Latest instrumentation in analytical chemistry Essay

Latest instrumentation in analytical chemistry

Introduction

Analytical Chemistry is a study of chemical compositions and characteristics of all matter and it also deals with the amount of chemicals that are present in the matter. But Analytical Chemistry is just confined to the analysis which involves in answering some basic questions related to chemistry.

Thus an Analytical Chemistry is completely a QUALITATIVE and QUANTITATIVE type analysis which involves in finding the type (organic/element or inorganic/functional group) and amount of sample respectively.

The next logical steps of understanding what it means, who could use it, how it fits into a system, is it easy? Can only be answered by modern analytical chemistry which can be approached in two different techniques

By Analytical Targets:

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·          Material analysis

·          Chemical analysis

·          Environmental analysis

By Analytical Methods:

·          Spectroscopy

·          Chromatography

·          Electro chemistry

Spectroscopy

It is a study of interaction of Radiation and molecules as a function of wavelength. Spectrometry is technique used to assess the concentration or the amount of a given sample or compound. The instrument that performs these measurements is a spectrometer.

Latest Instruments in spectroscopy:

·          VDIP-1 Fiber optic spectrophotometer

·          DLK-1000 Spectrophotometer

·          Laser Elemental Analyzer model- LEA-S500

DLK- 1000 Spectrophotometer:

It is an instrument which is used to determine the ability of the sample solution to absorb the incident light of specific wavelength by measuring the transmitted light.

Specifications:

Spectral range:                       338 to 854nm

Detector:                                1024 element CCD

Optical resolution:                  5nm FWHM

Sensitivity:                             0.001 AUFS

Size:                                       13”L×6”W×5”H

LEA-S500:

The LEA-S500 is a latest instrument which is basically a laser induced breakdown spectrometer (Atomic emission spectroscopy) which has bright analytical performance. This spectrometer summarizes the merits of recent developments in Laser techniques, Analytical Software and Spectroscopy.

The key feature of LEA is that it uses originally designed laser as an excitation source. This is used in the analysis of elemental and bulk chemical compositions in different materials. Both conducting and non-conducting materials like ceramics, glass, films etc can be analyzed using this laser instrument.

Brief description of LEA-S500:

The spectrum excitation used in this analyzer is developed using Q-Switched Nd:YAG. The average power generated by laser is of one watt and at a wavelength of 1064 nm which provides a peculiar temporal kinetics for pulse repetition. Specific conditions for the plasma cloud formation are created by the treatment of the material surface with pulses. These conditions lead to reduction of the density and erosivity of near surface layer of plasma resulting to a growth in the industry of spectral line with high exciting energies, the background level decreasing too and spectral lines becoming narrower.

Special pump has been installed in the sample compartment where spectrum excitation occurs to permit both creation of the required atmosphere in the breakdown region and air exhaust. Increase in the detection sensitivity of some volatile and elements which are difficult to excite is facilitated by air exhaust, for instance, in carbon, whose concentration is very important.

Analyzer high sensitivity is contributed by the spectrograph and beam focusing system. Spectra are detectable with a high performance CCD camera, which are developed for short time pulse processes. The implementation of the given technique produces an instrument with a variety of analytical functions.

The dedicated software controls all the performance characteristics of the analyzer through computer.

Software:

An operator can obtain any sort of information through this software. And the development of software is guaranteed by utilization of internal algorithms and control functions combined with calculations.

The distinguishing features of the software are as follows:

·          System stability control

·          Analyzer automatic control

·          Database for material types

·          Control of unexpected impurities

·          Control of quality and reliability of analytical results

·          Graphical representation of analysis results

·          Global re-calibration

·          Indication of deviation from the specified material type

·          Line profile control

·          Printout and mathematical treatment of analysis results

Specifications of LEA-S500:

Focal length (mm)                              500                             500                             500

Grating (grooves/mm)                                   1800                           2400                           3600

Wavelength range (nm)                     190-800                      190-600                      190-400

Dispersion (nm/mm)                          1.0                              0.7                              0.5

Wavelength resolution (nm)              0.028                          0.020                          0.014

Excitation:

Original Q-Switched Nd:YAG laser

Average pulse energy is 100mj

Energy stability is +/- 3% for 99% of pulses

Detection:

2048 pixels linear CCD, 14 bit, USB interface

Full spectrum detection

Sample compartment:

Sample size (without adapter): 12*12*2 mm (min), 75*75*40 mm (max)

Availability of sample displacement along XY axis is +/-5mm (for averaging of measurement results)

Analyzed zone size: diameter = 0.03-1.7 nm

Environment – air

Adapters for wire, foil, small size samples

Advantages of this latest instrument over traditional instrument:

·          Simultaneous multi-element determinations are possible

·          Rapid analysis is possible

·          Extremely low limits of detection

·          Very small samples are enough to carryout the analysis.

 Who would use it?

People dealing with analysis of various organic (elements) and inorganic (functional group) will use these latest instruments for accuracy and perfection.

Where are they used in?

LEA-S500 is widely used in-

Industries involving ferrous and non-ferrous metallurgy
Building materials
Mechanical Engineering
Semiconductor industries
Glass industries
For research in universities and laboratories

Chromatography

Chromatography, as the name itself contains the term “chroma” meaning color and it is a technique that is used in instrumentation for the separation of an element/ analyte from a mixture of molecules. This involves two phases- mobile and stationary phases. The mixture present in any mobile phase is allowed to pass through the stationary phase which then partitions the analyte to be measured from the other substances present in the mixture and helps it to get separated.

Chromatography could either be PREPARATIVE or ANALYTICAL.

§  Preparative      -separates the analytes for further usage just as in any purification process.

§  Analytical        -it normally measures the relative proportions of the elements/ analytes      present in a mixture.

Latest instruments for Gas Chromatography:

ta3000 Gas Analyzers:

The trace analytical ta3000 series belongs to the family of instruments which are designed in order to monitor trace levels of specific impurities in bulk gases, environmental applications and research applications. All ta3000 instruments possess a dedicated sample processing system, a on-board analysis electronics and a single high sensitivity detector. It consists of two models each having a different detector.

The two models are:

ta3000R

the analytes detected by this are H2, CO and Unsaturated Hydrocarbons
the detection limit of RGD (Reduction Gas Detector) is 10ppb
ta3000F

the analytes detected by this are Methane, Non-Methane Hydrocarbons and CO2
the detection limit of FID (Flame Ionization Detector )

Tradition of Excellence:

Analytical solutions for environmental monitoring, industrial process control and high purity gas monitoring applications are delivered by this latest instrument ta3000. The ta3000 possesses an internal sampling processing channel which intern is fallowed by either a RGD (Reduction Gas Detector) or FID (Flame Ionization Detector). For determination of hydrogen and carbon monoxide in air research, environmental samples, process control and bulk gas purification the RGD configuration is considered as a worldwide standard. It is also useful for ambient air monitoring for unsaturated hydrocarbons such as ethylene, isoprene. The main use of FID configuration is the determination of methane, non-methane hydrocarbons (NMHC) and CO2 in ambient air, water headspace, bulk gasses or process gas streams.

The ta3000 gas analyzer is a type of gas chromatograph which is configured with a either a Reduction Gas Detector or a Flame Ionization Detector .The instrument can also perform highly specialized task by configuring the ta3000’s Chromatograph hardware in several ways.

                        The main working principle of RGD is the strong absorption of UV light by mercury vapor. A proportionate amount of mercuric oxide, to its concentration in the sample gas, is released when the reducing species passes through the heated mercuric oxide bed in the detector.

              The most widely used detector for Gas Chromatograph is FID (Flame Ionization Detector). This detector detects the molecule with carbon hydrogen bonds. The CH bond breaks and forms ions when the gas molecules are exposed to the flame which is supported by the mixture of Hydrogen and the gas effluent from the gas chromatograph column. Therefore, electric signal is produced when these ions get collected on biased electrodes. The generated current is proportional to the concentration in the sample.

Features:

High sensitivity.
Best value and performance.
It has a very large detection range.
Its maintenance and operation are cost effective.
Expandable and multi-point stream selector.

Effective Monitoring Technology:

This instrument has been manufactured for operating in a continuous mode. It also best suits for the transport to the field for the spot tests and for surveys as it has roust construction, thus making it a highly versatile gas analyzer.

ta3000 gas analyzer can be interfaced with Sigma4000 multi-point stream selector; this can help in monitoring several sampling points. Control of the stream selector, processing of the data in a variety of formats and stored calibration parameters, can be controlled by the help of on board microprocessor. A special software called Trace Viewer helps in formatting the data, alarm status, reports and stores chromatograms on a local PC.

Typical applications:

REDUCTION GAS DETECTOR (ta 3000R)

§    It can identify the safer levels of ethylene oxide in air.

§    Bulk gas certification.

§    It can also measure the amount of hydrogen dissolved in water.

§    Trace level of detection of CO in atmosphere

§    It can monitor the ethylene in the atmosphere

FLAME IONISATION DETECTOR

§    It helps in the measurement of hydro carbons present in the ambient air.

§    It can detect Methane, Non-methane hydrocarbon in inert gas streams and CO2.

§    Monitoring hydrocarbons impurities in oxygen.

Merits of ta3000 analyzer:

The negligible matrix effects from permanent gasses and extreme sensitivity from parts per million (ppm) to parts per billion (ppb) are the primary strengths of ta3000 detectors. It is considered to be a very unique system as it has the combined effects of sensitivity and separating power of gas chromatography.

Ta3000 is the analyzer which has modern user interface which enable the user to measure the impurities selectively in the air. It can also be used for quality control of pure gas and research and for other gas monitoring applications.

Specifications:

Dimensions:       7”H × 16.8” W×26.5”D (18cm×43cm×67cm)

Weight:              35lb. (15.9 kg)

Power:               100 – 120 VAC, 50/60 Hz; 200 -240 VAC, 50/60 HZ

MGB1000 Micro Gas Blender:

This instrument helps in calibrating any gas analyzer at sub ppm levels. It provides consistent and reliable gas levels (concentrations) at blend ratios 4545 to 1. This instrument best suits for the calibration of some gas analyzers like the aforementioned ta3000, with ppb mixed component gas standard. Without consuming huge amounts of zero gas, the micro volume flow path helps single step blends reliably and quickly.

Long Term Stability:

As all the interconnecting fittings and tubing in the flow path of MBG1000 are made from stainless steel, electronic pressure gauges are stable to 0.1% of full scale reading per year and as a precaution each gas inlet is protected from matter by 2mm particle filter.

Features and Advantages:

Its design is very compact.
Blended glass flow rate up to 25 L/min or 1.5 L/min.
Cost of operation is very low.
Very fast equilibration time is achieved through the use of micro volume flow path.
The single step dilution is up to 46545:1.
It has got extremely low internal volume.
It has very low zero consumption.
It reduces the requirements of cylindrical gas stocking.
Total shut off CAL gas for blank runs

Specifications:

Electrical:

Standard                     110VAC, 50 – 60 Hz

Optional                     230VAC, 50 – 60 Hz

Maximum operating pressure is 100psig (6.9bar).

Net weight =              15.5lb (6.8kg)

Dimensions:                5.3”H×16.8”W×14.0”D

                                   (133mm×427mm×356mm)

Electrochemistry

It is a branch of science that deals with the chemical changes occurring along with the transfer of electric current, or vice versa where a chemical reaction is primarily used as the source of energy to generate electric current, just as in any battery. Electrolytes such as any liquid solutions or some liquid salts and few ionically conductive solids can be used. Ionic conduction in such electrolytes is a part of electro chemistry.

Electro analytical chemistry:

A large number of electrochemical measurements are necessary for practical analytical purposes. For these analytical purposes, many electrodes are used which basically work on the measurement of their potentials.

These include the following:

Glass electrode                      -used for PH measurements
Ion selective electrodes for    -used for potassium /sodium / calcium or fluoride       ions
Some other important analytical applications of electrochemistry are:

Cyclic voltammetry    -used to measure the currents with linear voltage   scan
Chronopotentiometry -used to measure potential- time transients under constant current conditions

Latest instruments in electrochemistry:

Scanning Electrochemical Microscope System (SECM370):

This instrument is a new in scanning probe electrochemistry, which has been manufactured for spatially resolved measurements in electrochemistry and for a range of ultra-high resolution order.

This model 370 scanning electrochemical microscope system enables the user to select the configuration most suited for the experiments with the help of flexible data acquisition system along with the nanometer resolution in a closed loop x, y, z  positioning system is fast and precise.

The SECM370 is precision scanning microelectrode system which helps in monitoring of imposing the current flow between a specimen surfaces in solution at extremely high spatial resolution and microelectrode.

Features:

User defined scan parameters like step size, number of data points, velocity, displacement and step scan and continuous mode.
It has programmable macro language for non-standard experiments.
It has got the x, y, z measurement at any point after the data acquisition.
This instrument has many standard electrochemical techniques which includes linear and cyclic voltammetry, chronoamperometry, square wave voltammetry, chronopotentiometry, normal and differential voltammetry.
Its data files can be exported through ASCII codes.
This can be used with new ultra microelectrodes. Microelectrodes ensure their strength in use and the fabrication methods are closely controlled for providing minimum diameter of glass at the probe tip. Platinum electrodes with diameters of 5µm, 15µm and 25µm are presently used.

The Scanning Probe Electrochemical Techniques performed by this instrument:

a)      Surface topography (OSP).

b)      Scanning Kelvin Probe (SKP).

c)      Localized Electrochemical Impedance Spectroscopy (LEIS).

d)     Scanning Vibrating Electrode Technique (SVET).

e)      Scanning Electrochemical Microscopy (SECM).

Ease of usage:

Using this instrument is very easy as it has user configurable visual templates.

Where is it used?

It is used in the height tracking.
This can be done using topography data from any source like SKP topography, or constant current SECM macro in any map experiment.

It can be used to analyze or modify the surface chemistry of a sample in solution.

Helps the chemist in future chemical analysis in the fields of:

Metallurgical industries         – for corrosion science
Biochemistry                          -study of enzyme stabilization
MEMS                                               -micro electro mechanical systems

Advantage of SECM 370 over the traditional model 370 scanning electrochemical workstation:

a)      SECM 370 includes in itself an integrated, versatile galvanostat / potentiostat system with model 370 scanning electrochemical workstation.

b)      All the parameters, data acquisition and variables are performed on a PC using a direct USB port. So made compatible with the computers very easily.

Works cited

Brochure,”MGB 1000 Micro Gas Blender”, AMETEK process instruments (2006)

Brochure,”ta3000 Gas Analyzer”, AMETEK process instruments (2006)

Cremers, Brefield, Koskelo “Applied Spectroscopy” volume 49, issue 6 (1995).

M.V.Mirkin, A.J.Bard,” Direct Electrochemical measurements by Scanning Electrochemical      Microscopy “(1992)

Model 370 Scanning Electrochemical Microscope Workstation, UNISCAN INSTRUMENTS

http://www.uniscan.com/secm.html

V.D.Kopachevskii, M.A.Krivosheeva. “Chemistry and Material Science”, volume 48

                Journal of Refractories and Industrial Ceramics (2007): 255-258