Frequently asked questions

Each pack holds 10 mL of colloid at an optical density (OD) of 1: 10 OD·mL, which is volume multiplied by optical density. Grove measures OD at the absorption peak: ~525 nm for Gold-PVP Red, ~580 nm for Gold-PVP Blue and ~590 nm for Gold-PEG Blue. 10 mL at OD 1 holds the same amount of material as 5 mL at OD 2 or 100 mL at OD 0.1. Grove estimates ~0.05 mg/mL of gold at OD 1, so a pack holds ~0.5 mg of gold. Gold-PVP Red and Gold-PVP Blue also come in 50 mL and 100 mL at OD 1; Gold-PEG Blue and Gold-L-Cysteine Fluorescent Red come in 10 mL packs only for now.

Grove estimates ~0.05 mg/mL of gold at OD 1, ~0.5 mg in a 10 mL pack. It's an estimate, not an ICP-MS measurement. The particle concentration isn't stated.

It depends on your excitation wavelength and the surface chemistry you need. The colloid guide matches each product to laser lines and applications. If you're still unsure, email us your wavelength, buffer and application and we'll suggest one.

Each product page shows Grove's example data: a TEM image, an absorption spectrum and a size distribution, plus a photograph under UV light for the fluorescent product. The data comes from an example batch, not the batch you receive. If you need data for your batch, ask when you order and we'll request it from Grove.

Yes. Published sizes and absorption peaks are typical values, not batch acceptance limits. If your results depend on the batch, record a UV–vis spectrum when it arrives and keep it with your data.

Yes, on every product page. Grove's safety data sheets (version 1.0, revised 14 August 2026) classify all four colloids as not hazardous and not regulated as dangerous goods for transport.

At 2–8 °C. Don't freeze it: freezing can aggregate the particles irreversibly.

No. They are for research use only, not for diagnostic or therapeutic procedures.

Yes, on Grove colloids. 10 mL packs count in any mix: 2–4 packs are £174.50 each, 5–9 packs £159.50 each and 10 or more £149.50 each. The discount is applied automatically in the basket and at checkout. The 50 mL (£749) and 100 mL (£1,399) sizes have their own prices and don't count towards it.

Yes. Any two packs cost £349 together, and the starter set has one pack of each of the four colloids for £599, £99 less than four separate packs.

No. The smallest size is 10 mL at OD 1.

Yes, by quotation. Use "Request a quotation" on the product page, or email us the product, amount and concentration.

Orders typically ship in 2–4 weeks. We'll confirm the dispatch date by email after you order. More than one pack of Gold-PEG Blue or Gold-L-Cysteine Fluorescent Red may take longer, and each pack comes from a different batch. Delivery is tracked, by DHL Express outside the UK, and transit time is added on top.

UK and Isle of Man delivery is free. Everywhere else, DHL Express delivery is free on orders from £500, after any discounts; smaller orders pay £45. See Shipping and international orders for each destination.

Yes. Enter your purchase order number in the basket, under "PO or card reference", and choose "Pay by invoice" at checkout. Nothing is charged: we'll email a pro forma invoice with the payment terms for your order. You can also email your purchase order to info@marixia.co.uk, quoting your quotation number if you have one. See Ordering and payment.

Yes, at checkout. For UK delivery, the basket shows the total with 20% VAT, so you can check it against your card limit; UK delivery is free. Enter your card reference in the basket so it appears on your order confirmation and invoice. See Ordering and payment.

Yes. Add what you need to the basket and choose "Email me a quotation of this basket". We email the quotation as a PDF, usually within one working day. It's valid for 30 days. For larger amounts or another concentration, request a quotation.

For larger orders from the UK, EU and US, yes: Where to buy lists our regional partners and the order values they take. Email us the products, delivery country and preferred partner, and we'll confirm the route before you order.

On Supplier information: company number, VAT number and registered office. We complete supplier set-up forms on request.

UK and Isle of Man orders are charged 20% VAT. Orders delivered anywhere else are not charged UK VAT.

In the EU and the rest of the world, the recipient pays import taxes to the courier on delivery. In the US, duties are collected at checkout.

Worldwide, with a few exceptions listed on Shipping and international orders.

Email photographs of the parcel and the product within 5 working days of delivery. Once the damage is confirmed, we'll arrange a replacement or a refund.

Published values are typical values, not batch limits. If a product does not match its description, email us within 14 days of finding the problem, and no later than 3 months after delivery, with your order number and measurements, such as a UV–vis spectrum. We'll review them with Grove and agree the next step with you, based on what the data shows.

No. We can't take products back for change of mind.