Chromex Scientific Ltd is an organisation dedicated to providing analytical products and services to the scientific community.
Chromex Scientific specialises in the supply and support of HPLC & GC columns and consumables along with a full range of Service plans and Service contracts for most makes of HPLC & GC including LC-MS & GC-MS. We recognise the individual needs of our clients as such we will tailor any Service package to your specific requirements.
We offer a broad range of products at very competitive prices and are committed to only recommending the best product for the job.
We constantly strive to offer the analytical community:
- High Quality Products
- Technical Expertise
- Excellent Customer Service
- Value for Money
Frequently Asked Questions
Why would I use a OneGuard Guard cartridge on my HPLC system and what impact would it have?
The OneGuard HPLC Guard Cartridge system offers one of the most cost effective ways to protect your HPLC column without any impact on your existing chromatography.
When would it be useful to use a pre-slit septum?
A pre-slit septum (a septum cap that already has a small cut in it) is useful when you need easy needle access with minimal coring and consistent resealing, especially in setups that require repeated punctures.
Some main advantages would be they make it easier to insert a syringe needle, reduce coring (small rubber fragments breaking off into the sample) and maintain a good seal after multiple punctures
What membrane should I use in my eXimo syringe filter?
The membrane choice is determined by the solvent you wish to pass through it. Speak to our technical team for guidance.
How often should I change my injector liners?
The short answer is as often as required. This is determined by how dirty your sample is and if you see any changes in the chromatography due to contamination in the liner. If you are involved in high throughput GC analysis you may consider changing your liner as part of a preventative maintenance schedule/programme.
How does the quality of glass in our autosampler vial effect my analysis?
The quality of glass in your autosampler vial can significantly affect analytical accuracy, sensitivity, and reproducibility - especially in trace analysis like LC-MS or GC-MS.
Lower-quality or untreated glass often has more active surface sites. These can bind basic compounds, polar compounds and trace-level analytes therefore resulting in lower peak areas, poor reproducibility, nonlinear calibration curves and apparent instability over time in the vial.
This is especially problematic in LC-MS trace quantitation, peptides, amines, acidic drugs and environmental trace analysis.
What’s the most cost effective way of protecting my expensive HPLC column?
Using a OneGuard HPLC Guard Cartridge system.
Why should I choose a mono-disperse HPLC column for my analysis?
Mono disperse HPLC particles have a narrower particle size distribution therefore offering increased efficiency and narrower peeks than non mono dispersed particles.
I’ve been offered some cheap autosampler vials and the pricing seems too good to be true, is this false economy?
Cheap autosampler vials may work for your analysis with no problems. However, they may be made from lower quality glass and may not have the tight tolerances required by your autosampler which can lead to stoppages and therefore increased costs due to down time. It may be a false economy. ChromaVial are manufactured from higher quality borosilicate glass and offer low extractables, high chemical resistance and low ion leaching.
There seems to be an excessive lead time on the column that I require, is it possible to use an alternative?
Depending on what column you’re using an alternative can be an option, depending on your method specifications.
Do you supply Method Development Kits and do you offer technical support?
Yes, Chromex Scientific supply many different method development kits from various manufacturers such as Fortis, Waters, Agilent, Sigma/Merck and Thermo Fisher.
How many batches of columns should I use for a robust method validation, and can you supply from different batches?
Yes, we can supply from different batches and the recommended regulatory guidance is to use from 3 different batch types.
I seem to be getting inconsistent results with my GC analysis therefore what solutions would you recommend?
Changing the liner regularly and make sure the septum is replaced frequently.
Should I always use a syringe filter on my sample prep and if so, what types do you supply?
It is always recommended to use a syringe filter on your sample prep to reduce unwanted contaminants getting into the instrument. We supply various eXimo syringe filters including sterile and non-sterile varieties.
How important is routine/preventative maintenance in my laboratory schedule?
Routine and preventative maintenance isn’t just “nice to have” in a laboratory schedule — it’s operational risk management. In most labs, it directly affects data integrity, compliance, safety, uptime, and long-term cost.
What columns should I use for THC or medicinal cannabinoids analysis?
The correct column depends on whether you're using HPLC (most common) or GC. Typically, a C18 150 x 4.6mm 5um would be a great starting point in HPLC and for GC a 5% Phenyl/95% Dimethylpolysiloxane 30m 0.25mm x 0.25um. Our technical team would be happy to help with your selection.
What advantage and when should I use a C12 column over a C18?
In reverse-phase HPLC, both C12 and C18 columns use alkyl chains bonded to silica, but the key difference is chain length, which affects hydrophobicity and retention.
C18 (Octadecylsilane, ODS) → 18-carbon chain → more hydrophobic
C12 (Dodecylsilane) → 12-carbon chain → less hydrophobic
Longer chain = stronger hydrophobic interactions = longer retention for nonpolar compounds.