ABSTRACT
For teaching purposes, human blood, saliva, urine, or feces are suitable and easily available material for TLC experiments. One-to 10-µl samples of serum or urine can often be spotted directly for various TLC analyses to show the presence of hydrophilic and lipophilic compounds. Saliva can be applied directly to the preadsorbent spotting area of precoated silica gel plates and analyzed by TLC (Touchstone et al., 1982; Zelop et al., 1985). Fecal material is useful to demonstrate bile pigments and various sterols using relatively simple techniques. Serum, urine, and feces are often “cleaned up” (purified) using sample preparation techniques described in Section II of this chapter. Considerable TLC literature is available on natural products from humans [for instance, see Zollner and Wolfram (1969) or Scott (1969)]. Introductory level students are often interested in the results of TLC analyses obtained from human samples. Moreover, abnormal samples of blood or urine may be available from pathology departments at local hospitals. These samples may be useful to detect by TLC such abnormal conditions as elevated lipid levels in the blood (hyperlipemia), or elevated levels in the urine (aminoacidurias) or particular amino acids associated with pathologic conditions. Analyses by simple TLC procedures will usually detect these disorders in abnormal urine and serum samples. An interesting and readily available source of human material is skin surface exudate, which can be obtained from the forehead with the aid of a cotton swab. The swab containing the lipids can be extracted in chloroform-methanol (2:1) and then analyzed by TLC for skin lipids as described by Downing (1979). Jain (1996) has provided useful information for obtaining human samples for use in TLC determinations in clinical chemistry.
