JPS6339853B2 - - Google Patents
Info
- Publication number
- JPS6339853B2 JPS6339853B2 JP55123989A JP12398980A JPS6339853B2 JP S6339853 B2 JPS6339853 B2 JP S6339853B2 JP 55123989 A JP55123989 A JP 55123989A JP 12398980 A JP12398980 A JP 12398980A JP S6339853 B2 JPS6339853 B2 JP S6339853B2
- Authority
- JP
- Japan
- Prior art keywords
- acid
- concentration
- hydrofluoric acid
- dialysis
- strong
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 claims description 38
- 239000002253 acid Substances 0.000 claims description 33
- 229910021645 metal ion Inorganic materials 0.000 claims description 18
- 238000000502 dialysis Methods 0.000 claims description 15
- 150000002500 ions Chemical class 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 10
- 239000000243 solution Substances 0.000 claims description 10
- 150000007513 acids Chemical class 0.000 claims description 5
- 239000003011 anion exchange membrane Substances 0.000 claims description 5
- 239000007864 aqueous solution Substances 0.000 claims description 2
- 229910052739 hydrogen Inorganic materials 0.000 claims description 2
- 239000001257 hydrogen Substances 0.000 claims description 2
- 150000001875 compounds Chemical class 0.000 claims 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 claims 1
- 238000005554 pickling Methods 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 7
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 7
- 229910017604 nitric acid Inorganic materials 0.000 description 7
- 229910015475 FeF 2 Inorganic materials 0.000 description 6
- 238000009792 diffusion process Methods 0.000 description 6
- -1 fluorine ions Chemical class 0.000 description 6
- 229910052742 iron Inorganic materials 0.000 description 5
- 239000012488 sample solution Substances 0.000 description 5
- 238000004448 titration Methods 0.000 description 5
- 238000004458 analytical method Methods 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 239000011737 fluorine Substances 0.000 description 4
- 229910052731 fluorine Inorganic materials 0.000 description 4
- 239000003014 ion exchange membrane Substances 0.000 description 3
- 238000002798 spectrophotometry method Methods 0.000 description 3
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 2
- 239000007769 metal material Substances 0.000 description 2
- 229910001220 stainless steel Inorganic materials 0.000 description 2
- 239000010935 stainless steel Substances 0.000 description 2
- 239000012086 standard solution Substances 0.000 description 2
- 239000011550 stock solution Substances 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- XWROUVVQGRRRMF-UHFFFAOYSA-N F.O[N+]([O-])=O Chemical compound F.O[N+]([O-])=O XWROUVVQGRRRMF-UHFFFAOYSA-N 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 239000007853 buffer solution Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 239000000385 dialysis solution Substances 0.000 description 1
- 230000005484 gravity Effects 0.000 description 1
- SHXXPRJOPFJRHA-UHFFFAOYSA-K iron(iii) fluoride Chemical compound F[Fe](F)F SHXXPRJOPFJRHA-UHFFFAOYSA-K 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000001509 sodium citrate Substances 0.000 description 1
- NLJMYIDDQXHKNR-UHFFFAOYSA-K sodium citrate Chemical compound O.O.[Na+].[Na+].[Na+].[O-]C(=O)CC(O)(CC([O-])=O)C([O-])=O NLJMYIDDQXHKNR-UHFFFAOYSA-K 0.000 description 1
- 238000004611 spectroscopical analysis Methods 0.000 description 1
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Investigating Or Analyzing Non-Biological Materials By The Use Of Chemical Means (AREA)
Description
本発明は、金属材料の酸洗または溶解等の工程
に使用されるふつ化水素酸と硝酸、硫酸、塩酸等
の強酸との混酸（以下単に混酸と記す）中の各遊
離酸の分析方法に関するもので、特に金属―ふつ
素錯イオンが共存する場合に陰イオン交換膜を通
して拡散する遊離酸の透析率を金属イオン濃度に
よつて補正することにより、より正確な遊離酸の
分析値を得ることを目的とし、ふつ素イオンと錯
イオンをつくりやすい鉄やウラニウム等の金属イ
オンが共存する系の遊離ふつ化水素酸および上記
に示した各種強酸濃度を測定するのに適した方法
である。
金属材料を酸洗又は溶解させる場合、例えば硝
酸―ふつ化水素酸の混合水溶液でステンレス鋼等
を酸洗する場合、酸洗浴内には次式の反応で生ず
るイオンあるいは分子子が存在する。
HNO3H+＋NO3 - (1)
HFH+＋F- (2)
2Fe＋6H+2Fe3+＋3H2↑ (3)
Fe3+＋HFFeF2+＋H+ (4)
FeF2+＋HFFeF2 +＋H+ (5)
FeF2 +＋HFFeF3↓＋H+ (6)
これらのイオン種のうち酸洗に有効なのはふつ
化水素酸および硝酸であり、これらの濃度を適正
に管理することが酸洗作業を効率良く行なうため
には必要である。そのため遊離酸濃度を正確に分
析する必要があるがFeF2+、FeF2 +等のふつ化鉄
錯イオンは不安定であるため、この酸洗液を直接
滴定したり、分光光度法で測定するためにPH調整
したり試薬を加えて発色操作を行なつたりすると
F-イオンを解離したりFeF2+イオンが共存する
HFを消費してFeF2 +となる等正確な分析値を求
めることは困難である。このため本出願人等は特
開昭55―40908号および特願昭54―6575号（特開
昭55―99062号）でのべたように陰イオン交換膜
を用い、FeFx n+等を残し、遊離の硝酸、ふつ化
水素酸のみを拡散透析させて分析する方法を発明
した。しかし、その後更に詳細に検討したところ
陰イオン交換膜を透析する硝酸、ふつ化水素酸の
酸量はふつ素と錯イオンをつくる金属が共存する
と大巾に減少することを見出した。
金属イオンを含む酸溶液をイオン交換膜で拡散
透析する場合、透析率が僅かに向上することは一
般に知られているがふつ化水素酸の場合に大巾に
透析率が減少することは予測できなかつた新らし
い知見である。このためふつ素と錯イオンをつく
る金属イオンを含む溶液のふつ化水素酸の濃度を
正確に求めるために、ふつ化水素酸濃度を透析率
で補正する方法を検討し、確立した。
本発明の方法は、
１ 特願昭54―6575（特開昭55―99062号）にのべ
たように陰イオン交換膜により酸洗液中のF-
イオン、強酸の陰イオンおよび水素イオンを拡
散透析させ、この溶液の一定量にクエン酸ナト
リウム溶液を加えイオン選択性電極で電位を測
定する、
２ 容量分析法、吸光光度分析法、あるいは比重
測定等により金属イオン濃度を求め、この金属
イオン濃度とふつ化水素酸および強酸の透析率
の関係を求めておく。実際には種々の濃度の金
属イオンを含むふつ化水素酸と強酸の混合溶液
の原液の鉄イオン濃度、遊離酸濃度を求めてお
き、イオン交換膜により拡散透析して得た遊離
酸濃度と原液の酸濃度の比を補正係数として縦
軸にとり、金属イオン濃度を横軸にとつてプロ
ツトして上記関係線を求める（第２図、第３図
参照）。
３ １で求めた試料溶液の電極電位Exと、濃度
既知の溶液の電極電位Esとから、酸濃度Cxは
(7)式によつて求められる。
Ex−Es＝alog10（Cs−Cx） (7)
ここで、Csは濃度既知の溶液の酸濃度であ
る。しかし、この酸濃度Csは、みかけの濃度
であり、真の酸濃度Ｃは、
Ｃ＝Cx×１／Ａ (8)
である。
ここで、Ａは２で求めた補正係数で、金属イ
オンとつぎの関係がある。
logA＝±α〔Mn+〕±logβ (9)
但し、Mn+；金属イオン濃度、α，β：係
数、透析時間およびイオン交換膜面積によつて
異なるので別に実験的に求める。
本発明はこのようにみかけの酸濃度をこれらの
透析率で補正し真のふつ化水素酸および強酸濃度
を求めることを特徴とする。
以下、本発明を第１図により詳細に説明する。
まず、(7)式のａを求めるため、既知濃度の硝酸
―ふつ化水素酸標準溶液Ｂを恒温槽２に導き、透
析槽３で一定時間拡散透析させる。拡散液を計量
装置４に導き、一定量の緩衝溶液Ｃを加えたのち
イオン選択性電極等を装備した酸濃度測定装置５
に入れ電極電位をよみとりコンピユーター、デイ
スプレイ７にインプツトする。濃度の異なつた別
の標準溶液を同様に操作し、そのときの電極電位
から(7)式のａを計算する。
つぎに試料溶液Ａを過器１から恒温槽２に導
き、同様にして酸の電極電位をコンピユーター・
デイスプレイ７中に記憶させる。一方過器１を
とおした試料溶液を金属イオン濃度測定装置６に
導き、金属イオン濃度とコンピユーター・デイス
プレイ７に入れる。
あらかじめ記憶させてある第２図および第３図
に示した補正係数対金属イオン濃度曲線から補正
係数をよみとり(8)式により計算させて試料溶液の
酸濃度を求める。
酸濃度測定装置５および金属イオン濃度測定装
置６としては中和滴定法、酸化還元滴定法、電導
度滴定法、吸光光度法等の任意の分析装置が適用
でき、イオン電極法にこだわらない。
つぎに本発明の実施例を示す。
実施例
ステンレス鋼板の酸洗液を用い、金属イオンに
よる補正をしないで分析したところ次の結果が得
られた。
The present invention relates to a method for analyzing each free acid in a mixed acid (hereinafter simply referred to as mixed acid) of hydrofluoric acid and strong acids such as nitric acid, sulfuric acid, and hydrochloric acid used in processes such as pickling or dissolving metal materials. In particular, when metal-fluorine complex ions coexist, the dialysis rate of the free acid that diffuses through the anion exchange membrane is corrected by the metal ion concentration to obtain more accurate free acid analysis values. This method is suitable for measuring the concentrations of free hydrofluoric acid and the various strong acids listed above in systems where metal ions such as iron and uranium, which tend to form complex ions with fluorine ions, coexist. When pickling or dissolving a metal material, for example when pickling stainless steel or the like with a mixed aqueous solution of nitric acid and hydrofluoric acid, ions or molecules generated by the following reaction are present in the pickling bath. HNO 3 H + +NO 3 - (1) HFH + +F - (2) 2Fe+6H + 2Fe 3+ +3H 2 ↑ (3) Fe 3+ +HFFeF 2+ +H + (4) FeF 2+ +HFFeF 2 + +H + (5) FeF 2 + +HFFeF 3 ↓+H + (6) Among these ionic species, hydrofluoric acid and nitric acid are effective for pickling, and proper control of their concentrations is essential for efficient pickling work. is necessary. Therefore, it is necessary to accurately analyze the free acid concentration, but since iron fluoride complex ions such as FeF 2+ and FeF 2 + are unstable, it is necessary to directly titrate this pickling solution or measure it using spectrophotometry. If you adjust the pH or add reagents for color development,
Dissociates F - ions and coexists with FeF 2+ ions
It is difficult to obtain accurate analysis values, such as HF being consumed to become FeF 2 + . For this reason, the present applicants used an anion exchange membrane as described in Japanese Patent Application Laid-open No. 55-40908 and Japanese Patent Application No. 54-6575 (Japanese Patent Application No. 55-99062), leaving FeF x n+ etc. We invented a method to analyze only free nitric acid and hydrofluoric acid by diffusion dialysis. However, after a more detailed study, it was discovered that the amount of nitric acid and hydrofluoric acid used to dialyze the anion exchange membrane is greatly reduced when fluorine and metals that form complex ions coexist. It is generally known that when an acid solution containing metal ions is subjected to diffusion dialysis using an ion-exchange membrane, the dialysis rate slightly improves, but in the case of hydrofluoric acid, it cannot be predicted that the dialysis rate will decrease drastically. This is new knowledge. Therefore, in order to accurately determine the concentration of hydrofluoric acid in a solution containing metal ions that form complex ions with fluorine, we investigated and established a method to correct the hydrofluoric acid concentration by the dialysis rate. The method of the present invention includes the following steps: 1. As stated in Japanese Patent Application No. 54-6575 (Japanese Unexamined Patent Publication No. 55-99062), F - in the pickling solution is removed using an anion exchange membrane.
ions, anions of strong acids, and hydrogen ions are subjected to diffusion dialysis, and a sodium citrate solution is added to a certain amount of this solution, and the potential is measured using an ion-selective electrode. 2. Capacity spectrometry, spectrophotometry, or specific gravity measurement, etc. The metal ion concentration is determined by , and the relationship between this metal ion concentration and the dialysis rate of hydrofluoric acid and strong acid is determined. In reality, the iron ion concentration and free acid concentration of the stock solution of a mixed solution of hydrofluoric acid and strong acid containing various concentrations of metal ions are determined, and the free acid concentration and stock solution obtained by diffusion dialysis using an ion exchange membrane are calculated. The above relationship line is obtained by plotting the acid concentration ratio as a correction coefficient on the vertical axis and the metal ion concentration on the horizontal axis (see FIGS. 2 and 3). 3 From the electrode potential Ex of the sample solution obtained in 1 and the electrode potential Es of the solution whose concentration is known, the acid concentration Cx is
It is determined by equation (7). Ex−Es=alog 10 (Cs−Cx) (7) Here, Cs is the acid concentration of a solution of known concentration. However, this acid concentration Cs is an apparent concentration, and the true acid concentration C is as follows: C=Cx×1/A (8). Here, A is the correction coefficient determined by 2, and has the following relationship with the metal ion. logA=±α[M n+ ]±logβ (9) However, M n+ is metal ion concentration, α, β are coefficients, and vary depending on the dialysis time and ion exchange membrane area, so they are determined separately experimentally. The present invention is characterized in that the apparent acid concentration is thus corrected by these dialysis rates to determine the true hydrofluoric acid and strong acid concentrations. Hereinafter, the present invention will be explained in detail with reference to FIG. First, in order to obtain a in equation (7), a nitric acid-hydrofluoric acid standard solution B of a known concentration is introduced into a constant temperature bath 2 and subjected to diffusion dialysis in a dialysis bath 3 for a certain period of time. The diffusion liquid is led to a measuring device 4, and after adding a certain amount of buffer solution C, an acid concentration measuring device 5 equipped with an ion-selective electrode etc.
read the electrode potential and input it to the computer and display 7. Treat other standard solutions with different concentrations in the same way, and calculate a in equation (7) from the electrode potential at that time. Next, the sample solution A is led from the thermostat 1 to the constant temperature bath 2, and the electrode potential of the acid is determined by computer in the same way.
Store it on display 7. On the other hand, the sample solution passed through the filter 1 is introduced into a metal ion concentration measuring device 6, and the metal ion concentration is displayed on a computer display 7. The acid concentration of the sample solution is determined by reading the correction coefficient from the previously stored correction coefficient versus metal ion concentration curve shown in FIGS. 2 and 3 and calculating it using equation (8). As the acid concentration measuring device 5 and the metal ion concentration measuring device 6, any analytical device such as neutralization titration method, redox titration method, conductivity titration method, spectrophotometry method, etc. can be applied, and the ion electrode method is not limited. Next, examples of the present invention will be shown. Example When a stainless steel plate pickling solution was analyzed without correction using metal ions, the following results were obtained.
【表】
基準値はふつ化水素酸はホウ素滴定法を、硝酸
は電導度滴定法を用いて決定した。
これから硝酸分析値は稍々高目の値をふつ化水
素酸分析値は低い値となつていることがわかる。
そこでこれらの試料溶液の鉄イオン濃度を求め第
２図および第３図の補正曲線を用いて補正したと
ころ、いずれも基準値とよい一致を示した。[Table] Standard values were determined using the boron titration method for hydrofluoric acid and the conductivity titration method for nitric acid. From this, it can be seen that the nitric acid analysis value is a slightly high value, and the hydrofluoric acid analysis value is a low value.
Therefore, when the iron ion concentrations of these sample solutions were determined and corrected using the correction curves shown in FIGS. 2 and 3, both values showed good agreement with the reference values.
第１図は本発明を実施するための分析装置の構
成を示す説明図、第２図は鉄イオン濃度に対応す
るHFの補正係数を示す補正曲線図、第３図は鉄
イオン濃度に対応するHNO3の補正係数を示す補
正曲線図である。
Figure 1 is an explanatory diagram showing the configuration of an analyzer for carrying out the present invention, Figure 2 is a correction curve diagram showing the correction coefficient of HF corresponding to iron ion concentration, and Figure 3 is a diagram corresponding to iron ion concentration. FIG. 3 is a correction curve diagram showing correction coefficients of HNO 3 .
Claims (1)
強酸とふつ化水素酸の混合水溶液中のふつ化水素
酸および強酸を透析させる各酸の濃度を分析する
方法において、あらかじめ金属イオン濃度とふつ
化水素酸および強酸の透析率の関係を求めてお
き、透析後のみかけのふつ化水素酸および強酸濃
度を共存する金属イオン濃度より求めた各々の酸
の透析率で補正することを特徴とするふつ化物錯
イオンを含む溶液中の強酸およびふつ化水素酸の
分析方法。1 In a method of analyzing the concentration of each acid in which hydrofluoric acid and strong acid are dialyzed in a mixed aqueous solution of strong acid containing metal ions and hydrofluoric acid using an anion exchange membrane, the metal ion concentration and the hydrofluoric acid are analyzed in advance. The method is characterized in that the relationship between the dialysis rates of hydrogen acid and strong acids is determined, and the apparent concentrations of hydrofluoric acid and strong acid after dialysis are corrected by the dialysis rate of each acid determined from the coexisting metal ion concentration. Method for analyzing strong acids and hydrofluoric acid in solutions containing compound complex ions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55123989A JPS5748653A (en) | 1980-09-09 | 1980-09-09 | Analytical method for strong acid and hydrofluoric acid in solution containing complex fluoride ion |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55123989A JPS5748653A (en) | 1980-09-09 | 1980-09-09 | Analytical method for strong acid and hydrofluoric acid in solution containing complex fluoride ion |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5748653A JPS5748653A (en) | 1982-03-20 |
| JPS6339853B2 true JPS6339853B2 (en) | 1988-08-08 |
Family
ID=14874280
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55123989A Granted JPS5748653A (en) | 1980-09-09 | 1980-09-09 | Analytical method for strong acid and hydrofluoric acid in solution containing complex fluoride ion |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5748653A (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100922564B1 (en) | 2002-12-24 | 2009-10-21 | 재단법인 포항산업과학연구원 | Analysis method of copper ion concentration in copper chloride solution for pickling process |
| KR100983102B1 (en) | 2010-03-30 | 2010-09-20 | 전주대학교 산학협력단 | Apparatus and method for measurement of hydrofluoric acid in cleaning solutions |
-
1980
- 1980-09-09 JP JP55123989A patent/JPS5748653A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5748653A (en) | 1982-03-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Eaton et al. | Thermodynamic aspects of the potassium hexacyano-ferrate (III)-(II) system. I. Ion association | |
| Rossotti | Design and publication of work on stability constants | |
| US6537822B1 (en) | Method for analyzing free fluorine in solutions containing hydrofluoric acid solution, and apparatus for practicing the method | |
| Fleet et al. | Analytical evaluation of a cyanide-ion selective membrane electrode under flow-stream conditions | |
| Cundiff et al. | Titration of Acids in Nonaqueous Solutions. Improved Quaternary Ammonium Hydroxide Titrant for Strong Acids | |
| Bazzelle | Applications of ion-selective electrodes | |
| Overman | Potentiometric titration of mercury using the iodide-selective electrode as indicator | |
| JPS6339853B2 (en) | ||
| JP2530711B2 (en) | Method and apparatus for simultaneous quantitative analysis of free acid and ferric ion in solution | |
| Bush et al. | Volumetric determination of silver using thioacetamide | |
| O'donnell et al. | Null-point potentiometric determination of fluoride | |
| US5286358A (en) | Method of analyzing the complexing power of a pickling liquor | |
| Kormalı et al. | N, N′-disalicylidene-1, 3-diaminopropane as a selective chelating titrant for copper (II) | |
| Katsumata et al. | Potentiometric flow titration of iron (II) and chromium (VI) based on flow rate ratio of a titrant to a sample | |
| Naumann et al. | Direct determination of trace elements in high purity materials by stripping voltammetry | |
| Eriksson | Determination of hydrofluoric acid in strong acid solutions such as stainless steel pickling baths with a lanthanum fluoride electrode and a permaplex membrane electrode | |
| Ponikvar et al. | Potentiometric determination of antimony in metal (II) hexafluoroantimonates (V) | |
| US3923608A (en) | Method of detecting low levels of cyanide | |
| JP2522536B2 (en) | Method and apparatus for simultaneous quantitative analysis of free acid and iron ion in solution | |
| Pentari et al. | Kinetic determination of EDTA and citrate by the displacement of fluoride from Al3+ F− complexes and use of a fluoride ion-selective electrode | |
| Pungor et al. | Precipitate-based selective ion-sensitive electrodes. Recent developments in theory and applications | |
| Ye et al. | Kinetic potentiometry simultaneous determination of iron (III) and zirconium (IV) by using the Kalman filter | |
| Barreto et al. | Indirect Potentiometric Titration of Fe (III) with Ce (IV) by Gran's Method | |
| Tuthill et al. | Precise Method for Assay of Potassium Iodate by Comparison with (Primary Standard) Arsenic Trioxide. | |
| JPH04121657A (en) | Method for simultaneously measuring concentrations of two or more iron salts contained |