title: New technique for the direct analysis of food powders confined in a small hole using transversely excited atmospheric CO(2) laser-induced gas plasma.
abstract: Taking advantage of the differences between the interactions of transversely excited atmospheric (TEA) CO(2) lasers with metal and with organic powder, a new technique for the direct analysis of food powder samples has been developed. In this technique, the powder samples were placed into a small hole with a diameter of 2 mm and a depth of 3 mm and covered by a metal mesh. The TEA CO(2) laser (1500 mJ, 200 ns) was focused on the powder sample surfaces, passing through the metal mesh, at atmospheric pressure in nitrogen gas. It is hypothesized that the small hole functions to confine the powder particles and suppresses the blowing-off of sample, while the metal mesh works as the source of electrons to initiate the strong gas breakdown plasma. The confined powder particles are then ablated by laser irradiation and the ablated particles move into the strong gas breakdown plasma region to be atomized and excited; this method cannot be applied for the case of Nd:YAG lasers because in such case the metal mesh itself was ablated by the laser irradiation. A quantitative analysis of a milk powder sample containing different concentrations of Ca was successfully demonstrated, resulting in a good linear calibration curve with high precision.
authors.affiliation: Department of Physics, Faculty of Education and Regional Studies, University of Fukui, Fukui 910-8507, Japan.
authors.forename: Ali
authors.initials: A
authors.lastname: Khumaeni
authors.forename: Muliadi
authors.initials: M
authors.lastname: Ramli
authors.forename: Yoji
authors.initials: Y
authors.lastname: Deguchi
authors.forename: Yong Inn
authors.initials: YI
authors.lastname: Lee
authors.forename: Nasrullah
authors.initials: N
authors.lastname: Idris
authors.forename: Koo Hendrik
authors.initials: KH
authors.lastname: Kurniawan
authors.forename: Tjung Jie
authors.initials: TJ
authors.lastname: Lie
authors.forename: Kiichiro
authors.initials: K
authors.lastname: Kagawa
mesh_terms: D001274:Atmospheric Pressure; D002245:Carbon Dioxide; D005504:Food Analysis / Q000379:methods*; D006801:Humans; D007834:Lasers; D015596:Nutrition Assessment; D012275:Oryza / Q000737:chemistry; D011208:Powders; D013057:Spectrum Analysis / Q000295:instrumentation / Q000379:methods*
chemical_list: D011208:Powders; D002245:Carbon Dioxide