Frequently Asked Questions

Lyophilized peptides should be stored at -20°C or -80°C in a sealed container with a desiccant. Protect peptides from light and moisture. Reconstituted peptide solutions should be aliquoted and stored frozen to avoid freeze-thaw cycles.

We offer custom peptide synthesis for any desired sequence, length, purity, or modification. Please contact our team to request a quote.

The numbers indicate the specific amino acid residue sequence corresponding to the parent full-length peptide chain. For example, (7-26) represents a fragment containing amino acid residues 7 through 26 of that peptide sequence.

Our custom peptide synthesis services start at milligram (mg) scale quantities up to multi-gram production batches.

Phoenix Pharmaceuticals routinely synthesizes peptides up to 100+ amino acid residues using advanced solid-phase peptide synthesis (SPPS) and ligation techniques.

Yes. We offer comprehensive custom labeling including biotin, fluorescent dyes (FITC, FAM, Cy3, Cy5, Rhodamine), stable isotopes (²H, ¹³C, ¹⁵N), and radioactive isotopes (I-125). See Custom Peptide Labeling.

No, this is normal. Lyophilized peptides are often present in microgram quantities and form a thin, transparent film on the inside walls or bottom of the vial. Centrifuge the vial before opening and reconstitute with the appropriate buffer.

Extraction eliminates large interfering proteins (such as hemoglobin, albumin, and clotting factors) found in biological matrices, reducing assay background noise and concentrating low-abundance circulating peptides for accurate quantification.

Plasma extraction typically requires C18 solid-phase extraction (SPE) columns, extraction buffers (e.g., 1% TFA in water and 60% Acetonitrile in 1% TFA), a vacuum manifold, and a centrifugal concentrator.

Plasma and serum samples should be aliquoted immediately after collection and stored at -80°C to preserve peptide stability and prevent enzymatic degradation.

Properly frozen biological samples stored at -80°C are stable for several years. Avoid repeated freeze-thaw cycles to maintain sample integrity.

EIA (Enzyme Immunoassay) and ELISA (Enzyme-Linked Immunosorbent Assay) are both enzyme-based quantification techniques. EIA typically uses competitive binding principles for smaller peptides, while ELISA often utilizes sandwich-assay formats for larger proteins.

Validated sample types include plasma, serum, tissue homogenates, cell culture supernatant, cerebrospinal fluid (CSF), and urine.

Unopened EIA/ELISA kits should be stored at 4°C (2–8°C). Avoid freezing kit reagents unless specified in the manual.

A standard 96-well kit allows for testing up to 40 samples in duplicate alongside standard curve calibration wells.

Standard EIA/ELISA protocols require 50 µL of sample per well (run in duplicate, requiring 100 µL total per sample).

Our EIA/ELISA kits typically have a shelf-life of 6 to 12 months when stored properly at 4°C.

Yes, our microtiter plates consist of 12 removable 8-well strips (96 wells total), allowing you to run smaller batch assays at different times.

Complete specification sheets including sensitivity (IC50), cross-reactivity profiles, assay range, and protocol instructions are included with each kit and available online.

Fluorescent (FEIA) and Chemiluminescent (CEIA) kits offer enhanced sensitivity and wider dynamic range, ideal for samples with extremely low baseline peptide concentrations.

Yes. All Phoenix antibodies are generated and purified in-house at our laboratory facility in Burlingame, California.

Antibodies are raised in rabbits by immunizing with synthetic peptide antigens conjugated to carrier proteins (such as KLH or BSA) following strict animal care protocols.

Phoenix specializes in high-affinity polyclonal antibodies raised in rabbits, providing superior sensitivity for peptide recognition.

“Antibodies” (antiserum) refers to whole crude serum containing total immunoglobulins, while “Purified IgG” has undergone Protein A or antigen affinity column purification to isolate specific IgG antibodies.

Store lyophilized antibodies at -20°C. Reconstituted antibodies should be stored in working aliquots at -20°C or -80°C. Avoid repeated freeze-thaw cycles.

The volume in microliters specifies the original volume of liquid antiserum before lyophilization. Reconstitute the dry powder with that exact volume of distilled water to restore its original concentration.

Our I-125 radiolabeled tracers are typically supplied at an activity of 10 µCi (370 kBq) per vial with high specific activity.

Store I-125 labeled tracers at -20°C in a lead-shielded storage container in compliance with local radiation safety regulations.

The half-life of 125-I is 59,408 days (approx. 59.4 days).

Radioactivity decay can be calculated using the formula A = A₀ × (0.5)^(t / 59.4), where A₀ is initial activity, t is elapsed time in days, and 59.4 is the half-life of Iodine-125.

In-stock catalog peptides ship within 1–2 business days. Custom peptide synthesis typically takes 2–3 weeks depending on sequence complexity and scale.

Catalog antibodies ship within 1–2 business days. Custom antibody production packages take approximately 14–18 weeks.

Standard labeled catalog peptides ship in 1–2 business days; custom labeling projects require approximately 2–4 weeks.

In-stock EIA/ELISA kits ship within 1–2 business days.

RIA kits and radioisotope tracers ship weekly via express courier to ensure maximum radioactive activity upon arrival.

We sell exclusively to verified academic, clinical, government, diagnostic, veterinary, and pharmaceutical research institutions for scientific research purposes.

First-time institutional buyers may be asked to provide institutional credentials, a tax ID/registration, or an authorized purchase order (PO). Please contact our team for purchasing assistance.