790
Anal. Chem. 1986, 58,790-797
Red and Near-Infrared Inductively Coupled Plasma Emission Spectra of Fluorine, Chlorine, Bromine, Iodine, and Sulfur with a Photodiode Array Detector John M. Keane’ and Robert C. Fry*
Department of Chemistry, Willard Hall, Kansas State University, Manhattan, Kansas 66506
The domain of a red to near-infrared (near-IR) photodiode array ICP atomic emission spectrograph has been expanded to Include slmuitaneous detectlon of fluorlne, chlorine, bromine, and sulfur. ICP excited spectra of atomic iodlne are also reported above 650 nm. Thlrty-five red-near-IR ilnes of iodlne were excited from atomized CF& A ilstlng of wavelengths and relative lntenslties for ICP excitation of F, Ci, Br, I, and S Is presented for the photodlode array detector. This complements an earlier photodiode array ilstlng for C, H, N, and 0. F, CI, Br, I, and S can be determined simultaneously wlh C, H, N, and 0 In a single exposure of less than 100 ms. I n spite of low spectrographlc resolutlon, interference-free lines of ail these elements (except sulfur) have been located within the 650-950 nm array “window”. A line selection scheme Is described for mlnlmlrlng spectral Interference.
Preliminary reports from this laboratory have described a 1024-channelphotodiode array spectrograph to simultaneously detect microwave or inductively coupled plasma (ICP) atomic emissions of the nonmetals carbon, hydrogen, nitrogen, and oxygen in the red and near-infrared (near-IR) region (1,Z). Emissions of these elements were recorded in a single 67-ms exposure by using a coarsely ruled grating to lower the dispersion enough to compress the entire spectral region 650-950 nm into the 25-mm format of a Reticon 1024s photodiode array chip (1). Despite limited optical resolution, interference-free lines were found, and a scheme for line selection was reported for the simultaneous determination of C, H, N, and 0 in samples of interest in synthetic chemistry (1). Red and near-IR atomic emissions of F, C1, Br, and S have also been previously characterized in the ICP, but only using single channel photomultiplier systems (3-5). A diode detector was also used to detect sulfur as a single element, but no multielement determinations were performed (6). To our knowledge, red and near-IR atomic emissions of iodine in the ICP have not been previously reported. The present study was undertaken to extend the number of elements that can be simultaneously detected in volatile organic compounds by the red-near-IR photodiode array spectrograph to include fluorine, chlorine, bromine, iodine, and sulfur. Tables of ICP excited atomic emission lines of these elements are presented here for the photodiode array detector and the region 650-950 nm. Labeled master reference spectra are presented as a visual aid to rapid qualitative identification involving elements present in organic compounds. Spectral interference is investigated, and a variable line selection scheme is outlined for minimizing spectral overlap in samples of interest to synthetic organic chemists. EXPERIMENTAL SECTION Apparatus and Procedure. The ICP source, external fiber optic, photodiode array spectrograph,and experimental procedure Present address: GTE Valeron Corp., Troy, MI. 0003-2700/86/0358-0790$01.50/0
Table I.” Atomic Iodine Emissions from 660 to 950 nm in Ar ICP
symbol I1 12
I3 I4,5 I6 17-9 110-13 I14 I16 I16 *I17 118 I19 I20 I21 I22 I23 I24 125-27 128
*I29 I30 I31,32 I33
I34,36
re1 intens
wavelength, nm
(Xdetector saturation )(lo2)
656.649 658.527 661.966 712.005 712.205 714.206 722.730 723.678) 723.784 740.206 741.050 741.120 741.648 746.899 755.418 770.020 804.374 816.938 822.257 824.005 839.330 848.611 866.495 870.080 885.324 885.380) 885.750 889.884 902.240 905.833
5.9 8.5 6.1 12; obs.b Ar14
1
t
1 942.715 t 942*671 911*391 912.803 933.505
4.5; obs. ArI5 42
16; obs. Arzz 27 6.1 8.5 52 7.9 2.3 12
