Clinical and Forensic.
The major advantage of SPE for clinical and forensic application is its portability, which might eventually be translated into an on-site sampling/sample preparation followed by immediate analysis on portable instruments or transport to the laboratory. This approach would allow better monitoring of patients condition during treatment or therapy, and better preservation of crime scenes since the object would not need to be removed to perform analysis.
Monitoring of human health can be achieved by noninvasive SPE methods. For example, breath contains the headspace of blood. Therefore, characterization of volatile components present inside the human body can be accomplished by adapting a SPE device to breath analysis.
Figure 1 illustrates an example of breath analysis.
The detection limits are in low nmol/L range, which provides sufficient sensitivity for practical applications of this approach to monitoring alcohol levels in blood and acetone concentrations for diabetics and patients on diets. SPE can be also used for rapid analysis of body fluids. Figure 2 illustrates the detection of several aromatic amines in the milk of a woman who is a smoker.
Analysis for alcohol and drugs in body fluids is frequently performed in clinical and forensic laboratories. SPE is suitable for monitoring alcohol levels in both urine and blood. Figure 3 shows the linear regression for ethanol determination in blood and urine by headspace SPE versus the static headspace technique.
The result indicates that both techniques give equivalent results for this application. Drugs in body fluids are more difficult to analyze, since they are semi volatile substances. However published results indicate that headspace SPE analysis at an elevated temperature, or even direct extraction after dialysis of urine or blood serum.