Adulteration of herbs and their extracts

What is Adulteration of Herbs?

Adulteration is presence of substance or material other than the label claim. Adulteration may due to deliberate attempt or accidental passage / inclusion of substitution by superficially similar but commercially cheaper natural substances, substitution by exhausted drugs adulteration by artificially manufactured substitutes, inferior material or substitution with spurious inferior quality material of cheaper commercial value, addition of  vegetative matter from the same plant, addition of synthetic principles and adulteration by addition of worthless heavy materials or simply lack of knowledge.
Adulteration may be in the form of spoiled ingredient, infestation of microbial contamination, infested with insects,
There is a provision of substitution of Herbs as an alternate as the substituted herb or drug may have more or less similar pharmacological properties as the originally intended drug to be used.

There are plenty of examples of adulteration;
Herbs and extracts                                            Adulterant
1.  Cassia senna                                                   Cassia angustifolia, Cassia obovata and Cassia auriculata
2.  Zingiber officinale                                          Zingiber mioga (Japanese Ginger)
3.  Belladonna                                                      Ailanthus Species
4.  Honey                                                              Sugar Syrup

5.  Black pepper                                                   Papaya seeds
6.  Cinnamomum verum                                      C. obtusifolium, C. tamala and other species.
7.  Holarrhena antidysentrica                              Wrightia tinctoria, W.tomentosa
8.  Pueraria tuberosa                                            Ipomoea digitata
9.  Boswellia serrata                                            B. cartelli, and other imported gums
10. Saraca asoka                                                  Stem bark of Bauhinia variengata, Polyalthia longifolia
11. Ferula assafoetida                                          F. galbaniflua.
12. Clove Bud oil (Syzygium ­aromaticum):        clove stem oil & isolates (eugenol) & eugenyl acetate.
13. Grapefruit oil                                                 Orange terpenes or sweet orange oil distilled
14. Sandalwood oil                                              Sandalwood terpenes, sandalwood fragrance chemicals etc.
15. Basil oil                                                          Llinalol to convert to Basil oil Sweet
The above are only a few examples.
Adulteration can be detected by various means of proper evaluation and analysis.
Scientific Methods are to be applied to Drug Adulteration and Verification
The various methods for detection of adulterants are as follows;
A. Macroscopy 
B. Microscopy to study internal structures
C.  Chemical and Instrumental methods such as;
Detection and Estimation of Active /Marker compounds by
a. Gravimetry
b. Titrimetry
c. TLC / HPTLC
d. UV-VIS Spectroscopy
e. Gas Chromatography
f. HPLC
g. Infra red Spectroscopy
Adulteration in oils can be checked by