Syngistix For Aa Software Manual
Gaby Zenz
1. You must have completed the familiarisation course of the specific major equipment provided by ENVF. User can also make a booking to take individual video training at ENVF Laboratory (RM 4109) during regular office hours.
2. You and your supervisor have completed and signed the User Competent Registration Form and email to env...@ust.hk or submit it to Room 4112 to update your competency. We assume you can operate both hardware and software equipment after signing the competent form.
We only accept services that are environmental related experiments and projects. We reserve the right to decline any service that are beyond our limit. Please email to us env...@ust.hk or drop by Room 4112 for discussion before issuing the service request.
Due to license issue, EDXRF can only be operated by ENVF staff members who registered with Hong Kong Radiation Board. User can submit the sample to us directly and send request using the same procedures of using major equipment.
If a user cannot provide standards with the same form and matrix, the results obtained are semi-quantitative (estimated using the standardless method). There is no guaranty of the accuracy due to the matrix effect and other physical effects such as particle size effect, as uncertainty cannot be estimated.
It is non-destructive to most of the sample that does not vacuum sensitive. If the sample can be affected by vacuum, we can use He medium for the measurement at the expense of sensitivity of some light elements. Please discuss your sample types and requirements with our staff before submitting them to us.
The autosampler accepts a 15ml conical tube. The minimum volume of the sample depends on the user's method requirements. 10 mL will be adequate for a method with a typical measurement time of less than 240 sec per sample.
If the user has only 2 mL or less sample and dilution of selection to the required volume is not an option, the user should seek another technique. In this case, GFAA (Graphite Furnace Atomic Absorption with Zeeman background correction) will be more suitable for metallic elements measurement at such a small sample volume. However, ENVF does not have a GFAA system. Please look for other departments in HKUST for this instrument.
User should note that this is the instrument detection limit (3 standard deviations of signal noise) of typically suggested emission lines, and it is not the method detection limit that depends on the sample matrix, analysis method and the required confidence limit such as LOQ (Limit Of Quantitation) or PQL (Practical Quantitation Limit).
Our system can be changed with an organic torch that can handle non-volatile organic solvents such as kerosene and xylene. User can dilute the oil sample with kerosene and then measure with the organic torch. Of course, users should prepare the element standards in the oil/kerosene matrix and inform ENVF staff to change the torch before booking it. ENVF might revert the torch back to aqueous type by default after the user's usage.
Unlike ICP-MS that can typically handle 0.2% dissolve solid continuously or 0.6% for a short period without the possibility of affecting the MS interface and cause a performance drift, AVIO 200 can handle high dissolve solid, and it is limited by the type of sample introduction system installed in it only.
Check that you have purged with a high flow of nitrogen into the optical system when measurement lines are below 200 nm. Below 200 nm Oxygen, Water and Carbon Dioxide in the air starts to absorb radiation significantly and reduce the emission signal to reach the detector. This is the VUV (Vacuum Ultra Violet) region. Purging the optics with dried nitrogen will significantly improve the signal attenuation due to the air. The nitrogen feature absorption bands become significant at wavelength below 145 nm, which is far below the wavelength range of the instrument (165 - 900 nm).
Please check the spectrum for any spectral interference. Use either Multicomponent Spectral Fitting (MSF) model or inter-element Correction (IEC) to solve the problem in case choosing other emission lines is not an option (such as not sensitive enough). Please refer to the handout from ENVF or the software manual on how to set up these models.
Another issue is the unmatched physical properties of standards and the sample. If the sample contains a surfactant, have viscosity different from the standards or have significant differences in dissolved solid content, please prepare a standard with a similar sample matrix or use the standard addition method to solve the problem.
No, ENVF will not provide ICP standards. ENVF will charge additionally some equipment related consumables that will not be shared by users, such as sample vials used in the autosampler if a user requests these items.
ENVF don't have a column that can separate compounds with a carbon number equal to or less than C2 at near ambient temperature. For this type of application, the suitable column is HP Plot-Q -PT column, PoraPLOT U (0.32mmID or 0.25 mmID X30m with particle trap), DB-ALC1, DB-ALC2 etc. Users should consult the literature to select the suitable column for their applications.
You can buy SPME (Solid Phase Micro Extraction) to extract the organic compounds from water and inject them manually into the GC system if the headspace sampler is not sensitive enough for the analysis or the target organic compound is not that volatile.
Since the GCs in ENVF is a communal system and different users might have different sample types and analysis methods, cross-contamination of injection liner with another user's sample residual is plain to see in the inlet. Hence, for the sake of minimising the possible issues due to cross-contamination, users are encouraged to use their own liner.
ENVF also provide a communal column to the user who does not have their own column. However, ENVF will not have any liability to ensure a contamination-free and low bleeding column. ENVF can provide DB5MS and DB35MS with typical column dimensions (30 m, 0.25 mm ID, 0.25 m film thickness column).
On the other hand, ENVF will charge additionally to some equipment related consumables that will not be shared with other users, such as injector liner, ferrules, nut, sample vials etc., if the user requests these items.
In order to analyse compounds by the GC method, the compounds should be volatile enough at the GC operation temperature. For compounds that are not volatile enough or unstable on heating, they should be derivatised to facilitate analysis by gas chromatography. Sometimes derivatisation might improve the detection (increase the detection sensitivity using a detector such as ECD or stabilise the ions formed in EI mode during MS measurement) and chromatographic behaviour such as broad peak for some compounds. The common derivatisation reactions include acylation, alkylation or silylation. Please refer to the literature for detailed information and procedures.
ENVF's GCMS does not have a fast vent module installed, and so it takes at least one working day to change the column. Unlike other GC detectors, the MS system is under vacuum. It takes about one to two hours for cooling before the MS can be vented and changed with a new column. It takes another two more hours to pump down, and thermal equilibrate the MS system before it can be tuned.
Sometimes an air leak in the GCMS interface will be found after specific GC temperature program thermal cycles. This is especially the case when a new Vespel Graphite ferrule is installed (due to shrinkage of the new ferrule). Air leak will cause premature failure of the detector, contamination of ion source/quadrupole, detection sensitivity issue etc.
Check whether there is any nitrogen purge in the sample compartment and the optical system. Below 200 nm Oxygen, Water and Carbon Dioxide in the air starts to absorb radiation significantly and reduce the emission signal to reach the detector. This is the VUV (Vacuum Ultra Violet) region. Purging the optics and sample compartment with dried nitrogen will significantly improve the signal attenuation due to the air. The nitrogen feature absorption bands become significant at wavelength below 145 nm, far below the instrument's lower operation wavelength range (175 nm).
Since SEM is operated under vacuum, sample with water content (biological sample) or sample with volatile components that will damage the structure due to uncontrolled dehydration/outgassing during the evacuation process are classified as sensitive vacuum sample.
Coating a gold layer is usually required for a non-conducting sample when observed in ENVF's SEM. For a slightly conductive sample, coating a gold layer will improve the image quality even though you can view the specimen under charge reduction mode.
However, if you are plan to do EDX for elemental mapping, you should take into account the effect of the gold layer. A gold layer might interfere with the mapping by overlaying a gold fluorescence signal on top of other elements and sometimes might attenuate the signal coming out of low atomic number elements beneath it.
If the user has another device, solution or apparatus that can minimise the charge up the effect by conducting the electron to the stage, then coating gold is not necessary. ENVF do not provide these types of devices/solution at the present moment.
Yes, it is the same as view the specimen with 15 kV potential energy. However, using EDX observation mode will shorten the life of filament as the current pass to the filament is higher than that of using 15 kV mode. EDX mode is just like shining the specimen using the same wavelength light source that has a higher intensity than that of 15kV mode.
However, due to lower fluorescence energy (especially for a low atomic mass element such as B, C), only boron atoms that are close to the sample surface will be detected. Boron inside the sample cannot be detected.
Three standards could be used for the water sample. Potassium Hydrogen Phthalate is used for Total Carbon, and Sodium Carbonate and Sodium Hydrogen Carbonate are for Inorganic Carbon. Sodium Nitrate is used for Nitrogen content. For a solid sample, two standards could be used. Glucose (40% C) is used for Total Carbon, and Sodium Carbonate (11.3% C) or Sodium Hydrogen Carbonate (14.3% C) is used for Inorganic Carbon.
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