title: Direct spectral analysis of tea samples using 266 nm UV pulsed laser-induced breakdown spectroscopy and cross validation of LIBS results with ICP-MS.
abstract: Tea is one of the most common and popular beverages spanning vast array of cultures all over the world. The main nutritional benefits of drinking tea are its anti-oxidant properties, presumed protection against certain cancers, inhibition of inflammation and possible protective effects against diabetes. Laser induced breakdown spectrometer (LIBS) was assembled as a powerful tool for qualitative and quantitative analysis of various brands of tea samples using 266 nm pulsed UV laser. LIBS spectra for six brands of tea samples in the wavelength range of 200-900 nm was recorded and all elements present in our tea samples were identified. The major toxic elements detected in several brands of tea samples were bromine, chromium and minerals like iron, calcium, potassium and silicon. The spectral assignment was conducted prior to the determination of concentration of each element. For quantitative analysis, calibration curves were drawn for each element using standard samples prepared in known concentration in the tea matrix. The plasma parameters (electron temperature and electron density) were also determined prior to the tea samples spectroscopic analysis. The concentration of iron, chromium, potassium, bromine, copper, silicon and calcium detected in all tea samples was between 378-656, 96-124, 1421-6785, 99-1476, 17-36, 2-11 and 92-130 mg L(-1) respectively. The limits of detection estimated for Fe, Cr, K, Br, Cu, Si, Ca in tea samples were 22, 12, 14, 11, 6, 1 and 12 mg L(-1) respectively. To further confirm the accuracy of our LIBS results, we determined the concentration of each element present in tea samples by using standard analytical technique like ICP-MS. The concentrations detected with our LIBS system are in excellent agreement with ICP-MS results. The system assembled for spectral analysis in this work could be highly applicable for testing the quality and purity of food and also pharmaceuticals products.
authors.affiliation: Laser Research Group, Physics Department and Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia. Electronic address: magondal@kfupm.edu.sa.
authors.forename: M A
authors.initials: MA
authors.lastname: Gondal
authors.affiliation: Laser Research Group, Physics Department and Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
authors.forename: Y B
authors.initials: YB
authors.lastname: Habibullah
authors.affiliation: Laser Research Group, Physics Department and Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
authors.forename: Umair
authors.initials: U
authors.lastname: Baig
authors.affiliation: Laser Research Group, Physics Department and Center of Excellence in Nanotechnology, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
authors.forename: L E
authors.initials: LE
authors.lastname: Oloore
mesh_terms: D053000:Analytic Sample Preparation Methods; D001966:Bromine / Q000032:analysis / Q000302:isolation & purification; D002857:Chromium / Q000032:analysis / Q000302:isolation & purification; D007501:Iron / Q000032:analysis / Q000737:chemistry; D007834:Lasers; D013058:Mass Spectrometry / Q000379:methods*; D011188:Potassium / Q000032:analysis / Q000302:isolation & purification; D013662:Tea / Q000737:chemistry*; D014466:Ultraviolet Rays
chemical_list: D013662:Tea; D002857:Chromium; D007501:Iron; D011188:Potassium; D001966:Bromine
keywords: Detection of carcinogenic Br and Cr; Laser induced breakdown spectroscopy; Plasma parameters; Spectral analysis of tea; Tea nutritional benefits