Choosing the Right Catalyst: Making a Difference in Kjeldahl Performance

Why use catalyst tablets in the Kjeldahl method

The digestion phase represents the longest and most critical step in the Kjeldahl analysis, as it involves breaking the bonds of protein compounds and transforming them into simpler molecules such as water, carbon dioxide, and ammonium sulfate. This process, known as mineralization, can be significantly slowed down by complex samples or resistant matrices, making it necessary to employ strategies to accelerate it without compromising the accuracy of the results.

The use of high temperatures and concentrated sulfuric acid is essential to initiate and sustain digestion, but the addition of specific catalysts makes it possible to optimize both the speed and the efficiency of the process. Catalysts based on copper, selenium, or titanium—used individually or in combination—facilitate the breakdown of protein bonds, reduce digestion times, and improve the completeness of the reaction. In particular, copper ensures good baseline reactivity, while selenium is ideal for more resistant samples, such as fats and oils, thanks to its rapid action.

Achieving optimal performance across a wide range of Kjeldahl applications also requires the use of high-quality consumables.

For these reasons, the use of catalysts is recognized and approved by the main international standards (AOCS, AOAC, AACC, ISO), becoming an essential standard for laboratories aiming for reliable, fast, and safe results in the digestion phase of the Kjeldahl method.

Velp KjTabs™ genuine Kjeldahl Catalyst tablets - From today with a new packaging

Our catalyst and anti-foaming tablets are now getting a fresh new look! Instead of the traditional metal jars, they will now come in convenient, lightweight plastic containers—designed for ease-of-use and optimized storage.

Each package will also feature a new safety seal to guarantee freshness and maintain product quality. To make things even simpler, each package will feature a clear color-coded label, so identifying the right product is quick and easy.

The KjTabs™ are carefully pre-dosed tablets based on sulfate (to raise the boiling point of sulfuric acid), copper (Cu), selenium (Se) or titanium (Ti) in the form of metallic salts, which accelerate the mineralization process.

Advantages of catalyst tablets:

Ready-to-use and pre-dosed: reduce preparation time and minimize the risk of human error
Increased safety: no volatile powders and easier handling
Analytical repeatability and consistency: ensured by a constant dosage
Space optimization: compact packaging of 500 and 1000 pieces
Maximum analytical performance: across a wide range of Kjeldahl applications, with the certified quality of original Velp tablets

To meet different analytical needs, Velp offers seven formulations of catalyst tablets and one antifoaming tablet which, thanks to their new format and dedicated colors, are now even easier to identify and use:

Code	Model	Composition	Applications
A00000274	KjTabs VCM - 1000 pcs/box	3.5 g K₂SO₄ + 0.1 g CuSO₄ × 5 H₂O	Determination of proteins in nuts and derivatives, meat and meat products, cereals and derivatives, flour (soy and lupins), compressed and granular yeast, sugar, syrup, molasses, wheat pasta, egg pasta. Determination of nitrogen in samples such as urea, water, raw natural rubber and rubber latex
A00000275	KjTabs VKPC - 500 pcs/box	4.5 g K₂SO₄ + 0.5 g CuSO₄ × 5 H₂O	Determination of proteins in bread and bakery products
A00000276	KjTabs VCT - 500 pcs/box	5 g K₂SO₄ + 0.15 g CuSO₄ × 5 H₂O + 0.15 g TiO₂	Determination of nitrogen in samples such as milk and dairy products
A00000277	KjTabs VST - 1000 pcs/box	3.5 g K₂SO₄ + 3.5 mg Se	Determination of proteins in beer and malt. Determination of nitrogen in soils, plants, forage, fertilizers, engine oils, fuels
A00000281	KjTabs VTCT - 1000 pcs/box	3.5 g K₂SO₄ + 0.105 g CuSO₄ × 5 H₂O + 0.105 g TiO₂	Determination of nitrogen in samples such as milk and dairy products
A00000282	KjTabs VW - 500 pcs/box	4.875 g K₂SO₄ + 0.075 g CuSO₄ × 5 H₂O + 0.050 g Se	Determination of proteins and nitrogen in feeds, pet foods, forage, cereals, and seeds
A00000283	KjTabs VS - 1000 pcs/box	0.97 g K₂SO₄ + 0.03 g Silicone	Antifoaming tablets, used together with catalyst tablets to reduce foam production

Find out more about the applications of Velp catalyst tablets by consulting the dedicated Application Note:

See the Application Note

The wide range of Velp KjTabs™ is the ideal choice for accurately tackling any type of analytical application, ensuring convenience, safety, and reliable results.

To guide you toward the solution best suited to your laboratory needs, Velp’s analytical team will be happy to provide all the support you require.

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