CHEMICAL TESTS

 

LICHENS PRODUCE UNI  QUE CHEMICAL SUBSTANCES

 

     WEAK PHENOLS

     FATTY ACIDS

 

CHEMICALS ARE DEPOSITED ON THE SURFACE OF THE HYPHAE

 

EACH LICHEN HAS A CONSTANT CHEMICAL MAKEUP

 

COLOR TESTS

 

DONE BY DROPPING CHEMICALS ON THE SURFACE OR MEDULLA OF THE LICHEN

 

A POSITIVE TEST IS SIGNALLED BY A RAPID COLOR CHANGE

 

IF THE TEST IS NEGATIVE THERE WILL BE NO CHANGE

 

COLOR CHANGE IS USUALLY TO RED OR YELLOW

 

SHOULD BE DONE UNDER A STEREOMICROSCOPE

 

DIFFERENT REAGENTS USED ARE:

 

     1.     CALCIUM HYPOCHLORITE, C

          (BLEACH)

 

     2.     POTASSIUM HYDROXIDE, K

 

     3.     PARAPHENYLENEDIAMINE, P

 

COLOR TESTS GENERALLY DONE ON THE MEDULLA

 

PROCEDURE:

 

1.     SCRAPE AWAY PART OF THE UPPER

     CORTEX WITH A RAZOR BLADE      EXPOSING 2 MM OF THE MEDULA

 

 

2.     APPLY CHEMICAL WITH A THIN

     PIPETTE

 

3.     OBSERVE ANY COLOR CHANGE

 

MICCROCHEMICAL TESTS

 

1.     CRYSTAL TESTS - ACID DISSOLVED

     FROM SMALL FRAGMENTS OF      THALLUS WITH ACETONE

 

     ACID RECRYSTALLIZED FROM

     VARIOUS REAGENTS

 

     a.     G.E. (GLYCERIN-ACETIC ACID,

                    3:1)

 

     b.     G.A.W. (GLYCERIN-95%                          ALCOHOL-WATER)

 

     c.     G.A.o.T (GLYCERIN-ALCOHOL-

          o-TOLUIDINE)

 

 

 

     d.     G.A.An (GLYCERIN-ALCOHOL-

          ANILINE)

 

     e.     G.A.Q (GLYCERIN-ALCOHOL-                QUINOLINE)

 

TECHNIQUE:

 

1.     FRAGMENTS OF THALLUS PILED      INTO THE CENTER OF A      MICROSCOPE SLIDE

 

2.     ACETONE ADDED DROPWISE SEVERAL

     TIMES

 

3.     AFTER ACETONE EVAPORATES THE

     RESIDUE IS BRUSHED AWAY

 

4.     CHEMICAL OF CHOICE ADDED AND A

     COVERSLIP ADDED

 

5.     SLIDE IS GENTLY HEATED UNTIL

     BUBBLING STARTS

 

6.     SLIDE COOLED AND CRYSTAL      FORMATION STARTS

 

7.     OBSERVE UNDER MICROSCOPE AT

     100X

 

8.     COMPARE TO PHOTOS IN BOOK

 

CHROMATOGRAPHY

 

FLORESCENCE ANALYSIS

 

EXAMINE LICHENS WITH A FLORESCENT LAMP

 

     WHITE - SQUAMATIC ACID

 

     HIGHLY FLUORESCENT -                               LECTORONIC ACID

         

     FLUORESCENT

          DIVARICATIC ACID

          EVERNIC ACID

          PERLATOLIC ACID

 

     BRILLIANT ORANGE

          LICHEXANTHONE ACID

          RHIZOCARPIC ACID

 

USES OF LICHENS

 

     EXTRACTS USED FOR ANTIBIOTICS

 

     OILS USED AS A PERFUME BASE

 

     MAY BE BOIL FOR A SOUP BASE

 

     LICHEN DYES IN LITMUS PAPER

 

     LICHENS USED AS “TREES” IN

          MODELS