CN101776585B

CN101776585B - Photochemical steam generating-atomic spectrometry for determining trace iron

Info

Publication number: CN101776585B
Application number: CN2010101206770A
Authority: CN
Inventors: 侯贤灯; 郑成斌; 何绍攀
Original assignee: Sichuan University
Current assignee: Sichuan University
Priority date: 2010-03-09
Filing date: 2010-03-09
Publication date: 2011-07-20
Anticipated expiration: 2030-03-09
Also published as: CN101776585A

Abstract

The invention relates to a photochemical steam generating-atomic spectrometry for determining trace iron, comprising the following steps of generating photochemical steam and detecting by introducing an atomic spectrometer. Different from the traditional method for pneumatic atomization and sample introduction, the spectrometry comprises the step of directly reacting formic acid and iron ions in a water solution under the radiation of ultraviolet light to generate the chemical steam (i.e. carbonyl iron) of the iron. The generated carbonyl iron is carried into the atomic spectrometer, an atomic fluorescence spectrophotometry (AFS) and an inductive coupling plasma-atomic emission spectrometer/mass spectrometer (ICP-AES/MS) for determination by carrier gas. The invention has the characteristics of sensitivity, economy, simplicity, safety, environmental protection, strong anti-jamming capability and the like.

Description

Measure the photochemical vapor generation-atomic spectrometry determination of trace iron

Technical field

Photochemical vapor generation-the atomic spectrometry determination of measuring trace iron belongs to the trace analysis technical field of analytical chemistry, relates to a kind of new chemical evapn genetic method is used for trace iron as sample introducing mode mensuration.

Background technology

Iron is widely used in national defence, multiple field such as civilian, is the mankind's indispensable a kind of elements of depending on for existence.In addition, iron is the trace element of needed by human, is the pith of haemoglobin, and the shortage of iron can cause anaemia.Yet body iron content is too high, can cause the illeffects that iron is potential in vivo, and the storage of discovering iron in the body is too much relevant with multiple disease such as heart and liver diseases, diabetes, some tumour.Iron also is indispensable element in the growth and development of plants simultaneously, and it is playing the part of important role in photosynthesis of plants, biological nitrogen fixation and respiration.

Though iron is content abundant (5.6%) in the earth's crust, the content of iron is low-down in some samples, and for example the content of iron only is 10ng L in seawater ^-1It is existing that what adopt about the standard GB 11911-89 that measures iron in the water quality and standard GB/T 14609-93 of measuring iron in the cereal all is the NITRATE BY FLAME ATOMIC absorption process.This method detection limit is very high can't to satisfy needs of production.In addition, measure iron method commonly used and also have inductively coupled plasma-atomic emission spectrometry/mass spectroscopy (ICP-AES/MS).But comprise the NITRATE BY FLAME ATOMIC spectroscopic methodology, the input mode of the pneumatic nebulization that these methods adopt, it is very low that sample is introduced efficient, only is about 1% usually.Thereby causing the sensitivity of method low, detection limit can not satisfy the requirement of actual analysis, and the pneumatic nebulization input mode also is subjected to the interference of sample matrices easily.Particularly ICP-MS when measuring iron ( ⁵⁶Fe ⁺) be subjected to easily from matrix or plasma ( ⁴⁰Ca ¹⁶O ⁺, ⁴⁰Ar ¹⁶O ⁺) interference, thereby cause the limit for height that detects of method, can't directly detect the iron in the water sample sample that particularly iron content such as seawater sample is low, therefore often must adopt complicated loaded down with trivial details separation and concentration step, sample is vulnerable to pollute simultaneously, determinand easily loses.

Chemical evapn is the material that the organism of nonvolatile material such as metal or nonmetallic ion, metal or nonmetalloid etc. is generated volatilization or half volatile by mechanisms such as physics, chemistry, biologies.This method has the following advantages as the sample introducing mode of atomic spectroscopic analysis: effectively separate in the matrix (1), reduces the interference that matrix brings, the detection limit of improvement method; (2) high sample introduction efficiency it has been generally acknowledged that to reach 100%; (3) transmit owing to being based on the gas phase determinand, so interface is fairly simple and stable, is easy to and the coupling of various atomic spectroscopic analysis technology; (4) instrument is simple, and is easy to robotization.

Document (RiginV.Simultaneous atomic fluorescence spectrometric determination of traces of iron, cobalt and nickel after conversion to their carbonyls and gas-phase atomization bymicrowave-induced plasma, Anal.Chim.Acta, 1993,283,895-891) the steam method for generation of report iron, this method is to react the generation iron carbonyi with CO under high pressure-temperature after adopting potassium borohydride that ferric ion is reduced into iron simple substance, in fact high and many reasons such as reaction complexity and danger are difficult to the detection of iron owing to blank value.

Goal of the invention

Set up a kind of novel trace iron chemical evapn generation-atomic spectrometry determination, realized that sample matrices is effectively separated and the introducing efficient of raising sample, thereby improved the sensitivity of measuring iron and reduce detection limit.

Technical scheme

In iron-containing liquor, add formic acid, regulate the pH value then, this solution is entered the photochemical reactor reaction generate iron carbonyi under the promotion of peristaltic pump, the solution that contains iron carbonyi enters under the promotion of peristaltic pump and carries out gas-liquid separation in the gas-liquid separator, is loaded in the atomic spectrograph by carrier gas through isolated iron carbonyi and detects.Its concrete steps are:

(1) preparation typical curve: the standard solution series of preparation iron, it is 50% that adding formic acid makes formic acid concn, with ammoniacal liquor pH value of solution is adjusted to 2.0-3.0, is diluted to scale.

(2) determination step: the first step, peristaltic pump is loaded into the iron standard solution or the sample of certain volume in the Photoreactor; In second step, peristaltic pump stops, and allows reactant liquor receive ultraviolet radiation in Photoreactor and generates iron carbonyi in 5 minutes; The 3rd step, to open solution that peristaltic pump will contain iron carbonyi and be written into and carry out gas-liquid separation in the gas-liquid separator, logical argon gas is separated iron carbonyi from solution, and purges to atomic spectrograph and measure.

Description of drawings

The device accompanying drawing 1 of realizing above method comprises: 1: reagent bottle (formic acid+Fe²⁺/Fe ³⁺); 2: the waste liquid cylinder; 3: peristaltic pump; 4: the photochemical vapor reactor; 5: the one-level gas-liquid separator; 6: carrier gas (argon gas or nitrogen); 7: the secondary gas-liquid separator; 8: condensing unit; 9: atomic spectrograph (Atomic absorption, atomic fluorescence or inductively coupled plasma-atomic emission spectrum/mass spectrograph). Wherein the photochemical vapor generator is made up of a uviol lamp, crystal reaction tube and the aluminium foil that coats uviol lamp and crystal reaction tube. In the cold steam generator that photochemical vapor takes place, quartzy spiral reaction tube is to be wrapped on the quartz socket tube of protecting uviol lamp. The uviol lamp of other specifications, crystal reaction tube also are feasible, and the final iron chemical evapn that adopts of the present invention device that reacts is uviol lamp by 17W, and 25cm is long, interior diameter is formed by the quartzy coil pipe of 3mm. The atom spectrum detector is respectively atomic fluorescence spectrophotometry (AFS), inductively coupled plasma atomic emission spectrum/mass spectrograph (ICP-AES/MS).

The invention effect

Measure the photochemical steam generating-atomic spectrometry of Trace Iron and compare with traditional atomic spectroscopic analysis method of tradition take pneumatic nebulization as input mode, mainly contain following characteristics/advantage:

(1) sample introduction efficiency improves greatly, thereby makes sensitivity obtain about 80 times raising;

(2) the gaseous state sample introduction is not brought water smoke into, and plasma is more stable, thereby the detection limit of method obtains the improvement about 100 times;

(3) since chemical evapn take place as input mode iron to be separated with sample matrices such as calcium etc., when adopting ICP-MS as detector, can eliminate by⁴⁰Ca ¹⁶The interference that O+ brings, and owing to adopt the gaseous state sample introduction, need atomization temperature relatively low, can also adopt low temperature plasma to come atomization, and in low temperature plasma, produce⁴⁰Ar ¹⁶O+ greatly reduces, thereby adopts photochemical vapor to take place to measure iron as input mode and can greatly reduce the interference that ICP-MS measures iron, and detection limit is improved greatly;

(4) be easy to be implemented in line analysis and saving analytical test time;

(5) primary product after the test is CO except that iron carbonyi ₂And H ₂O, environmentally friendly.

Table 1 is listed every method index of photochemical vapor generation-atomic absorption spectrometry iron, and with the comparison of other traditional analysis method.As can be seen, photochemical vapor generation-atomic spectroscopy is measured iron than classic method, and sensitivity and detection limit are improved widely.

The index table of comparisons of (PVG)-atomic spectrometry determination and direct pneumatic nebulization atomic spectrometry determination (same instrument) mensuration iron takes place in table 1 photochemical vapor

Embodiment

Embodiment 1:

In the concentration of iron scope is 1-100 μ gL ^-1Standard solution series in, adding formic acid, to make formic acid concn be 50%.The pH value of standard solution is adjusted to 2.5.Standard solution according to the ferriferous chemical evapn of determination step, and is imported among the ICP-AES and measures, and set up typical curve.The equation of typical curve is: y=1618.8[Fe ²⁺]-9675 and y=1610.8[Fe ³⁺]-4625.8, related coefficient is better than 0.99.Take by weighing 0.25g standard substance (DORM-3, DOLT-3 and DOLT-4, Canadian national standard material center) respectively in different micro-wave digestion jars, add 7mL HNO ₃With 0.2mL H ₂O ₂, use micro-wave digestion after the sealing.Clarified solution after clearing up changes in the 25mL volumetric flask fixed molten standby.Get the 0.25mL reserve liquid in sample hose and at 80 ℃ of following evaporates to dryness, it is 50% that adding formic acid makes formic acid concn, regulate pH to 2.5 back according to the operation of standard solution measurement operation step with ammoniacal liquor, detect iron, measure concentration and compare (table 2) with the canonical reference value with ICP-AES.

Table 2. sample analysis result (the photochemical vapor generation-ICP-AES)

Embodiment 2:

According to the step operation of method 1, measured the iron of standard substance TORT-2 and DORM-3 with the ICP-MS method.Its result is as shown in table 3:

Table 3. sample analysis result (the photochemical vapor generation-ICP-MS)

Claims

1. photochemical vapor generation-atomic spectrometry determination that is used to measure trace iron, it is characterized in that: in iron-containing liquor, add formic acid, regulate the pH value then, this solution is downloaded into photochemical reactor reaction generation iron carbonyi in the promotion of peristaltic pump, the solution that contains iron carbonyi enters under the promotion of peristaltic pump and carries out gas-liquid separation in the gas-liquid separator, be loaded in the atomic spectrograph by carrier gas through isolated iron carbonyi and detect, its concrete steps are:

(1) preparation typical curve: the standard solution series of preparation iron, it is 50% that adding formic acid makes formic acid concn, with ammoniacal liquor the pH value of solution value is adjusted to 2.0-3.0, is diluted to scale;

(2) determination step: the first step, peristaltic pump is loaded into the iron standard solution of certain volume in the photochemical reactor; In second step, peristaltic pump stops, and allows reactant liquor receive ultraviolet radiation in photochemical reactor and generates iron carbonyi in 5 minutes; The 3rd step, to open solution that peristaltic pump will contain iron carbonyi and be written into and carry out gas-liquid separation in the gas-liquid separator, logical argon gas is separated iron carbonyi from solution, and purges to atomic spectrograph and measure.