Paper chromatography sample detection

Cinnamyl anthranilate can be assayed by a method based on ester hydrolysis. Bulk samples of food-grade cinnamyl anthranilate have been analysed for purity by thin-layer chromatography and high-performance liquid chromatography. A method has been described for determining the content of this compound in food products by steam distillation followed by paper chromatography and examination under ultraviolet light it has a limit of detection of 1 pg (lARC, 1983). 

Three standardized methods were found in the Official Methods ofAnalysis of the Association of Official Analytical Chemists (AOAC 1990). The first of these methods is based on the extraction of crops (kale, endive, carrots, lettuce, apples, potatoes, and strawberries) with ethyl acetate and isolation of the residue followed by a sweep codistillation cleanup prior to GC/thermionic detection (Method 968.24). The second of these methods utilizes Florisil column chromatography clean-up followed by GC/FPD (Method 970.53). In the third method (Method 970.52), the sample is extracted with acetonitrile, and the residue is partitioned into petroleum ether followed by Florisil clean-up and GC/KC1 thermionic detection. Identifications are based on combinations of gas, thin-layer, and paper chromatography. The recovery for diazinon in this method is stated to be greater than 80% no data on limits of detection were given. 

Partition chromatography as described in this section may be applied to two major types of problems (1) identification of unknown samples and (2) isolation of the components of a mixture. The first application is, by far, the more widely used. Paper chromatography and TLC require only a minute sample size, the analysis is fast and inexpensive, and detection is straightforward. Unknown samples are applied to a plate along with appropriate standards, and the chromatogram is developed as a single experiment. In this way any changes in experimental conditions (temperature, humidity, etc.) affect standards and unknowns to the same extent. It is then possible to compare the Rf values directly. 

Saccharin has been detected and estimated after extraction from food samples on Whatman No. 1 filter paper (61,62). The sample in solution form, such as carbonated water can be used for paper chromatography. The spotted paper is developed in BuOH-ACOH-HpO (k0 l0 22) for l8 hours and sprayed with a solution of phthalic acid and aniline for spot development. Saccharin with an Rp 0.17 can be estimated colorimetrically after elution of the spot with 60 AcOH (62). 

Hydrodynamic chromatography was originally described by Small (7) in 1974. A number of publications have appeared since then which describe the separation mechanism and sample detection methods used with HDC (5, 8-18). In addition, Van Gilder, et. al. (19) used HDC as the primary particle sizing technique in research on the particle size versus viscosity relationship of high solids paper coating latices. 

Many penicillins, including penicillin V, are metabolized in the human body to other active compounds. Rolinson and Batchelor 140 administered the drugs orally or by intramuscular injection and evaluated both blood and urine samples by paper chromatography. Active metabolites were detected by bioautographic plates. Vanderhaeghe, Parmentier and Evrard 141 identified the major metabolite of penicillin V as p-hydroxyphenoxy-methyl penicillin. It represented about 10% of the microbiological activity in the urine. A small amount of o-hydroxyphenoxymethyl penicillin was also observed while in the urine of some patients another metabolite was detected. They speculated this might be the dihydroxy derivative. 

Paper chromatography is usually used for highly polar compounds such as sugars, amino acids and natmal pigments. Some advantages of paper chromatography are a small amount of sample is required, a high level of resolution, ease of detection and simphcity of the apparatus. 

The requirement for drug screening is to have the ability to detect as wide a range of compounds as possible in as little sample (plasma/serum/whole blood, urine/vitreous humour, stomach contents/vomit or tissues) as possible at a high sensitivity but with no false positive(s). Ideally some sample should be left to permit confirmation of the results using another technique such as paper chromatography or TLC, and quantification of any poison(s) present to aid clinical interpretation of the results. 

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