An evaluation of solid‐phase microextraction for analysis of volatile organic compounds in drinking water

Abstract

Solid‐phase microextraction (SPME) has been applied to the quantitative analysis of 60 volatile organic compounds (VOCs) in drinking water. Equilibration curves for the partitioning of the VOCs between the fiber coating and fortified water obtained at 20, 50, and 80 °C are found between the theoretical curves for completely agitated and non‐agitated samples. Two important factors for the amount adsorbed by the SPME fiber coating are the extraction time and the fiber coating/water distribution coefficient, KFW. Both depend on the sample temperature, but in a counteracting manner: Increasing the temperature shortened the equilibration times, especially for the heavier VOCs, but also lead to lower KFW values, and consequently a lower sensitivity of the method. KFW values are determined for 33 of the VOCs at 40, 60, and 80°C and the heats of adsorption,–ΔH, are calculated. The nature of the adsorption is found to be exothermic which explains the decreasing sensitivity of the method with increasing temperature. Detection limits were typically from 20 ng/l to 200 ng/l, except for the very light VOCs with which detection difficulties were encountered. For all of the VOCs the linear range extended from the lowest concentration at which they were actually detected to at least 5 mg/l. The precision, 3% average standard deviation when an internal standard was used, was satisfactory for most quantitative routine analysis. SPME was also applied to head‐space (HS) analysis of drinking water through the coupled equilibrium between water/head‐space/fiber coating. HS‐SPME is demonstrated to have shorter equilibration times than SPME directly from the water and equal sensitivities, except for the very light VOCs. Water samples from a drinking water plant contaminated in the low μg/l range with 1,1,1‐trichloroethane, trichloroethene and tetrachloroethene were analyzed. There seems to be a reasonable agreement between results obtained by SPME and purge & trap. It is concluded that SPME has a great potential for drinking water analysis.

Determination of petroleum contamination in shellfish using solid phase micro-extraction with gas chromatography-mass spectrometry

“…Equilibration times are generally faster in the gas phase than in the liquid phase as the rate of diffusion is faster in the gaseous phase [24]. As can be seen from 149 Fig.…”

Determination of dichloromethane, trichloroethylene and perchloroethylene in urine samples by headspace solid phase microextraction gas chromatography–mass spectrometry

“…According to the literature, both the fiber coating and the detection system used are relevant factors in determining the sensitivity of the HS-SPME-GC method. When a PDMS 100 or 95 m fiber was used for sampling, the LODs for halo- genated compounds in aqueous samples were reported to be 20-50 g/l using flame ionization detector (FID) [26], or in the range 20-200 ng/l with MS detection [27], or even lower (1-130 ng/l) when an electron-capture detector (ECD) was used [25]. In addition, the Carboxen/PDMS coating material showed a better affinity towards these chlorinated compounds as compared to PDMS alone [24].…”

Sample Preparation for Trace Analysis

“…Since its development, this innovative technique has found widespread use in environmental analysis. It has, for example, been applied in the determination of volatile organic compounds [241], [242], phenols [243], pesticides [244], polyaromatic hydrocarbons, and polychlorinated biphenyls [245] in water. SPME fibers have been used as air sampling devices for volatile organic compounds in ambient and workplace air and give results that are in good agreement with traditional sampling methods [246].…”