Abstract: A method of analysis, analysis system, apparatus, program product and method of supplying analysis of value that incorporates at least one data acquisition device, a central processor which may be located in the cloud with storage capacity and user-friendly interface on any web-enabled device with a communication link between the data acquisition device and the central processor and the central processor and the user interface on a web-enabled device. In the central processor, models of calibration predict values of the properties of interest; a classifier interrogates data to minimize errors in cases that the response variable is nonlinear by writing equations to follow each data segment; and a quantifier associates a data class with a specific pre-determined calibration model to compute specific parameters of interest. Results of analysis can be determined on the user interface at multiple stages of the analysis.

Abstract: A plasma spectroscopic analysis method includes a concentration process of concentrating a target in a sample, in the vicinity of one of a pair of electrodes in the presence of the sample; a plasma generation process of generating plasma in the sample by applying a voltage to the pair of electrodes; and a detection process of detecting emission of the target generated by the plasma, wherein the plasma generation process is performed in the presence of a defoaming agent.

Abstract: To improve detection sensitivity, detection accuracy, and reproducibility when electric discharge is caused in a sample solution to perform analysis with light emission in the plasma, a flow channel 101 provided with a narrow part is filled with a conductive sample solution, plasma is generated in bubbles formed by applying an electric field to the flow channel, and a region other than the narrow part in the flow channel is set as a measurement object region to measure light emission.

Abstract: In one embodiment, a gas contamination detection apparatus includes a gas analyzer adapted to receive a sample of a gas to be delivered to a patient and to analyze the gas sample to determine whether the gas contains a contaminant, and a gas shut-off valve adapted to automatically prevent the gas from being delivered to the patient if the gas is determined to contain a contaminant.

Abstract: A spark chamber for an optical emission analyser, comprising: a gas inlet located on a first side of the spark chamber for supplying a gas into the spark chamber; and a gas outlet located on a second side of the spark chamber arranged to convey the gas from the spark chamber; wherein an elongated electrode having an electrode axis generally along the direction of elongation is located within the spark chamber; and wherein: the first and second sides of the spark chamber lie at either side of the elongated electrode in directions generally perpendicular to the electrode axis; there is a gas flow axis through the spark chamber between the gas inlet and the gas outlet; and on passing along the gas flow axis from the gas inlet to the gas outlet the unobstructed internal cross sectional area of the spark chamber perpendicular to the gas flow axis remains constant to within a factor A, wherein A lies between 1.0 and 2.

Abstract: A spark-induced breakdown spectroscopy apparatus can have a housing with an inlet and an outlet that define an analyte flow path. A laser can define a laser pathway generally transverse to an intersecting the analyte flow path. A pair of electrodes, which can have insulating shields, can be mounted within the housing and can define a spark path. An optical detection element defines an optical path. The apparatus can be used to identify an aerosolized analyte.

Abstract: A method of determining the carbon content of an iron alloy may include starting of the measurement of a sample in a spark spectrometer, creation of a plasma in a pre-sparking phase, detection and recording of an intensity signal for the carbon, calculation and cutting out of an unstable plasma phase, calculation of an excessive rise in the carbon signal, and calculation of the content of dissolved and undissolved carbon.

Abstract: Particles of a flow of aerosol are collected and analyzed by passing them through a housing having an inlet area, an outlet area, and a collection and analysis area interconnecting the inlet and outlet areas. A collection electrode has a tip disposed in the collection and analysis area and particles are collected thereon. After collection, the particles are ablated and atomic emissions are collected for analysis of the particles.

Abstract: A spark-induced breakdown spectroscopy apparatus can have a housing with an inlet and an outlet that define an analyte flow path. A laser can define a laser pathway generally transverse to an intersecting the analyte flow path. A pair of electrodes, which can have insulating shields, can be mounted within the housing and can define a spark path. An optical detection element defines an optical path. The apparatus can be used to identify an aerosolized analyte.

Abstract: A spark optical emission spectrometer comprising: a spark source for causing spark induced emission of light from a sample; a single entrance slit; a toroidal mirror for directing the light through the single entrance slit; a plurality of diffraction gratings for diffracting light that has been directed through the entrance slit by the mirror, whereby the plurality of diffraction gratings are simultaneously illuminated; and at least one array detector for detecting the diffracted light from the plurality of diffraction gratings, wherein the minor is for directing the light through the entrance slit such that light from different regions in the spark source is spatially separated in an image of the light at the gratings whereby a first diffraction grating is preferentially illuminated with light from a first region of the spark source and simultaneously a second diffraction grating is preferentially illuminated with light from a second region of the spark source.

Abstract: The invention provides a spark generator for generating a spark for optical emission spectroscopy (OES), wherein the spark has a current waveform comprising a first modulated portion which comprises a plurality of relatively high current and high gradient peaks of variable amplitude and/or inter-peak duration and a second modulated portion of relatively low current and low gradient which is substantially without modulated peaks. The spark is preferably generated from two or more programmable current sources. The invention also provides an optical emission spectrometer comprising the spark generator and a method of optical emission spectroscopy using the spark generator.

Abstract: The proposed method is related to the field of technical physics, in particular, to spectral methods for determining elemental composition of liquid media using an electric discharge in the liquid as a source of spectra. The method can be implemented in devices for determining elemental composition of liquid media. The areas of application include water treatment systems at public water supply facilities, nuclear and thermal power industries, chemical industry, food industry processes (for water quality control), environment monitoring, etc. The technical result of the invention is higher stability and reproducibility of measurement results and better long-term operation reliability of the device.

Abstract: A system and method for reliably testing for toxic substances is described. Based on spectrographic means, the system embodies one or more types of spectrometers, designed for the detection of toxic elements such as lead, and alternatively designed for the detection of toxic compounds such as asbestos. By restricting the broad functionality common to a typical spectrometer, dramatic cost reductions can be made permitting the device to be cost-effectively manufactured and made available to the typical consumer. The device is can be portable and incorporates safety systems to inhibit improper use.

Abstract: An atomizing furnace, in particular for atomic absorption spectroscopy, includes a tube furnace apparatus and a sample carrier. The sample carrier is disposed within the tube furnace apparatus, and includes at least three supporting protrusions by which the sample carrier is punctually supported on an interior wall of the tube furnace apparatus. The supporting protrusions are disposed in a common plane running through a longitudinal axis of the sample material, wherein at least two supporting protrusions are formed on respectively opposite ends of the sample carrier.

Abstract: The invention relates to a spectrometer for analyzing the optical emission of a sample by means of pulsed excitation of an optical spectral emission, having an excitation source, a gap arrangement, at least one dispersive element and having detectors for the emitted spectrum, in which two beam paths are provided with two dispersive elements, the first dispersive element of which images the spectrum of the emission onto a number of spatially resolving detectors and the second dispersive element of which images the spectrum of the emission onto a number of time-resolving detectors.

Abstract: An optical emission spectroscopic (OES) instrument includes a spectrometer, a processor and an adjustable mask controlled by the processor. The adjustable mask defines a portion of an analytical gap imaged by the spectrometer. The instrument automatically adjusts the size and position of an opening in the mask, so the spectrometer images an optimal portion of plasma formed in the analytical gap, thereby improving signal and noise characteristics of the instrument, without requiring tedious and time-consuming manual adjustment of the mask during manufacture or use.

Abstract: An emission spectrophotometer capable of inhibiting non-uniformity of spectral intensities of component elements is provided. The emission spectrophotometer generates pulse light emission by supplying an energy accumulated in an electricity accumulating and discharging unit to a gap between an electrode and a test material, and the emission spectrophotometer includes a detection unit, for detecting an energy charged to the electricity accumulating and discharging unit before the pulse light emission; and a detection unit, for detecting an energy remaining in the electricity accumulating and discharging unit after the pulse light emission. It is determined whether the detected light is emitted by fully using the energy accumulated in the electricity accumulating and discharging unit.

Abstract: To improve detection sensitivity, detection accuracy, and reproducibility when electric discharge is caused in a sample solution to perform analysis with light emission in the plasma, a flow channel 101 provided with a narrow part is filled with a conductive sample solution, plasma is generated in bubbles formed by applying an electric field to the flow channel, and a region other than the narrow part in the flow channel is set as a measurement object region to measure light emission.

Abstract: An apparatus for multi-elemental analysis comprises an excitation site (1, 31) having an extended flat surface area for holding sample to be excited, and being adaptive to plural physical forms of sample and to retention of large wear metal particles which, in turn, appear as an uneven spatial distribution of elements on the surface. A scan mechanism (12-13, 32) is associated with the excitation site, a spectrometer, and an excitation source for evaluating the emission from each point in a defined region on the surface. A method of using the excitation site for retaining and analyzing inhomogeneous ingredients in a sample is provided. The apparatus further includes a heating mechanism (18, 34) for heating the sample on the surface.

Abstract: Techniques and devices are disclosed for detecting particle composition. In one aspect, a method performed by a detector to detect particles includes receiving particles at an aerosol inlet of the detector. The method includes carrying the received particles within a stream of gas and charging the particles within the stream of gas using a charger to have a charge. The method includes transporting the charged particles to a location of a collection electrode. The method includes biasing the collection electrode to a voltage using a high-voltage supply to attract either negatively or positively charged particles, and analyzing the particles.

Abstract: An optical emission analyzer is provided with a circuit-closing switch (56) for changing the state of an arc-generating circuit 5 between the closed state and the open state and a reverse-blocking diode (55) for preventing a spark current from flowing into the circuit-closing switch (56). The circuit-closing switch (56) is turned on before the beginning of a spark discharge between a discharge electrode (31) and a sample (32) to initiate excitation of a coil (53). Consequently, the excitation current of the coil (53) can be increased to a target value within the duration of the spark discharge without using a low-inductance coil or increasing the switching frequency of a switching element (52).

Abstract: A spark chamber for an optical emission analyser, comprising: a gas inlet located on a first side of the spark chamber for supplying a gas into the spark chamber; and a gas outlet located on a second side of the spark chamber arranged to convey the gas from the spark chamber; wherein an elongated electrode having an electrode axis generally along the direction of elongation is located within the spark chamber; and wherein: the first and second sides of the spark chamber lie at either side of the elongated electrode in directions generally perpendicular to the electrode axis; there is a gas flow axis through the spark chamber between the gas inlet and the gas outlet; and on passing along the gas flow axis from the gas inlet to the gas outlet the unobstructed internal cross sectional area of the spark chamber perpendicular to the gas flow axis remains constant to within a factor A, wherein A lies between 1.0 and 2.0.

Abstract: Particles of a flow of aerosol are collected and analyzed by passing them through a housing having an inlet area, an outlet area, and a collection and analysis area interconnecting the inlet and outlet areas. A collection electrode has a tip disposed in the collection and analysis area and particles are collected thereon. After collection, the particles are ablated and atomic emissions are collected for analysis of the particles.

Abstract: The invention relates to analytical chemistry. In the analyser, mercury placed in a spectral lamp is enriched with a mercury isotope having an even neutron number, wherein said isotope constitutes not less than 50% of the total mercury content in the spectral lamp. Moreover, the discharge cavity of the spectral lamp is connected to a ballast cavity, the volume of which is greater than the discharge cavity volume, and electrical discharge generating means, the discharge cavity and the ballast cavity are designed in such a way that the discharge generated in the discharge cavity does not penetrates into the ballast cavity. A buffer gas in the spectral lamp contains a noble gas in a quantity equal to or greater than 50%, the charge of the atomic core of said gas being not less than 36. Said invention makes it possible to lower the detection level of mercury in a carrier gas and to reduce a drift.

Abstract: A hand-held, self-contained, battery-powered test instrument for analyzing composition of a sample includes an exciter for exciting at least a portion of the sample, a compact cross-dispersed spectrometer for receiving an optical signal from the excited portion of the sample and a processor for processing spectral data about the optical signal from the spectrometer. The exciter may include a spark generator and a counter electrode, a laser or other device for generating the optical signal from the sample portion. The spectrometer has a wavelength range broad enough to enable the test instrument to detect and determine relative quantities of carbon, phosphorous, sulfur, manganese, silicon, iron and other elements necessary to identify common alloys. The spectrometer includes a structural member made of a light-weight material having a small coefficient of thermal expansion (CTE).

Abstract: A method of determining the carbon content of an iron alloy may include starting of the measurement of a sample in a spark spectrometer, creation of a plasma in a pre-sparking phase, detection and recording of an intensity signal for the carbon, calculation and cutting out of an unstable plasma phase, calculation of an excessive rise in the carbon signal, and calculation of the content of dissolved and undissolved carbon.

Abstract: An optical emission spectroscopic system contains multiple distinct light paths that provide increased light to a spectrometer, thereby increasing sensitivity and signal-to-noise of the system.

Abstract: The invention provides a spark generator for generating a spark for optical emission spectroscopy (OES), wherein the spark has a current waveform comprising a first modulated portion which comprises a plurality of relatively high current and high gradient peaks of variable amplitude and/or inter-peak duration and a second modulated portion of relatively low current and low gradient which is substantially without modulated peaks. The spark is preferably generated from two or more programmable current sources. The invention also provides an optical emission spectrometer comprising the spark generator and a method of optical emission spectroscopy using the spark generator.

Abstract: A metal identifying device precisely identifies a metal material in a metal member having a plurality of through-hole portions penetrating through the metal member. The metal identifying device of the present invention includes a measurement unit that obtains a measurement value by measuring an electrical property and/or optical property of a test object, a threshold value determination unit that determines a threshold value with use of a reference value obtained by measuring the property of a metal member having a metal composition to be identified and information indicating a ratio of the through-hole portions to a measurement area in the test object and/or information indicating a configuration of the through-hole portion, and a comparison/identification unit that identifies a metal composition of the test object by comparing the measurement value and the threshold value.

Abstract: An ambient atmosphere glow discharge spectrometer is disclosed having a capillary, two electrodes and a means for recording the atomic emissions.

Abstract: Method and systems related to obstructing a first predefined portion of at least one defined wavelength of light incident upon a first photo-detector array; and detecting the at least one defined wavelength of light with a photo-detector in a second photo-detector array.

Abstract: The invention relates to a method for the spectral analysis of metal samples with the following steps: a. Recording of a spectrum of an unknown sample with a number of preset excitation parameters, b. Comparison of the spectrum with stored spectra of a number of control samples, c. Determination of the control sample with the best concordance of spectra, d. Setting of the excitation parameters, which are stored for the best and closest control sample determined in step c, e. Recording of the spectrum of the unknown sample with the excitation parameters set in step d, f. Calculation of the intensity ratios of the analysis lines stored for the control sample and the internal standards of the spectrum recorded in step e.

Abstract: The invention relates to analytical chemistry. In the analyser, mercury placed in a spectral lamp is enriched with a mercury isotope having an even neutron number, wherein said isotope constitutes not less than 50% of the total mercury content in the spectral lamp. Moreover, the discharge cavity of the spectral lamp is connected to a ballast cavity, the volume of which is greater than the discharge cavity volume, and electrical discharge generating means, the discharge cavity and the ballast cavity are designed in such a way that the discharge generated in the discharge cavity does not penetrates into the ballast cavity. A buffer gas in the spectral lamp contains a noble gas in a quantity equal to or greater than 50%, the charge of the atomic core of said gas being not less than 36. Said invention makes it possible to lower the detection level of mercury in a carrier gas and to reduce a drift.

Abstract: An optical emission analyzer is provided with a circuit-closing switch (56) for changing the state of an arc-generating circuit 5 between the closed state and the open state and a reverse-blocking diode (55) for preventing a spark current from flowing into the circuit-closing switch (56). The circuit-closing switch (56) is turned on before the beginning of a spark discharge between a discharge electrode (31) and a sample (32) to initiate excitation of a coil (53). Consequently, the excitation current of the coil (53) can be increased to a target value within the duration of the spark discharge without using a low-inductance coil or increasing the switching frequency of a switching element (52).

Abstract: The invention relates to a spectrometer for analysing the optical emission of a sample by means of pulsed excitation of an optical spectral emission, having an excitation source, a gap arrangement, at least one dispersive element and having detectors for the emitted spectrum, in which two beam paths are provided with two dispersive elements, the first dispersive element of which images the spectrum of the emission onto a number of spatially resolving detectors and the second dispersive element of which images the spectrum of the emission onto a number of time-resolving detectors.

Abstract: A micro-sized gas detecting device with two electrodes separated by a gap of width ranging from 1 to 500 microns, where the detection is based on emission spectroscopy of gases in an electric discharge across the gap (discharge region) as the gas flows through the region. The characteristic light emitted by molecules during the discharge can be detected directly with photodiodes or transferred through optical fiber and detected with remote optical sensing components. The device can have single or multiple discharge regions in an array so that light emitted can be monitored at different wavelengths simultaneously. The device can operate under gaseous pressure ranging from a few milli-Torr to a few atmospheres. The device consumes little power (50 mW-100 mW) and can be powered with an alternating current and has the potential to be battery powered.

Abstract: Methods and systems for discriminating among sparking modes are disclosed. In one embodiment, a method includes receiving light from a spark into a spectrometer, generating a light intensity spectrum using the spectrometer, and classifying the sparking mode based on an analysis of the light intensity spectrum. The light intensity spectrum may be analyzed for the presence of an atomic emission and a broad blackbody emission. In further embodiments, light emitted by the spark may be received into a photodetector, and the classification of the sparking mode may be based on an analysis of an intensity profile, including at least one of a rise-time phase, a peak intensity, and a drop-off phase.

Abstract: The present invention provides a plasma generating electrode inspection device capable of efficiently inspecting the parallelism, flatness, surface roughness, and dielectric strength of a plasma generating electrode. A plasma generating electrode inspection device 100 includes a reference quartz plate 2 provided with a film-shaped transparent conductor 1 disposed on one surface (outer surface 2a), a reference spacer 3 disposed on the outer edge of the other surface (inner surface 2b) of the reference quartz plate 2, a reference clamper 4 which can secure a plasma generating electrode 11 as an inspection target between the reference spacer 3 and the reference clamper 4, and a pulse power supply 5 capable of applying a pulse voltage between the transparent conductor 1 and the plasma generating electrode 11 as an inspection target while changing the voltage.

Abstract: Methods for remotely detecting a gun muzzle flash, using frequency-optimized detection methods. Small explosive charges are best detected at I/R and visible wavelengths, using optical detectors, whereas large explosive charges may also be detected with antennas. Details of the time course and spectral properties of the flash can be used to distinguish gun muzzle flashes from other radiation.

Abstract: The invention relates to a method for the spectral analysis of metal samples with the following steps: a. Recording of a spectrum of an unknown sample with a number of preset excitation parameters, b. Comparison of the spectrum with stored spectra of a number of control samples, c. Determination of the control sample with the best concordance of spectra, d. Setting of the excitation parameters, which are stored for the best and closest control sample determined in step c, e. Recording of the spectrum of the unknown sample with the excitation parameters set in step d, f. Calculation of the intensity ratios of the analysis lines stored for the control sample and the internal standards of the spectrum recorded in step e.

Abstract: Two or more high-frequency microphones are used to determine where an individual spark or other excitation beam strikes a sample in an optical emission spectroscopy (OES) instrument. The position of the spark can be correlated with the elemental composition of the material in the sample vaporized by the spark. The microphones are placed appropriately in air around a sparker of the instrument, or appropriately on the sample, or on both the sample and in the air. Arrival times of sound from the spark to the microphones, or a difference in the arrival times, yields information, from which the position of the spark relative to the microphones, and hence the absolute position of the spark, is deduced, such as by triangulation. Optionally or in addition, a signal that indicates a time when the spark is produced is correlated with one or more spectra detected by a spectrometer, so a spectrum that results from the vaporized sample can be distinguished from a spectrum that results from heated gas above the sample.

Abstract: A method and device are provided for analysis of a molten material using optical emission spectrometry. The molten material may be, for example, a molten metal, such as casting iron or steel, or slag, glass, or lava. A sensitive element is used having at least one emission spectrometer and at least one excitation device to effect the excitation of the molten material and to enable the partial or complete generation of a radiation to be analyzed by a spectrometer present in the sensitive element. The sensitive element is brought into contact with the molten material and transmits information, which contains analysis elements supplied by the spectrometer. An immersion sensor is also provided for carrying at least part of the device for performing the analysis method.

Abstract: An optical emission analysis apparatus includes a discharge gap, an ignitor circuit, and a main discharge power supply. The ignitor circuit includes an ignition transformer, a pair of current control devices, and an excitation power supply. On a secondary coil of the ignition transformer, the discharge gap and the main discharge power supply are connected in series to form a main discharge current path. On a primary coil of the ignition transformer, the pair of current control devices and the excitation power supply are connected in series to form an excitation current path. A pair of current control devices is connected to each other via mutually opposite polarities. The polarity of the high voltage generated in the secondary coil is reversed by reversing the polarity of the voltage of the excitation power supply. The direction of the main discharge current is reversed by reversing the polarity of the voltage of the main discharge power supply.

Abstract: In an ingredient analysis method and an ingredient analysis apparatus in accordance with the present invention, high-frequency power is supplied from a power source 4 while helium gas is supplied to an atmospheric pressure plasma source 2 disposed near a substance to be analyzed, whereby plasma 5 is generated, and the substance to be analyzed is exposed to the plasma 5 and emits light. The light is guided to a filter 7 and a photodiode 8 via an optical fiber 6 and subjected to photoelectrical conversion. The signal obtained by the photoelectrical conversion is sent to a controller 9. The controller 9 judges whether a specific element is present or not in the substance to be analyzed.

Abstract: A hemispherical goniophotometer is disclosed, in which two pivoting arms are articulated on a revolving rotating arm and are each fitted with a measurement head. The geometry of the arrangement is chosen such that the measurement heads can move along the envelope surface of a hemisphere during rotating of the rotating arm through 360° and pivoting of the pivoting arms through 180°.

Abstract: An optical emission spectrometer for analysis, identification or identity testing of metallic materials, and a method for optical emission analysis of metallic materials with a spectrometer, wherein the spectrometer has at least one arc or spark generator for producing a discharge between an electrode and a workpiece in a spark stand chamber of the generator. A cleansing apparatus for air about the discharge includes a pump for feeding air into the spark stand chamber, and a container through which air can flow. The container contains an alkaline metal or alkaline earth metal hydroxide or another substance that binds CO2 present in air.

Abstract: An apparatus and process are provided for detecting whether a corona discharge has occurred external or internal to equipment in which a broadband optical spectra sensor is placed. The broadband optical spectra sensor senses both the ultraviolet energy of the corona discharge and the infrared energy of afterglow of the discharge when the discharge occurs internal to the equipment. The sensed broadband optical spectra signal is processed and a determination is made as to whether the corona discharge occurred external or internal to the equipment from the pulse width of the sensed energy pulse.

Abstract: A measurement device and method are provided for OES measurements in air. An arc electrode (201, 501) has a certain thickness and a pointed end having a certain grinding angle. Holding means (202, 502) hold the arc electrode (201, 501) at a certain distance from the material to be measured. A voltage and current supply (203) generates and maintains a voltage between the arc electrode and the material to be measured and supplies current through the arc. Focusing and detection optics (205, 206, 402, 403, 404, 405, 406, 407, 408, 505, 506, 509, 604) collect and detect optical radiation. The thickness of the arc electrode (201, 501) is between 3 and 10 mm and the grinding angle is between 50 and 130 degrees. The arc distance is between 0.5 and 3 mm. An ignition spark voltage is between 5 and 20 kV, an arc voltage between 20 and 160 V and an arc current between 1 and 10 A.

Abstract: A measurement device and method are provided for OES measurements in air. An arc electrode (201, 501) has a certain thickness and a pointed end having a certain grinding angle. Holding means (202, 502) hold the arc electrode (201, 501) at a certain distance from the material to be measured. A voltage and current supply (203) generates and maintains a voltage between the arc electrode and the material to be measured and supplies current through the arc. Focusing and detection optics (205, 206, 402, 403, 404, 405, 406, 407, 408, 505, 506, 509, 604) collect and detect optical radiation. The thickness of the arc electrode (201, 501) is between 3 and 10 mm and the grinding angle is between 50 and 130 degrees. The arc distance is between 0.5 and 3 mm. An ignition spark voltage is between 5 and 20 kV, an arc voltage between 20 and 160 V and an arc current between 1 and 10 A.

Abstract: A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical.