Quote List
Quote List

Support

COMMENT AND SUGGESTION

FREQUENTLY ASKED QUESTIONS

Q

Where can I obtain a quote for TLC products?

A

All of information regarding pricing and availability are available through email only. Please contact us at research@tlcstandards.com for this information.

Q

Are TLC pricing VAT?

A

No. Our pricing do not include duties and taxes that may be incurred by your country's customs.

Q

What is the status of my back ordered items?

A

Please contact us at research@tlcstandards.com for this information.

Q

Can you customize the ordered sample to the exact quantity we need it at? Do you provide exact weighing record?

A

Yes we can provide exact weighing upon request. We provide the exact printed weighing record to 2 decimal places for sample packing less than 5 mg.

Q

What is the recommended shipping and storage condition of the products?

A

All products are generally shipped at room temperature. If ever short term stability at such condition would be suspected to pose an issue, TLC will inform the customer that lower temperature shipment is recommended. Options for lower temperature shipping (at an addition fee) are: cool shipment (with ice packs and insulated packaging) or temperature controlled shipment using a specialized courier.

Q

What are my courier options?

A

Currently we only ship by DHL or FedEx.

Q

Can you ship overnight?

A

All shipments for domestic and most of continental US destinations are overnight. Unfortunately delays due to customs are completely out of our control.

Q

Who will be clearing our package in the customs? Can we use our own broker for clearance?

A

By default, upon the arrival of package to customs, FedEx or DHL will contact you for clearance instructions. FedEx and DHL provide customs clearance services at additional cost billed to the consignee. If you have your own broker, please provide us with the detailed information of your broker to add to the shipping documents.

Q

Can you ship our package in cargo mode?

A

We cannot ship in cargo mode. Our FedEx and DHL shipments are only done through courier mode.

Q

Do you offer temperature controlled services or any other cold chain shipping option?

A

Yes. We offer cold chain shipping services at additional cost. Temperature controlled shipping services are outsourced to a reliable third party courier. Shipments with ice packs and dry ice (available only to some countries due to shipping restrictions) are available upon request. Feel free to ask our sales team for more details on the options available to you!

Q

How are TLC Reference Standards certified?

A

TLC Standards can be used as certified reference materials (CRM) and are certified using two or three independent analytical methods. If necessary, we will compare our product with compendial available reference standards (such as EP or USP).

Q

Are methods used on Certificates of Analysis validated?

A

No, COA are issued based on methods developed internally for purity and characterization. These methods are not validated unless method validation was part of the quotation.

Q

What are standard tests included in a TLC certificate of analysis (COA)?

A

Our standard COA includes HPLC/GC, IR, MS, NMR and Assay as well as Water content whenever possible.

Q

How to determine the retest date of the sample? At what point are samples retested? How long does it take to retest the sample?

A

Most of our offered compounds are stable and the retest date is generally set at three years. We can re-certify a batch if less than one year remains on its retest date and if it remains the current lot supplied. Please consider one week to allow for re-certifications.

Q

What is the difference between purity and assay?

A

The purity of a compound is a measure in relation to its associated impurities. The Assay is a determined value that measures the content of the main component of a compound. It takes into account not only the related impurities (as does the purity) but also humidity, solvents and potentially other contaminants not seen in the chromatography. Generally an assay value should always be equal or lower than a purity value.

Q

How is isotopic purity determined and why is it not taken into account in the assay calculation?

A

We usually obtain Isotopic Enrichment through NMR , MS. Isotopic Enrichment of the sample indicates what percentage of atoms (labeled position) are labeled and it shouldn't be taken into account in the assay calculation.

Q

What typical parameters do we provide for chiral compounds?

A

For chiral compounds containing less than 5 chiral centers, we will provide Optical Rotation value and the chiral purity by chiral HPLC (If its enantiomer is available).

Q

What is difference between normal HPLC and chiral HPLC?

A

Normal HPLC will show the purity and organic impurities, while chiral HPLC will provide the chiral purity and the enantiomer impurity content of the sample.

Q

How come the appearance of the compound does not match the stated appearance on the COA?

A

Some samples may be hygroscopic, and despite precautions taken, in some instances the hygroscopic nature of the compound may alter its appearance during shipment. Please note that this is only a change of the physical property but does not affect the chemical properties of the samples.

Q

Can we dry hygroscopic samples following receipt?

A

Yes, here is a small procedure that may be applied: Materials: Desiccator, oil pump, Kimwipes (low dust wipes).
Temperature: room temperature
Time: 12h
Method:
1. Remove the cap of the vial and wrap the vial with Kimwipes (if there are no Kimwipes, use other low-dust wipes instead)
2. Place the vial in a desiccator with suitable drying agents and vacuum the desiccator by using oil pump for 2 h (make sure the desiccator is evacuated well).
3. Allow the desiccator that has been evacuated to stand overnight at room temperature.
4. Deflate under N2 protection next day (If deflate directly, the sample will catch moisture again from the air.)

Q

How could we weigh the sample that is a sticky oil?

A

Method 1: Materials: A glass capillary, clean vial, analytical balance, latex-free gloves.
Procedure:
1. Weigh the empty vial first.
2. Block one end of the glass capillary with the index finger and take a small amount of the sample at the other end. Place the sample taken into an empty vial. (Be sure to handle it gently during this step to avoid the capillary being broken.) Repeat until you get the desired amount.
Method 2:
Materials: A spatula, a clean vial, an analytical balance, and latex-free gloves.
Procedure:
1. Weigh the empty vial first.
2. Dip the spatula into the sample and place the sample into an empty vial. Repeat until you get the desired amount.