Microwave-acid digestion is a common sample preparation step for atomic absorption, atomic emission, or inductively coupled plasma analysis of metals. Microwave digestion takes minutes, compared to hours for conventional hot plate digestion. Because it uses high temperature and strong acids—commonly nitric and hydrofluoric—microwave digestion mineralizes any matrix. For example, EPA method 3052, based on microwave digestion, provides total metal analysis from soil, sediments, sludge, oils, plastics, and biological materials.
Top 5 Questions You Should Ask When Buying a Microwave Digester
- What is the system’s maximum microwave power output? Microwave energy heats substances quickly to high temperatures. The higher the temperature, the faster and more completely substances are digested. Extractions also need sufficient power, as some solvents can act as a heat sink and are difficult to heat.
- Can the system monitor and control every vessel? Temperature and pressure monitoring and control are extremely important. Inadequate safeguards can result in damaged vessels and equipment, and a lack of temperature and pressure control can pose a safety hazard to lab personnel.
- How many samples can be processed per run? Though the number of samples processed is dependent upon your laboratory’s needs, planning for growth is always a good idea.
- Does the company offer free applications support? Do they offer dedicated, direct service support and local factory- trained field service technicians? Dependable applications and service support are essential since you never know what may go wrong.
- How user-friendly is the system? As with many instruments, if a system is very complicated to operate, it generally becomes either a glorified shelf to store things on or a headache to those having to operate it. The easier a microwave system is to use, the better off you will be. Also make sure the vessels are easy to handle and set up.
Acid types used by survey respondents for microwave digestion:
| Nitric acid | 57% |
| Hydrochloric acid | 57% |
| Sulfuric acid | 21% |
| Hydrofluoric acid | 29% |
| Other | 32% |
Microwave digestion applications as reported by survey respondents:
| Analyzing metals | 29% |
| Trace metal analysis | 14% |
| Material analysis | 14% |
| Biological sample analysis | 11% |
| Other | 32% |
Nearly 55% of respondents are engaged in purchasing a new microwave digester. The reasons for these purchases are as follows:
| Replacement of aging systems | 36% |
| Addition to existing systems, increase capacity | 24% |
| Replacement of damaged system | |
| Setting up a new lab | 21% |
| First time purchase | 12% |
| Other | 3% |
Top 10 Features/Factors Respondents Look for When Purchasing a Microwave Digester:
| High Durability | 61% |
| Service and Support | 61% |
| Vendor Reputation | 57% |
| Low Maintenance | 50% |
| Price | 43% |
| Speed of Heating | 32% |
| Intuitive Controls and Software | 32% |
| Short Cool-Down Time | 32% |
| Large Capacity | 29% |
| Small Footprint | 29% |
Need to change your digestion parameters on the fly?Here are some examples of important upgrades in microwave digestion technology. LabManager.com/microwave-upgrade | For more information on microwave digesters, including useful articles and a list of manufacturers, visit www.labmanager.com/microwave-digesters |
