LaMotte SMART Spectro User manual

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SMART
Spectro
Spectrophotometer
OPERATOR’S
MANUAL
LMott
v2.2 • Printed-04.08
2000-MN

TABLE OF CONTENTS
GENERAL INFORMATION
Packaging & Delivery ······································································5
General Precautions ········································································5
Safety Precautions ···········································································5
Limits of Liability ·············································································5
Limited Warranty··············································································6
Limitations························································································6
Specifications ···················································································6
Statistical and Technical Definitions
Related to Product Specifications··················································· 7-8
Contents and Accessories·································································8
EPA Compliance ··············································································9
CE Compliance·················································································9
Declaration of Conformity································································ 9
CHEMICAL TESTING
Water Sampling for Chemical Analysis ··········································· 10
Filtration ··························································································11
An Introduction to Colorimetric Analysis & Spectroscopy ············ 12
Reagent Blank ·················································································13
Spectrophotometer Tubes ································································13
Selecting an Appropriate Wavelength ············································· 13-14
Calibration Curves ···········································································14-15
Preparing Dilute Standard Solutions················································ 16
Standard Additions ··········································································16
Sample Dilution Techniques & Volumetric Measurements ············ 17
Interferences ····················································································18
Stray Light Interference ···································································18
OPERATION OF THE SMART SPECTRO SPECTROPHOTOMETER
Overview ·························································································19
Power Supply ····················································································19
Components ····················································································20
Quick Start ······················································································21-22
GENERAL OPERATING PROCEDURES
The Keypad ······················································································23
Sample Holders·················································································23
The Display & the Menus ·······························································24
CALIBRATION
Calibrate Wavelength ······································································25
PROGRAMMED TESTS
Introduction ·····················································································26
Sequences of Tests ···········································································27
General Testing Procedures ····························································· 28
SMART SPECTRO SPECTROPHOTOMETER 10.07 3

TABLE OF CONTENTS (cont.)
Testing with the Programmed Tests ················································· 28-29
SETUP & EDIT SEQUENCES & USER TESTS
Edit a Sequence ···············································································30
Adding or Deleting Tests ·································································31-33
Edit User Tests ·················································································34-35
Naming the Test ··············································································36
Selecting the Wavelength ································································37
Entering a New Calibration ·····························································398-40
Selecting the Numerical Format of the Result ································ 41-42
MEASURING IN THE %T/ABS MODE
········································································································43-44
PC LINK
Output ·····························································································45
Computer Connection ·····································································45
EDIT CLOCK
········································································································45
ENERGY MODE
········································································································45
STORE METHOD
········································································································45
TEST MODE
········································································································46
BATTERY OPERATION
Charging the Batteries ·····································································46
Running the SMART Spectro Using Batteries ································ 46
MAINTENANCE
Cleaning ···························································································47
Light Bulb ························································································47
Clock Battery ···················································································47
Meter Disposal··················································································47
TROUBLESHOOTING GUIDE
Error Messages ·················································································47-48
Helpful Hints ···················································································48
SMART REAGENT SYSTEMS
Available Test Kits ············································································49-51
SMART SPECTRO TEST INSTRUCTIONS
APPENDIX
4 SMART SPECTRO SPECTROPHOTOMETER 10.07

GENERAL INFORMATION
nPACKAGING & DELIVERY
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.
nGENERAL PRECAUTIONS
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 Spectro should not be stored or used in a wet or corrosive
environment. Care should be taken to prevent water or reagent chemicals from
wet spectrophotometer tubes from entering the SMART Spectro chamber.
NEVER PUT WET TUBES IN SPECTROPHOTOMETER.
nSAFETY PRECAUTIONS
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 Technique
nLIMITS OF LIABILITY
Under no circumstances shall LaMotte Company be liable for loss of life,
property, profits, or other damages incurred through the use or misuse of their
products.
SMART SPECTRO SPECTROPHOTOMETER 1.06 5

nLIMITED WARRANTY
This instrument is guaranteed to be free from defects in material and
workmanship for a period of one (1) years from original purchase date. In the
event that a defect is found during the warranty time frame, LaMotte Company
agrees that it will be repaired or replaced without charge except for the
transporation costs. This guarantee does not cover batteries.
This product can not be returned without a return authorization number from
Lamotte Company. For warranty support or a Return Authorization Number,
contact LaMotte Company at 1-800-344-3100 or tech @ lamotte.com.
nLIMITATIONS
This guarantee is void under the following circumstances:
• Damage due to operator negligence, misuse, accident or improper application.
• Damage or alterations from attempted repairs by an unauthorized
(non-LaMotte) service.
• Damage due to improper power source, AC adapter or battery.
• Damage caused by acts of God or natural disaster.
• Damage occurred while in transit with a shipping carrier.
LaMotte Company will service and repair out-of warranty products at a nominal
charge.
nSPECIFICATIONS
nINSTRUMENT TYPE: Colorimeter
Readout Graphical 4 line, 16 character per line LCD
Wavelengths 430nm, 520 nm, 570 nm, 620 nm
Wavelength Accuracy ±2
Readable Resolution Determined by reagent system
Wavelength Bandwidth 10 typical
Photometric Range –2 to + 2AU
Photometric Precision ± 0.001AU at 1.0AU
Photometric Accuracy ± 0.005AU at 1.0AU
Sample Chamber Accepts 25 mm diameter flat-bottomed test tubes, 10 mm square cuvettes, 16 mm COD test tubes
Light Sources 4LEDs
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 mini-DIN, 9600b, 8, 1, n
Power Requirements Battery Operation: 9 volt alkaline, Line Operation: 110/ AC; 50/60 Hz with adapter, 6V 500 mA
DC
Dimensions (LxWxH) 8.5 x 16.2 x 6.7 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
6 SMART SPECTRO SPECTROPHOTOMETER 10.07

nSTATISTICAL AND TECHNICAL DEFINITIONS RELATED
TO PRODUCT SPECIFICATIONS
Method Detection Limit (MDL): “The method detection limit (MDL) is
defined as the minimum concentration of a substance that can be measured and
reported with 99% confidence that the analyte concentration is greater than
zero and is determined from analysis of a sample in a given matrix containing
the analyte.”1Note that, “As Dr. William Horwitz once stated, ‘In almost all
cases when dealing with a limit of detection or limit of determination, the
primary purpose of determining that limit is to stay away from it.’”2
1. CFR 40, part 136, appendix B
2. Statistics in Analytical Chemistry: Part 7 – A Review, D. Coleman and
L Vanatta, American Laboratory, Sept 2003, P. 31.
Precision: Precision is the numerical agreement between two or more
measurements.3The precision can be reported as a range for a measurement
(differencebetweentheminandmax).Itcanalsobereportedasthestandard
deviation or the relative standard deviation. It is a measure of how close
together the measurements are, not how close they are to the correct or true
value. The precision can be very good and the accuracy very bad. This is a useful
measure of the performance of a test method.
3. Skoog,D.A.,West,D.M.,Fundamental of Analytical Chemistry, 2nd ed.,
Holt Rinehart and Winston, Inc, 1969, p. 26.
Accuracy: Accuracy is the nearness of a measurement to the accepted or true
value.4The accuracy can be expressed as a range, about the true value, in which
a measurement occurs (i.e. ±0.5 ppm). It can also be expressed as the %
recovery of a know amount of analyte in a determination of the analyte (i.e.
103.5 %). This is a useful measure and what most customers are interested in when
they want to know about the performance of a test method.
4. SkoogD.A.,WestD.M.,Fundamental of Analytical Chemistry, 2nd ed.,
Holt Rinehart and Winston, Inc, 1969, p. 26.
Resolution: Resolution is the smallest discernible difference between any two
measurements that can be made.5Formetersthisisusuallyhowmanydecimal
places are displayed. (i.e. 0.01). For titrations and various comparators it is the
smallest interval the device is calibrated or marked to (i.e. 1 drop = 10 ppm, 0.2
ppm for a DRT, or ±half a unit difference for an octaslide or color chart). Note
that the resolution many change with concentration or range. In some cases the
resolution may be less than the smallest interval, if it is possible to make a
reading that falls between calibration marks. This is often done with various
comparators. One caveat is, that resolution has very little relationship to accuracy or
precision. The resolution will always be less than the accuracy or precision but it is not
a statistical measure of how well a method of analysis works. The resolution can be
very very good and the accuracy and precision can be very, very bad! This is not a
useful measure of the performance of a test method.
5. Statistics in Analytical Chemistry: Part 7 – A Review, D. Coleman and
L Vanatta, American Laboratory, Sept 2003, P. 34.
SMART SPECTRO SPECTROPHOTOMETER 05.04 7

Sensitivity: Sensitivity is the resolution based on how this term is used in
LaMotte catalogs. This term is not listed in any of the references. Sometimes it
is used for detection limit. It is a confusing term and should be avoided.
Repeatability: Repeatability is the within-run precision.6A run is a single
data set, from set up to clean up. Generally, one run occurs on one day.
However, for meter calibrations, a single calibration is considered a single run or
data set, even though it may take 2 or 3 days.
6. Jeffery G. H., Basset J., Mendham J., Denney R. C., Vogel’s Textbook of
Quantitative Chemical Analysis, 5th ed., Longman Scientific & Technical,
1989, p. 130.
Reproducibility: Reproducibility is the between-run precision.7
7. Jeffery G. H., Basset J., Mendham J., Denney R. C., Vogel’s Textbook of
Quantitative Chemical Analysis, 5th ed., Longman Scientific & Technical,
1989, p. 130.
nCONTENTS AND ACCESSORIES
nCONTENTS
SMART Spectro Spectrophotometer
Te s t Tu b e s , w i t h C a p s
Sample Cell Holder, Universal
Sample Cell Holder, 10 mm Square
Power Cable
Battery Charger
Power Supply, 110/220V
SMART Spectro Quick Start Guide
SMART Spectro Manual
NOTE: The battery pack is not included and must be purchased separately. An
empty slot is placed in the foam packing material for the original shipment.
nACCESSORIES
Battery Pack with Holder (rechargeable) Code 2000-BP
Cigarette Lighter Adapter Code 1917
Carrying Case Code 2000-CS
SMARTLink 2 Software with Cable (3.5 disk) Code 1912-3
SMARTLink 2 Software with Cable (compact disk) Code 1912-CD
8 SMART SPECTRO SPECTROPHOTOMETER 05.04

nEPA COMPLIANCE
The SMART Spectro 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.
nCE COMPLIANCE
The SMART Spectrophotometer has been independently tested and has earned
the European CE Mark of Compliance for electromagnetic compatibility and
safety.
SMART SPECTRO SPECTROPHOTOMETER 05.04 9
Application of Council Directives:
Standards to which Conformity Declared:
Manufacturer's Name:
Manufacturer's Address:
Type of Equipment:
Model Name:
Year of Manufacture:
Testing Performed By:
89/336/EEC
EN61326-1:97, EN61000-3-2:1995,
EN61000-3-3:1995
802 Washington Avenue
PO Box 329
Chestertown, MD 21620
Spectrophotometer
SMART Spectro
2000
Intertek Testing Services
40 B Commerce Way
Totowa, NJ 07512
LaMotte Company
I, the undersigned, hereby declare that the equipment specified above
conforms to the above Directive and Standards.
Place
Chestertown, Maryland
Date
12/01/00
Signature
Name
Scott H. Steffen
P
os
iti
o
n
Director of Product Development
DECLARATION OF CONFORMITY

CHEMICAL TESTING
nWATER SAMPLING FOR CHEMICAL ANALYSIS
nTaking Representative Samples
Theunderlyingfactortobeconsideredforanytypeofwatersamplingiswhether
or not the sample is truly representative of the source. To properly collect a
representative sample:
lSample as frequently as possible.
lCollect a large sample or at least enough to conduct whatever tests are
necessary.
lMake a composite sample for the same sampling area.
lHandle the sample in such a way as to prevent deterioration or
contamination before the analysis is performed.
lPerform 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.
lMake 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.
nSampling 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.
This weighted device is lowered to the sampling depth and allowed to rest at
10 SMART SPECTRO SPECTROPHOTOMETER 05.04

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,
thedevicehasflusheditselfapproximately 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.
nSampling 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.
nFILTRATION
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 SPECTRO SPECTROPHOTOMETER 05.04 11

nAN INTRODUCTION TO COLORIMETRIC ANALYSIS
& SPECTROSCOPY
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 LaMotte
SMART Spectro 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 or spectrophotometer 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
thetestsampleismostsensitive,wewouldseealargedifferencebetweenthe
light before it passes through the sample and after it passes through the sample.
The SMART Spectro uses a quartz halogen lamp as the source of white light.
The white light passes through an entrance slit and is focused on a ruled grating
consisting of 1200 lines/mm. The grating causes the light to be dispersed into its
various component wavelengths. The monochromator design allows the user to
select which specific wavelength of interest will be passed through the exit slit
and into the sample. The use of mirrors and additional filters prevents light of
undesired wavelengths (overtones, stray light) from making it to the sample. A
photodetector measures the amount of light which passes through the sample.
The difference in the amount of monochromatic light transmitted through a
colorless sample (blank) and the amount of monochromatic light transmitted
through a test sample is a measurement of the amount of monochromatic light
absorbed by the sample. In most colorimetric tests the amount of
monochromatic light absorbed is directly proportional to the concentration of
the test factor producing the color and the path length through the sample.
However, for a few tests the relationship is reversed and the amount of
monochromatic light absorbed is inversely proportional to the concentration of
the test factor.
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)
12 SMART SPECTRO SPECTROPHOTOMETER 05.04

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.
nREAGENT BLANK
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.Noteresultof
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.
nSPECTROPHOTOMETER TUBES
Spectrophotometer 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 spectrophoto-
meter 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 spectrophotometer have an index mark to
facilitate this. If possible, use the same tube to SCAN BLANK and SCAN
SAMPLE.
nSELECTING AN APPROPRIATE WAVELENGTH
The most appropriate wavelength to use when creating a calibration curve is
usuallytheonewhichgivesthegreatestchangefromthelowestreacted
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 %T/ABS 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 SPECTRO SPECTROPHOTOMETER 05.04 13

Below is a list of suggested wavelength ranges for the color of the reacted
samples. Use these as a starting point.
Sample
Color
Wavelength
Range
Yellow 350-450
Yellow-Orange 450-490
Orange 490-510
Pink 510-570
Red 570-600
Green and Blue 600-750
nCALIBRATION CURVES
The SMART Spectro contains precalibrated tests for the LaMotte reagent
systems (see page 49). The first step in using a non-LaMotte reagent system with
your SMART Spectro 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 Spectro.
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 Spectro (see EDIT USER
TESTS, page 33).
nPROCEDURE
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 Spectro. Select the appropriate %T/ABS wavelength
from the %T/ABS 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 spectrophotometer by
using it to scan blank.
4. Following the individual reagent system instructions, react each standard
solution including 0 ppm. Record the reading and the standard solution
concentration on a chart. Readings can be recorded as percent
transmittance (%T) or absorbance (A).
14 SMART SPECTRO SPECTROPHOTOMETER 05.04

5. Plot results on graph paper or computer using any available plotting
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.
A sample of each type of graph appears below:
SMART SPECTRO SPECTROPHOTOMETER 05.04 15
0
1
10
100
123456
Concentration in ppm
%T vs. Concentration
CALIBRATION CURVE
%T Transmission
891070
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
123456
Concentration in ppm
Absorbance vs. Concentration
CALIBRATION CURVE
Absorbance
89107

nPREPARING 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 B100).
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 DE=F).
A sample chart appears below:
ABC=Ax
B
I00 DEF=Cx
DE
Maximum
concentration
of test
%of
Maximum
concentration
Final
concentration
of Diluted
Standard
Volume of
Standard
Concentration
of Original
Standard
mL of
Original
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
nSTANDARD ADDITIONS
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.
16 SMART SPECTRO SPECTROPHOTOMETER 05.04

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.
nSAMPLE DILUTION TECHNIQUES
& VOLUMETRIC MEASUREMENTS
If a test result using the SMART gives an OUT OF RANGE! 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
requiresmallvolumesofthewatersample.Graduatedpipetsshouldbeusedfor
all dilutions.
Size of Sample
Deionized Water to Bring
Volume to 10 mL Multiplication Factor
10 mL 0 mL 1
5mL 5mL 2
2.5 mL 7.5 mL 4
1mL 9mL 10
0.5 mL 9.5 mL 20
If the above glassware is not available, dilutions can be made with the
spectrophotometer 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 SPECTRO SPECTROPHOTOMETER 05.04 17

nINTERFERENCES
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.
Chlorine interference can be removed with the use of glycine. Very high levels
of chloramines may interfere if the test result is not read immediately. Oxidized
manganese interferences but can be removed with arsenite. Bromine and iodine
interferes but can be removed with a thioacetamide blank correction.
Interferences due to high concentration of the substance being tested, can be
overcome by sample dilution (see page 16).
nSTRAY LIGHT INTERFERENCE
Normal indoor lighting causes no interference with the SMART. Always be sure
the sample chamber lid is closed when scanning blanks or samples.
18 SMART SPECTRO SPECTROPHOTOMETER 05.04

OPERATION OF THE SMART SPECTRO
nOVERVIEW
The SMART Spectro is a portable, microprocessor controlled, direct reading,
single beam spectrophotometer. It has a 4 line, 20 character liquid crystal display
for alphabetical and numerical messages. The operation is controlled with the
keypad through menu driven software in response to selections shown on the
display.
The test library consists of 100 LaMotte tests (not all 100 may be available at
present) and 25 “User Tests”. The spectrophotometer is also capable of running
%T/Absorbance tests over the entire wavelength range of 350 - 1000 nm. The
LaMotte tests are precalibrated for LaMotte reagent systems. The
spectrophotometer displays the results of these tests directly in units of
concentration. The 25 “User Tests” may be used to enter additional calibrations.
All of these tests may be arranged in any of 3 sequences. These sequences can
be modified a limitless number of times to meet changing testing needs.
The optics feature a quartz halogen bulb as a light source with a minimum life
expectancy of 1000 hours. The incident white light is dispersed into its
component wavelengths by a 1200 lines/mm ruled grating. The microprocessor
controls the positioning of the grating, automatically positioning the grating to
the correct wavelength for the test that has been selected. The monochromatic
light is passed through the sample cell and is detected by a silicon photodiode.
The SMART Spectro is powered by an AC adapter that automatically
recognizes the input voltage (110/220V) and converts it to the 12V needed to
run the instrument. An optional battery pack is available for use where
portability is important. To save power an automatic shut-off feature can be
utilized (Energy Savings Mode).
A RS-232 serial port on the back of the spectrophotometer, and optional
software, allows the spectrophotometer to be interfaced with an IBM compatible
personal computer for real time data acquisition and data storage. This port also
allows an interface with a RS-232 serial printer.
Due to its portability, alternate power sources, and rugged construction, the
SMART Spectro is ideal for lab and field use.
nPOWER SOURCE
To use the SMART Spectro with an AC power supply:
1. Plug the Power Supply into the AC Adapter socket on the back of the
SMART Spectro.
2. Connect the Power Cable to the Power Supply and an electrical outlet.
To use the Battery Pack, see page 45.
SMART SPECTRO SPECTROPHOTOMETER 05.04 19

nCOMPONENTS
Figure 1 shows a diagram of the SMART Spectro and the components.
20 SMART SPECTRO SPECTROPHOTOMETER 05.04
ONEXIT
OFF
ENTER
LAMOTTE
SMART SPECTRO
PRESS ENTER
Scrolling
arrows for
scrolling
between
choices
Turning
off the
spectro
For
making
selections
Display
For
exiting
menus
Scrolling
arrows for
scrolling
between
choices
For
turning
on the
spectro
Chamber
AC
adapter
socket
RS232
serial
port
10mm
square
cell in
Adapter
25mm
round
cell in
Universal
Adapter