Assessment of metal contents in spices and herbs from Saudi Arabia.

In the recent years, there has been a growing interest in monitoring heavy metal contamination of spices/herbs. Spices and herbs are sources of many bioactive compounds that can improve the tastes of food as well as influence digestion and metabolism processes. In the present study, the levels of some essential and toxic elements such as iron (Fe), zinc (Zn), copper (Cu), chromium (Cr), manganese (Mn), cobalt (Co), nickel (Ni), lead (Pb), and cadmium (Cd), present in common spices/herbs that were purchased from the local market in Saudi Arabia, were analyzed by atomic absorption spectroscopy after digestion with nitric acid/hydrogen peroxide mixture. Samples from the following spices/herbs were used: turmeric, cloves, black pepper, red pepper, cumin, legume, cinnamon, abazir, white pepper, ginger, and coriander. The concentration ranges for the studied elements were found as 48.8-231, 4.7-19.4, 2.5-10.5, below detection level (BDL)-1.0, 8.8-490, 1.0-2.6, and BDL-3.7 µg g(-1) for Fe, Zn, Cu, Cr, Mn, Ni, and Pb, respectively, while Cd and Co levels were below the detection limit. Consumers of these spices/herbs would not be exposed to any risk associated with the daily intake of 10 g of spices per day as far as metals Fe, Zn, Cu, Cr, Mn, Ni, and Pb are concerned.

Detection of hazardous pollutants in chrome-tanned leather using locally developed laser-induced breakdown spectrometer.

Highly toxic contaminants like Cr, As, and Pb were detected in chrome-tanning process of animal skin to produce leather by applying locally developed laser-induced breakdown spectrometer. An Nd-YAG laser with 1,064 nm wavelength was focused on the surface of leather samples (natural and manufactured) to generate a plasma spark and spectrally resolved spectra were used for identification and quantification of contaminants. The leather samples were collected from a tannery located in industrial cities of Riyadh and Jeddah, Saudi Arabia. The study was carried out on fully, half manufactured (wet blue leather), and natural hide (skin). To the best of our knowledge, this is the first attempt where laser-induced breakdown spectroscopy (LIBS) technique has been applied for the analysis of leather before and after tanning process. The maximum concentration of different elements of environmental significance like chromium, lead, arsenic, sulfur, magnesium were 199, 289, 31, 38, and 39 ppm, respectively, in one of the manufactured leather samples. The limit of detection (LOD) of our LIBS system for chromium, lead, arsenic, sulfur, and magnesium were 2, 3, 1.5,7, and 3 ppm, respectively. The safe permissible limit for tanned leather for highly toxic elements like chromium, lead, and arsenic are 1, 0.5, 0.01 ppm, respectively, as prescribed in Environmental Regulation Standards for Saudi Industries set by Royal Commission Jubail, Saudi Arabia. The LIBS technique is superior to other conventional techniques like ICP or atomic absorption that a little or no sample preparation is required, no chemicals are needed, multi-elemental analysis is possible for all kinds of samples (natural and anthropogenic materials), microgram of sample is essential, and LIBS could be applied for remote analysis. It is highly selective and sensitivity higher than ICP, and as no sample and chemicals are required, it is cost effective for multi-sample analysis per unit time as compared with other conventional techniques. The concentration of some toxic elements (Cr, Pb, As) is much higher than the safe permissible limits set by Occupational Safety and Health Administration in USA or Saudi environmental regulatory agencies. Results obtained with our LIBS systems were in close agreement with the results obtained using other standard analytical technique such as the inductively coupled plasma atomic emission spectroscopy.

Laser enhanced photo-catalytic removal of phenol from water using p-type NiO semiconductor catalyst.

Phenol is a carcinogen to humans and is a serious health concern, even at low concentrations. The efficient removal of phenol inside waste water is highly desirable. Laser induced photo-catalysis has been applied for removal of phenol from waste water using p-type NiO semiconductor catalyst for the first time. The characteristics of phenol removal using laser induced photo-catalytic process were investigated. The dependence of phenol removal on laser energy (100-250 mJ) and laser irradiation time (0-60 min) was studied. The rate of phenol removal process was characterized using UV absorption spectrometry, Raman spectroscopy and gas chromatography. In addition, the role of pH changes during the removal process was also investigated. Laser induced photo-catalytic process is highly efficient in removal of phenol in water over a short period of time (in minutes) as compared to conventional methods using lamps (hours). The phenol removal process pursued the first order kinetics with decay constant=0.0125 min(-1).

Facile preparation of g-C3N4 modified BiOCl hybrid photocatalyst and vital role of frontier orbital energy levels of model compounds in photoactivity enhancement.

A novel hybrid photocatalyst (g-C3N4/BiOCl) using g-C3N4 series modified with BiOCl having controllable mass ratios among the g-C3N4 and BiOCl molecules was prepared through hydrolysis process of Bi(3+) onto g-C3N4, using NaBiO3 and g-C3N4 produced from pyrolysis of melamine as the starting materials. The microstructure, morphology and optical properties of the synthesized g-C3N4/BiOCl were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-Vis diffuse reflection spectroscopy (DRS) and photoluminescence (PL) emission spectroscopy. The photoactivity of the g-C3N4/BiOCl was evaluated by photodegradation of Rhodamine B(RhB) from water as a model toxic contaminant. The RhB photodegradation results revealed that the photocatalytic activity of g-C3N4/BiOCl hybrid photocatalyst (mass ratio of g-C3N4/BiOCl equals to 2:8) exhibits superior activity as compared with pure BiOCl under visible light irradiation. The effects of pH, initial concentration of the model contaminant as well as the catalyst recycling on the photoactivity (or photostability) of g-C3N4/BiOCl were investigated in depth as well. Quantum chemical calculations revealed that the photoactivity enhancement is strongly dependent on the active role played by the frontier orbital energy levels of dye molecules and a probable correlation of "structure-activity" relationship was established.

Spectroscopic detection of health hazardous contaminants in lipstick using Laser Induced Breakdown Spectroscopy.

Laser Induced Breakdown Spectroscopy (LIBS) technique was applied to determine the concentrations of different toxic elements like lead, chromium, cadmium and zinc in four different lipstick brands sold at local markets in Saudi Arabia. These samples contain toxic elements like lead, cadmium and chromium which are carcinogen dermatitis, allergic and eczematous. Their extraction from human body takes over 40 years and accumulation in the body cause problems like disruption of nervous systems and kidney damage. They could trigger to systemic lupus erythematosus (SLE). In order to test the validity of our LIBS results, standard technique like (ICP-AES) was also applied. To the best of our knowledge, this is the first study where LIBS technique was applied for the measurement of toxic substances in lipsticks. The maximum concentration detected in four lipstick brands was much higher than the permissible safe limits for human use and could lead to serious health problems. It is worth mentioning that the lipstick is not a solid rather is in fluid state which is not trivial to analyze using LIBS technique. For this purpose, special treatment of the lipstick samples was necessary to analyze with our LIBS method.