Automated calibration transfer

Agilent Technologies and Infometrix have developed a technique called Automated Calibration Transfer (ACT) that allows users to transfer e-nose applications from one instrument to another simply by running a few calibration samples. Running ACT also adjusts for long-term sensor drift and for tune-induced shifts. In brief, ACT improves the stability and reliability of the MS sensor. 

Sample preparation, injection, calibration, and data collection, must be automated for process analysis. Methods used for flow injection analysis (FLA) are also useful for reliable sampling for process LC systems.1 Dynamic dilution is a technique that is used extensively in FIA.13 In this technique, sample from a loop or slot of a valve is diluted as it is transferred to a HPLC injection valve for analysis. As the diluted sample plug passes through the HPLC valve it is switched and the sample is injected onto the HPLC column for separation. The sample transfer time typically is determined with a refractive index detector and valve switching, which can be controlled by an integrator or computer. The transfer time is very reproducible. Calibration is typically done by external standardization using normalization by response factor. Internal standardization has also been used. To detect upsets or for process optimization, absolute numbers are not always needed. An alternative to... 

For the extraction of total phosphate a weighed aliquot of sediment (0.3-0.5g), together with 3 0.1g of potassium persulphate (Analar) and 5.00ml of concentrated sulphuric acid, was added to the bomb, which was then heated in an oven at 135 5°C for 2h. The contents of the bomb were then transferred quantitatively into a 500ml calibrated flask. After dilution to volume with distilled water, the extract (containing 1% v/v of sulphuric acid) was analysed for total phosphate by the automated procedure outlined below. 

The interface provides efficient transfer of samples into the Merlin, and, most importantly, a rapid flush-out there is no hold up of mercury (which is a feature of the commonly used atomic absorption techniques). To aid the transfer of mercury vapour, the tin(II) chloride regime is used, together with a gas/liquid separator designed for this task. Mercury is sparged from the reaction vessel into the Merlin Detector. Full automation is provided by using a simple standard DIO card fitted into an IBM compatible computer system with the PSA Touchstone software. This is an easy-to-use menu-driven system which controls the modules used in the instrumentation, calibrates the system, collects, collates and reprints the results, and which finks to host computer systems. 

A sample is placed in a glass vial that is closed with a septum and thermo-stated until an equilibrium is established between the sample and the vapor phase. A known aliquot of the gas is then transferred by a gas-tight syringe to a gas chromatograph and analyzed. The volume of the sample is determined primarily from practical considerations and ease of handling. The concentration of the compound of interest in the gas phase is related to the concentration in the sample by the partition coefficient. The partition coefficient is included in a calibration factor obtained on a standard. The analysis can easily be automated where a series of samples is to be analyzed, resulting in improved precision. 

In this method, the water-insoluble methylene blue salt of the anionic surfactants is transferred into chloroform by shaking. To eliminate any interference by other substances which react with methylene blue such as proteins and humic acids, the chloroform extract is shaken with an acid methylene blue solution. The blue chloroform extract, made up to the correct volume, is subjected to photometry and the result is evaluated by reference to a calibration curve. An advantage of this method is that it can be automated. Soaps do not react with methylene blue. 

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