Table 10 Comparison between conventional and non-conventional methods for lipids determination
Methods | Advantages | Disadvantages |
|---|---|---|
Conventional | ||
 Gravimetric | The easiest method to quantify total lipids in a short time, no need for special equipment or training | Requires cell disruption, extraction, not suitable for small amounts of sample |
 Chromatographic coupled with detector | Well-established procedures for lipid profiling | Requires cell disruption, extraction, and (in situ) transesterification, multi-step process; Depends on microalgae strains and cellular extraction method |
Non-conventional | ||
 FTIR | Identification of lipid classes on the basis of standards, cellular content determination without disruption of cells, small amount of samples | FTIR band shifts are species-specific, cannot differentiate different species when a mixture of cultures is used |
 Raman spectroscopy | Label-free, no sample preparation, in vivo analysis, real-time, non-destructive | Fluorescent pigments and carotenoids interfere with analysis; quantification is focused mainly on determining the degree of unsaturation, there is need for calibration based on other methods such as gravimetric analysis; difficult to translate to an industrial setting |
 NMR | Can be non-destructive, application to whole cells, extracted and transesterified lipids | Need for internal standards for quantification; difficult to translate to an industrial setting |
 Dielectric spectroscopy | Rapid, non-invasive, and label-free method; potential for automated process for biomonotring | Total lipid detection, no profiling |
 Fluorescence spectrometry | High-throughput potential | Uptake and intensity depends on dye and cell wall; only detects neutral lipids |
 Nile Red | Mostly used in literature | Photo-bleaching of agent; poor penetration of cells; interference with chlorophyll autofluorescence and green fluorophores; limited specificity to lipids |
 BODIPY 505/515 | More lipid-specific, narrower emission spectrum, higher sensitivity, and better reproducibility, requires lower concentration of solvent carrier | Interference with green fluorophores |
 AC-202 | More sensitive than BODIPY; low-background signal | Not used for quantification yet |
 Colorimetry | High-throughput potential Low cost | Total lipid detection only |
 SPV | Color formation is stable for hours Fast, low detection limit Solvent extraction can be omitted depending on the assay | Requires presence of double bond or free hydroxyl groups (unsaturated lipids) Is dependent on standard |
 TAG kit | Fast, automated process | Detects only TAGs; requires cell disruption and extraction |
 Copper extraction | Fast, high detection limit, can be adapted to microcentrifuge format | Requires solvent addition and cell disruption |