EnzLab    Tips and Tricks

We would be very pleased to receive your comments and tips for working with EnzLab. If you agree, your information will be posted on this list.

(1)  Change of Factor for a Different Concentration Unit
The user guide and the online help state that the analytical factor must be changed within the method if a different concentration unit is applied. The standard factor is valid for the standard units g/L and %. For the other listed units, the standard factor must be multiplied by a factor as summarized below:
            mg/L                * 1000
            mg/mL            unchanged
            g/mL             * 1000
            ppm                * 10 6

(2) Additional Functions in Operation Hints
Several methods require an incubation of the cells (e.g. 15 minutes at 37 C for ascorbic acid). If this time is set as the wait time, the measurement of Ex will start immediately after this time has elapsed. When working with a cell changer, this requires that the user remove the cells from the thermostat and insert them in the spectrometer beforehand. There are 2 options to avoid possible errors:
 –  The wait time is set to zero. This requires that the user control the incubation time with an additional stopwatch. The analysis is started, or continued, by following the appropriate prompt.
 –  The incubation time is entered as the wait time in the method. Additionally the corresponding operation hint is extended by a double arrow (>>) with an additional text. The >> characters will halt the system and present the usual ‘Proceed’ button. Any message after the >> characters is displayed, e.g. ‘Place cells in the spectrometer’. This option is not yet described in the software documentation but can be checked with the Ascorbic Acid method. This option is not applicable if addition of another reagent is necessary after incubation.

(3) Modifications of Sample Volume and Test Volume
EnzLab allows the sample volume to be varied, since the analytical factor does not include the sample volume. However it does include the total test volume so that it is necessary to use an appropriate volume of redistilled water according to the change of sample volume. This is as described in the operation procedures. It is recommended that the method operation hints be modified accordingly.
If however the total test volume is modified, e.g. to perform a semi micro assay to save reagents, it is necessary to modify the analytical factor as well:

new factor =  standard factor  * new test volume  /  standard test volume

The sample volume must be entered to EnzLab with its real value.

(4) Alternative file types for data and safety sheets
The test data sheets and safety instructions are contained in EnzLab as PDF-files (Acrobat Reader ®). If these files are addressed, the Acrobat, reader is called.
However also data files of other types can be bundled to the method, e.g. standard PDF-files (Microsoft Word ®) standard txt-files or even sound and video files. All file types are applicable, that are associated to an appropriate execution routine.
To use this option,
- the method has to be edited respectively,
- the file to be presented has to be resident in the procedure subdirectory to the
 method directory
- and the executing software has to be installed.

(5) Sometimes it is requested to document an EnzLab method by a paper printout. There is no function within the software <vers. 4.0 to do that. However EnzLab methods (*.mth) are text files holding the various parameters line by line. A The standard Windows editor can be used to load the files and to print them. The manual describes the contents of the lines in detail.

(6) Boehringer Test-Combinations Nitrate and Sulfite (for potato and vegetable products) require a third reading E3. The difference E3 - E2 is then subtracted from the sample absorbance difference. Actually this is a simplified obligatory creeping correction. EnzLab does not offer exactly this option. However the EnzLab creeping correction can be considered equivalent. It offers the advantage of a shortened measurement time, especially when a constant creeping slope is detected. With version 2.4 it has become possible to switch off the automatic termination of creeping measurements so that always the full 20 min creeping measurements are performed.