Biomedical subjects

I H Suffet

Publications and source records attributed to I H Suffet.

33 records · Page 2Linked to original sources

PubMed1987

The effect of cyclohexene, a preservative in dichloromethane on the liquid-liquid extraction and analysis of chlorinated drinking water.

Liquid-liquid extraction with dichloromethane is the Environmental Protection Agency's (EPA) method of choice for the analysis of acid or base neutral organic chemicals in water. Free radical chlorination and oxidation products of cyclohexene (the solvent preservative) in dichloromethane have been observed in extracts of chlorinated drinking water (after 10(5) fold concentration) by gas chromatography and gas chromatography-mass spectrometry. The chlorinated cyclohexene derivatives limit the quantitative and qualitative analysis of compounds eluting at Kovát's index less than 700-1000 and the use of these extracts for organoleptic and mutagenic studies. The effect of residual free chlorine in water on the cyclohexene present in the solvent was studied. Over ten cyclohexene derivatives were produced in every case when any residual free chlorine was present in the water. When chlorine is reduced to chloramine, the cyclohexene derivatives were greatly reduced in number and amount.

Chloramines↗

PubMed1987

Analysis of acetone-hexane artifacts produced in the Soxhlet extraction of solid environmental samples.

A study was performed to examine the artifact formation during the acetone-hexane Soxhlet extraction of suspended materials collected on glass fiber filters. Capillary gas chromatographic analysis showed a great number of artifacts of significant concentration in the Soxhlet extractions of the filters after cleaning, the acetone solvent blank and the acetone-hexane Soxhlet blank. Gas chromatographic-mass spectrometric analysis indicated that the compounds are primarily condensation products of acetone produced during the Soxhlet extraction process and solvent impurities. Acetone and hexane washes of the glass fiber filters showed a large variety of compounds to be present on the filters as received from the manufacturer. A reaction scheme is proposed to explain the formation of some of the acetone condensation products identified in this study. A comparison study using methylene chloride to clean and extract the filters showed considerably less artifact formation and solvent impurities. The development of an appropriate quality assured extraction method, which minimizes artifact formation, is needed for the broad spectrum analysis of non-polar trace organics associated with suspended materials in aquatic samples.

Acetone↗

PubMed1986

Predominant bacterial genera in granular activated carbon water treatment systems.

Granular activated carbon (GAC) beds may be used for removal of dissolved organic matter during the treatment of drinking water. However, they might also change the microbiological quality of the water entering the distribution system either by changing the predominant bacteria or the bacterial density of the treated water. A 3-year pilot plant study of water treatment using GAC beds was conducted at the Baxter Water Treatment Plant in Philadelphia. During the study, bacteria were isolated from the raw water and from the effluents of the GAC treatment units. At the end of the study, bacteria were also isolated from the GAC units and from sand beds operated in parallel with the GAC units. Bacterial genera in the GAC effluents and in the GAC units themselves were similar to those found in the raw water and in the sand beds. Prechlorination and (or) preozonation of the water before GAC treatment had no noticeable effect on the bacterial genera found as compared with GAC unit having no predisinfection. The bacterial genera found in this study were similar to those found in seven other studies of GAC water treatment that used a variety of treatment schemes and a variety of heterotrophic plate count techniques to evaluate bacterial populations. From these several studies it appears that GAC treatment does not change the nature of the bacterial populations associated with drinking water.

Adsorption↗

PubMed1983

Assessment of bacterial growth and total organic carbon removal on granular activated carbon contactors.

The overall growth rate of bacteria on granular activated carbon (GAC) contactors at the Philadelphia Torresdale Water Treatment Pilot Plant facility was found to decrease until steady state was reached. The growth rate was found to fluctuate between 6.94 X 10(-3) and 8.68 X 10(-4) doublings per h. The microbiological removal of total organic carbon (TOC) was calculated by considering the GAC contactors as semiclosed continuous culture systems and using growth yield factors determined in laboratory experiments. After ozonation, the average TOC entering the contactors was 1,488 micrograms/liter, and the average effluent TOC was 497 micrograms/liter. Microbiological TOC removal was found to average 240 micrograms/liter on GAC contactors, which was not significantly different from microbiological TOC (220 micrograms/liter) removal across a parallel sand contactor where no adsorption took place. Thus, GAC did not appear to enhance biological TOC removal. Bacterial growth and maintenance was responsible for approximately 24% of the TOC removal on GAC under the conditions of this study.

Bacteria↗

PubMed1978