Masking Ability of Various Metal Complexing Ligands at 1.0 mM Concentrations on the Potentiometric Determination of Fluoride in Aqueous Samples

Table 1

Fluoride content of 60 water samples measured by F-ISE with different masking agents.

Sample ID	Mean fluoride concentration (mg L^−1)										EC (μS/cm)
	Ref.	CDTA	EDTA	HE-EDTA	TEA	Citrate	Tartrate	Phosphate	Acetate	Photometer
1	1.842	1.730	1.689	1.645	1.595	1.475	1.493	1.556	1.469	N/A	126.4
2	1.619	1.614	1.603	1.558	1.524	1.467	1.317	1.364	1.098	1.30	177.8
3	1.868	1.703	1.542	1.669	1.620	1.193	1.506	1.548	1.321	N/A	149.1
4	1.543	1.503	1.456	1.492	1.422	0.975	1.218	1.266	0.969	1.03	165.1
5	1.734	1.625	1.592	1.556	1.526	1.332	1.518	1.530	1.221	N/A	127.5
6	1.563	1.503	1.486	1.426	1.403	1.083	1.153	1.259	0.974	1.15	288.0
7	1.486	1.450	1.455	1.388	1.317	0.863	1.052	1.240	0.784	0.91	181.2
8	1.854	1.763	1.715	1.703	1.593	1.485	1.662	1.598	1.475	N/A	221.0
9	1.916	1.892	1.889	1.809	1.762	1.440	1.545	1.672	1.360	N/A	156.3
10	1.476	1.390	1.383	1.323	1.104	0.522	0.962	1.067	0.486	0.96	231.0
11	0.864	0.758	0.753	0.645	0.542	0.188	0.238	0.352	0.186	0.24	117.9
12	0.796	0.764	0.743	0.559	0.544	0.408	0.456	0.486	0.419	0.40	78.9
13	0.686	0.659	0.611	0.598	0.487	0.415	0.648	0.467	0.420	0.42	53.3
14	0.693	0.637	0.522	0.486	0.496	0.403	0.445	0.458	0.374	0.42	92.6
15	1.352	1.260	1.334	0.959	0.921	0.800	0.817	0.837	0.808	0.82	79.9
16	0.749	0.641	0.627	0.605	0.577	0.512	0.545	0.571	0.513	0.53	97.0
17	0.695	0.457	0.437	0.392	0.355	0.319	0.338	0.359	0.309	0.34	115.2
18	1.261	0.885	0.859	0.801	0.797	0.593	0.717	0.775	0.720	0.73	134.6
19	1.344	1.179	1.154	1.121	1.114	0.876	0.983	1.055	0.862	0.94	194.5
20	1.652	1.478	1.413	1.391	1.618	1.147	1.294	1.354	1.137	1.29	191.2
21	0.722	0.607	0.604	0.582	0.566	0.206	0.521	0.494	0.196	0.49	282.0
22	0.679	0.504	0.524	0.469	0.441	0.142	0.194	0.244	0.149	0.16	339.0
23	1.476	1.291	1.225	1.230	1.039	0.889	0.409	0.977	0.912	0.91	128.6
24	1.455	1.390	1.314	1.187	1.065	0.916	1.018	1.069	0.831	1.00	261.0
25	0.636	0.628	0.569	0.424	0.333	0.206	0.318	0.269	0.111	0.26	188.5
26	0.696	0.642	0.633	0.576	0.420	0.132	0.297	0.307	0.209	0.29	342.0
27	1.098	1.019	1.029	0.986	0.720	0.528	0.601	0.976	0.495	0.52	296.0
28	0.986	0.767	0.773	0.640	0.561	0.220	0.352	0.448	0.115	0.30	154.7
29	0.954	0.739	0.716	0.820	0.702	0.533	0.680	0.686	0.529	0.58	79.0
30	1.956	1.706	1.651	1.596	1.587	1.503	1.521	1.548	1.489	N/A	196.6
31	0.611	0.578	0.535	0.519	0.482	0.282	0.320	0.467	0.239	0.39	382
32	0.636	0.632	0.576	0.518	0.482	0.244	0.299	0.437	0.237	0.25	87.8
33	0.654	0.457	0.375	0.319	0.282	0.169	0.241	0.260	0.161	0.13	65.1
34	0.924	0.756	0.893	0.712	0.672	0.431	0.518	0.678	0.315	0.44	179.4
35	0.701	0.592	0.533	0.527	0.493	0.237	0.425	0.511	0.210	0.39	83.1
36	0.694	0.675	0.583	0.565	0.329	0.280	0.422	0.453	0.289	0.33	88.8
37	0.671	0.686	0.475	0.437	0.396	0.221	0.311	0.376	0.208	0.24	97.2
38	0.682	0.552	0.483	0.387	0.447	0.264	0.358	0.387	0.225	0.30	116.0
39	0.679	0.542	0.475	0.401	0.376	0.253	0.318	0.370	0.369	0.30	111.1
40	0.659	0.436	0.562	0.588	0.648	0.415	0.472	0.516	0.142	0.44	55.6
41	0.671	0.550	0.521	0.456	0.377	0.224	0.360	0.389	0.219	0.23	276.0
42	0.678	0.583	0.521	0.433	0.378	0.204	0.298	0.336	0.192	0.27	70.3
43	1.046	0.924	0.873	0.745	0.820	0.535	0.679	0.753	0.547	0.59	72.0
44	1.076	0.889	0.859	0.848	0.720	0.547	0.652	0.677	0.498	0.61	73.6
45	0.709	0.683	0.657	0.646	0.618	0.410	0.453	0.583	0.383	0.43	62.4
46	0.884	0.793	0.778	0.760	0.723	0.521	0.685	0.697	0.400	0.67	401.0
47	0.784	0.687	0.642	0.596	0.566	0.439	0.518	0.555	0.410	0.49	353.0
48	1.083	0.880	0.863	0.757	0.548	0.583	0.679	0.694	0.586	0.67	84.9
49	0.771	0.650	0.441	0.456	0.408	0.284	0.355	0.385	0.281	0.28	132.4
50	0.821	0.777	0.753	0.706	0.672	0.357	0.561	0.587	0.288	0.54	318.0
51	0.864	0.719	0.656	0.420	0.620	0.424	0.547	0.589	0.409	0.52	481.0
52	0.933	0.820	0.779	0.765	0.718	0.544	0.686	0.699	0.457	0.62	382.0
53	0.822	0.727	0.722	0.698	0.633	0.464	0.577	0.629	0.357	0.57	252.0
54	1.095	0.866	0.821	0.739	0.721	0.453	0.690	0.701	0.457	0.61	231.0
55	1.412	1.294	1.276	1.187	1.133	0.944	1.003	1.160	0.819	0.95	149.3
56	0.835	0.817	0.718	0.826	0.626	0.453	0.556	0.578	0.408	0.54	153.2
57	1.094	0.836	0.865	0.833	0.812	0.617	0.718	0.783	0.549	0.68	251.0
58	0.828	0.752	0.781	0.679	0.634	0.326	0.552	0.627	0.223	0.34	263.0
59	0.892	0.870	0.726	0.648	0.638	0.421	0.446	0.439	0.395	0.38	116.0
60	0.868	0.745	0.666	0.626	0.596	0.337	0.518	0.518	0.422	0.40	57.6

N/A = not analyzed; Ref. = WTW TISAB solution; TEA = triethanolamine; EC = electrical conductivity.