阅读说明：本技术 一种同时检测氯化亚铁中痕量As、Pb、Cd、Zn、Cr元素含量的方法 (Method for simultaneously detecting contents of trace As, Pb, Cd, Zn and Cr elements in ferrous chloride ) 是由 车莹 杨柳荫 何开景 钱藏藏 曾慧 于 2020-04-16 设计创作，主要内容包括：本发明提供了一种同时检测氯化亚铁中痕量As、Pb、Cd、Zn、Cr元素含量的方法；该方法包括：(1)样品前处理：称取2-10g氯化亚铁样品,加入20-50mL优级纯盐酸,加入适量氧化剂并加热至样品溶解和氯化亚铁氧化完全,将待测样品转移至分液漏斗中,加入10-30mL乙酸丁酯,萃取3-5次将Fe<Sup>3+</Sup>萃取干净,取水层,水浴富集至5-20mL,将样品溶液转移至25mL容量瓶中,定容摇匀,同时做空白；(2)选择元素谱线；(3)绘制标准曲线；(4)检测试样：将试样溶液通过进样系统引入ICP-OES,测定各元素所对应的发射光强度,根据标准曲线确定各元素含量。本发明方法所得各元素标准曲线线性关系良好,检出限低,对各元素含量的测定具有高的准确度和精密度,可用于标准样品和生产产品的分析。(The invention provides a method for simultaneously detecting the content of trace As, Pb, Cd, Zn and Cr elements in ferrous chloride, which comprises (1) sample pretreatment, wherein the sample pretreatment comprises the steps of weighing 2-10g of ferrous chloride sample, adding 20-50m L guaranteed hydrochloric acid, adding a proper amount of oxidant, heating until the sample is dissolved and the ferrous chloride is completely oxidized, transferring the sample to be detected into a separating funnel, adding 10-30m L butyl acetate, extracting for 3-5 times to obtain Fe 3+ Extracting, collecting water layer, enriching to 5-20m L in water bath, transferring sample solution to 25m L volumetric flask, fixing volume, shaking up, and making blank, (2) selecting element spectral line, (3) drawing standard curve, (4) detecting sample, introducing sample solution into ICP-OES through sample injection system, measuring emission light intensity corresponding to each element, determining content of each element according to standard curveThe method has the advantages of good linear relation of the standard curves of all elements, low detection limit, high accuracy and precision in the determination of the content of all elements, and can be used for the analysis of standard samples and produced products.)

1. A method for simultaneously detecting the contents of trace As, Pb, Cd, Zn and Cr elements in ferrous chloride is characterized by comprising the following steps:

(1) sample pretreatment: weighing 2-Putting 10g of sample into a beaker with the thickness of 100m L, adding 20-50m L of high-grade pure hydrochloric acid and a proper amount of oxidant, heating until the sample is dissolved and ferrous chloride in the sample is completely oxidized, transferring the sample to be detected into a separating funnel, adding 10-30m L of butyl acetate, extracting for 3-5 times, and adding Fe³⁺Extracting, collecting water layer, concentrating in water bath to 5-20m L, transferring sample solution into 25m L volumetric flask, adding distilled water to constant volume, shaking, and making blank;

(2) selecting an element spectral line: selecting the optimal analysis spectral line of each element according to the matrix composition and impurity components of the sample;

(3) drawing a standard curve: preparing standard solutions of As, Pb, Cd, Zn and Cr, introducing the standard solutions into an inductively coupled plasma emission spectrometer (ICP-OES) through a sample introduction system, measuring the emission intensity of each element under the optimal analysis spectral line, and drawing a standard curve;

(4) detecting a sample: introducing the sample solution obtained in the step (1) into an inductively coupled plasma emission spectrometer through a sample introduction system, measuring the intensity of emitted light corresponding to As, Pb, Cd, Zn and Cr, and determining the content of each element according to a standard curve;

(5) wherein the working conditions of the inductively coupled plasma emission spectrometer in the steps (3) and (4) are that the radio frequency power is 950-.

2. The method of claim 1, wherein: in the step (1), the oxidant is one of superior pure nitric acid, hydrogen peroxide and sodium chlorate.

3. The method of claim 1, wherein: the water bath enrichment temperature in the step (1) is 100 ℃.

4. The method of claim 3, wherein: the distilled water is first-grade water which meets the specification of GB/T6682.

5. The method of claim 1, wherein: the optimal spectral lines of the elements in the step (2) are as follows: 193.759nm for As, 220.3nm for Pb, 214.43nm for Cd, 213.856nm for Zn and 267.72nm for Cr.

6. The method of claim 1, wherein the As, Pb, Cd, Zn and Cr standard solutions prepared in step (3) have concentration gradients of 0 mg/L, 0.006 mg/L, 0.03 mg/L, 0.15 mg/L, 0.6 mg/L and 1.5 mg/L.

7. The method of any one of claims 1-6, wherein: the inductively coupled plasma emission spectrometer used was an ICAP7000 type full spectrum direct reading inductively coupled plasma emission spectrometer from Siemer Feishale, USA.

Technical Field

The invention relates to the technical field of element analysis, in particular to a method for simultaneously detecting contents of As, Pb, Cd, Zn and Cr elements in ferrous chloride, and specifically relates to a method for simultaneously detecting contents of trace elements such As As, Pb, Cd, Zn and Cr in ferrous chloride by using an inductively coupled plasma emission spectrometer (ICP-OES).

Background

Ferrous chloride is used as a water treatment agent and an industrial product, and heavy metal elements harmful to human bodies, water bodies and the environment in the ferrous chloride need to be limited and detected. When the As is tested in HG/T4538-2013 water treatment agent ferrous chloride, an atomic absorption spectrophotometer is used for testing Pb, Cd, Zn and Cr by adopting an arsenic spot method, and when each element is tested by a sample, a standard solution and the sample are required to be prepared independently, so that the operation is complex, the steps are tedious, the time and the labor are consumed, and the efficiency is low, so that a new testing method is necessary to be developed.

The inductively coupled plasma emission spectrometer (ICP-OES) has the advantages of low detection limit, small matrix effect, high precision, high sensitivity, and wide linear range (up to 10)⁵) And various elements can be simultaneously measured, and the method can be developed to simultaneously detect various trace heavy metals in ferrous chloride as a conventional laboratory analytical instrument. When trace elements such As As, Pb, Cd, Zn, Cr and the like in ferrous chloride are directly tested, due to the fact that the content of an iron matrix is too high and the content of the trace elements is too low, spectral interference phenomena such As high background, disconnection of background, pull-up of main peak, drift of main peak, disconnection of main peak and the like can be caused during testing, so that a test result has large deviation, trace elements such As As, Pb, Cd, Zn, Cr and the like in ferrous chloride cannot be directly tested, the iron matrix needs to be separated, and weight loss metal cannot be introduced or damaged in the separation process.

Disclosure of Invention

The invention aims to provide a method for simultaneously detecting the contents of trace As, Pb, Cd, Zn and Cr elements in ferrous chloride by using an inductively coupled plasma emission spectrometer (ICP-OES) aiming at the defects of the existing detection method, and the method has higher accuracy and precision.

In order to solve the technical problems, the invention adopts the following technical scheme:

a method for simultaneously detecting the contents of trace As, Pb, Cd, Zn and Cr elements in ferrous chloride by utilizing ICP-OES comprises the following steps:

(1) sample pretreatment, namely weighing 2-10g of sample in a beaker with the thickness of 100m L, adding 20-50m L of high-grade pure hydrochloric acid, adding a proper amount of oxidant, heating until the sample is dissolved and ferrous chloride in the sample is completely oxidized, transferring the sample to be detected to a separating funnel, adding 10-30m L of butyl acetate, extracting for 3-5 times, and adding Fe³⁺Extracting, collecting water layer, concentrating in water bath to 5-20m L, transferring sample solution into 25m L volumetric flask, adding distilled water to constant volume, shaking, and making blank;

(2) selecting an element spectral line: selecting the optimal analysis spectral line of each element according to the matrix composition and impurity components of the sample;

(3) drawing a standard curve: preparing standard solutions of As, Pb, Cd, Zn and Cr, introducing the standard solutions into an inductively coupled plasma emission spectrometer through a sample introduction system, measuring the emission light intensity of each element under the optimal analysis spectral line, and drawing a standard curve;

(4) detecting a sample: introducing the sample solution obtained in the step (1) into an inductively coupled plasma emission spectrometer through a sample introduction system, measuring the intensity of emitted light corresponding to As, Pb, Cd, Zn and Cr, and determining the content of each element according to a standard curve;

(5) wherein the working conditions of the inductively coupled plasma emission spectrometer in the steps (3) and (4) are that the radio frequency power is 950-.

The purity of the oxidant in the step (1) of the method is guaranteed to be superior grade purity; preferably, the distilled water is primary water according to the specification in GB/T6682. The mass of the sample in the step (1) is 2-10g, and the sample is determined according to the content of impurity elements in the sample, less mass is selected to be weighed when the impurity content is high, and more samples are weighed when the impurity element content is low; due to Fe²⁺The ferrous chloride is difficult to be extracted, and the ferrous chloride is completely oxidized by adding oxidants such as nitric acid, hydrogen peroxide, sodium chlorate and the like before extraction; fe³⁺Must be complexed under strong acidic conditionSynthesis of [ FeCl₄]^-Can be extracted by butyl acetate, and the lower the proportion of the sample to the hydrochloric acid is, the more favorable the dissolution and extraction of the sample are; the smaller the ratio of the amount of sample and hydrochloric acid to the amount of butyl acetate, the more favorable the Fe³⁺Is extracted to be clean; because a large amount of high-concentration hydrochloric acid is added, in order to protect ICP-OES and enrich a sample, the sample needs to be evaporated and concentrated, the volatilization of impurity elements is reduced by selecting a water bath mode, and the water bath with the temperature of 100 ℃ is preferred to shorten the detection time.

In the step (2) of the method, because the trace elements are detected, spectral lines with high sensitivity, small interference, low background and good linear coefficient are selected as analysis spectral lines in the spectral lines recommended by the instrument, and the optimal spectral lines of the elements are as follows: 193.759nm for As, 220.3nm for Pb, 214.43nm for Cd, 213.856nm for Zn and 267.72nm for Cr.

The concentration gradients of each element selected in the standard solution prepared in step (3) of the method are 0 mg/L, 0.006 mg/L, 0.03 mg/L, 0.15 mg/L, 0.6 mg/L and 1.5 mg/L.

In order to achieve the purpose of measuring trace elements in a ferrous chloride sample, the invention preferably selects the working parameters of key instruments such as radio frequency power of 1150W, pump speed of 50r/min, auxiliary gas flow of 0.5L/min, atomizer flow of 0.65L/min, observation height of 12cm, integration time of 30S and the like in the test, and ensures the detection accuracy and precision.

The invention oxidizes ferrous chloride into ferric trichloride by nitric acid, hydrogen peroxide, sodium chlorate and other oxidants, and utilizes butyl acetate to oxidize Fe³⁺Extraction separation due to the fact that butyl acetate is opposite to Fe in a hydrochloric acid system³⁺Has strong selectivity of only Fe³⁺And extracting the heavy metal elements, and not extracting the other heavy metal elements, so that a large amount of iron matrix is separated without influencing the test of the other heavy metals. And (3) removing the iron matrix from the sample, testing the sample on a machine, matching the sample peak shape chart with the standard liquid peak shape chart, and eliminating spectral interference. The verification proves that the method has high accuracy and precision, and can be used for simultaneously detecting various trace elements such As As, Pb, Cd, Zn, Cr and the like in the ferrous chloride.

In conclusion, the invention has the following beneficial effects:

1. the method has the advantages that the iron matrix is extracted and separated, the spectral interference caused by the iron matrix is effectively eliminated, the detection limit of the method is reduced, the method for simultaneously determining multiple trace elements in the ferrous chloride by using the inductively coupled plasma emission spectrometer is created, the detection time is shortened, and the working efficiency is improved.

2. According to the invention, by controlling the working parameters of the key instrument, the linear correlation coefficients corresponding to the element standard curves are respectively as follows: as: 0.999942, Pb: 0.999956, Cd: 0.999997, Zn: 0.999999, Cr: 0.999997, the linear correlation coefficient is above 0.9999, which can ensure the precision and accuracy of detection, and can be used for the analysis of standard samples and production samples.

3. The reagent used in the experimental process is relatively safe, and a chemical reagent with high hazard is not used, so that the experimental safety is improved, the environmental pollution is not caused, and the method is relatively environment-friendly.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to specific embodiments.