Detection of micro-toxic elements in commercial coffee brands using optimized dual-pulsed laser-induced spectral analysis spectrometry.

A fast detection system based on dual-pulsed laser-induced breakdown spectroscopy (DP-LIBS) was successfully developed and optimized for the estimation of micro-toxic element contents in commercial coffee brands to monitor pollution and ensure food safety. A series of 13 various coffee brands were quantitatively analyzed in this study utilizing DP-LIBS and a standard analytical technique like inductively coupled plasma/optical emission spectrometry (ICP-OES). The micro-toxic elements, such as aluminum (Al), lead (Pb), zinc (Zn), and chromium (Cr), that exist in the coffee brands were exactly identified. We prepared standard matrices in a known concentration in the coffee sample to draw the standard calibration curves for each element, as well as by utilizing a tactic based on the intense line emission of the element of interest as a quantitative analysis. The analytical routines were approved under the expectations that the plasma created by the dual-pulsed lasers was in local thermodynamic equilibrium (LTE) and was optically thin. We investigated the influence of different parametric dependence studies to enhance our DP-LIBS detection sensitivity. Furthermore, the precision of our DP-LIBS data for determining the concentration of micro-toxic elements present in coffee samples was validated via the ICP-OES technique. The results achieved by the DP-LIBS technique were in full agreement with the ICP-OES results. In addition, the estimated limit of detection of our DP-LIB spectrometer for Al, Pb, Zn, and Cr were 105.13±07, 90.17±12, 83.58±15, and 68.78±09 µg L-1, respectively. The suggested protocols demonstrated the excellent benefits of the DP-LIBS for the detection of micro-toxic elements existing in coffee and for checking the purity and quality of food products.

Detection of carcinogenic metals in kidney stones using ultraviolet laser-induced breakdown spectroscopy.

The UV single-pulsed (SP) laser-induced breakdown spectroscopy (LIBS) system was developed to detect the carcinogenic metals in human kidney stones extracted through the surgical operation. A neodymium yttrium aluminium garnet laser operating at 266 nm wavelength and 20 Hz repetition rate along with a spectrometer interfaced with an intensified CCD (ICCD) was applied for spectral analysis of kidney stones. The ICCD camera shutter was synchronized with the laser-trigger pulse and the effect of laser energy and delay time on LIBS signal intensity was investigated. The experimental parameters were optimized to obtain the LIBS plasma in local thermodynamic equilibrium. Laser energy was varied from 25 to 50 mJ in order to enhance the LIBS signal intensity and attain the best signal to noise ratio. The parametric dependence studies were important to improve the limit of detection of trace amounts of toxic elements present inside stones. The carcinogenic metals detected in kidney stones were chromium, cadmium, lead, zinc, phosphate, and vanadium. The results achieved from LIBS system were also compared with the inductively coupled plasma-mass spectrometry analysis and the concentration detected with both techniques was in very good agreement. The plasma parameters (electron temperature and density) for SP-LIBS system were also studied and their dependence on incident laser energy and delay time was investigated as well.

Detection of trace elements in nondegradable organic spent clay waste using optimized dual-pulsed laser induced breakdown spectrometer.

The detection of trace elements present in nondegradable organic spent clay waste has been carried out using an optimized dual-pulsed laser induced breakdown spectrometer. The two laser pulses at 1064 and 266 nm were collinearly collimated and focused on the sample surface in order to enhance the signal intensity. The atomic transition lines at 568.8 nm (Na-I), 504.2 nm (Pb-II), 405.8 nm (Pb -I), 443.56 nm (Ca-I), 469.41 nm (S-I), 520.8 nm (Cr-I), 643 nm (Cd-I), and 928.1 nm (Cl-I) were used as marker wavelengths, and the concentrations of 688, 300, 204, 460, and 2440 ppm of Pb, S, Cd, Cr, and Cl, respectively, were detected in the 5% spent clay in the binder. The limits of detection of Pb, S, Cd, Cr, and Cl were estimated to be 6.7, 17.2, 6.5, 5.1, and 14.8 ppm, respectively, from the calibration curve for each element. In order to confirm the reliability of our system, the concentrations of the reported elements detected using our system were compared to the ones obtained with inductively coupled plasma emission spectroscopy and found to be in good agreement.

High sensitive detection of nitric oxide using laser induced photoacoustic spectroscopy at 213 nm.

Trace level detection of nitric oxide (NO) is of great interest for a wide range of applications such as environment and human health. For this purpose, a high sensitive sensor based photoacoustic spectroscopy (PAS) principle has been developed at our laboratory for detection of NO at very low concentration (ppbV). For optimization of the PAS signal and to achieve higher sensitivity, parametric dependence investigation was carried out where PAS signal dependence on NO gas pressure, cell geometry, buffer gas (Ar, N2, He), and laser pulse energy used three PAS cells developed locally. The best sensitivity achieved with three cells was 41, 11, 20 ppbv, respectively. It is worth reporting that the best PAS signal to noise ratio was achieved by using a cylindrical cell having three acoustic filters and argon as a buffer gas.