Molecular weight determination, drinking

Figure 4. Molecular weight determination of a drinking water concentrate with Sephadex LH20. Sampling, 10 -fold concentration of drinking water before and after chlorination (L5 mg/L of CI2, Meuse River source) on XAD-4/8, elution with DMSO (neutral fraction), and subsequent gel filtration were as described in Materials and Methods. After measuring the absorbance at 263 mm, the fractions were pooled as indicated. After dilution in water, the fractions were reconcentrated on XAD-4/8, eluted with DMSO, and assayed in the Salmonella mutagenicity test (strain TA98 S9).

But there are signs that simpler, less expensive LC/MS systems designed and priced for the general laboratory bench chemist, production facilities, and quality control laboratories may soon be possible. It remains to seen whether manufacturers will decide to produce these systems. Older MS systems have been purchased, attached to HPLC systems equipped with relatively inexpensive interfaces, and pressed into service for molecular weight determination as a 30,000 detector, indicating that the desire and need exists for general laboratory LC/MS systems. As prices continue to drop and technology advances work their way out of the research laboratories, the LC/MS will become a major tool for the forensic chemist whose separations must stand up in court, for the clinical chemist whose separations impact life and death, and for the food and environmental chemist whose efforts affect the food we eat, the water we drink, and the air we breathe. 

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