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Please contact us for additional details regarding these and other questions.


  1. Which bifunctional ligand should I use?

    The choice of bifunctional ligand depends on the type of functional group that you plan to use for covalent attachment. We currently offer isothiocyanate and NHS-esters for attachment to primary amines, maleimides for attachment to thiols, and amine functionalized bifunctionals that can be attached to electrophilic groups. For conjugation reactions performed under aqueous conditions B-205, B-305, and B-280 are representative examples of some very popular bifunctional ligands based on isothiocyanates and NHS-ester linkages: We also carry a variety of other bifunctional ligands that are specifically designed for optimal performance with different metals and for use in solid phase and organic solvent applications.

  2. What are typical conditions for preparing lanthanide complexes?

    Typically, the bifunctional ligand is first conjugated to a protein, peptide, or an antibody prior to complexation. The key to successful complexation is to make sure the conjugate is adequately buffered at a slightly acidic pH prior to introduction of the lanthanide. If the metal experiences a basic pH upon addition, it is likely to form the hydroxide species [Ln(OH)3] which undergoes complexation at a much slower rate relative to the LnCl3 species. Formation of the hydroxide can be detected visually by the appearance of a slightly turbid suspension. Ultimately this condition leads to a reduce percentage of complexation.

  3. What can I do to increase conjugation efficiency?

    Isothiocyanate bifunctional ligands react quickly with primary amines at neutral to moderately basic conditions whereas the NHS-ester begins to react under slightly acidic conditions. Both will undergo competitive hydrolysis under these same conditions which reduces conjugation efficiency. For this reason it is important to combine the bifunctional ligand with the targeting vector in a properly buffered medium and to avoid preparing the bifunctional ligand solution too far in advance. It is also advantageous to use an excess of bifunctional ligand as some degree of hydrolysis is unavoidable.

  4. What are Macrocyclics’ Product Classification?

    Our products are classified as organic non-hazardous chelating agents for basic research.


  1. How do I place an Order?

    Our preferred Method for order placement is thru the online ecommerce. Enter Complete Billing and Shipping information. Products are manufactured and distributed from Plano,Texas. You will automatically receive an order and payment confirmation upon completion. Final invoice, all document support and shipment tracking confirmation will be emailed upon shipment completion. Payment may be paid by credit card, check or wire transfer. Additional options for ordering: Fax (+1 972-250-2245) or email your order direct to

  2. What is Macrocyclics’ Macrocyclics Return Policy?

    No refusal of merchandise shipment is acceptable without prior approval. Product Package and Product vial cannot have been opened, seal broken or product tampered with. If upon approved package receipt return, 10% restocking fee is accessed plus shipping and customs fees charges will be billed and due Upon receipt.


  1. How should I store Macrocyclics products?

    Macrocyclics ships all products by overnight, two-day air, or FedEx international. In all cases our products are stable during transit and do not require refrigerated packaging. However, for long term storage we recommend that reactive isothiocyanates and NHS-esters be stored at -20ºC upon receipt by the customer.

  2. How is the product packaged (ex.: bottle, vial etc.) and what is the packaging material made of (ex. metal, plastic, glass, etc)?

    Macrocyclics’ products are shipped in the highest quality glass vials. They are sealed with a screw top containing a Teflon liner to maintain the integrity of the product.

  3. How are Macrocyclics products shipped?

    Products are packaged in a quality glass vial with storage temperature stated on the vial as well as the U-line instruction white box. It is then placed in a small FedEx box for shipment. FedEx Shipping is Next day or 2nd day for domestic orders within the US. International Delivery eta: 3-10 days pending Customs Clearance Fees. Customs Fees are additional and the responsibility of the recipient upon arrival where applicable.

  4. Are there any additional Fees?

    In addition to normal FedEx shipping costs there may be Customs Clearance Fees and wire transfer fees which are the responsibility of the recipient and may be due upon delivery where applicable.

  5. Please contact us for additional product information related to:

    • Conjugation and Labeling Procedures for Isothiocyanato Derivatives
    • Analytical Methods, Chelation and Stability Measurements
    • Application of DOTA-tris(tert-Bu) in the Synthesis of DOTA- peptides
    • Coupling with DOTA and Activated Esters of DOTA
    • TmDOTP as an in vivo Temperature Probe
    • Product MSDS sheets
    • Certificate of Analysis
    • Product application references
  6. Talk To An Expert

    • Macrocyclics is committed to providing unsurpassed technical support. Our experts are eager to help and can be reached by phone during working hours (8 AM-5 PM CDT) or by email.
    • For more information on Macrocyclics’ cGMP quality system, please contact our Senior Manager QA/QC, Rob Chastain,