CN112946103B

CN112946103B - Pretreatment method and detection method for detecting content of 21 elements in hair

Info

Publication number: CN112946103B
Application number: CN202110111042.2A
Authority: CN
Inventors: 冯振; 景叶松; 弭兆元
Original assignee: Shandong Ying Sheng Biotechnology Co ltd
Current assignee: Shandong Ying Sheng Biotechnology Co ltd
Priority date: 2021-01-27
Filing date: 2021-01-27
Publication date: 2022-03-15
Anticipated expiration: 2041-01-27
Also published as: CN112946103A

Abstract

The invention discloses a pretreatment method and a detection method for detecting the content of 21 elements in hair, which comprises the following steps: cleaning, drying and weighing the collected hair sample, and then putting the hair sample into a sample injection tube; adding concentrated nitric acid, standing at room temperature until most of hair is digested, placing the sample inlet pipe on a graphite furnace, and digesting to be nearly dry; and cooling the digested sample, and adding a diluting working solution for dilution for later use. By adopting the processing method, the problem of sample overflow can be well solved, and the labor is saved.

Description

Pretreatment method and detection method for detecting content of 21 elements in hair

Technical Field

The invention belongs to the technical field of human element detection, relates to a pretreatment method and a detection method for detecting the content of 21 elements in hair, and particularly relates to a pretreatment method and a detection method for detecting the content of potassium, calcium, sodium, magnesium, iron, copper, zinc, lithium, phosphorus, aluminum, chromium, manganese, cobalt, nickel, selenium, molybdenum, arsenic, mercury, thallium, lead and cadmium elements in hair.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

The element is an important substance for maintaining normal metabolism and life activity of human bodies, has the functions of regulating permeability of cell membranes and maintaining excitability of nerve muscles, and is also an important index for reflecting nutritional conditions of human bodies, and the deficiency and enrichment of the element can cause various diseases. And heavy metals such as arsenic, mercury, thallium, lead, cadmium and the like have extremely low toxicity under a very low dose and an ultra-long biological half-life after entering a human body, are easy to cause gene mutation once exceeding the standard, can generate teratogenesis or induce various diseases such as cancer and the like when serious, and greatly damage various functions of the body. Therefore, the method has very important significance for measuring trace elements and harmful elements of human bodies, determining the nutritional status of essential elements, discussing etiology, estimating illness, diagnosing and treating diseases, monitoring environment, preventing diseases and the like by selecting an efficient and accurate detection method.

Elements circulating in the blood will bind to proteins by forming covalent complexes with the thiol group of the amino acid cysteine. Keratin is the major structural protein in hair and nails, contains many cysteine residues, and is therefore one of the major sites for accumulation of trace elements, and trace elements are not readily reabsorbed once they precipitate.

Compared with common clinical samples such as blood, urine and the like, the hair has the characteristics of easy sampling and easy storage as the sample; the accumulation of elements in hair is higher than that of other parts such as blood, urine and the like; and the hair can be used to record the time of exposure, thus truly reflecting the storage condition of trace elements in a period of time.

Common methods for hair digestion include a microwave digestion method, a graphite furnace digestion method, an ashing method and the like, but the microwave digestion method has the problems of high microwave digestion equipment, low accessory price, low cooling speed and the like, the ashing method causes volatilization loss of volatile elements to be detected in the ashing process, so that the element recovery rate is low, and the graphite furnace digestion method has the advantages of short cooling time, low loss, simple subsequent treatment and the like.

The inventor discovers that the following matters can be obtained in the process of carrying out hair digestion experiments by using a graphite furnace digestion instrument: adding concentrated nitric acid into the sample introduction pipe with the hair sample, directly placing graphite furnace and digesting the appearance on the back, the temperature rise in the sample introduction pipe, the hair sample reacts with nitric acid rapidly, produce a large amount of foams, need uncovered placing to digest when the sample introduction pipe sample is digested, it is excessive together to lead to upper hair that does not digest and foam, need operating personnel to attend to at any time, otherwise can cause the sample loss, but when carrying out a large amount of sample processing, operating personnel probably takes care of untimely, still can lead to partial sample to spill over, finally influence the accuracy of experimental result.

Meanwhile, in the experimental process, it is found that the third-party quality control of As and Hg elements is not easy to be carried out, the measured results are both high, and the sample recovery rate result is not good, and the reference is found that the signal is increased probably due to the fact that the carbon matrix in the sample enables the high ionization energy elements to be sensitized, and the signal can be enhanced or inhibited and the ion interference can be reduced by adding a small amount of carbon-containing organic reagents such As ethanol, n-butanol and the like into the solvent.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a pretreatment method and a detection method for detecting the content of 21 elements in hair. By adopting the processing method, the problem of sample overflow can be well solved, and the labor is saved.

To solve the above technical problem, one or more of the following embodiments of the present invention provide the following technical solutions:

in a first aspect, the invention provides a pretreatment method for detecting the content of 21 elements in hair, which comprises the following steps:

cleaning, drying and weighing the collected hair sample, and then putting the hair sample into a sample injection tube;

adding concentrated nitric acid, standing at room temperature until most of hair is digested, placing the sample inlet pipe on a graphite furnace, and digesting to be nearly dry;

and cooling the digested sample, and adding a diluting working solution for dilution for later use.

In a second aspect, the invention provides a method for detecting the content of 21 elements in hair, which comprises the pretreatment method.

Compared with the prior art, one or more technical schemes of the invention have the following beneficial effects:

the method is simple to operate, the problem of sample overflow can be effectively solved, and the accuracy of the method is improved; meanwhile, the labor cost can be saved. And the problem of inaccurate determination result caused by matrix sensitization of part of high ionization energy elements can be solved.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a standard curve of Al element in accordance with an embodiment of the present invention;

FIG. 2 is a Cr element standard curve diagram according to an embodiment of the present invention;

FIG. 3 is a graph showing a standard curve of Mn element in the embodiment of the present invention;

FIG. 4 is a standard curve diagram of Li element in the embodiment of the present invention;

FIG. 5 is a graph showing the standard curve of Na element in the example of the present invention;

FIG. 6 is a graph showing a standard Mg element curve according to an embodiment of the present invention;

FIG. 7 is a P element standard curve diagram according to an embodiment of the present invention;

FIG. 8 is a K element standard curve diagram according to an embodiment of the present invention;

FIG. 9 is a graph showing the standard curve of Ca element in the embodiment of the present invention;

FIG. 10 is a graph of a standard Fe element curve according to an embodiment of the present invention;

FIG. 11 is a graph showing a standard curve of Cu element according to an embodiment of the present invention;

FIG. 12 is a standard curve diagram of Zn element in accordance with the embodiment of the present invention;

FIG. 13 is a graph of a standard Co element according to an embodiment of the present invention;

FIG. 14 is a standard curve diagram of Ni element in accordance with an embodiment of the present invention;

FIG. 15 is a standard curve of Se element in accordance with an embodiment of the present invention;

FIG. 16 is a Mo element standard curve diagram in accordance with the present invention;

FIG. 17 is a standard curve diagram of Cd element in the embodiment of the present invention;

FIG. 18 is a graph of the standard Tl element curve according to the embodiment of the present invention;

FIG. 19 is a graph showing a standard curve of Pb element in accordance with the embodiment of the present invention;

FIG. 20 is a standard graph of Hg element for an embodiment of the present invention;

FIG. 21 is a graph showing standard As element curves according to the embodiment of the present invention.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

adding concentrated nitric acid, standing at room temperature until most of hair is digested, placing the sample inlet pipe on a graphite furnace, and digesting until the hair is nearly dry, wherein the residual liquid amount is less than one-fifteenth of the original volume;

In some embodiments, the hair sample is washed sequentially with acetone-ultrapure water-acetone (acetone → deionized water → acetone for 10min each, the first time washing off fat-soluble impurities from the hair with acetone, the first time washing off water-soluble impurities with water, the second time further washing off fat-soluble impurities from the hair with acetone, and the second time washing off last due to the low boiling point of acetone in the organic solvent.

Further, the cleaning time of each link is 10 min.

In some embodiments, the room temperature is between 20 ℃ and 28 ℃.

In some embodiments, the volume of hair allowed to stand clear at room temperature is 3/4-2/3 of the total hair sample.

In some embodiments, the volume of concentrated nitric acid added per gram of hair sample is 15-20 mL.

In some embodiments, the dilute working solution is ultrapure water containing an internal standard.

Furthermore, the volume of the diluted working solution added in each gram of hair sample is 19-20 mL.

In some embodiments, the method further comprises the step of preparing different concentration solutions of the element calibrator to be tested.

Further, the method also comprises the step of drawing a standard curve by using calibrator solutions with different concentrations.

Further, the elements to be detected comprise potassium, calcium, sodium, magnesium, iron, copper, zinc, lithium, phosphorus, aluminum, chromium, manganese, cobalt, nickel, selenium, molybdenum, arsenic, mercury, thallium, lead and cadmium elements.

Further, different concentrations of calibrator solutions were prepared using a 1% dilute nitric acid solution containing 0.05% ethanol containing an internal standard (dilute nitric acid and ethanol act to create matrix conditions consistent with the sample, ethanol provides a small amount of carbon matrix, and nitric acid leaves the standard and sample in the same acidic environment).

In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the technical solution of the present invention will be described in detail below with reference to specific examples and comparative examples. The mass spectrometer system used in the following examples is YS EXT 8600MD, manufactured by shandong engsheng biotechnology limited.

Example 1

In this embodiment, a pretreatment method for detecting the content of 21 elements in hair is provided.

(1) Collecting a pencil-width hair at the back of head, and cutting off the hair from the vicinity of scalp with scissors, if the hair is short, cutting enough hair (0.5 g at least);

(2) cleaning collected hair by acetone-water-acetone method for 10min in each step;

(3) putting the cleaned hair on an oven for drying;

(4) weighing the dried hair, and taking 0.2g of each sample;

(5) putting the weighed hair into a sample inlet pipe, adding 3mL of concentrated nitric acid, standing at room temperature until most of the hair is digested (about 45min), putting the sample inlet pipe filled with the sample on a graphite furnace, and digesting to be nearly dry (about 1h 30 min);

(6) taking out the digested sample, cooling, adding a sample dilution working solution (ultrapure water added with an internal standard, wherein the internal standard comprises 7 elements of bismuth (Bi), holmium (Ho), indium (In), rhodium (Rh), scandium (Sc), terbium (Tb) and yttrium (Y)) for dilution, and detecting for later use;

(7) the same method as that of the sample was applied to 0.2g of the human hair component analysis standard substance purchased in the sample tube.

(8) The blank of the reagent is that 3mL of concentrated nitric acid is added into a sample injection tube, and the subsequent treatment is the same as that of the sample;

(9) taking potassium, calcium, sodium, magnesium, iron, copper, zinc, lithium, phosphorus, aluminum, chromium, manganese, cobalt, nickel, selenium, molybdenum, arsenic, mercury, thallium, lead and cadmium element calibrator solution, diluting the calibrator solution by using a standard curve to prepare 7 concentration gradients, and storing the calibrator solution at room temperature for later use.

Example 2

In this embodiment, a method for detecting the content of potassium, calcium, sodium, magnesium, iron, copper, zinc, lithium, phosphorus, aluminum, chromium, manganese, cobalt, nickel, selenium, molybdenum, arsenic, mercury, thallium, lead, and cadmium in hair is provided.

A standard substance is used for making a standard curve, as shown in fig. 1-21, the concentration of the standard solution is taken as an X axis, and the signal intensity of the standard substance is taken as a Y axis; and carrying out linear regression analysis to obtain a regression equation. The contents of 21 elements in the hair sample were calculated separately.

Conditions of Mass Spectrometry

Data are collected in a KED mode, and the collision gas is helium. The instrument parameters are as follows: forward power (Plasma power) 1550V; atomizer flow rate (Nebuliser flow) 1.0L/min; the assist flow rate (Auxiliary flow) was 0.8L/min; cooling gas flow rate (Cool flow) 14L/min; the Sampling depth (Sampling depth) is 5 mm.

Example 3

In this example, the type and concentration of the organic phase in the standard curve diluent was optimized.

The preliminary test shows that organic reagents such as ethanol, n-butanol and the like can increase the signal value of elements, and are respectively prepared into a sample diluent containing an internal standard 2% ethanol solution and a sample diluent containing an internal standard 2% n-butanol solution, a standard curve diluent containing an internal standard and added with 2% ethanol solution and 1% dilute nitric acid and added with 2% n-butanol solution and a standard curve diluent containing an internal standard and added with 2% n-butanol solution and 1% dilute nitric acid:

marking a dilution solution of a standard curve: 1% dilute nitric acid containing internal standard added with 2% ethanol;

second, standard yeast diluent: 1% dilute nitric acid containing an internal standard;

③ marking the dilution of the yeast: 1% dilute nitric acid containing internal standard added with 2% n-butanol;

sample diluent: 2% ethanol solution containing internal standard;

sample diluent: ultrapure water containing an internal standard;

sixthly, sample dilution: 2% n-butanol solution containing an internal standard;

after the hair was digested as in example 1, diluents (c) and (c) were added to the hair digestion solution, respectively, and the prepared standard was diluted with the diluents (c) and (c), respectively, and the results are shown in table 1.

TABLE 1 dilution with and without ethanol signals for each element

As can be seen from Table 1, after ethanol and n-butanol were added to the diluent, the signal values of As and Hg were significantly increased compared to those of the other elements, and the signal values of As and Hg in the sample and the standard curve were both increased compared to those without ethanol or n-butanol, and the signal value increase in the standard curve was higher than that of As and Hg in the sample, indicating that after ethanol or n-butanol was added to the diluent, the signal values of As and Hg could be significantly increased, and that after ethanol or n-butanol was added to the standard curve, the signal increase was significant. Because the n-butanol has pungent smell, the invention finally selects ethanol for experiment.

The problems existing in the actual measurement process are that the quality control is higher, the measurement result is inaccurate, the quality control is possibly controlled by improving the As and Hg signals of the standard curves, and the accuracy of the measurement result is improved

2. The concentration of ethanol in the standard curve diluent was optimized, 1% nitric acid solutions containing 2%, 1%, 0.5%, 0.1% and 0.05% ethanol were prepared to prepare standard curve diluents, and the hair quality control diluted with the sample diluent (ultrapure water containing an internal standard) after digestion was quantified. The measurement results are shown in Table 2 (only As and Hg elements with obvious effects are shown because the signal changes little after other elements are added into ethanol and the result changes little).

TABLE 2 quality control of the dilutions of the standard solutions after addition of ethanol of different concentrations

As can be seen from Table 2, both As and Hg were controlled after the dilution was added with 0.05% ethanol. Probably, in the digestion process, the organic matters in the hair cannot be completely digested, a small part of carbon matrix exists, and the As and Hg signals in the sample are sensitized, so that the measurement result of the sample is higher, and after a small amount of ethanol is added into the standard curve, the carbon content of the standard curve is similar to that of the sample, so that the measurement result is more accurate.

3. Detection limit measurement: the blank solution was measured 10 times under the above-mentioned treatment conditions, and 3 times the standard deviation of the results was used as the detection limit of each element.

Detection limits of 321 elements of the Table

4. The calculated recovery rates for each element after the hair sample was subjected to the standard addition treatment are shown in table 4.

TABLE 421 recovery of elements

As can be seen from tables 3 and 4, the method has low detection limit of each element after treatment, high recovery rate and is suitable for detecting the content of the element in the hair sample.

The test data prove that the method disclosed by the invention is simple to operate, can measure the content of 21 elements in the hair at one time, is low in detection limit, meets the requirement on accuracy, can effectively solve the problem of sample overflow, and saves the labor cost.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting the content of 21 elements in hair is characterized in that:

the method comprises the following pretreatment steps:

adding concentrated nitric acid, standing at room temperature until the hair digestion volume accounts for 2/3-3/4 of the total amount of the hair sample, placing a sample inlet pipe on a graphite furnace, and digesting to be nearly dry; the volume of concentrated nitric acid added into each gram of hair sample is 15-20 mL;

cooling the digested sample, and adding a diluting working solution for dilution for later use;

the method also comprises the step of preparing solutions with different concentrations of the element calibrator to be detected;

and drawing a standard curve by using the calibrator solutions with different concentrations;

wherein the elements to be detected comprise potassium, calcium, sodium, magnesium, iron, copper, zinc, lithium, phosphorus, aluminum, chromium, manganese, cobalt, nickel, selenium, molybdenum, arsenic, mercury, thallium, lead and cadmium elements;

the calibrator solutions of different concentrations were prepared using a 1% dilute nitric acid solution containing 0.05% ethanol with an internal standard.

2. The detection method according to claim 1, characterized in that: in the pretreatment step, cleaning a hair sample by sequentially adopting acetone, water and acetone;

the cleaning time of each link is 10 min.

3. The detection method according to claim 1, characterized in that: in the pretreatment step, the temperature of the mixture placed at room temperature is 20-28 ℃.

4. The detection method according to claim 1, characterized in that: in the pretreatment step, the diluted working solution is ultrapure water containing an internal standard;

the volume of the diluted working solution added in each gram of hair sample is 19-20 mL.