14 Affordable UV-Vis Spectroscopy to Suit Application Needs


Global scientific instrument manufacturer Biochrom now offers high performance, double beam and variable bandwidth UV-Vis spectrophotometers as part of the popular Biochrom Libra range. Application-led design with colour touch screens and USB data port means each new Biochrom Libra instrument can be tailored to meet the specific requirements of a wide range of academic, research, or industry applications. Now available through the company’s international network of sales organisations and specialist distributors, the new range includes: the Biochrom Libra S50, a robust, split beam workhorse; the Biochrom Libra S60, a multi-user, double beam spectrophotometer; the Biochrom Libra S70, a 1nm bandwidth double beam system ideal for routine pharmaceutical applications; and, the Biochrom Libra S80, a high performance variable bandwidth double beam instrument that meets both the regulatory and budget-conscious demands of even the most tightly controlled laboratory.


Biochrom Libra includes powerful application-based software for all stand-alone and PC controlled instruments. Stand-alone instruments feature a full suite of standard applications including single wavelength, wavelength scanning, standard curves, kinetics and life science protocols. Data can be stored on the instrument or USB drive and manipulated post run using the Trace Manager function. Biochrom’s new Equation Editor allows users to programme specific methods that include calculations based on measured data. A groundbreaking modular PC package – Resolution – provides the ultimate flexibility in control and data handling. ‘Quick Read’ and ‘Quick Scan’ options make routine operation fast and straightforward whilst a powerful Method Developer allows complex scanning, kinetic and quantitative protocols to be created and run. System qualification, pharmacopeia requirements and FDA 21 CFR Part 11 compliance are all supported.


Circle no. 34


CHROMATOGRAPHY & SPECTROSCOPY


Spectrophotometers Prescribed to Measure Aspirin Concentration


Commonly included in chemistry courses to demonstrate the principle of using light to measure concentration, analysis of aspirin tablets can be carried out accurately by two different methods using Jenway’s 73 series spectrophotometers. A new Jenway Application Note describes and compares how to determine the concentration of acetylsalicylic acid in aspirin tablets, using both the UV and visible wavelength capabilities of the 73 series spectrophotometers. Method 1 measures salicylic acid’s absorption maxima at 303nm while Method 2 quantifies a violet coloured complex at 530nm after salicylic acid has been derivatised with Fe(III). Three tablets were tested using each method and the results and standard deviations are given in the Application Note.


Pharmaceutical manufacturers routinely use the acid/base titration method to check the aspirin content of commercial tablets. However, assay results obtained using the two methods for the 73 series spectrophotometer gave values in agreement with the manufacturer’s own test results for the batch of tablets used in the Jenway study. This finding demonstrates the value of UV and visible wavelength spectroscopy for the quantitative determination of aspirin concentration within an educational context. Ideal for use in education and routine quality control applications, the four spectrophotometers in the 73 series feature a large graphical display incorporated into the lid, thereby minimising the overall footprint and saving bench space. The basic models, 7300 and 7305, offer measurement modes for absorbance, % transmittance and concentration, while models 7310 and 7315 add scanning, kinetics and quantitation modes as well as the ability to save results and methods to USB memory stick. Models 7305 and 7315 have a wavelength range extending into the UV region of the spectrum; bandwidth is a narrow 5nm for all four instruments.


Circle no. 35


Rapid and Accurate Analysis of Selenium in Shampoo


Thermo Fisher Scientific, Inc has released a new method guide for the analysis of selenium in shampoo. The method, which aligns with the European Union commission directive 97/73/EEC stipulating the methods of analysis necessary for checking composition of cosmetic products, features the Thermo Scientific iCE 3000 Series atomic absorption spectrometers. These spectrometers include deuterium background correction as standard and offer a fast and accurate solution for the analysis of selenium in shampoo. The iCE 3000’s wizard-driven SOLAAR software also provides simple spectrometer optimization and method development tools. Pityriasis capitis, more commonly known as dandruff, and seborrheic dermatitis, an inflammatory disease of the skin, are treated with selenium disulphide, which is contained in lotions and shampoos. After rinsing, selenium disulphide residues may remain on the scalp and can enter the body through broken or damaged skin. Since the element is considered to be a potential carcinogen, limits have been set for its content in shampoos and lotions. Commission directive 93/73/EEC mandates flame atomic absorption spectrometry with deuterium background correction as the formal method to measure and regulate the concentration of selenium disulphide in shampoo.


The new application note demonstrates how the iCE 3000 Series can be used for the identification and determination of selenium disulphide in a range of medicinal shampoos. Identification is performed by observation of a reactionary colour change, while flame atomic absorption spectrometry is used for the quantitative determination of selenium. The spectrometer can be optimised simply and quickly using the wizard-driven SOLAAR software. Deuterium background correction is implemented to ensure regulatory compliance and spiked recoveries used to verify the accuracy of the method. Experimental results have demonstrated that flame atomic absorption spectrometry with deuterium background correction is the ideal technique for the dependable analysis of selenium disulphide in shampoo.


Circle no. 36


More Sensitive Vacuum UV Spectrometer


McPherson’s vacuum ultraviolet spectrometer, Model 234/302, is now available with improved efficiency over a wide wavelength range. New Platinum coated gratings are ideal for use at windowless wavelengths, shorter than 120 nanometers (>10eV.) The compact 200mm focal length spectrometer can be supplied with various gratings to spread optimization over the entire 30nm to 550nm wavelength range; an advantage allowed by the optical design.


In combination with windowless, sensitive, cooled, scientific grade CCD detectors, adjustable slits, and f/4.5, the McPherson Model 234/302 provides fast, sensitive data collection. Extreme and vacuum ultraviolet radiation and emission spectra can be analyzed with sub- nanometer spectral resolution.


Adjustable slit width provides for best light throughput and for better spectral resolution to resolve closely spaced spectral lines. Tunability of the installed grating to longer or shorter wavelengths provides means to collect different simultaneous wavelength swaths for general-purpose spectroscopy, plasma physics, and process monitoring without compromising resolution or signal strength.


The newly introduced Platinum coated optics improve utility of the Model 234/302 vacuum ultraviolet spectrometer system. Furnished with spectral calibration certificate, the McPherson spectrometer is available with standard light sources, reflective condenser optics, and vacuum differential sections. McPherson’s application consultation assures the ultraviolet spectrometer is ready for implementation in your specific application.


Circle no. 37


INTERNATIONAL LABMATE - AUGUST/SEPTEMBER 2010 - CHROMATOGRAPHY & SPECTROSCOPY


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