Mystrica colorimeter Simple, robust design Versatile use as stand-alone or through a computer Performance criteria that rival instruments many times the price Choice of three colours of light Readings displayed as absorbance or transmittance Long battery life USB link displays and stores results as tables and graphs Fully supported suggestions for practical activities at www.mystrica.com 1 2 Applications The unit is intended primarily for applications in secondary science education, particularly for Biology and Chemistry. Detailed suggestions for practicals can be found at www.mystrica.com and include:
investigations with enzymes effects of temperature, pH, inhibitors enzyme kinetics quantitative determination of biological molecules sugars, protein, vitamins, etc quantitative determination of inorganic ions nitrate, phosphate, etc population growth of micro-organisms and others The colorimeter is suitable for educational use. for clinical, commercial or research applications. intended is not It 3 Controls The power switch turns the unit on. The unit switches off after 30 seconds to conserve battery power. It can be kept on indefinitely by holding the power switch down. When the unit is connected to a computer through the USB cable it stays on all the time so this switch does nothing. CAL calibrates the unit to 0.000 Absorbance or 100.0% Transmittance RGB switches between the red, green and blue light sources A/T switches display between Absorbance and Transmittance 4 Display Cuvettes The samples to be measured are placed in standard 4.5ml glass or plastic cuvettes. The length of the light path is 10mm. Satisfactory results can be obtained with volumes down to 1ml. For lower volumes semi-
micro cuvettes can be used but the unit is not intended for semi-micro or micro applications. Some cuvettes have four clear faces. Most have two clear faces and two frosted or ribbed faces. The clear faces must be aligned with the light path, (i.e. across the unit parallel to the display). The unit is supplied with ten plastic cuvettes with lids and one cuvette stand. Additional cuvettes, lids and cuvette stands are available through www.mystrica.com 5 6 Power supply The unit uses 6V from four AA batteries. These are inserted by removing the screw on the battery holder. When the batteries need to be replaced the display will show ba t on startup. Battery life for 1000mAh AA batteries is estimated at 100 hours of continuous use. Since this would be 36,000 readings of 10 seconds each, battery replacement should be a very rare event. When connected to a computer through the USB link the unit draws its power through the link and is permanently on. Connecting to a computer The unit connects to a computer through the mini USB connector shown. In this mode the unit is always on and the power switch has no function. The USB link allows data from the unit to be displayed on the computer as tables or graphs using the software provided. Data can be displayed and stored as separate events or as a continuous data stream. 7 8 How the colorimeter works How to use the colorimeter The light source is one of three light emitting diodes,
(LEDs), which provide Red
(~630nm), Green
(~525nm) or Blue (~465nm) light. The light passes through the sample in the cuvette and is detected by a photodiode. Transmittance is a measure of the intensity of light passing through the sample, or an indication of the amount of light energy passing through. There is a simple linear relationship between transmittance and intensity which can be expressed as:
I T = /
Io Io where Io is the intensity of the light entering the sample and I is the intensity of light coming out of the sample. This value is usually given as a percent. Absorbance is defined as log10( / ), or 2 log10T%
There is a linear relationship, (Beers Law or the Beer-Lambert Law), between absorbance and the concentration of the light-absorbing substance in the sample. is determined by concentration and by the length of the light path through the sample. For most experiments in biology and relationship with concentration makes absorbance the measurement of choice. fact absorbance chemistry linear the In I Calibration This sets the value of a predetermined solution, (the blank), to 100% transmittance, or an absorbance of 0. The blank would usually be pure water though this is not necessarily the case. Press the power switch , (unless you are using the USB link), and select the colour of light you want to use by pressing RGB. Select absorbance or transmittance by pressing A/T Insert a cuvette containing the blank in the colorimeter. Make sure the clear faces are aligned with the light path. Press CAL. The display will show C A L for a few seconds, then either .000 (A), or 100.0 (T). Taking readings
Replace the blank with a cuvette containing the liquid you want to measure, close the cap, press the power switch, (if the unit has switched off) and read the value from the display. The colorimeter will switch off automatically after 30 seconds to conserve battery power. The settings are retained so when you want to take a reading you just need to press the power switch, there is no need to recalibrate or to try to rush through all the operations before the unit switches off. This does not apply when the unit is connected to a computer through the USB link, in this case it will stay switched on indefinitely. 9 10 Light path Cuvette alignment Cuvettes may have four clear faces, but many have two clear and two frosted or ribbed faces. If the cuvette has two clear faces these must be aligned in the same direction as the light path, i.e. across the unit parallel to the display. Make sure the clear faces are clean and remove bubbles that may interfere with the light path by tapping the cuvette. Warming up Temperature changes will cause variations in readings, though these are small and will be insignificant for most uses. Avoid using the unit in direct sunlight. When the colorimeter is connected through the USB link it is permanently on and will gradually warm up over the first ten minutes. This is likely to cause a small drift in the calibration value, typically about 2% T, 0.001A To minimise the effect of temperature frequent recalibration is advisable:
when working in an environment where the temperature is not constant
when there is a lengthy interval between readings
when measuring small changes at low absorbance, (high transmission). 11 Software The software is FREE to DOWNLOAD see www.mystrica.com Using the colorimeter connected to a computer by the USB link you can:
set up project and experiment files to collect and store results
display and store data as tables and graphs
collect data as a continuous stream or as separate events
carry out simple data manipulations such as calculating rates of reaction and lines of best fit
copy data into more sophisticated data analysis applications such as Excel or Autograph 12 System requirements
Windows 2000, XP,Vista, Windows 7 or 8 with the .NET Framework 2.0 or later installed To install the software follow the on-screen instructions.
[The driver USBUART.inf for the colorimeter is included with the software and should install automatically. If it does not install use the Browse option in the Found New Hardware Wizard to locate it in the folder Program Files/Mystrica Ltd/Mystrica Colourimeter/Driver. ]
The programme screens display information as shown below. colorimeter settings and value list of experiments and result sequences in the current project folder result sequences displayed as tables or graphs Creating a new project A project folder contains a set of related experiments. Each experiment can contain any number of sequences of data. The name of a project could be for example the name of the person whose work this is or a general title for a set of related experiments. The first time you start the programme an empty project folder is opened, (called 'Colorimeter Project' -
right click on this folder to rename it). Subsequently the programme will always open with the project folder that was last used. The 'Files' option on the menu bar can be used to create a new project, to select and open an existing project, and to save the current project. Project folder The left side of the screen displays, below the current readings and settings from the colorimeter, a list of the experiments and data sequences contained in the project folder, (double click the project folder and experiment files to view these). 13 14 Creating a new experiment Right click on New Experiment. The box shown below will appear and you can enter a title and any other information. folder and click the project The experiment file can contain any number of sequences of results collected from the colorimeter. Continuous readings When you select New Continuous Reading the box show below appears. You can enter a name for the sequence of results you are about to collect, the data and time are optional but it is usually good practice to leave these. The Description box can be used to give details of the sequence, concentrations of reactants, temperature, pH, etc. Preparing to collect data Right click the experiment file. The box shown below will appear. If you select New Continuous Reading you will be able to collect data in a continuous stream for however long you set. New Separate Events allows you to capture and store only the current value from the colorimeter. When you click Next the box show below appears. Use this to enter the length of time you want to collect data for, (Hours/Minutes/Seconds), and the interval between data points. Click Next then on the next page click Take Readings to start collecting data. 15 16 Displaying results as Tables or Graphs Separate Events The data can be displayed as a table or graph, (except when text is entered using Separate Events). In graph view you can select to display the y-axis as either Transmittance or Absorbance and to join the points with straight lines, curves or not at all. Data collection can be stopped prematurely, discarded or saved by clicking the labelled buttons. Select Grid or Graph Graph as Absorbance or Transmittance Click here to take readings The procedure for Separate Events is similar to that for Continuous Readings except that you will be asked to select whether the readings should be associated with a numerical value or with text. If numeric the data captured can be displayed as a graph with the numeric values on the x-axis. If text the readings will only appear as a table. When you click Take Readings only the current value from the colorimeter will be recorded as a single, discrete entry. Drawing lines of best fit A straight line of best fit can be drawn through any number of points on a graph. Select the points by clicking them then click 'Draw Best Fit Line'. The equation will be displayed in the form y = ax + b where a is the slope of the line and b is the intercept of the line on the y axis. More information about using the software can be found at www.mystrica.com/Software 17 18 Mystrica Ltd www.mystrica.com email: enquiries@mystrica.com copyright 2013 mystrica ltd 19 20 FCC statements:
This device complies with part 15 of the FCC rules. Operation is subject to the following two conditions: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation. NOTE: The manufacturer is not responsible for any radio or TV interference caused by unauthorized modifications or changes to this equipment. Such modifications or changes could void the users authority to operate the equipment. NOTE: This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation. This equipment generates uses and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
Reorient or relocate the receiving antenna. Increase the separation between the equipment and receiver. Connect the equipment into an outlet on a circuit different from that to which the receiver is connected. Consult the dealer or an experienced radio/TV technician for help.