Knowledge


2018.12.10
Utilization of multi-element containing standard sample on CIC: December 06-07, 2018 at Tokyo Metropolitan Industrial Technology Research Institute (TIRI)
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35th Ion Chromatograph Forum
At Tokyo Metropolitan Industrial Technology Research Institute (TIRI), December 6-7, 2018

Abstract: O-01

Utilization of multi-element containing standard sample on CIC:
Combustion Ion Chromatograph

Hisomu Nagashima*1
Hiroshi Ueno*2

*1 NAC Techno Service (Tokyo and Chiba, Japan), *2 TIRI (Tokyo, Japan)

1. Introduction

In these 13 years, we have developed 3 different simultaneous halogens (F,Cl,Br,I)/sulfur automatic combustion analysis system, such as for organic elemental analysis, for conforming to environmental samples of JIS regulation, and for high temperature combustion type for inorganic samples, by combination of combustion furnace and ion chromatograph (CIC).
By these systems, it enabled to comply with wider range of application samples from pharmaceutical products to environmental sample and steel samples.
On the other hand, to parallel with development of the system, collaborating with TIRI executed for newly investigation of organic standard samples containing multi-elements, in order to utilize them to organic calibration line method.
We have developed 3 different standard samples and obtained the patents: NAC-st1, NAC-st2 and NAC-st4. NAC-st4 is able to implement calibration curve of 5 targeted elements in one identical sample, since NAC-st4 contains 4 kinds of halogens and sulfur in its compound.
In this report, calibration curve constructing method with NAC-st4 and so forth are introduced from actual application facet.

2. Experiment

2-1. Analytical system

The system is composed from combustion decomposition electric furnace unit (SQ-1), absorption unit (HSU-35), auto-sampler (THA-24) and ion chromatograph (IC). SQ-1, HSU-35 and THA-24 were collaboratively developed with Yanaco LID Company.
Measuring conditions are described on Table 1.
Structure and property data of NAC-st4 are shown in Fig. 1.

Fig.1

Fig. 1
Structure and property data of NAC-st4
N-(2-fluoro-3-chloro-4-bromophenyl)-4-iodobenzenesulfoamide
Molecular Formula: C12H7NO2FClBrIS
Elemental analysis: <0.3% (C, H, N, F, Cl, Br, I, S) Molecular Weight: 490.51 m.p.: 183 to 184℃ IR: 3235cm-1NH, 1170cm-1 S=0
NMR: 6.81 (1H, N-H), 7.38 to 7.50 (4H, aromatic), 7.84 to 7.86 (aromatic)

Table1


2-2. Creating calibration curve

At the time of alteration of JIS K0127, “Ion chromatography general ordinance” in 2013, new item was added as “Combustion pre-treatment for organic compounds”. In the item, calibration curve creating method (Organic calibration method) that organic standard sample or standard sample containing halogens and sulfur are step-wisely combusted was added, other than preparing method using standard sample for volumetric analysis or anion standard solution (Inorganic calibration method).

Organic calibration method is not so familiar in the field of environmental analysis; however, in the field of trace organic elemental analysis, it is routinely implemented with micro- or ultra-micro balances.
Advantages of organic calibration method are as follows:
1) In case of total automatic analysis method, 4 to 6 kinds of standard solutions were automatically introduced into IC by exchanging one by one with external solution selector. In contrast, as the organic calibration method can implement internally, so there is no necessity for preparation of standard solution and external introduction. This method enables to simplify the system significantly.
2) Calibration creating and sample measurement are implemented in the same operation in the organic calibration method, so it can delete various error factors such as absorption efficiency.

3. Results and consideration

Fig.2

Fig. 2.
Ion chromatogram obtained by NAC-st4 (3.0mg)

3-1. Chromatogram obtained by combustion

Chromatogram of NAC-st4 obtained with TSKgel
Super IC-Anion HS high-speed column, is shown in Fig.2.
All ions including iodine ion are eluted within 8 minutes, and respective peak is illustrated in sharp and conspicuously.
The numbers of theoretical plates of 5 species ions illustrate 5,000 to 11,000 plates, and especially in SO42-, quite high plates (11,000 plates) are obtained.

3-2. Calibration curve by organic calibration method

NAC-st4 was weighed as 0.558 to 4.025mg (n=5), and secondary approximation correlation formula between sample quantity (mg) and peak area, was determined in order to create calibration curve.

Table 2 shows the result that obtained quite good correlation more than R2
: 0.999.
By utilizing multi-elements containing standard sample and the combination of high-speed combustion system and high-speed column, it enables to determine respective concentration of multi-elements (F, Cl, Br, I, S) simultaneously, in rapidly and highly accurate way.

Table2

Bibliography

1) H. Nagashima, Y. Dewa, Analytical Chemistry, 66, 81 (2017)
2) H. Nagashima, Patent, No. 5266440 (2013)
3) H. Nagashima, 85th Trace organic analysis symposium, p13 (2018)
4) H. Ueno, Y. Kikuchi, E. Mine, H. Nagashima, Patent, No. 5572459 (2014)