How do Digesters work?
Digestion breaks down a sample matrix so that the analytes of interest enter solution in a measurable form. In block digestion, tubes or vessels are heated on a temperature-controlled aluminium block and acid is added, often with reflux. In Kjeldahl digestion, the sample is heated with sulfuric acid and a catalyst to convert nitrogen compounds to ammonium sulfate. In closed-vessel and microwave digestion, acid and sample are sealed in a pressure-rated vessel and heated rapidly, so higher temperatures are reached, volatiles are retained and less acid and time are needed. Reagent choice, temperature, pressure and time determine completeness, and the resulting digest is diluted and filtered before measurement.
Which Digesters variants are available?
- Block Digestion System — A block digestion system heats samples and acid in tubes on a temperature-controlled block.
- Microwave Digestion System — A microwave digestion system heats sealed vessels with microwave energy to dissolve difficult samples rapidly.
- Kjeldahl Digestion System — A Kjeldahl digestion system converts nitrogen in a sample to ammonium sulfate using sulfuric acid and heat.
- Closed Vessel Digestion System — A closed vessel digestion system seals sample and acid in a pressure-rated container and heats it to dissolve difficult matrices.
- Automated Digestion System — An automated digestion system performs reagent addition, heating, mixing and cooling under program control.
How do I choose the right variant?
Choose a digester according to the sample matrix, the analytes and the required detection limits. Block digestion suits routine, high-throughput work with simple matrices and volatile analytes that are retained, such as nitrogen and some metals. Kjeldahl systems are specific to nitrogen and protein determination. Closed-vessel and microwave digestion suit difficult matrices, volatile elements and low detection limits, because they reach higher temperatures and retain volatiles. Automated systems add reagent dosing, heating programmes and cooling for reproducibility. Confirm the vessel material and pressure rating suit the acids used, the temperature reaches the method requirement, and the throughput matches the workload.
Where are Digesters used?
Digesters are specified in environmental soil, sediment and sludge analysis, food and feed elemental analysis, metals and alloy trace analysis and pharmaceutical and biological sample preparation.
Which standards and certifications apply?
Work with Digesters is commonly governed by EPA 3051A, EPA 3050B, EPA 200.2, ISO 11466 and IEC 61010-1. Instrument certifications such as CE marking are confirmed per configuration and never assumed.
What are the key considerations before purchase?
Add acids in a fume hood and use the protective equipment specified for the reagent, including face and eye protection, gloves and an acid-resistant apron. Do not exceed the rated temperature or pressure of the vessels, and allow closed vessels to cool before opening to avoid acid spray. Digest a reagent blank and, where required, a certified reference material to verify recovery and completeness. Check vessels for scratches and damage, and replace them on schedule, since worn vessels may fail. Follow the applicable method, such as EPA 3051A, EPA 3050B, ISO 11466 or the Kjeldahl procedure, and record all temperatures, times and reagent volumes.
