Absorption analyzer

A method comprising:

• a) injecting a sample into a sample port of an absorption analyzer,
• wherein the absorption analyzer includes:
• a spectral lamp,
• wherein the spectral lamp includes buffer gas and mercury,
• wherein the spectral lamp includes a discharge cavity,
• wherein the discharge cavity includes electrodes connected to a high frequency excitation generator,
• wherein the discharge cavity is positioned between magnet poles,
• a photoelastic modulator,
• a photodetector,
• a signal processing unit,
• a polarizer,
• an analytical cell,
• wherein the spectral lamp, photoelastic modulator, and polarizer are in optical connection with the analytical cell,
• wherein the analytical cell is in optical connection with the photodetector,
• wherein the photodetector detects radiation from the spectral lamp that passes through the photoelastic modulator, polarizer, and the analytical cell and generates analytical signals, corresponding to sensed radiation, which are provided to the signal processing unit,
• wherein the signal processing unit is operative to output concentration signals responsive to the analytical signals, wherein the concentration signals are representative of mercury concentration or benzene concentration of gas from the sample in the analytical cell,
• a gas system,
• wherein the gas system comprises at least three gas channels, a sampling port, an input port of the analytical cell, and a gas channels selector,
• wherein at least one of the gas channels is operative to remove benzene from a gas stream,
• wherein at least one of the gas channels is operative to remove mercury from the gas stream,
• wherein at least one of the gas channels is permeable for mercury,
• wherein at least one of the gas channels is permeable for benzene,
• wherein at least one of the gas channels has known different permeability rates for mercury and benzene,
• wherein the sampling port is operatively fluid connectable with the input port of the analytical cell through the at least three gas channels and the gas channels selector,
• wherein the gas channels selector is selectively operative to connect the sampling port and the input port through any selected one of the at least three gas channels,
• b) selecting through the operation of the gas channels selector to connect the sampling port through each of the at least three gas channels with the analytical cell at different times,
• wherein subsequent to (b) the signal processing unit provides an output signal corresponding to mercury or benzene concentration of gas from the sample.