Frequently Asked Questions
Answers on product selection, quality control, custom synthesis and OEM supply, ordering and shipping. If your question is not covered here, contact us directly.
Products, Selection & Technical Support
What is the scope of Qihe Biotech's fluorescent dye catalog, and which reactive chemistries are available for antibody and biomolecule conjugation?
Qihe Biotech's online catalog lists 359 products across 1,572 individual pack-size specifications, organized into 16 categories that cover reactive dyes, streptavidin conjugates, nucleic acid dyes, assay kits, crosslinkers and click-chemistry reagents, proteins and tandem dyes, and transfection reagents. Measured across the catalog, excitation wavelengths run from 346 to 785 nm and emission from 420 to 814 nm. The most common conjugation-ready reactive groups on the dyes are NHS ester (65 products), maleimide (32) and azide (30), plus a DBCO family of 62 products (30 DBCO, 16 PEG4-DBCO, 16 PEG12-DBCO). The catalog also lists 24 ready-to-use streptavidin conjugates, 8 tandem dyes and 4 fluorescent proteins as separate categories. These figures describe the products listed online; Qihe Biotech also supplies custom-synthesized and made-to-order products that are not published in the online catalog.
What click-chemistry and bioorthogonal labeling reagents does Qihe Biotech offer?
Fluorescent dyes carrying copper-free click handles are listed within Qihe Biotech's AF, Cyanine, BODIPY and SF reactive-dye series: 92 products carry azide or DBCO chemistry (30 azide, 30 DBCO, plus 16 PEG4-DBCO and 16 PEG12-DBCO spacer variants) for strain-promoted, copper-free azide–alkyne cycloaddition. Separately, the crosslinkers and click-chemistry category (20 non-fluorescent products) includes 4 tetrazine-bearing linkers and 1 BCN linker for metal-free inverse-electron-demand Diels–Alder (IEDDA) and copper-free click ligation, plus 1 azide-bearing linker for downstream conjugation to a separately labeled dye. The online catalog does not currently list a plain alkyne-functionalized reagent; alkyne handles can be requested as a custom synthesis.
Does Qihe Biotech publish measured performance data for its SF-series dyes?
Yes, for two dyes — SF488 and SF647 (comparable data for the rest of the SF line has not been published). Both were benchmarked against Qihe Biotech's own earlier-generation AF-series dyes, which are the company's alternatives to Alexa Fluor dyes, so the published comparison is between two generations of Qihe Biotech product rather than against another supplier's material. In a Mouse CD4 (clone GK1.5) flow-cytometry staining experiment, SF488 at 0.4 µg/test gated 23.08% of events inside the CD4+ gate versus 20.59% for the AF488 control; separately, SF647 at 0.08 µg/test (a different dose from the SF488 run) gated 24.42% versus 19.68% for the AF647 control. The panels shown on the homepage are cropped from the original plots for layout; gates and percentages are unaltered.
What technical support and online tools does Qihe Biotech provide?
Qihe Biotech's technical support covers three areas: application consultation (reagent selection and experimental-design recommendations), protocol guidance, and troubleshooting for labeling, imaging, storage and handling issues. Free online tools include an interactive excitation/emission chart that plots real product spectra against the four common flow-cytometry laser lines (405/488/561/640 nm), with each point linking directly to its product page, and a protein-labeling calculator that computes the reagent volumes needed for a target dye-to-protein molar ratio, alongside calculators for DNA quantification, dilution, RCF/RPM conversion, molarity, cell counting and buffer preparation. Inquiries submitted through the contact form receive a reply within 24 hours on business days.
Quality Control & Documentation
What quality control does each product lot undergo before release, and how can I verify the Certificate of Analysis (CoA)?
Before release, every product lot goes through Qihe Biotech's Outgoing Quality Control (OQC) panel of six tests: appearance, HPLC purity (release criterion ≥95%), LC-MS molecular weight (within ±0.5 Da of the theoretical value), solubility, fluorescence spectrum, and moisture content by Karl Fischer titration (≤0.5%). NMR structural confirmation is an additional check applied to critical raw materials at incoming inspection (IQC), not to every finished lot. Customers look up the CoA online by entering both the catalog number and the lot number; the system performs an exact match on the two fields and displays a certificate showing product name, catalog number, lot number, molecular weight, purity, appearance, solubility, storage conditions, test date and expiry date, viewable on screen and printable. If a lot cannot be found, contact info@qihe-bio.com.
How can I get the Safety Data Sheet (SDS/MSDS) for a specific product?
To obtain the Safety Data Sheet (SDS/MSDS) for a specific product, email info@qihe-bio.com with the catalog number and the team will send the current version for that product. Before handling any chemical reagent, review its SDS and the container label, and follow the personal protective equipment (PPE) requirements and emergency procedures set out on the Safe Handling page.
Custom Synthesis & OEM Supply
Does Qihe Biotech offer custom dye synthesis or chemical modification services?
Yes. Qihe Biotech offers custom dye synthesis and chemical modification, including custom reactive groups, linker chemistry and packaging formats specified by the project. Custom-synthesized products are handled as a separate order category from catalog items: for non-quality reasons they are not eligible for return once produced. Feasibility, scope, lead time and pricing are discussed case by case — submit your requirements through the Custom Synthesis & OEM Services page, or select "Custom synthesis" as the inquiry type on the contact form.
Does Qihe Biotech supply OEM, private-label or bulk contract arrangements for commercial manufacturers?
Yes. Qihe Biotech supplies OEM and private-label packaging as well as bulk contract supply for manufacturers who need fluorescent dyes or bioconjugation reagents at production scale. Batch scale, packaging format and supply-agreement terms are negotiated per project. Submit your target product, expected volume and packaging requirements through the Custom Synthesis & OEM Services page to start a discussion.
Is there a Minimum Order Quantity (MOQ) for catalog products, and how does MOQ work for OEM or custom orders?
Qihe Biotech sets no minimum order quantity for standard catalog products — items can be ordered by the individual pack size listed on the product page. For OEM and custom-synthesis orders, minimum quantities are tiered by project scale rather than fixed at a single threshold. Volume pricing applies separately to orders of ≥5 units of the same catalog item or a total order value of ≥$1,000. Quotations are typically valid for 30 days, and preferential terms for large orders or annual framework contracts are available on negotiation.
Ordering & Shipping
How can an overseas buyer request a quotation or place an order?
Overseas buyers can order directly through the Qihe Biotech website — browse the catalog, add items to the cart, and submit shipping and billing details — or request pricing by email to info@qihe-bio.com stating the catalog number, required quantity and pack size, estimated usage date and billing entity. Quotations are typically valid for 30 days, and preferential terms for large orders or annual framework contracts are available on negotiation. Qihe Biotech does not operate a separate free-sample program; for trial quantities, order the smallest listed pack size or contact info@qihe-bio.com to discuss.
What is the typical turnaround for order dispatch, and how are lead times handled for custom orders?
Qihe Biotech dispatches in-stock orders confirmed before 15:00 China time on a business day the same day; orders confirmed after 15:00, or on weekends and public holidays, ship the next business day. For destinations outside mainland China, Qihe Biotech sends a shipping quote and estimated transit time within one business day of receiving the order, and dispatches only after the customer confirms it. Lead times for custom-synthesis and OEM orders are given with the individual project quotation rather than as a fixed published range.
How are temperature-sensitive fluorescent reagents packaged for shipping, and how is international freight handled?
Within mainland China, Qihe Biotech ships under three temperature-controlled packaging options based on each product's storage requirement, all carried by SF Express: shock-resistant foam packaging for ambient-stable products; medical-grade blue ice with an insulated box, maintaining 2–8°C for 48 hours, for refrigerated items such as most dyes and antibody conjugates; and industrial dry ice with a high-strength insulated box for products requiring -20°C or -80°C transport, which arrive still frozen. For destinations outside mainland China, freight plus any cold-chain or dry-ice surcharge is quoted per destination and packaging requirement, and duties, import taxes and customs clearance fees are payable by the recipient.
Still have a question?
Product selection, custom synthesis and bulk quotations can all be discussed directly with our team — we reply within 24 hours on business days.