A SIMPLE GREEN REDUCTION STRATEGY TO SUBSTITUTE CADMIUM IN ANALYTICAL REDUCTION OF NITRATE IN GRIESS–ILOSVAY METHOD

Matias, Alexsandro Antônio; Oliveira, André Fernando de; Neves, Antônio Augusto; Queiroz, Maria Eliana Lopes Ribeiro de

doi:10.21577/0100-4042.20170669

Acessibilidade / Reportar erro

Brasil

Español English

sumário « anterior atual seguinte »

Sumário

Artigo • Quím. Nova 44 (2) • Feb 2021 • https://doi.org/10.21577/0100-4042.20170669 copy

A SIMPLE GREEN REDUCTION STRATEGY TO SUBSTITUTE CADMIUM IN ANALYTICAL REDUCTION OF NITRATE IN GRIESS–ILOSVAY METHOD

Authorship SCIMAGO INSTITUTIONS RANKINGS

Nitrate is an abundant ion that is present in many industrialized products and the environment. Various analytical methods have been described using the Griess-Ilosvay reagent for the determination of nitrate in different matrices after its reduction to nitrite, in most cases with metallic cadmium as the reducer. This work proposes a new method using aluminum spheres coated with a copper film for this reduction. To optimize the method, it was important to evaluate the conditions for the deposition of the copper film on the aluminum spheres, using a Doehlert matrix. The optimized method provided an analytical range from 2.0 to 100 µmol L^-1, with a coefficient of determination of 0.9996 and a standard deviation of residuals (s_res) of 7.59 x 10^-4. The Limits of Detection and Quantification were 0.59 and 2.0 µmol L^-1 respectively. The method was applied using mineral water samples and was shown to provide repeatability less than 6.98% and accuracy obtained through recovery essays between 81.1 and 104.6% for the determination of nitrate in this type of sample.

Keywords:
nitrate; aluminum spheres; Griess-Ilosvay reagent; analytical resolution

CODED VALUES		EXPERIMENTAL VALUES
A	B	pH	log c(Cu²⁺)
-1.0	0.000	8.5	-2.0
-0.5	-0.866	9.0	-3.0
-0.5	0.866	9.0	-1.0
0.0	0.000	9.5	-2.0
0.5	-0.866	10.0	-3.0
0.5	0.866	10.0	-1.0
1.0	0.000	10.5	-2.0
0.0	0.000	9.5	-2.0

Number^a a name of each experiment;	Variables		Parameters of the analytical curves
Number^a a name of each experiment;	pH	log c(Cu²⁺)^b b mol L-1;	Sensitivity / (L nmol^-1)	N9	rA^c c analytical resolution. / (mmol L^-1)
1	8.50	-2.0	0.12	0.72	53.9
1'	8.54	-2.0	0.69	0.56	67.3
2	9.01	-3.0	3.82	2.01	11.2
2'	9.03	-3.0	3.82	2.79	4.7
3	9.00	-1.0	0.10	0.45	83.0
3'	9.00	-1.0	0.11	0.59	62.7
4	9.53	-2.0	0.18	0.99	37.0
4'	9.55	-2.0	0.21	1.31	24.6
5	10.00	-3.0	2.83	0.99	37.9
5'	10.03	-3.0	3.71	2.06	10.2
6	9.99	-1.0	0.02	0.06	296.7
6'	10.02	-1.0	0.07	0.44	82.7
7	10.51	-2.0	0.12	0.69	54.6
7'	10.51	-2.0	0.16	0.78	48.1

Sample	Concentration added (µmol L^-1)	% Recovery (%rec.^a a %rec.: percentage recovery; ± s_rec^b b srec: standard deviation of the percentage recovery (n = 3). )
1	20.0	101.2 ± 4.1
	40.0	100.3 ± 4.4
	80.0	81.1 ± 0.5
2	20.0	90.5 ± 2.2
	40.0	94.8 ± 2.0
	80.0	84.2 ± 4.0
3	20.0	104.6 ± 5.8
	40.0	100.0 ± 1.1
	80.0	110.3 ± 2.4
4	20.0	95.6 ± 2.1
	40.0	102.8 ± 1.0
	80.0	84.2 ± 1.4

Sample	c(NO₃^-) (µmol L^-1)		% error
Sample	Proposed method	Reference method	% error
1	39.95 ± 0.93	38.94 ± 0.14	2.52
2	41.75 ± 2.29	39.14 ± 0.29	6.25

Sample	Direct determination (DD) (n^a a n: number of replicates; = 3)	Determination using standard additions (DSA) (n = 6)	Error^b b Error = (DD-DSA) / (DSA). (%)
	c(NO₃^-) (µmol L^-1)	c(NO₃^-) (µmol L^-1)
1	170.05 ± 5.70	167.89 ± 0.48	1
2	5.58 ± 0.28	5.02 ± 0.04	11
3	30.62 ± 2.41	34.79 ± 0.09	-12
4	5.90 ± 0.96	4.57 ± 0.08	28
5	29.98 ± 1.46	32.82 ± 0.47	-9
6	9.89 ± 1.00	7.60 ± 0.09	30

Sociedade Brasileira de Química Secretaria Executiva, Av. Prof. Lineu Prestes, 748 - bloco 3 - Superior, 05508-000 São Paulo SP - Brazil, C.P. 26.037 - 05599-970, Tel.: +55 11 3032.2299, Fax: +55 11 3814.3602 - São Paulo - SP - Brazil
E-mail: quimicanova@sbq.org.br

Acompanhe os números deste periódico no seu leitor de RSS

[1] *e-mail: andref.oliveira@ufv.br