Column calibration

In any case, even if all the above statements are 100% true, it does not affect our discussion because they are beside the point. The behavior of calibration algorithms in the face of noisy data is an important topic and perhaps should be studied in depth, but it was not at issue in the Linearity in Calibration column. 

Steere, R. E., and G. K. Ackers Restricted diffusion chromatography through calibrated columns of granulated agar gel a simple method for particle-size determination. Nature /9d, 475 76 (1962). 

Caroli and his co-workers [14] published multielement speciation results including data about Mn speciation. These data regarded samples from 60 mothers (approximately day 30 after delivery) living in different areas of Italy. The investigation was based on SEC fractionation using a mass calibrated column and total concentration of Mn was found to be around 3 p,g l-1. They found 28 percent of Mn in the void fraction (>2000 kDa), 30 percent bound to the nonprotein fraction, (relatively LMW compounds), and the remaining Mn was found at low levels in the other fractions. 

Ion exchange methods separate elements by passing a sample through calibrated columns of eluting agents. 

To relate the retention time to molecular weight for a given series of columns, we use molecular weight standards. They are commercially available. Manufacturers supply the data of M , M, and M, where Mp, the peak molecular weight, is the molecular weight at the peak of the SEC retention curve. A calibrated column can convert the retention curve into the plot of the molecular weight distribution. 

Some optimization system models rely on predetermined libraries of compounds already calibrated on several common stationary phases. If a peak of interest is in such a library and the analyst is using one of the characterized phases, then no additional calibration may be necessary as long as (1) the calibration column and the experimental column dimensions are known with good accuracy, (2) the calibration gas chromatograph s oven temperature and experimental oven temperatures are standardized, and (3) the pressure drops and ambient pressures for the calibration and experimental systems are known accurately. If not, then the simulations will be less accurate. However, small errors in these areas will not distort simulated results so much that peak elution order and relative retention will be meaningless. Even when not exact down to the second, simulations provide a wealth of useful information about peak retention behavior under a range of test conditions. 

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