CN101666743A - Method for measuring nitrate in pectin - Google Patents

Abstract

The invention discloses a method for measuring nitrate in pectin, which comprises the following steps: a, preprocessing a pectin sample; b, measuring absorbance; c, drawing a standard curve; and d, calculating a result. The method has the characteristics of simple operation and accurate detection result, and is capable of detecting the nitrate in the pectin effectively.

Description

A kind of assay method of nitrate in pectin

Technical field:

The present invention relates to the pectin production technical field, is a kind of assay method of nitrate in pectin specifically, promptly utilizes the acidifying ethanolic solution that sample is carried out pre-treatment, with ultraviolet spectrophotometer sample is detected.

Background technology:

At present, no matter be GB or traditional nitrate detection method, nitrate when sample pre-treatments in the pectin sample all fully lixiviate come out, and during according to GB operation pre-treatment, for pectin this be insoluble in water and meet water with regard to unite, the sample of swelling, very difficulty and cause the loss of nitrate easily makes testing result inaccurate.

Summary of the invention:

The objective of the invention is to overcome the deficiency of above-mentioned prior art, and a kind of assay method of nitrate in pectin is provided, mainly solve conventional detection when sample pre-treatments the nitrate in the pectin sample fully lixiviate come out and easily cause the nitrate loss to make problems such as testing result is inaccurate.

In order to achieve the above object, the present invention is achieved in that a kind of assay method of nitrate in pectin, and its special character is that it comprises following processing step:

A, pre-treatment: with concentration is the pectin (decide on nitrate in pectin content) that 60% acidifying ethanolic solution disperses 1～5g, does not have precipitation to pectin, filters reservation filtrate after stirring 30-60min;

B, absorbance measuring: get filtrate 1-10mL in the 50mL color comparison tube, to wherein adding 1mL hydrochloric acid solution (1mol/L), 3-5mL sulfaminic acid ammonium salt solution (50g/L) is settled to scale with distilled water, shakes up.On ultraviolet spectrophotometer, in wavelength 210nm place,, make reference with reagent blank with the quartzy absorption vessel of 1cm, measure absorbance (A210); Adjust wavelength to the 275nm place, still make reference, survey absorbance (A275) again with reagent blank;

The drafting of c, typical curve: the curve of preparing standard solution, and drawing standard as required;

D, result calculate:

$A_{\mathrm{NO}{3}^{-}}=A_{210}-2A_{275}$

${\mathrm{\ρ}}_{{\mathrm{NO}3}^{-}}=\frac{m-m_0}{\frac{m_1\×V_1}{V_2}}$

In the formula:

-deduct the light absorption value of nitrate radical after the organism absorption value;

The mass concentration of nitrate radical in the-sample, mg/Kg;

After m-deducts the organism absorption value, from typical curve (the nitrate radical quality of λ=210nm) check in, μ g;

m ₀-deduct the organism absorption value after, from typical curve (the nitrate radical quality of the blank solution of λ=210nm) check in, μ g;

m ₁-sample mass, g;

V ₁-get amount of filtrate, mL;

V ₂-dispersion sample milliliter the number of acidifying ethanol, mL.

Accurately measure the content of nitrate in pectin thus.

Compared with the prior art the assay method of a kind of nitrate in pectin of the present invention has outstanding substantive distinguishing features and marked improvement, 1, adopt the acidifying ethanolic solution that pectin is disperseed, obtained good effect, the nitrate when sample pre-treatments in pectin sample lixiviate fully comes out and is not easy to cause the nitrate loss; Carry out the measurement of absorbance with ultraviolet-visible pectrophotometer when 2, detecting, but though introduce medium during leaching nitrate can eliminate by blank, data result is reliable; 3, simple to operate, testing result is accurate, can detect the nitrate in the pectin effectively.

Embodiment:

In order to understand better and to implement, describe the present invention in detail below in conjunction with embodiment.

Embodiment 1, with concentration is that 60% acidifying ethanolic solution disperses 2.5g pectin, to pectin, there is not precipitation, filter after stirring 45min, keep filtrate, get filtrate 5.5mL in the 50mL color comparison tube, to wherein adding 1mL hydrochloric acid solution (1mol/L), 4mL sulfaminic acid ammonium salt solution (50g/L) is settled to scale with distilled water, shakes up; On ultraviolet spectrophotometer, in wavelength 210nm place,, make reference with reagent blank with the quartzy absorption vessel of 1cm, measure absorbance (A210); Adjust wavelength to the 275nm place, still make reference, survey absorbance (A275) again with reagent blank; The curve of preparing standard solution, and drawing standard as required; The result is calculated as follows:

$A_{\mathrm{NO}{3}^{-}}=A_{210}-{2A}_{275}$

${\mathrm{\ρ}}_{\mathrm{NO}{3}^{-}}=\frac{m-m_0}{\frac{m_1\×V_1}{V_2}}$

In the formula:

-deduct the light absorption value of nitrate radical after the organism absorption value;

The mass concentration of nitrate radical in the-sample, mg/Kg;

After m-deducts the organism absorption value, from typical curve (the nitrate radical quality of λ=210nm) check in, μ g;

m ₀-deduct the organism absorption value after, from typical curve (the nitrate radical quality of the blank solution of λ=210nm) check in, μ g;

m ₁-sample mass, g;

V ₁-get amount of filtrate, mL;

V ₂-dispersion sample milliliter the number of acidifying ethanol, mL.

Accurately measure the content of nitrate in pectin thus.

Embodiment 2, with concentration is that 60% acidifying ethanolic solution disperses 1g pectin, to pectin, there is not precipitation, filter after stirring 30min, keep filtrate, get filtrate 10mL in the 50mL color comparison tube, to wherein adding 1mL hydrochloric acid solution (1mol/L), 3mL sulfaminic acid ammonium salt solution (50g/L) is settled to scale with distilled water, shakes up; On ultraviolet spectrophotometer, in wavelength 210nm place,, make reference with reagent blank with the quartzy absorption vessel of 1cm, measure absorbance (A210); Adjust wavelength to the 275nm place, still make reference, survey absorbance (A275) again with reagent blank; The curve of preparing standard solution, and drawing standard as required; The result is calculated as follows:

$A_{\mathrm{NO}{3}^{-}}=A_{210}-{2A}_{275}$

${\mathrm{\ρ}}_{\mathrm{NO}{3}^{-}}=\frac{m-m_0}{\frac{m_1\×V_1}{V_2}}$

In the formula:

-deduct the light absorption value of nitrate radical after the organism absorption value;

The mass concentration of nitrate radical in the-sample, mg/Kg;

After m-deducts the organism absorption value, from typical curve (the nitrate radical quality of λ=210nm) check in, μ g;

m ₀-deduct the organism absorption value after, from typical curve (the nitrate radical quality of the blank solution of λ=210nm) check in, μ g;

m ₁-sample mass, g;

V ₁-get amount of filtrate, mL;

V ₂-dispersion sample milliliter the number of acidifying ethanol, mL.

Accurately measure the content of nitrate in pectin thus.

Embodiment 3, with concentration is that 60% acidifying ethanolic solution disperses 5g pectin, to pectin, there is not precipitation, filter after stirring 60min, keep filtrate, get filtrate 1mL in the 50mL color comparison tube, to wherein adding 1mL hydrochloric acid solution (1mol/L), 5mL sulfaminic acid ammonium salt solution (50g/L) is settled to scale with distilled water, shakes up; On ultraviolet spectrophotometer, in wavelength 210nm place,, make reference with reagent blank with the quartzy absorption vessel of 1cm, measure absorbance (A210); Adjust wavelength to the 275nm place, still make reference, survey absorbance (A275) again with reagent blank; The curve of preparing standard solution, and drawing standard as required; The result is calculated as follows:

$A_{\mathrm{NO}{3}^{-}}=A_{210}-{2A}_{275}$

${\mathrm{\ρ}}_{\mathrm{NO}{3}^{-}}=\frac{m-m_0}{\frac{m_1\×V_1}{V_2}}$

In the formula:

-deduct the light absorption value of nitrate radical after the organism absorption value;

The mass concentration of nitrate radical in the-sample, mg/Kg;

After m-deducts the organism absorption value, from typical curve (the nitrate radical quality of λ=210nm) check in, μ g;

m ₀-deduct the organism absorption value after, from typical curve (the nitrate radical quality of the blank solution of λ=210nm) check in, μ g;

m ₁-sample mass, g;

V ₁-get amount of filtrate, mL;

V ₂-dispersion sample milliliter the number of acidifying ethanol, mL.

Accurately measure the content of nitrate in pectin thus.

Claims (1)

1, a kind of assay method of nitrate in pectin is characterized in that it comprises following processing step:

A, pre-treatment: with concentration is the pectin that 60% acidifying ethanolic solution disperses 1～5g, filters after stirring 30-60min, keeps filtrate;

B, absorbance measuring: get filtrate 1-10mL in the 50mL color comparison tube, to the hydrochloric acid solution 1mL that wherein adds 1mol/L, 50g/L sulfaminic acid ammonium salt solution 3-5mL is settled to scale with distilled water, shakes up; On ultraviolet spectrophotometer, in wavelength 210nm place,, make reference with reagent blank with the quartzy absorption vessel of 1cm, measure absorbance A 210; Adjust wavelength to the 275nm place, still make reference, survey absorbance A 275 again with reagent blank;

The drafting of c, typical curve: the curve of preparing standard solution, and drawing standard as required;

D, result calculate:

$A_{{\mathrm{NO}3}^{-}}=A_{210}-2A_{275}$

${\mathrm{\ρ}}_{{\mathrm{NO}3}^{-}}=\frac{m-m_0}{\frac{m_1\×V_1}{V_2}}$

In the formula:

-deduct the light absorption value of nitrate radical after the organism absorption value;

The mass concentration of nitrate radical in the-sample, mg/Kg;

After m-deducts the organism absorption value, from the nitrate radical quality that typical curve λ=210nm checks in, μ g;

m ₀-deduct the organism absorption value after, the nitrate radical quality of the blank solution that checks in from typical curve λ=210nm, μ g;

m ₁-sample mass, g;

V ₁-get amount of filtrate, mL;

V ₂-dispersion sample milliliter the number of acidifying ethanol, mL.

Accurately measure the content of nitrate in pectin thus.