Absorption spectroscopy is widely used to determine absorption and transmission spectra of chromophores in solution, in addition to suspensions of particles, including micro-organisms. Light scattering, caused by photons deflected from part or all of the cells or other particles in suspension, results in distortions to the absorption spectra, lost information and poor resolution. A spectrophotometer with an integrating sphere may be used to alleviate this problem. However, these instruments are not universally available in biology laboratories, for reasons such as cost. Here, we describe a novel, rapid, and inexpensive technique that minimises the effect of light scattering when performing whole-cell spectroscopy. This method involves using a custom made dual compartment cuvette containing titanium dioxide in one chamber as a scattering agent. Measurements were conducted of a range of different photosynthetic micro-organisms of varying cell size and morphology, including cyanobacteria, eukaryotic microalgae and a purple non-sulphur bacterium. A concentration of 1 mg ml⁻¹ titanium dioxide, using a spectrophotometer with a slit width of 5 nm, produced spectra for cyanobacteria and microalgae similar (1–4% difference) to those obtained using an integrating sphere. The spectrum > 520 nm was similar to that with an integrating sphere with the purple non-sulphur bacterium. This system produced superior results to those obtained using a recently reported method, the application of the diffusing agent, Scotch™ Magic tape, to the side of the cuvette. The protocol can be completed in an equivalent period of time to standard whole-cell absorbance spectroscopy techniques, and is, in principle, suitable for any dual-beam spectrophotometer.

吸收光谱法广泛用于测定溶液中发色团的吸收和透射光谱，以及包括微生物在内的颗粒悬浮液。由部分或全部细胞或悬浮液中的其他粒子偏转的光子引起的光散射会导致吸收光谱失真、信息丢失和分辨率低下。可以使用带有积分球的分光光度计来缓解这个问题。然而，由于成本等原因，这些仪器在生物实验室中并不普遍可用。在这里，我们描述了一种新颖、快速且廉价的技术，可在进行全细胞光谱分析时将光散射的影响降至最低。该方法包括在一个腔室中使用定制的双隔室比色皿，其中包含二氧化钛作为散射剂。对一系列具有不同细胞大小和形态的不同光合微生物进行了测量，包括蓝细菌、真核微藻和紫色非硫细菌。浓度为 1 mg ml^-1二氧化钛，使用狭缝宽度为 5 nm 的分光光度计，产生的蓝藻和微藻光谱与使用积分球获得的光谱相似（差异 1-4%）。> 520 nm 的光谱与带有紫色非硫细菌的积分球的光谱相似。该系统产生的结果优于使用最近报道的方法获得的结果，即在比色皿侧面应用扩散剂 Scotch™ 魔术胶带。该协议可以在与标准全细胞吸收光谱技术相当的时间内完成，并且原则上适用于任何双光束分光光度计。