Texas OilTech Laboratories, Inc. offers one of the most sophisticated and well-equipped commercial facilities for the multielement determination of trace elements, utilizing one of several available techniques that have varying limits of detection (LOD):
- Spectrochemical Analysis, 21 elements, LOD = 5 ppm
- Inductively Coupled Plasma, ICP, 60 elements, LOD = 1 ppm
- Metals by Atomic Absorption and Flame Emission Spectrometry, LOD = 0.1 ppm
- Metals by Graphite Furnace Atomic Absorption, GFAA, LOD = 0.05 ppm
- Trace Elements by Inductively Coupled Plasma - Mass Spectrometer, LOD = 0.001 ppm
- Less than 1 part per billion or 1 ug/L
Our Inductively Coupled Plasma - Mass Spectrometer is a Thermo-Elemental X7-ICP/MS
and is one of the most complete ICP/MS instruments available today. It has
the highest signal-to-noise ratio of any quadrapole-based ICP-MS. ICP-MS is
a relatively new analytical method that combines the high temperatures of
a plasma (about 6000 to 8000 degrees K) with a highly sensitive mass spectrometer.
The sample is introduced into the radio frequency (RF) induced plasma in the
form of a solution, vapor or solid. The high thermal energy and electron-rich
environment of the ICP converts most atoms into ions. The quadrapole mass
spectrometer detects the ions at each mass in rapid sequence, allowing signals
from the individual isotopes of an element to be scanned. The detection limit
for most elements is in the range of parts per billion (ppb) or below.
For some elements, it may be in the parts per trillion (ppt) range. Various sample introduction techniques and analytical techniques add to the versatility of this instrument. Routine analysis of rare earth metals, platinum group metals, and others permits the measurement of more than 80 elements.
Trace Metals
Trace metals refer both to those metals present as metallic compounds in solution
and to metals present in particles such as rust. They can be dissolved or
suspended in the fuel hydrocarbons or in free water present in the fuel. Lower
levels of trace metals in a liquid or gaseous fuel in a power plant will generally
promote longer turbine service from a corrosion standpoint.
For lubricants, trace metals analysis is used to monitor the rate of disappearance of the desirable metal additives and to simultaneously monitor the rate of appearance of the undesirable wear metals with time. Environmental regulations dictate the measurement of discharge waters, sediments, sludges and stack gasses in many plant processes.
Elemental Analysis
The appropriate test for elemental analysis depends on several factors. Most
samples must first be treated so as to make the metallic content more easily
detectable by the various instruments (ICP, ICP-MS, AA, GFAA), or to reflect
a particular prerequisite or condition of the samples, e.g., Extractable,
Dissolved, or Suspended solids. Other factors involved are:
- Limits of detection required
- Matrix
- Regulatory compliance
- Manufacturers' specifications
