Frequently Asked Questions
This section addresses common questions about our PEG products, including storage, handling conditions, lead time, procedures and specifications, etc. Please scroll through the list below to see if your question is answered. If you don't find the information you need, feel free to contact us directly. You can email us at sales@biochempeg.com with any questions, comments, or concerns.
1. How does Biopharma PEG ship your products?
All of our products are shipped in foam boxes with ice packs. In the US, overnight delivery is the default option. International shipments typically take 3-5 days, with deliveries to European countries usually arriving within three days. We use FedEx as our carrier. Shipping costs will be prepaid and added to the invoice unless the customer provides a valid FedEx or DHL account number.
2. What are the storage conditions for your products?
PEG products are sensitive to temperature, light, and moisture. Upon receipt, store them in a freezer at -15°C or colder. Most of our products are in solid form, except those with very low molecular weight. Keep the vials away from light, especially UV light. Before opening, let the vials and products reach room temperature to prevent moisture absorption. For long-term storage, keep our products in their original solid state and avoid storing them in any solutions.
3. What is the lead time for your products?
Products listed as in-stock can be shipped within one week. Since PEG products are sensitive, we conduct a quality test on each batch before shipment to ensure they are in good condition. For products not in stock, the lead time is typically around 3 weeks. If there are any special lead time requirements, we will contact you for confirmation.
4. What solvents can PEG be dissolved in?
PEG products have good solubility in a variety of organic solvents, including dichloromethane, chloroform, N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), etc. They can also be dissolved in alcohols (methanol, ethanol, isopropanol), toluene, and tetrahydrofuran (THF) when heated to a recommended temperature of 40-50℃. DMF and DMSO are suitable for preparing stock solutions of PEG reagents with water-sensitive functional groups, which can then be diluted or mixed with aqueous buffers for experiments requiring aqueous-based solvents.
5. Do you provide protocols or procedures for using your products?
We do not provide detailed protocols or procedures for using our products because they are used in a wide variety of experiments that often require customized conditions. However, we have collected some published papers that describe the use of our products with experimental details. Please visit our References page to find suitable publications for guidance.
6. What is the difference between monodispersed PEG and polydispersed PEG?
Monodispersed PEG is a pure compound with a precise, discrete molecular weight and an exact molecular formula. In contrast, polydispersed PEG is a polymer mixture with an average molecular weight, such as 2K, 5K, 10K, etc. Often polydispersity index (PDI) is used to determine how narrow the molecular weight distribution is. A narrower PDI indicates a more uniform molecular weight distribution. Biopharma PEG offers polydispersed PEG with a very narrow PDI, typically ≤1.05, which performs better in experiments.
7. What is the mass range covered by ESI, APCI, and MALDI?
ESI and APCI typically cover a mass range from 50 to 2000 Daltons; some instruments can extend this range up to 4000 or even 6000 Daltons. However, since API machines always produce multiple charges for large molecules, a 6000 Da peptide may bear 10 to 20 charges and therefore show in the 300 to 1000 mass range. Therefore, large mass ranges for API spectrometers are not very useful anyway. MALDI can measure masses up to 500,000 Daltons, but it generally provides high-quality signals only up to around 200,000 Daltons. Larger molecules are challenging to laser-desorb and ionize effectively.
Disclaimer: The information provided above is intended as a general guide for selecting PEGylation reagents and for general customer convenience. For detailed and specific PEGylation procedures, please refer to relevant publications. Biopharma PEG assumes no liability for the information provided within this web page or website.