How to Clean a Platinum Crucible

Platinum crucibles are known for their excellent resistance to chemical attacks by acids and fusion mixtures and are crucial tools in many scientific experiments. They are widely used in many fields due to their high ductility, corrosion and oxidation resistance, and ability to withstand high temperatures. Common applications of platinum crucibles include digestion ash testing, loss on ignition (LOI) analysis, and sample preparation for fusion samples. However, for these tools to provide optimal results, they must be adequately cleaned. In this blog post, we will discuss the methods and procedures for effectively cleaning a platinum crucible, ensuring accurate and reliable results.

What Methods Can Be Used to Clean a Platinum Crucible?

Cleaning platinum crucibles properly will help ensure their accuracy and longevity are maintained, as well as prevent cross-contamination between experiments. Several methods can be implemented for cleaning, so let’s look at what they are. 

Cleaning in Citric Acid

Platinum crucibles can be cleaned effectively by adding a solution of citric acid (20%) into an ultrasonic bath. Set the bath to vibrate at 50°C for ten minutes. This will effectively eliminate any flux or impurities from the crucibles.

However, to maintain optimum cleaning performance, it is important to regularly replace the citric acid solution. After the cleaning process is complete, ensure proper drying of the labware. This can be achieved by using a clean air stream or placing the crucibles in a drying oven.

Cleaning with Fused Potassium Bicarbonate

When cleaning with bicarbonate, any residue from previous experiments must be removed from the platinum crucible. The crucible must be filled with potassium bicarbonate in its solid form, past the residual line of remaining material from experiments. 

Afterwards, the crucible is placed on a burner to melt the bicarbonate. The melt must be stirred frequently until a layer of red potassium salt appears on the surface, after which it should be poured out of the platinum crucible and rinsed with hot water. The crucible must be dried thoroughly and left to cool.

Soaking in Diluted Hydrofluoric Acid

Platinum crucibles can be soaked in a diluted hydrofluoric acid solution for at least 24 hours, followed by boiling for three hours for effective cleaning. This process removes any residual materials or contaminants that may be present on the crucible’s surface. After boiling, the crucible should be carefully rinsed with water and, if necessary, mechanically cleaned using an ultrasonic bath to ensure thorough cleaning.

Where Can I Purchase Platinum Crucibles?

At XRF Scientific, we pride ourselves on providing an extensive range of high-quality platinum crucibles, dishes, and moulds for your laboratory needs. Whether you require standard configurations or specialised platinum products, our team is dedicated to meeting your requirements with precision and excellence.

Why Platinum?

When it comes to laboratory apparatus, the metals used must possess specific properties such as high-temperature strength, a high melting point, ductility, corrosion resistance, and oxidation resistance. Platinum and its alloys meet all these requirements, making platinum the most widely used metal for analytical laboratory apparatus. Let’s take a closer look at some common platinum alloys and their properties.

Platinum (Pt)

Platinum boasts a high melting point of 1773 degrees Celsius and offers excellent resistance to chemical attack by acids. It also has superior ductility and oxidation resistance, making platinum an ideal choice for laboratory ware.

Platinum 10% Rhodium (Pt/Rh)

This alloy offers even greater hardness and higher strength than other platinum alloys. With a melting point of 1850 degrees Celsius, it maintains its shape under the hottest furnace conditions.

Platinum 5% Gold (Pt/Au)

Universally accepted as the material of choice for crucibles and casting moulds in spectrographic analysis by X-ray fluorescence (XRF), this alloy possesses higher temperature strength than pure platinum. Its “non-wetting” property allows for easy sample removal after fusion, resulting in reproducible assays.

Platinum Gold Rhodium (90/5/5)

By combining the “non-wetting” property of the Pt/Au alloy with the extra strength and durability of Pt/Rh alloys, this alloy offers optimal performance in various laboratory conditions.

Platinum 3.5% Rhodium (Pt/Rh)

Rhodium alloys, including Pt/Rh, are known for their higher hardness and high-temperature strength. This alloy is particularly suitable for more aggressive conditions.

Trust XRF Scientific for Reliable Platinum Crucibles

When it comes to platinum crucibles, dishes, and moulds, you can rely on XRF Scientific to provide you with the highest quality products. All our platinum meets International Metal Standards, ensuring consistent and accurate results in your laboratory. Whether you need basic platinum utensils or intricate customised designs, we are here to assist you.

Contact our team today to learn more about our extensive range of platinum products tailored to your specific requirements.