper dilutions. Use volumetric flasks and volumetric pipets for all dilutions.
1. In Column A – Record the maximum concentration of test as determined by the range and path length.
2. In Column B – Record the percent of the maximum concentration the standard solution will be.
3. In Column C – Calculate the final concentration of the diluted standard solutions by multiplying the maximum concentration (In Column A) by the % of maximum concentration divided by 100. (C = A x
B
).
100
4. In Column D – Record the final volume of the diluted sample (i.e. volume of volumetric flask).
5. In Column E – Record the concentration of the original standard.
6. In Column F – Calculate the milliliters of original standard required
(C x
D
E
= F).
A sample chart appears below:
A B C = A x
B
I 00
D E F = C x
Final
Maximum
concentration
of test
% of
Maximum
concentration
concentration
of Diluted
Standard
Volume of
Standard
Concentration
of Original
Standard
Standard Required
10.0 ppm 90 9.0 ppm 100 mL 1000 ppm 0.90 mL
10.0 ppm 70 7.0 ppm 100 mL 1000 ppm 0.70 mL
10.0 ppm 50 5.0 ppm 100 mL 1000 ppm 0.50 mL
10.0 ppm 30 3.0 ppm 100 mL 1000 ppm 0.30 mL
10.0 ppm 10 1.0 ppm 100 mL 1000 ppm 0.10 mL
10.0 ppm 0 0 ppm 100 mL 1000 ppm 0 mL
mL of
Original
D
E
STANDARD ADDITIONS
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A common method to check the accuracy and precision of a test is by standard additions. In this method a sample is tested to determine the concentration of the test substance. A second sample is then “spiked” by the addition of a known quantity of the test substance. The second sample is then tested. The determined concentration of the spiked sample should equal the concentration of the first plus the amount added with the spike. The procedure can be repeated with larger and larger “spikes.” If the determined concentrations do not equal the concentration of the sample plus that added with the “spike”, then an interference may exist.
13 SMART 2 COLORIMETER OPERATOR’S MANUAL
For example, a 10.0 mL water sample was determined to contain 0.3 ppm iron. To a second 10.0 mL sample, 0.1 mL of 50 ppm iron standard was added. The concentration of iron due to the “spike” was (0.10 mL x 50 ppm)/10.0 mL =
0.50 ppm. The concentration of iron determined in the spiked sample should
be 0.3 + 0.5 = 0.8 ppm iron. (Note: any error due to the increased volume from the “spike” is negligible).
LaMotte offers a line of calibration standards which can be used to generate calibration curves and perform standard additions.
SAMPLE DILUTION TECHNIQUES
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& VOLUMETRIC MEASUREMENTS
If a test result using the SMART 2 Colorimeter gives an OVERRANGE message then the sample concentration could be over range or under range. If it is over range, the sample must be diluted. Then the test should be repeated on the diluted sample to obtain a reading which is in the concentration range for the test. (Note: This is not true for colorimetric determination of pH.)
Example:
Measure 5 mL of the water sample into a graduated cylinder. Add demineralized water until the cylinder is filled to the 10 mL line. The sample has been diluted by one-half, and the dilution factor is therefore 2. Perform the test procedure, then multiply the resulting concentration by 2 to obtain the test result.
The following table gives quick reference guidelines on dilutions of various proportions. All dilutions are based on a 10 mL volume, so several dilutions will require small volumes of the water sample. Graduated pipets should be used for all dilutions.
Deionized Water to Bring
Size of Sample
10 mL 0 mL 1
5 mL 5 mL 2
2.5 mL 7.5 mL 4 1 mL 9 mL 10
0.5 mL 9.5 mL 20
Volume to 10 mL Multiplication Factor
If the above glassware is not available, dilutions can be made with the colorimeter tube. Fill the tube to the 10 mL line with the sample then transfer it to another container. Add 10 mL volumes of demineralized water to the container and mix. Transfer back 10 mL of the diluted sample to the tube and follow the test procedure. Continue diluting and testing until a reading, which is in the concentration range for the test, is obtained. Be sure to multiply the concentration found by the dilution factor (the number of total 10 mL volumes used).
Example: 10 mL of sample is diluted with three 10 mL volumes of demineralized water;
the dilution factor is four.
SMART 2 COLORIMETER OPERATOR’S MANUAL 14
INTERFERENCES
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LaMotte reagent systems are designed to minimize most common interferences. Each individual test instruction discusses interferences unique to that test. Be aware of possible interferences in the water being tested.
The reagent systems also contain buffers to adjust the water sample to the ideal pH for the reaction. It is possible that the buffer capacity of the water sample may exceed the buffer capacity of the reagent system and the ideal pH will not be obtained. If this is suspected, measure the pH of a reacted distilled water reagent blank using a pH meter. This is the ideal pH for the test. Measure the pH of a reacted water sample using the pH meter. If the pH is significantly different from the ideal value, the pH of the sample should be adjusted before testing.
Interferences due to high concentration of the substance being tested, can be overcome by sample dilution (see page 14).
STRAY LIGHT INTERFERENCE
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When scanning samples in 16 mm tubes, such as COD, the sample chamber lid can not be closed. The COD adapter minimizes stray light. To further reduce stray light interference, do not scan sample in direct sunlight.
15 SMART 2 COLORIMETER OPERATOR’S MANUAL
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