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 are your products shipped?
All products are shipped in insulated foam boxes with ice packs to ensure stability during transit. In the U.S., we offer overnight delivery by default. International shipments typically take 3–5 business days, with most deliveries to Europe arriving within three days. We use FedEx as our primary carrier. Shipping charges are prepaid and added to the invoice unless a valid FedEx account number is provided by the customer.
Shipping Fee Details
▶ Domestic (U.S.):
- • 2-Day Delivery: $45
- • Overnight Delivery: $55
▶ International Shipping: $120
▶ If you prefer to use your own FedEx account, a $25 packaging and handling fee will be applied.
2. What are the recommended storage conditions for your products?
PEG products are sensitive to temperature, light, and moisture. They should be stored in a freezer at -15°C or below upon receipt. Most products are in solid form, except those with very low molecular weights. Protect vials from light, especially UV exposure. Before opening, allow the vials to reach room temperature to prevent moisture condensation. For long-term storage, keep products in their original solid form and avoid storing them in solution.
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 out-of-stock items, the lead time typically ranges from 4 to 5 weeks, depending on the complexity of the synthesis. If there are any special lead time requirements, we will contact you to confirm the details.
4. What solvents can PEG be dissolved in?
PEG products are highly soluble in many organic solvents, such as dichloromethane, chloroform, dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). They can also dissolve in alcohols (methanol, ethanol, isopropanol), toluene, and tetrahydrofuran (THF), especially when gently heated to 40–50°C. For PEG reagents with water-sensitive groups, DMF and DMSO are ideal for preparing stock solutions, which can later be diluted or combined with aqueous buffers for use in water-based experiments.
5. Do you offer protocols or procedures for using your products?
We do not offer specific protocols or procedures, as our products are used in a wide range of experiments with varying requirements. However, we have compiled a selection of published studies that include experimental details using our products. You can find these references on our References page 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.