1250 Chiang Mai J. Sci. 2014; 41(5.2)

Chiang Mai J. Sci. 2014; 41(5.2) : 1250-1261http://epg.science.cmu.ac.th/ejournal/Contributed Paper

Development of a Simple Jam-jar Apparatus forDirect Analysis of Solid and Liquid SamplesChanatip Kookarinrat [a], Napaporn Youngvises [a], Phoonthawee Saetear [b, c],Duangjai Nacapricha [b, c] and Kamonthip Sereenonchai*[a, b][a] Department of Chemistry, Faculty of Sciences and Technology, Thammasat University,

Paholyothin Road, 12120 Pathumthani, Thailand.[b] Flow Innovation-Research for Science and Technology Laboratory (FIRST Labs), Thailand.[c] Department of Chemistry and Center of Excellence for Innovation in Chemistry, Faculty of Science,

Mahidol University, Rama VI Road, 10400 Bangkok, Thailand.*Author for correspondence; e-mail: ksereenonchai@hotmail.com

Received: 9 April 2013Accepted: 8 September 2013

ABSTRACTThis work describes a method based on vaporization techniques, for direct

determination of calcium carbonate in fortified calcium tablets and for determination of totalcarbonate content in water. A discarded jam jar was adapted to be used as a closed reactionchamber. A piece of cylindrical glass was fitted at the bottom to form a base for the samplevial. In the experiment, a vial containing a carbonated sample was placed inside the jar,surrounded by a pH indicator solution (acceptor solution). The samples containing thecarbonate were transformed from these solid or liquid states by acidification to a carbondioxide gaseous phase inside the jar. The diffused carbon dioxide was then trapped into theindicator acceptor (Cresol red). The change of the absorbance of cresol red, based on alterationof solution pH, was detected at wavelength 440 nm. The system showed good linearitybetween absorbance and carbonate concentration allowing direct measurement of carbonatein both solid and liquid samples. The results show that the developed system is both performswell and is cost-effective for quality control in industry and in environmental measurement.

Keywords: jam jar, carbonate, vaporization

1. INTRODUCTIONCarbonate compounds such as calcium

carbonate (CaCO3) are important compoundsthat are widely used in several manufacturingsectors, including the pharmaceutical [1]and cement industries [2]. In pharmaceuticalproducts, CaCO3 is commonly usedmedicinally as a calcium supplement or as anantacid. Calcium intake should be sufficient

to maintain constant concentrations ofcalcium in blood, muscle and intercellularfluids [3], but excessive consumption canbe hazardous. However, calcium dietarysupplements are sometimes required fortreatment of calcium deficiency, especially inchildren, pregnant and lactating women,postmenopausal women and the elderly

Chiang Mai J. Sci. 2014; 41(5.2) 1251

[4-5]. To control the calcium content of thesupplement, CaCO3, the major compound,should be measured before distribution inthe pharmaceutical market.

In the environmental field, carbonatesplay an important role in water pollutionwhich is one of the most problematicenvironmental issues. Dissolved carbonatelevels are key parameters reflecting waterquality in terms of alkalinity and waterhardness. Moreover, measurement of totalcarbonate in aqueous solution is equivalent tomeasurement of dissolved CO2. DissolvedCO2 is in equilibrium with atmospheric CO2,which is now being closely monitored due toconcerns about climate change [6]. In industrialsettings, water hardness must be constantlymonitored to avoid costly breakdowns inboilers, cooling towers, and other equipmentthat comes in contact with water. Therefore,carbonate content in water must also becontrolled.

Most methods for analysis of calciumcarbonate (CaCO3) or hydrogen carbonate(HCO3

-) in solid and liquid samples are basedon generation of CO2(g) from either CO3

2-

(aq)or CaCO3(s)as shown in reaction (1.1) and(1.2).

NaHCO3(aq) + HCl(aq)→NaCl(aq) + H2O(l)

+ CO2(g)(1.1)CaCO3(s) + 2HCl(aq)→CaCl2(aq) + H2O(l)

+ CO2(g) (1.2)

In the literatures, there are a limitednumber of methods available fordetermination of carbonate in solid samples.Most of them are based on analysis ofCaCO3 in soil [7-12] and a few publicationsreport on analysis of CaCO3 in cement[2, 13] and calcium supplements [1].

In contrast, there are several methodsfor determination of carbonate in water

samples. Titration is employed as therecommended method from the Associationof Analytical Communities (AOAC) fordetermination of total alkalinity [14-15].However, the titration method suffers frominadequate sensitivity and sample turbidity.Therefore, analysis of carbonate in aqueoussamples can be carried out by using moresensitive techniques such as the infraredspectrometric method (IR) [16-17] and theion chromatographic method [18-19].These instruments, however, are expensive topurchase, operate and maintain.

For on-line analysis of carbonatecompounds via volatilization, membrane-based techniques [7, 20-27]as well asmembranless techniques [1-2, 28-30] hasbeen popular coupled with flow injection.Carbonates and its related forms areacidified on-line to produce CO2 gas. In themembrane-based method, CO2 then diffusesacross a hydrophobic semi-permeablemembrane while in the membranelss method,CO2 diffuses through the air gap into anacceptor solution. Then, detection occurs inthe CO2-absorbed acceptor. Detection ofCO2in the acceptor stream can be carried outusing various techniques such as photometricdetection of acid-base indicators [20-21, 23],traditional conductometric detection [23]and contactless conductivity detection [24-25].

This work attempts have been applieda jam jar as a simple scientific device fordirect analysis of carbonate contents inboth solid and liquid samples. Cresolred indicator acceptor, which is normallyused for carbonate analysis, [6, 20, 23]was also employed in this work forabsorption of the generated CO2. The cresolred acceptor was subsequently transferredto a detection cell and was monitoredby spectrophotometric detection.

1252 Chiang Mai J. Sci. 2014; 41(5.2)

2. MATERIALS AND METHODS2.1 Design of the Jam-jar Apparatus

Figure 1 presents a schematic diagramof the jar apparatus. A jar was slightlymodified to be a reaction cell consistingof four parts.

The first part was the jar (85 mm height,45 mm i.d.) that was used as the acceptorcontainer.

The second part was a small glass vial tobe used as a sample holder (20mm height,30mm i.d.). The bottom of the holder was

Figure 1. Schematic diagram of a home-made jar apparatus for vaporization.

glued and placed in the center of the jar to fixthe position of the sample.

The third part was a sample / standardvial (38 mm height, 28 mm i.d.) with amagnetic bar. The liquid sample wastransferred into the sample vial by using a3-mL plastic syringe as well as solid samplewas directly weighed into the vial.

The last part was a plastic lid. A hole wasdrilled into the center of the lid and a needlehub was glued to fit in the hole for insertionof a syringe for acid injection.

In order to develop a carbonate kit inthe future, disposable plastic syringes wereused instead of micropipette to quantifyvolume of solutions. Two 5-mL plasticsyringes (Nipro, Thailand) were employedthroughout the work. One was for loadingthe cresol red acceptor into the jar and anotherone was for acid injection into the samplevial. A small size of 3-mL plastic syringe(Nipro, Thailand) was used to transfer analiquot of 2.0 mL of carbonate standardsolutions and liquid samples into the vial.A magnetic stirrer (Model IKA colorsquid,

Germany) was employed for providingbetter and faster homogenization between theacid and carbonate.

2.2 Chemicals and ReagentsAll chemicals used in this work were

of analytical reagent (AR) grade. Deionized-distilled water was used for preparation ofstandard and reagent solutions.

In optimization, it is more convenient touse solutions of sodium hydrogen carbonatefor analysis of solid [1] and liquid samples.For the optimization studies, a stock carbonate

Chiang Mai J. Sci. 2014; 41(5.2) 1253

solution (40 mmole CO32-) was prepared by

dissolving 3.36 g of sodium hydrogencarbonate (Unilab, Philippines) in waterand this solution was made up to the markwith water in a 50-mL volumetric flask.Appropriate dilution of this solution wasemployed for calibration of the analysis ofcalcium supplement and the analysis ofwater sample. In addition, crystals of calciumcarbonate (Analar, England) were useddirectly as standards in some calibrationwork.

Cresol red (Merck, Germany) employedin the acceptor solution was preparedaccording to previous literatures [1, 20]. Acidused to solubilize both carbonate standardand sample was 1 M HCl (LobaChemie,India).

2.3 Sample PreparationFour brands of calcium supplements

(tablet form) were used. Samples were groundin a mortar. In quantitative analysis, groundsamples were accurately weighed into the glassdonor vials. The weight of solid sampleemployed in an analysis was 7 mg for tabletswith 1000 or 1500 mg CaCO3 / tablet, and27 mg for tablets with 625 mgCaCO3 /tablet.The samples were analyzed as described inthe procedure.

Aquatic samples were analyzed withoutsample preparation. Each liquid sample (2 mL)was directly transferred into the glass donorvials with a magnetic bar.

2.4 General ProcedureAs shown in figure 1, 5.0 mL of cresol

red solution was firstly loaded into the jar asthe acceptor container by using the 5-mLsyringe. The standard carbonate or sample wasaccurately transferred into the small vial witha magnetic bar, and then this vial was situatedon the sample holder inside the jar. The plasticlid was then closed tightly and 1 mL of acid

(1 M) was subsequently injected into thesample vial via the needle hub by usinganother syringe. The syringe was fixed in theneedle hub during analysis. Carbonate in thesample/standard was suddenly converted intoCO2(g)and the liberated CO2diffused from thevial into the headspace above it. Some of theCO2 gas was scrubbed into the cresol redacceptor for a fixed time. After that the lidwas opened and the sample vial wasimmediately removed from the jar. The cresolred solution was subsequently transferred toa 10-mm cuvette. The color change of cresolred, which corresponded to the generatedCO2, was monitored by a Shimadzuspectrophotometer (Model UV-265FW,Japan) at 440 nm. Absorbance readings wereused for the calibration plot and samplequantitation. All these steps were repeated forthe next sample.

3. RESULTS AND DISCUSSION3.1 Concentration of Indicator Acceptor

In this work, the color change ofthe cresol red (from purple to yellow), basedon alteration of solution pH, was monitoredat wavelength 440 nm for quantification ofcarbonate in the sample. Concentrations ofcresol red in the range of 0.001 to0.008% (w/v) were investigated. A higherconcentration of cresol red produces a darkercolor, solution as shown in Figure 2.

Figure 2. A photograph of variousconcentrations of cresol red solution (pH 9.0)from 0.001 to 0.008 %(w/v) (left to right).

1254 Chiang Mai J. Sci. 2014; 41(5.2)

From the experiment, concentrationof cresol red at 0.008% (w/v) resulted in

Table 1. The effect of concentration of indicator acceptor on sensitivity.

poor linearity, therefore this concentrationwas omitted.

According to the results in Table 1,all concentrations except concentration of0.008% (w/v) seem to be valid for adoptionas acceptor solutions due to their linearcalibrations. Although sensitivity is not a crucialproblem for analysis of carbonate in solidcalcium supplement samples, a highly sensitivemethod is preferred to accommodatesamples containing low carbonate contentssuch as water sample. 0.004% (w/v) cresolred was selected as the acceptor solution as itprovided the most sensitive condition.

3.2 Optimization of Solid Analysis3.2.1 Influence of Trapping Time andVolume of Acid on CO2 Diffusion

Trapping time in this work is defined asthe interval between HCl being injected intothe sample under the closed system and thelid being removed.

Table 2. Effect of trapping time and volume of acid reagent.

[Indicator](%(w/v))

0.0010.0020.0040.008

Linear equation(0.04 - 0.16 mmoleCO3

2-)y = (1.429±0.005)x -(0.035±0.005)y = (2.496±0.148)x - (0.075±0.016)y = (5.730±0.155)x - (0.165±0.017)y = (7.608±0.725)x - (0.195±0.079)

r2

0.9980.9930.9980.982

For samples containing high carbonatecontent such as fortified calcium tablets, thesensitivity is not crucial; however the trapping-time interval was studied in order to balancebetween absorbance signal and throughput.The period of trapping time was optimizedusing 0.24 mmole CO3

2- of standard solution(corresponding to 24 mg CaCO3) with 3-mLof acid volume. According to the results inTable 2, the absorbance moderately increasedwith increasing trapping time. As expected,decreasing the trapping time resulted infaster sample throughput (data not shown).Unfortunately, the shortest interval time,which means maximizing sample throughput,gave the poorest precision(19.64 %RSD)owing to submerged bubbles sticking on thewall of the vial as well as on the magnetic bar.Occurrence of these bubbles containingCO2(g), caused irreproducible signals.

Volume of1 M HCl (mL)

3

1

Trapping time (s)

306090306090

Absorbance ± SD

0.331 ± 0.0650.515 ± 0.0720.709 ± 0.0290.481 ± 0.0130.762 ± 0.0090.838 ± 0.010

%RSD(n = 5)

19.6413.984.092.701.181.19

Chiang Mai J. Sci. 2014; 41(5.2) 1255

In order to achieve a system with highsample throughput and good precision,decreased acid volume was further testedfrom 3 mL to 1 mL. As shown in Table 2.,results indicated that the absorbance notonly gradually increased as the volume ofacid decreased at the same trapping timebut also dramatically improved precision forthose interval times (<3%RSD). The smallerin depth the dispensed acid (inside the samplevial) the better the sensitivity. Decreasingthe volume of acid reagent (decreasingdepth) led to enhanced release of CO2(g) fromthe sample vial for reaction with cresolred in the acceptor container (jar) [1].

Therefore, for solid analysis in this work,30 s of trapping time with 1 mL of acidreagent was chosen as the optimumcondition because this condition gaveadequate absorbance readings and fastthroughput of samples (120 samples h-1).

3.2.2 Effect of Mole of the Acid ReagentThe mole of HCl required was studied

using 0.8 M, 300 μL of standard NaHCO3

solution corresponding to 0.24 mmoleCO3

2-. The amount of HCl was variedfrom 0.02 to 1 mmole. Any amount ofacid above 0.2 mmoleHCl was adequate(Figure 3).

Figure 3. Effect of HCl.

However, to ensure excess acid tocompensate for other possible neutralizationprocesses of sample metrics, 1 mmoleHClwas selected as the optimum.

3.3 Optimization of Liquid Analysis3.3.1 Trapping Time and Aquatic SampleVolume

Natural water normally contains lowlevels of carbonate [6]. Therefore, sensitivityis the first priority. There were two possibleways to enhance sensitivity of this developed

system: elongation of trapping time andutilization of high volumes of sample.The trapping time was first studied by useof 1 mM CO3

2-2 mL as test sample.We found that the increase of trapping timeallowed CO2to be trapped more and moreduring vaporization, resulting in sensitivityenhancement (data not shown). However,long trapping times, speed of analysisdiminished. A trapping time of 180 s wasselected to obtain sufficient absorbancereading as shown in Table 3.

1256 Chiang Mai J. Sci. 2014; 41(5.2)

Table 3. Effect of sample volume on absorbance and precision for trapping time 180 s.

Sample volume (mL)2.003.005.00

Absorbance ± SD0.013 ± 0.0010.022 ± 0.0030.035 ± 0.006

%RSD(n = 5)7.6913.6417.14

Another way to gain sensitivity wasby increasing the sample volume. Samplevolumes from 2.00 to 5.00 mL wereexamined. Results in Table 3 showed thatabsorbance gradually increased as thesample volume was increased from 2.00to 5.00 mL. However, the precisionbecome suddenly poorer because the depthlevel of the mixture in the sample vialhindered the diffusion of CO2(g)(the sameobservation as in optimization of solidanalysis).

Therefore, the volume of sample andacid solution required per analysis shouldnot be greater than 3 mL. In this work,2 mL of sample volume with 180s oftrapping time was chosen with acceptableprecision.

3.4 Precision Assessment of the PlasticSyringe for Control Volume of Solution

In order to develop this jam-jar systemto be a carbonate test-kit in the future, simpleand low-cost apparatuses are required.Thus, a cost-effective plastic syringe wasstudied to use for control volume of liquidsample and standard solutions instead ofmicropipette. Calibration curves of standardcarbonate solution from both syringe andmicropipette were compared (Figure 4).Results show good linearity of calibrationcurves and show no significant differencein the sensitivity (slope of equation) betweenplastic syringe and micropipette. This provesthat the plastic syringe with the optimalcondition could be able to control volumein sufficient precision for this analysis.

Figure 4. The possibility study for use of disposable syringe for limiting volume.

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3.5 The Recommended Condition of theJam-jar System

In order to summarize the recommendedcondition for determination of carbonateby the home-made jar apparatus in Figure1, Table 4 was constructed.

3.6 Analytical PerformanceUnder the recommended conditions

and operations, the final analyticalperformance of the developed methodwas examined (Table 5).

Table 4. Studied and selected parameters for optimization conditions for determination ofcarbonate in solid and liquid samples by jam-jar apparatus.

Parameters

[indicator](%(w/v))Trapping time (s)Sample amountVolume of 1 M HCl(mL)

Studied0.001 to 0.008

30 to 120-

1 and 3

Selected0.004

307 to 27 mg

1

Studied-

30 to 1802 to 5 mL

-

Selected0.004180

2 mL1

Solid Liquid

Table 5. Analytical performance of the jam-jar system for determination of carbonate.

(a) Carbonate contents in solid sample sranged from 0.060 to 0.078 mmole CO32- Standard carbonate added ranged

from 0.060 to 0.058 mmole CO32- Carbonate found ranged from 0.120 to 0.134 mmole CO3

2-

(b) Carbonate contents in liquid samples ranged from 1.17 to 1.57 mM CO32- Standard carbonate added ranged from

1.17 to 1.26 mM CO32- Carbonate found ranged from 2.34 to 2.79 mM CO3

2-

Vaporization of the analyte to formCO2 vapor before detection allowed useof external calibration, which is veryconvenient. Linear calibrations for bothsolid and liquid samples (r2> 0.99) wereobtained. With external calibration,

recovery ranged from 96 to 104% for watersamples. The recovery from 96 to 102%of solid samples was carried out by addingexact amounts of standard CaCO3 powderinto sample vials together with samples ofcalcium supplements. Results also provided

Performance

Linear working range

Throughput (sample h-1)

Reproducibility (%RSD),n = 10

Detection limit (3S/N)

%recovery

Solid sample0.04-0.16 mmole CO3

2-

(4.0-16.0 mgCaCO3)

120

3.53(0.08 mmole CO32-)

0.036 mmole CO32-

(3.6 mgCaCO3)

96-102(a)

Liquid sample1-4 and 4-8 mM CO3

2-

(100-400 and 400-800 mgCaCO3/L)

20

3.40(3.0 mM CO32-)

1 mM CO32-

(100 mgCaCO3/L)

96-104(b)

Value

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satisfying reproducibility (RSD) of lessthan 5%. The developed jam-jar systemgave rapid analysis of calcium carbonate insolid supplements (120 samples h-1) and gavean acceptable through put of to totalcarbonate contents in natural water(20 samples h-1).

3.7 Application to Samples andValidations

In order to investigate the analyticalapplicability of the proposed method, themethod was applied to the determinationof calcium carbonate in calcium supplement

tablets (Figure 5) and the determination oftotal carbonate contents in natural water(Figure 6).

AOAC titration techniques [14] wereemployed for comparison to the proposedmethod. Paired t-test at 95% confidence [31]shows no significant different between thecarbonate contents given by the developedmethod and those given by the standardmethods (for solid: tstat = 0.09, tcritical= 2.20for liquid: tstat = 1.58, tcritical = 2.08). Thisshows that the developed methods areaccurate and reliable

Figure 5. The CaCO3 contents in calcium supplement tablets (n = 3), determined by thedeveloped jam-jar apparatus compared with labeled value and standard titration methods.

Figure 6. The total carbonate contents in water samples (n = 3), given by our method andcompared with the standard titration method.

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4. CONCLUSIONIn this work, a discarded jam jar was

adapted to be a valuable scientific tool foranalytical techniques by using the basicprinciple of vaporization. The proposedsystem with two developed methods hasbeen successfully applied for determinationof calcium carbonate in fortified supplementtablets and for determination of carbonatecontents in natural water. The home-madejar apparatus is cheap and easy to use, yetshowed high accuracy and good precision.

AUTHORS DISCLOSURE STATEMENTThis work has been supported by

Office of Research Administration,Thammasat University (Young ScientistResearch 2011). This paper is dedicated toProf. Kate Grudpan on the anniversary ofhis 60th birthday.

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