A novel implementation of broadband cavity enhanced absorption spectroscopy (BBCEAS) has been used to perform sensitive visible wavelength measurements on liquid-phase solutions in a 2 mm cuvette placed at normal incidence to the cavity mirrors. The overall experimental methodology was simple, low cost, and similar to conventional ultraviolet-visible absorption spectroscopy. The cavity was formed by two concave high reflectivity mirrors. Three mirror sets with nominal reflectivities (R) of R = 0.99, 0.9945, and 0.999 were used. The light source consisted of a high intensity red, green, blue, or white LED. The detector was a compact charge-coupled device (CCD) spectrograph. Measurements were made on the representative analytes, Ho(3+), and the dyes brilliant blue-R, sudan black, and coumarin 334 in appropriate solvents. Cavity enhancement factors (CEF) of up to 104 passes for the high reflectivity mirrors were obtained. The number of passes was limited by relatively high scattering and absorption losses in the cavity, of approximately 1 x 10(-2) per pass. Measurements over a wide wavelength range (420-670 nm) were also obtained in a single experiment with the white LED and the R = 0.99 mirror set for Ho(3+) and sudan black. The sensitivity of the experimental setup could be determined by calculating the minimum detectable change in the absorption coefficient alpha(min). The values ranged from 5.1 x 10(-5) to 1.2 x 10(-3) cm(-1). The limit of detection (LOD) for the strong absorber brilliant blue-R was 620 pM. A linear dynamic range of measurements of concentration over about two orders of magnitude was demonstrated. The overall sensitivity of the experimental setup compared very favorably with previous generally more experimentally complex and expensive liquid-phase cavity studies. Possible improvements to the technique and its applicability as an analytical tool are discussed.

The first demonstration of a cavity enhanced absorption spectroscopy (CEAS) based technique, applied to HPLC detection is reported. Broadband cavity enhanced absorption spectroscopy (BBCEAS) has been used for detection in a HPLC system (HPLC-BBCEAS). Measurements were made on the dyes rhodamine 6G and rhodamine B between 450 and 600 nm. The sensitivity of the measurements as determined by the minimum detectable change in the absorption coefficient, alpha(min), were 2.9 x 10(-5) cm(-1) at 527 nm and 1.9 x 10(-5) cm(-1) at 556 nm, the peak absorption wavelengths of rhodamine 6G and rhodamine B, respectively. The limits of detection (LOD) for the two dyes were 426 and 271 pM, respectively. The LOD of the HPLC-BBCEAS setup was found to be between 54 and 77 times lower than with a Perkin-Elmer HPLC (series 200) comprising a 200EP photodiode array detector. The sensitivity of the developed setup also compared favorably with the previous single wavelength HPLC-CRDS studies while using a considerably lower cost experimental setup and simpler experimental methodology. The use of BBCEAS detection also allowed the discrimination following an isocratic HPLC separation of the nearly co-eluting dyes rhodamine 6G and rhodamine B.

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 $ 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 (a min ) was 3.4 Â 10 À7 cm À1 . Further measurements were made on the strong absorber methylene blue dissolved in acetonitrile at 655 nm. A white LED was used with the R $ 0.99 cavity mirrors, leading to a CEF of 78 and a min ¼ 4.4 Â 10 À7 cm À1 . The use of a more intense red LED also allowed measurements with higher reflectivity R $ 0.999 cavity mirrors, leading to a CEF of 429 and a min ¼ 2.8 Â 10 À7 cm À1 . The sensitivity was limited by dark noise from the detector but nevertheless appears to represent the most sensitive liquid-phase absorption measurement to date.

The new designer drug 5-(2-aminopropyl)indole (5-IT) is an indole derivative with stimulant properties. Its synthesis was first described by Albert Hofmann and Franz Troxler in 1962. We report four deaths associated with 5-IT and a validated high-performance liquid chromatography method for quantitation of the drug. In all four deaths, an autopsy was performed, and femoral venous blood, heart blood, urine and vitreous humor were submitted for toxicological analysis. The blood specimens were subjected to comprehensive testing that included alcohol analysis by headspace gas chromatography (GC-FID), acidic/neutral, basic drug and opiates screening by liquid chromatography-mass spectrometry (LC-MS-MS), and acidic/neutral, basic and acidic drugs screening by HPLC. In Case 1, a 25-year-old male, 3,4-methylenedioxymethamphetamine (MDMA; <0.08 mg/L) and 5-IT (preserved femoral blood 1.2 mg/L; unpreserved femoral blood 0.8 mg/L; cardiac blood 1.2 mg/L; vitreous 0.8 mg/L and urine >10 mg/L) were detected, and death was attributed to the toxic effects of 5-IT. In Case 2, a 25-year-old female, 3,4-methylenedioxy-N-methylcathinone (methylone, not quantitated), 6-(2-aminopropyl)benzofuran (6-APB; femoral blood <0.08 mg/L) and 5-IT (preserved femoral blood 1.0 mg/L; unpreserved femoral blood 0.9 mg/L; cardiac blood 2.6 mg/L; vitreous 1.4 mg/L and urine >10 mg/L) were detected, and death was attributed to the toxic 'cocktail effects' of the drugs. In Case 3, a 22-year-old male with a history of epilepsy, 5-IT (0.5 mg/L femoral blood) and 6-APB (0.2 mg/L femoral blood) were detected, and death was attributed to the toxic effects of the drugs, with the role of epilepsy being indeterminate. In Case 4, a 25-year-old female, 5-IT (0.4 mg/L femoral blood), amphetamine (0.4 mg/L femoral blood), MDMA (1.5 mg/L femoral blood), 4-methyl-N-ethylcathione, 3,4-methylenedioxyamphetamine HCl (MDA), benzylpiperazine and 6-APB were detected, and death was attributed to the 'cocktail effect' of the drugs.

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