Biomedical subjects

R C Lao

Publications and source records attributed to R C Lao.

14 recordsLinked to original sources

PubMed2000

Analysis of polycyclic aromatic hydrocarbons in sediment reference materials by microwave-assisted extraction.

The microwave-assisted extraction (MAE) of polycyclic aromatic hydrocarbons (PAHs) from harbor sediment reference material EC-1, marine sediment reference material HS-2 and PAH-spiked river bed soil was conducted. The extraction conditions for EC-1 were carried out at 70 degrees C and 100 degrees C under pressure in closed vessels with cyclohexane acetone (1:1), cyclohexane-water (3:1), hexane acetone (1:1), and hexane-water (3:1) for 10 min. A comparison between MAE and a 16-h Soxhlet extraction (SX) method showed that both techniques gave comparable results with certified values. MAE has advantages over the currently used Soxhlet technique due to a faster extraction time and lower quantity of solvent used. The consumption of organic solvent of the microwave method was less than one-tenth compared to Soxhlet.

Acetone↗

PubMed1979

Mercury vapor as a contaminant of hospital environment.

Surveys for airborne mercury in two Ottawa hospitals have been conducted. Two different analytical methods were used. Although the concentrations of mercury vapor were below the TLV, all samples analyzed showed measureable amounts of mercury to be present. Predominant sources of mercury contamination are broken thermometers and sphygmomanometers.

Air Pollutants↗

PubMed1976

Improved methods for sampling and analysis of vinyl chloride.

An analytical scheme was developed for vinyl chloride, which is applicable to ambient and in-plant atmospheres. Using computerized gas chromatographs equipped with automatic injection system and flow rate control, high reproducibilities are achieved in the ppb range. Samples from various sources have been analyzed.

Air Pollutants↗

PubMed1976

Is internal-external control an age-related variable?

Following the suggestion proposed by Duke, Shaheen, and Nowicki, this study was designed to test the basic hypothesis that the meaning of internal-external control (I-E) may differ with age. Such variables as age, educational level, socioeconomic status, self-confidence, etc., which have consistently been found to relate to I-E for children through college age Ss, were examined to see if these bear a relationship to I-E for a group of parents (95 fathers and 107 mothers) of college students (father mean age 48, mother mean age 46). Results indicated that with the exception of father education, there was no significant relationship between I-E and all other variables. Thus, these findings support the notion that I-E is an age-related variable, that generalizations from previous studies to older people should be re-evaluated, and that future research should study the meaning and dynamics of I-E for older people.

Age Factors↗

PubMed1975

Computerized gas chromatographic-mass spectrometric analysis of polycyclic aromatic hydrocarbons in environmental samples.

Substantial progress has been made in the last few years in the development of a rapid method for determining polycyclic aromatic hydrocarbons (PAH) in environmental samples. The three-step method consists of (i) a preliminary separation of PAH by solvent and/or column chromatography, (ii) identification by a combination of gas chromatography with quadrupole mass spectrometry and computer, and (iii) measurement by computerized gas chromatography using internal standards. Samples of industrial effluents, coke oven emissions, coal tar and airborne particulates have been investigated. The efficiencies of different gas chromatographic columns were evaluated during these investigations.

Chromatography, Gas↗

PubMed1975