Using DMSO for chlorophyll spectroscopy

DMSO (dimethyl sulphoxide, (CH3)(2)SO) is an alternative solvent for spectroscopic assay of chlorophylls (Chls) but has mainly been used on Chl a & b organisms. Here, we develop algorithms for the estimation of Chl a, b & c(1)c(2), and d in DMSO solvent. The common unicellular green alga Chlorella sp. (Chl a & b) is used as an example of an oxygenic photo-organism with Chl a as the primary photosynthetic pigment and Chl b as the accessory Chl. The cyanobacterium Synechococcus is used as an example of organisms containing only Chl a. The diatom Chaetoceros sp. is used as the representative Chl a & c(1)c(2) organism. The unusual chlorobacterium Acaryochloris marina has Chl d & a. Algorithms for use on mixed phytoplankton and algal mats (Chl a, b & c) were also developed. The algorithms for DMSO solvent are compared to those developed for 90% acetone as the benchmark solvent. DMSO solvent offers the advantages of low volatility, low toxicity, low flammability, biodegradability, and ease of transport and is an effective extractant of chlorophylls. However, there appear to be significant storage problems with DMSO extracts of chlorophylls because of its high freezing point (+18.4 degrees C) and probable breakdown in chlorophylls in DMSO over several days.

Automated summary

Algorithms for estimating different chlorophylls in DMSO solvent were developed, including Chl a, b, c(1), c(2), and d, as well as for mixed phytoplankton and algal mats. DMSO solvent offers many advantages, but storage issues may affect the extraction and stability of chlorophylls.