Regarding ICP analysis
4. For each of the following electrical discharge sources list the major strengths and limitations:
a. dc arcs,
b. ac arcs,
c. ac sparks.
To evaluate the strengths and limitations of different electrical discharge sources used in inductively coupled plasma (ICP) analysis, let's examine each source individually:
a. DC Arcs:
- Strengths: DC arcs are capable of generating higher temperature and longer-lived discharges compared to other sources. This results in better excitation and atomization of analyte elements, leading to higher sensitivity and a wider linear dynamic range.
- Limitations: The main limitation of DC arcs is their high power consumption, often requiring 10-20 kW of electrical power. Additionally, DC arcs can produce a non-constant plasma emission spectrum due to fluctuating current.
b. AC Arcs:
- Strengths: AC arcs provide better plasma stability compared to DC arcs. The alternating current helps to stabilize the discharge, resulting in a more consistent and reproducible plasma. AC arcs also have good excitation capabilities and can achieve high sensitivity.
- Limitations: The major limitation of AC arcs is that they have lower temperatures compared to DC arcs. This may result in insufficient excitation for some high ionization potential elements. AC arcs also require a substantial amount of electrical power, typically between 5-10 kW.
c. AC Sparks:
- Strengths: AC sparks are characterized by shorter-lived and highly energetic discharges. This makes them well-suited for transient signals or time-resolved analysis. AC sparks also produce a very broad emission spectrum, which enables the simultaneous determination of multiple elements.
- Limitations: AC sparks have low sensitivity compared to arcs and may not provide the same level of excitation for all elements. They also require significant electrical power and can produce a fluctuating plasma emission spectrum.
To determine the major strengths and limitations of electrical discharge sources used in ICP analysis, you can refer to scientific literature, research papers, or textbooks on ICP-MS or ICP-OES. These sources will provide detailed information and comparisons of various electrical discharge sources based on their performance, power requirements, and applications.