The determination of occupational exposure to polycyclic aromatic hydrocarbons by the analysis of 1-hydroxypyrene in urine using a simple automated online column switching device and high-performance liquid chromatography.

An analytical method using a liquid chromatograph combined with a simple online column switching sample pre-treatment system was developed for the determination of 1-hydroxypyrene (1-HP) in urine. This compound is the metabolite of pyrene and is used to assess the exposure of workers to polycyclic aromatic hydrocarbons (PAHs). After enzymatic hydrolysis, a urine sample was directly injected into a high-performance liquid chromatograph (HPLC) where it automatically underwent a sample cleanup using a column switching device. The procedure is simpler than previous methods because it uses only one switching valve, one extraction column and one HPLC pump. The analyte was retained on a short extraction column and after interferences were eluted to waste, was subsequently switched onto the analytical column. This allowed a short analysis time of 15 min. The calibration graph was found to be linear within the concentration range of 0.5 to 20 µg/L with a coefficient of determination exceeding r(2) = 0.99. Recoveries were found to be greater than 96% in the range 1 to 10 µg/L with intermediate precision of 2.5 to 5.8% relative standard deviation. This online method was verified by a comparison with an existing manual method by the analysis of 81 urine samples from workers exposed to PAHs and showed that the test results from both methods were in agreement with a probability obtained from the paired Student's t-test of P > 0.76. The proposed online method was found to be simple, fast and suited to routine analyses of 1-HP in urine for the assessment of occupational exposure to PAHs.

Determination of quartz in bulk materials from workplace environments using X-ray diffractometry and the absorption diffraction method.

A method is described for the determination of crystalline quartz in bulk materials from workplace environments as part of occupational hygiene investigations using X-ray powder diffractometry. The absorption-diffraction model was used for quantification with mass absorption coefficients for samples being experimentally determined using an absorption cell placed in front of the diffracted beam anti-scatter slit. The method was found to be reliable for samples containing from 0.5 to 100 wt.% crystalline quartz, where mass absorption coefficients did not exceed 120 cm(2)g(-1). Repeatability studies found that mass absorption coefficient determinations and crystalline quartz determinations were both generally within 1-2% relative standard deviation. The method was assessed for accuracy and found to be within 2% absolute when a National Institute of Standards and Technology (NIST) quartz certified reference material (SRM1879a) was analysed. The technique was compared to an internal standard procedure and a paired students t test showed that there was no significant statistical difference between the two methods at the 95% confidence level where the t value was found to be 0.40 (p>0.05=0.69) and the t critical value being t(crit,0.05,29)=2.05. The method was suitable for a variety of matrixes including those containing amorphous material and could be routinely applied to most samples of occupational interest.