Gibberellin nomenclature

GA₁ GA₂ GA₃ GA₄ GA₅ GA₆ GA₇ GA₈ GA₉ GA₁₀ GA₁₁ GA₁₂ GA₁₃ GA₁₄ GA₁₅ GA₁₆ GA₁₇ GA₁₈ GA₁₉ GA₂₀ GA₂₁ GA₂₂ GA₂₃ GA₂₄ GA₂₅ GA₂₆ GA₂₇ GA₂₈ GA₂₉ GA₃₀ GA₃₁ GA₃₂ GA₃₃ GA₃₄ GA₃₅ GA₃₆ GA₃₇ GA₃₈ GA₃₉ GA₄₀ GA₄₁ GA₄₂ GA₄₃ GA₄₄ GA₄₅ GA₄₆ GA₄₇ GA₄₈ GA₄₉ GA₅₀ GA₅₁ GA₅₂ GA₅₃ GA₅₄ GA₅₅ GA₅₆ GA₅₇ GA₅₈ GA₅₉ GA₆₀ GA₆₁ GA₆₂ GA₆₃ GA₆₄ GA₆₅ GA₆₆ GA₆₇ GA₆₈ GA₆₉ GA₇₀ GA₇₁ GA₇₂ GA₇₃ GA₇₄ GA₇₅ GA₇₆ GA₇₇ GA₇₈ GA₇₉ GA₈₀ GA₈₁ GA₈₂ GA₈₃ GA₈₄ GA₈₅ GA₈₆ GA₈₇ GA₈₈ GA₈₉ GA₉₀ GA₉₁ GA₉₂ GA₉₃ GA₉₄ GA₉₅ GA₉₆ GA₉₇ GA₉₈ GA₉₉ GA₁₀₀ GA₁₀₁ GA₁₀₂ GA₁₀₃ GA₁₀₄ GA₁₀₅ GA₁₀₆ GA₁₀₇ GA₁₀₈ GA₁₀₉ GA₁₁₀ GA₁₁₁ GA₁₁₂ GA₁₁₃ GA₁₁₄ GA₁₁₅ GA₁₁₆ GA₁₁₇ GA₁₁₈ GA₁₁₉ GA₁₂₀ GA₁₂₁ GA₁₂₂ GA₁₂₃ GA₁₂₄ GA₁₂₅ GA₁₂₆ GA₁₂₇ GA₁₂₈ GA₁₂₉ GA₁₃₀ GA₁₃₁ GA₁₃₂ GA₁₃₃ GA₁₃₄ GA₁₃₅ GA₁₃₆

Numbers

Gibberellins are assigned A-numbers in order of discovery according to the system proposed by MacMillan and Takahashi (Nature 217, 170-171, 1968).

Numbers will be assigned to novel GAs for which evidence is presented for their natural occurrence and an unequivocal assignment of structure. Identification can be established by:

Isolation of the pure compound and determination of structure from physical, primarily spectroscopic, properties.
Comparison of the compound with a fully-characterised synthetic standard by GC-MS or equivalent method. Matches are based on KRI and m/z values with relative intensities from a full spectrum.

Retention Indices

Retention indices can be obtained from capillary GC-MS to provide additional criteria for identification. To overcome variations in column temperature and flow-rate, the retention index procedure of Kovats(1958) is recommended.

A solution of each n-alkane from C16 to C36 is co-injected with the sample and the retention times of the n-alkanes peaks are recorded. The retention time of the peak of interest is also recorded.

The retention index is calculated with the following formulae.

C_x = (Rt(peak of interest) - Rt(preceding n-alkane) + Cn(preceding n-alkane)_x ) / ( Rt(following n-alkane) - RT(preceding n-alkane) )

C_x × 100 = Retention index.

Reference: Kovats E (1958) Gas chromatographische Charakteriserung organischer Verbindungen.I.Retentions indices aliphatischer halogenide, alkohole, aldehyde und ketone Helv Chim Acta 41: 1915-1932