School of Science and Technology, University of Teesside, Borough Road, Middlesbrough, UK TS1 3BA.
Analyst. 2009 Sep;134(9):1887-95. doi: 10.1039/b907316g. Epub 2009 Jul 10.
Sensitive liquid-phase measurements have been made in a 20 cm cell using broadband cavity enhanced absorption spectroscopy (BBCEAS). The cavity was formed by two high reflectivity mirrors which were in direct contact with the liquid-phase analytes. Careful choice of solvent was required to minimise the effect of background solvent absorptions. Measurements were made on the broad absorber Sudan black, dissolved in acetonitrile, using a white LED light source and R > or = 0.99 cavity mirrors, leading to a cavity enhancement factor (CEF) of 82 at 584 nm. The sensitivity as measured by the minimum detectable change in the absorption coefficient (alpha(min)) was 3.4 x 10(-7) cm(-1). Further measurements were made on the strong absorber methylene blue dissolved in acetonitrile at 655 nm. A white LED was used with the R > or = 0.99 cavity mirrors, leading to a CEF of 78 and alpha(min) = 4.4 x 10(-7) cm(-1). The use of a more intense red LED also allowed measurements with higher reflectivity R > or = 0.999 cavity mirrors, leading to a CEF of 429 and alpha(min) = 2.8 x 10(-7) cm(-1). The sensitivity was limited by dark noise from the detector but nevertheless appears to represent the most sensitive liquid-phase absorption measurement to date.
使用宽带腔增强吸收光谱（BBCEAS）在 20 厘米的池体中进行了灵敏的液相测量。该腔由两个高反射率镜形成，它们与液相分析物直接接触。需要仔细选择溶剂以最小化背景溶剂吸收的影响。在宽吸收体苏丹黑（溶解在乙腈中）上进行了测量，使用白色 LED 光源和 R>或=0.99 腔镜，导致在 584nm 处的腔增强因子（CEF）为 82。通过吸收系数（alpha(min)）的最小可检测变化来测量灵敏度，灵敏度为 3.4×10^(-7)cm^(-1)。在 655nm 处，进一步在强吸收体亚甲蓝（溶解在乙腈中）上进行了测量。使用白色 LED 和 R>或=0.99 腔镜，导致 CEF 为 78 和 alpha(min) = 4.4×10^(-7)cm^(-1)。使用更强烈的红色 LED 还允许使用更高反射率 R>或=0.999 的腔镜进行测量，导致 CEF 为 429 和 alpha(min) = 2.8×10^(-7)cm^(-1)。灵敏度受到探测器的暗噪声限制，但它似乎仍然代表了迄今为止最灵敏的液相吸收测量。
