Fe, Cu, Mg, Zn, and Ca are trace elements necessary for human physiological activities. Trace element detectors play an important role in maintaining normal body metabolism, promoting children's growth and development, and enhancing immune function. The lack of trace elements in the body can cause a series of biochemical disorders, growth and development, immune processes, cell division, intellectual development, etc. are all interfered with, and there are many pathological changes and various diseases. Accurate determination of the content of trace elements in hair is helpful for the diagnosis, treatment, prognosis estimation, and observation of the efficacy of many diseases, as well as clarifying the pathogenesis of certain diseases, thereby providing new methods and measures for preventing these diseases. The purpose of this study is to determine the feasibility and stability of atomic absorption spectrophotometric determination of trace elements in children's hair by atomic absorption spectrophotometric determination of Fe, Cu, Mg, Zn, Ca absorbance in healthy children's hair.

1. Instruments and reagents

1.1 Instrument

TAS-990 atomic absorption spectrophotometer LWP-500 micro pipette

1.2 Reagent

Fe, Cu, Mg, Zn, Ca standard solution (1mg / ml) each, nitric acid (superior grade pure); hydrogen peroxide (superior grade pure).

2. Sample

Random sampling method was used to select 90 healthy children aged 3-7 years who voluntarily accepted the trace element test. Using stainless steel scissors, cut approximately 2g of hair without hair follicles from the hair roots of each research subject's headrest. In the sampling bag, to be tested.

3. Determination method

After the sample was treated with nitric acid-hydrogen peroxide in advance, the atomic absorption spectrophotometer was used to measure the absorbance values ​​of Fe, Cu, Mg, Zn, and Ca.

3.1 Sample pretreatment

Each hair sample was pre-soaked with detergent, rinsed with distilled water, then rinsed repeatedly with deionized water, and dried in an oven at 60 ° C for 3 hours. From each dried hair sample, accurately weigh 0.5 grams of sample, place it in a 100ml beaker, add 50ml of nitric acid-hydrogen peroxide (HNO3: H2O2 = 1: 1), heat it to near dryness and make it completely digested. Cool, dissolve and dilute with 2% nitric acid solution, and transfer to a 10ml volumetric flask.

3.2 Drawing of standard curve

Precisely measure 1ml of Fe, Cu, Mg, Zn and Ca standard solutions in a 10ml volumetric flask, dilute each with 2% nitric acid solution to 10ml, dilute to volume, shake well, and dilute to 100μg / ml standard solution. Then accurately measure 0.20, 0.40, 0.60, 0.80, 1.00ml of the above diluted Fe, Cu, Mg, Zn, Ca standard solutions in 10mL volumetric flasks, and dilute each with 2% nitric acid solution to 10ml, and bring to volume , Shake well and place for testing.

4. Statistical methods

SPSS13.0 statistical software was used for data analysis. The average content of trace elements in day and night measurement data was compared by t test.

5. Results

5.1 Linear relationship of standard curve

Take the pre-prepared standard solutions of Fe, Cu, Mg, Zn, and Ca, determine the relationship between the respective absorbance and concentration, and draw the standard curve, as shown below.

5.2 Precision test

Take 10 samples after pretreatment, digest them according to the above method, measure the concentration of five elements Fe, Cu, Mg, Zn, Ca in each sample under the same conditions as the standard curve, calculate the average and The relative standard deviation is shown in Table 1.

5.3 Sample recovery test

Take 10 samples after pretreatment, of which 5 were added quantitative Fe, Cu, Mg, Zn, Ca five trace element standard solutions, respectively, to determine the content of trace elements, the data is shown in Table 2. 5.4 day and night difference analysis and pretreatment After 5 samples, each sample was measured for trace element content day and night, continuously measured for 3 days, and analyzed the effect of day and night conditions on the measurement results. The data are shown in Table 3. The above data was processed by statistical software, and the results showed that the tested samples were more stable after the above processing, and there was no significant difference between day and night analysis (P> 0.05).

6. Discussion

At present, domestic scholars have done more research on trace elements in human hair, but there are not many researches on the determination methods of trace elements in hair, especially research reports on the determination of trace elements in children's hair by atomic absorption spectrophotometry . It is reported in the literature that the determination of trace elements by atomic absorption method has the advantages of quickness, simplicity and accuracy. In this experimental study, atomic absorption spectrophotometry was used to determine the trace elements in the hair of 90 healthy children aged 3 to 7 years who were voluntarily tested. The feasibility and stability of this method for the determination of trace elements in hair were discussed. The experimental research results show that the atomic absorption spectrophotometric determination of trace elements has a positive correlation between absorbance and concentration, and the linear dependence is good. The precision and recovery rate test proves that the systematic error and accidental error occurrence rate of the trace element measurement test by this method Low, less interference by external factors during the test, stable laboratory environment and instrument working conditions, instrument operation, test solution preparation, etc. are correct and feasible. Through day-night difference analysis, it can be known that the atomic absorption spectrophotometric method is used to measure trace elements in the sample, and the experiment process is not affected by time. The experiment is progressing smoothly in different time periods. This study not only determined that the atomic absorption spectrophotometric method is feasible for detecting trace elements in children's hair under different environments, the monitoring data is accurate, and the measurement conditions are stable and reliable, but also for future related topics on the determination of trace elements in hair and other similar experiments Research provides reference.

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