THORNTON is now offering detachable pH and ORP sensors. These detachable sensors allow you to pick an appropriate electrode, housing and preamp specifically suited to your application.

Detachable sensors feature VP (Vario Pin) electrical connectors directly on the electrode body, allowing more flexible and lower cost electrode replacement, separate from the preamplifier. A variety of housings, including retractable models are only available in this series.

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The ONLY Stick style pH Meter with a:

Flat Surface Electrode measures pH in liquids, semi-solids, and solids. No more electrode breakage or clogged junctions.

RENEW indicator tells you it's time to replace your electrode. Eliminates guesswork.

CAL alert tells you it's time to recalibrate. Ensures accuracy.

Memory records and recalls 15 sequentially tagged readings. Allows detection of changes over time.

Analog bargraph displayed on LCD. Shows trends in acidity or alkalinity

More Features/Functions:

• 1, 2 or 3 point calibration automatically recognizes buffer solutions

• Automatic Temperature Compensation

• Simultaneous display of pH and Temperature

• Display indicates when the reading is stabilized

• Data Hold, Auto power off and low battery indication

• Waterproof design floats in water and protects the meter in wet environment

• Interchangeable electrodes give you the versatility to change electrodes

• Optional weighted base (EX006) holds plastic cup and ExStik® meter

• Complete with flat surface pH electrode, protective sensor cap, sample cup with cap, four SR44 button batteries, and 48" (1.2m) neckstrap

The discovery by Blau in the closing years of the last century of the red and blue colors that ferrous and ferric salts form with the organic bases phenanthroline and 2,2'-bipyridine was reinvestigated in 1931 by Walden, Hammett and Chapman who found that the ferric-ferrous (blue-red) system, being reversible in nature, constituted a fine, high-potential oxidation-reduction indicator. Somewhat later, H.H. Willard and G. Frederick Smith, practically simultaneously, utilized the formation of the red color of ferrous iron with 1,10-phenanthroline for the colorimetric determination of iron. This method has proved so satisfactory that it is now almost universally used.

Subsequently, G. Frederick Smith, having enlisted the aid of Professor Francis Case of Temple University in the synthesis phase of the research, investigated over one hundred derivatives of 1,10-phenanthroline. As a result of this work, there is now available a series of oxidation-reduction indicators covering the potential range 0.85 to 1.25 volts in small steps. A number of the organic bases and the ferrous derivatives in the form of the sulfate and perchlorate salts have now been made available commercially.

The investigation of the phenanthrolines by Smith has also led to a number of new colorimetric reagents. 4,7-Diphenyl-1,10-phenanthroline, given the common name Bathophenanthroline, is a sensitive reagent for iron, the ferrous derivative having a molar extinction coefficient almost twice that of the ferrous derivative of 1,10-phenanthroline. This ferrous complex may be extracted into immiscible solvents and this enables not only a concentration of the color which increases the sensitivity but provides a means of extracting the iron in the reagents and water used in the test and thus of reducing the blank to zero. Bathophenanthroline makes possible the quantitative determination of iron in amounts as low as 0.002 parts per million (2ppb).

Another outstanding development in the field of phenanthroline chemistry is the discovery that phenanthrolines substituted in the 2,9-positions do not react with iron but do react with cuprous copper. A similar effect is observed with 6,6'-substituted 2,2'-bipyridines. Of particular interest for the determination of copper are Cuproine (2,2'-biquinoline), Neocuproine (2,9-dimethyl-1,10-phenanthroline), and Bathocuproine (4,7-diphenyl-2,9-dimethyl-1,10-phenanthroline) all of which are excellent colorimetric reagents for copper.

Of special interest to clinical chemists are the sulfonated phenanthroline reagents. Sulfonated bathophenanthroline (No. 286) and sulfonated bathocuproine (No. 294) are readily soluble in aqueous solutions and retain the high sensitivity toward iron and copper of the parent reagents. Their use in clinical applications is free of solubility and turbidity complications when extraction procedures are to be avoided.

The six most sensitive iron reagents available are now included in our list, PPT,2,4-BDTP and PPDT and their sulfonated derivatives. These reagents are the latest in the continuing efforts of Case and Schilt to find the very best. The sulfonated reagents can be substituted in nearly any procedure using sulfonated bathophenanthroline or sulfonated PDT by merely changing the wavelengths used.

Mettler-Toledo Thornton announces the release of a new pH sensor for measuring rinsed hydrofluoric acid (HF) from the Flat Panel Display substrate & silicon etching processes. Flat Panel and Semiconductor waste and reclaim water treatment can now obtain accurate pH measurement and control with extended sensor life. The new sensor uses a proprietary fluoride-resistant glass membrane, robust XEROLYT® PLUS reference system and integral temperature compensator to achieve this level of performance.

The new pH sensor may be used with Thornton's M300pH, M300 multiparameter and 770MAX instruments.

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With the growth of our manufacturing capabilities and product drying efficiencies, GFS now produces ton lots of reagents such as anhydrous cerous chloride, used in the synthesis of pharmaceutical intermediates, and other synthetic precursors. Our extensive experience with all kinds of Rare Earth chemistries has made us the supplier of choice for many manufacturers of catalysts and industrial formulations. We'll address any product, any purity, any form – including nano-dispersions of Rare Earth oxides described later in this section. Let us know how we can help you.

Ceric Compounds as Analytical Reagents As a result of the pioneering research work of H.H. Willard, N.H. Furman, G. Frederick Smith, and many others, tetravalent cerium compounds are now used as standard solutions in volumetric analysis for the determination of a variety of inorganic and organic materials in routine quality control and in research work. These uses of tetra-valent cerium solutions as standard oxidizing agents have become so common that the general methods of preparing and using the solutions and their specific applications can be found in any good elementary quantitative analysis text, as well as in reference work and volumes of official methods of analysis. The reduction potential of tetra-valent cerium varies with the nature and the concentration of the acid present in the solution in which it is dissolved; it is weakest in hydrochloric acid solution (formal reduction potential, 1M HCl, Eo = 1.28 volts) and progressively stronger in sulfuric acid (Eo = 1.44 volts), nitric acid (Eo = 1.61 volts) and perchloric acid (Eo = 1.71volts). This variation in reduction potential results from the union of the cerium with the radicals of the acid to form complex anions, thus, sulfatoceric acid, H4Ce(SO4)4, and the nitratoceric acid, H2Ce(NO3)6. The corresponding ammonium salts are ammonium sulfatocerate, (NH4)4Ce(SO4)4, and ammonium hexanitratocerate, (NH4)2Ce(NO3)6. The single most important cerate compound is undoubtedly ammonium hexanitratocerate (cericammonium nitrate). By its preparation it is possible to separate cerium from the other rare earths in a single crystallization. The composition of this salt corresponds exactly to the formula (NH4)2Ce(NO3)6 and the compound may be prepared of such quality as to be useful as a primary standard in oxidimetry. From it can be prepared ceric hydroxide, CeO2•2H2O, and sulfatoceric acid. Standard cerate solutions for volumetric analysis can be prepared starting with various cerate or cerous salts, the most convenient starting materials being ammonium hexanitratocerate and ceric hydroxide. The ceric hydroxide marketed by GFS is ground to 100 mesh and is especially convenient for the preparation of cerate solutions. From a research standpoint, the most active phase of cerate oxidimetry is the quantitative and stoichiometric oxidation of organic compounds. For a full treatment of the subject of the preparation and analytical applications of these materials, the reader is referred to the book, Cerate Oxidimetry, by G. Frederick Smith; this book may be obtained without charge (see page facing inside back cover). GFS Etchants Solutions of ceric ammonium nitrate in dilute perchloric acid are being widely used as etchants for preparation of printed circuits, for preparation of metal samples and for cleaning surfaces prior to fabrication by soldering. It is particularly useful for etching nichrome, monel, stainless steel and many other ferrous and non-ferrous alloys. An etchant that does not contain perchloric acid is also available. Nano-suspensions of Rare Earth Oxides In collaboration with the National Institute of Standards and Technology, GFS Chemicals has been actively involved in the use of modified flow reactor technology to develop aqueous nano-suspensions of Rare Earth and other metal oxides. Isolation of selected powder forms of novel morphologies is also being explored. As a result of this research, GFS is able to offer a variety of Rare Earth oxides as nanosuspensions in slightly alkaline aqueous medium. Studies suggest particulate size that is typically under 50 nanometers, in some cases considerably less. These materials are more fully represented in the alphabetical product section of this catalog, and listed in the Rare Earths Index that follows this section. In addition, GFS can also make available, on an "inquire/project" basis, nano-powder forms of selected metal oxides dried according to customer specifications on a confidential basis. Please contact us with your requirements. As with all GFS technologies, enjoy the advantages of working directly with the manufacturer.

The Greenspan AQUALAB Water Quality Analyzers are a Cost-Effective Solution to all your Water Quality Monitoring Needs. It is configurable analyser allowing you to select the appropriate chemistry package for your application from wastewater to environmental monitoring.

AQUALAB can be configured to perform any selection of physical parameters (pH, electrical conductivity, dissolved oxygen, turbidity, temperature and oxidation reduction potential - ORP) and nutrient parameters (total reactive phosphorus, nitrate, ammonia and ammonium).

The analysers are designed to meet the analysis requirements of the user and the harsh environment of remote locations. AQUALAB offers multiple physical and chemical parameters housed in an environment controlled enclosure. Analysis parameters are housed in chemistry modules within the analysers, the configurations of the chemistry modules and analysers are:

Module Parameter

• Physicals - Electrical Conductivity, pH, Dissolved Oxygen, Oxygen Reduction Potential, Temperature, Turbidity

On board standards and dynamic calibration in association with standard laboratory methodologies ensures that AQUALAB will provide accurate and laboratory comparable data. The functionality of the AQUALAB allows for unattended operation with a minimum of field visits and the advantage that data review, system monitoring and diagnostics can all be performed via your desktop PC.