FAQ

Use Of Facilities

How to become ENVF registered user?

To become an ENVF registered user, you MUST fulfil the following requirements:

  1. You must be a frequent laboratory user at your department.
  2. You must have completed necessary HSEO Mandatory Safety Training Courses; which are MC07 Chemical Safety I, MC03 Chemical Safety II for analytical equipment, and MC06 Biological Safety, MC05 Pressure Safety (for Autoclave users) for biological equipment. 
  3. Fill In User Registration & Safety Clearance Form
  4. Please send an email to envflab@ust.hk to arrange a time slot with our safety office for safety clearance and completion of registration.
  5. Please also take your time to read the Policies & Rules under ENVF. 

How to become a Qualified User of specific major equipment?

There are two ways to become a Qualified User: 

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 envflab@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.

How frequent training is provided?

Mass session of the trainings are provided in every 1st and 2nd semester. On-demand video training is also offered. Please refer to our training page for details. 

Can I enter ENVF facilities using my HKUST Access Card?

After completing the registration, we will grant your access right to room 4109 and/or Service corridor (Biological Facility) during office hour (09:00 – 17:00) within three working days.

If a user cannot access the facility after the mentioned period, please email envflab@ust.hk or come to room 4112 during office hour to fix the issue.

How to book or view the availability of the equipment?

Please refer to these pages: http://envflab.ust.hk/booking/ or here

Can I work at ENVF after office hour?

For long experiments that need extended working hours in ENVF Laboratory, please complete the Extended Hour Form and send it to envflab@ust.hk or submit it to Room 4112.

Please observe all the "Additional rules" for working outside office hours specified in the Policies and Rules.

How can I request ENVF Services?

You can submit a service request through the "General Request 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 envflab@ust.hk or drop by Room 4112 for discussion before issuing the service request.

How can I contact ENVF?

You can contact ENVF via the following emails.

Equipment Related FAQs

Energy Dispersive X-Ray Fluorescence (EDXRF)

There is no familiarisation course for EDXRF. How can I analyse the sample using this equipment?

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. 

Please contact and discuss with our staff the measurement requirements before submitting the sample or raising the request.

Do I need to prepare the sample for EDXRF measurement?

ENVF only provide the measurement service, and we will not provide sample preparation. Please discuss your sample type and how to prepare your sample with our staff first.

Can I quantify the elements in my sample?

Yes, if the user can provide standards with the same physical form and similar matrix, the measurement accuracy will be good—for example, steel measurement against a calibration of a series of known elements concentration steel standards.

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.

Is EDXRF measurement non-destructive to the sample?

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.

Inductively Coupled Plasma - Optical Emission Spectrophotometer [Perkin Elmer/Avio 200]

How many samples do I need to place in the autosampler?

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.

What is the detection limit of AVIO 200?

The instrument detection limit of AVIO 200 is in the low µg/L range for most elements when it is operated in axial view, whereas it is in the high µg/L range when it is conducted in radial view.

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).

What concentration range of standards should I prepare?

The concentration range of standards depends upon elements and the selection of emission lines. The following ranges give the user a rough idea only:

  • Radial view: From 1, to 1000 µg/mL
  • Axial view: From, 0.1 to 100 µg/mL

In the case of a detector, saturation occurs at the concentration range required; the user might select attenuation mode in Syngistix software.

Can I measure the elements in the oil sample without digestion?

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.

Can I measure hydride forming elements in order to achieve a lower detection limit (about 5-10 times lower than axial view)?

Yes, our AVIO200 is equipped with a vapour generation unit. Please inform ENVF staff to configure the vapour generation unit prior to your analysis.

If my sample is digested with HF, can I use it with the AVIO 200 ICP?

Yes, please use all plastic sample introduction system Ryton Scott Spray chamber. The glass cyclone spray chamber cannot be used. Please ask ENVF staff for help if you are not sure.

Can I aspirate seawater sample directly into AVIO 200 ICP?

The default aqueous cross-flow nebuliser can handle dissolve solid up to 5%, and so a typical seawater sample (~3.5 % dissolve solid) can be introduced into AVIO 200 without the need for dilution.

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.

The detection of my analytes that have emission lines below 200 nm is poor. How to resolve this?

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).

I found my results always higher/lower than expected. What is the problem?

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.

Do ENVF provide ICP standards or consumables?

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.

On the other hand, gas, Type I reagent water and sample tubing that are necessary for the instrument operation and items that are shared by users will be provided without additional charge.

Gas Chromatograph (including Mass Selective Detector System both EI and CI, ECD, FID)

Can I use GC to separate and measure alcohol or other organic compounds with a carbon number equal to or less than C2?

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.

Can I measure volatile organic compounds (VOCs) in an aqueous solution using the GCMS or GC-FID, GC-ECD?

Yes, you can use our headspace sampler to extract the VOCs from water and inject them into the GCs system automatically.

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.

Why ENVF require the user to use its own injector liner?

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.

Will ENVF provide solvent for needle washing?

No, ENVF will not provide solvent for needle washing. User needs to prepare their solvents.

What type of consumables will be provided by ENVF?

Gas that is necessary for the instrument operation, such as carrier, reagent and makeup gas, will be provided.

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 µm 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.

Why do we need to derivatise the sample in some applications when using GC as the measurement technique?

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.

How long does it take to change a GC column in the GCMS system?

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.

ENVF recommend waiting overnight before tuning the MS system again.

For GC with ECD and FID, the time requires to change the column is about 2 to 4 hours, including the cooling and heating time of the inlet and detector.

Can I tune the MS myself?

Yes, the tuning is automatically after the user has invoked the procedures through the software menu/button.

Why do I need to check for air leak in MS before analysis?

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.

UV/VIS/NIR Spectrometer

Is there any temperature control for the integrating sphere?

No, there is no temperature control for the integrating sphere. The temperature control that comes with the system is only used with a liquid sample compartment.

What is the specimen size when performing reflectance measurement?

The size of the sample should be larger than 24 mm diameter when no custom made mask has been used.

User can make a custom sample mount and mask for a sample with a size smaller than 24 mm.

Does ENVF have a mount for the sample in the transmittance and the reflectance port?

ENVF do not provide any mount for a sample that can be installed in these ports as different sample shape or form requires different mounting methods.

My spectrum below 200 nm is very noisy. How to resolve this?

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).

Scanning Electron Microscope with EDX System

What is the maximum size of the sample that can be placed in Hitachi TM3030 SEM?

Sample with dimensions as large as 70 mm diameter and 50 mm thick can be handled by this microscope.

What sample requirements should be met before it can be examined by this SEM?

Sample must be conductive, vacuum insensitive and non-magnetised unless the user has a specific device to shield/hold the samples and conduct the electron away to tackle the charge up phenomenon.

What is vacuum sensitive sample?

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.

How to prepare the sample so that it can meet the sample requirements?

Please refer to the ENVF's familiarisation training handout for details.

Do I need to coat gold on the sample for SEM?

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.

Can I use EDX setting to view my sample?

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.

We would also like to know whether the SEM/EDX can detect the boron element.

Yes, according to the datasheet. The EDX system can measure Boron. 

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.

Please check for the depth of analysis of elements. 

TOC System

Which chemicals are used to be the standard for water and solid sample?

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.

Should we prepare and refill the IC reagent?

Yes! IC reagent should be checked and refilled before starting. IC reagent is 17% Phosphoric acid.

Should we use distilled or deionised water for the water tank?

Milli-Q water is used only which the TOC value is lower than 0.1 ppm.

What is the suitable sample vials for water samples?

Only one size of sample table for this TOC model, the glass sample vial is 24 ml in volume and 85mm Height x 23mm OD in size.

How can I analyse Nitrogen content in a solid sample? 

No! In this model, there are no such devices for nitrogen analysis in a solid sample.

What size of sample boat should be used for a solid sample?

In this model, only a 1-inch ceramic sample boat is used, which should be obtained from Hong Kong dealer - Comfort Technology Ltd.

Should I get the user manual?

Yes! It would send it to you after video training and as requested.

Does the water sample has been filtering before analysis?

It should be better if any suspended particles could be seen. The sampling line will be blocked if large particles are in.

 

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