Determination of two quaternary ammonium salts in disinfector by portable capillary electrophoresis device based on smartphone

doi:10.3724/SP.J.1123.2021.04030

Abstract

Abstract:

The existing miniature capillary electrophoresis (CE) devices use a tablet or a computer for data processing and analysis, which hinders their portability. In order to solve this problem, a smartphone-based CE device was proposed, which allowed for real portable quantitative analysis. The device integrated the functions of capacitively coupled contactless conductivity detection (C⁴D) and Bluetooth communication. Furthermore, a Kotlin language-based application with a user-friendly interface was developed. The application could not only control the electrophoresis run in the CE device but also receive the data from the C⁴D detector in real time, display the electrophoretogram, and process the data. The peak areas could be calculated automatically on the smartphone, and the migration time could be obtained. The size of the developed device was 20 cm×20 cm×15 cm, and its weight was 2 kg. Quaternary ammonium salts (QAs) in disinfectors (dodecyl dimethyl benzyl ammonium bromide (DDBAB) and dodecyl trimethyl ammonium bromide (DTAB)) were used as the analytes to verify the performance of the developed device. The experimental data showed that the linear ranges of DDBAB and DTAB were from 20 to 1000 and from 30 to 1000 μmol/L, respectively. The correlation coefficients (R²) of DDBAB and DTAB were 0.9995 and 0.9989, respectively, indicating good linearity between the peak area and concentration. The limits of detection (LODs) of DDBAB and DTAB were 10 and 13 μmol/L, respectively. The intra-day relative standard deviations (RSDs, n=3) of DDBAB and DTAB were 1.9% and 2.7% respectively, revealing good repeatability. In addition, a mixture of DDBAB and DTAB was tested. Two QAs were separated within 8 min, showing good selectivity. Finally, QAs in a bromo geramine disinfector used in the field were tested to further validate the performance of the designed device. The recoveries of DDBAB and DTAB were 100.5%-101.5% and 96.2%-99.3%, respectively, indicating good accuracy. The developed device has the advantages of good linearity, low LOD, good repeatability, high accuracy, and real portability, and it can be used for the quantitative detection of QAs in disinfectors.

Key words: capillary electrophoresis (CE), capacitively coupled contactless conductivity detection (C⁴D), smartphone-based portable device, quaternary ammonium salts (QAs), disinfector

CLC Number:

O658

WANG Yuanyu, ZHANG Ruihua, ZHANG Qiang, CAO Chengxi, FAN Liuyin, LIU Weiwen. Determination of two quaternary ammonium salts in disinfector by portable capillary electrophoresis device based on smartphone[J]. Chinese Journal of Chromatography, 2021, 39(11): 1151-1156.

Figures/Tables 7

Fig. 1 Smartphone-based portable capillary electropho- resis with capacitively coupled contactless conductivity detection (CE-C4D) device with (a) high voltage supply and detection module and (b) smartphone controller MCU: microcontroller unit; DAC: digital to analog converter.

Fig. 2 Schematic diagram of CE-C4D device a. capillary; b. high voltage supply; c. anode background electrolytes (BGE) vial; d. cathode BGE vial; e. sample vial; f. C4D sensor.

Table 1 Linear equations, correlation coefficients (R2), liner ranges, LODs and RSDs of two quaternary ammonium salts (QAs)

Compound	Regression equation	R²	Linear range/(μmol/L)	LOD/(μmol/L)	RSD (n=3)/%
DDBAB	Y=6.2478X+0.0057	0.9995	20-1000	10	≤1.9
DTAB	Y=5.3290X-0.0940	0.9989	30-1000	13	≤2.7

Fig. 3 Electrophoretograms of (a) background electrolytes, (b) DDBAB, (c)DTAB and (d) their mixed ion solution a. 25 mmol/L Lac-β-Ala; b. 25 mmol/L Lac-β-Ala with 1 mmol/L DDBAB; c. Lac-β-Ala with 1 mmol/L DTAB; d. 25 Lac-β-Ala with 1 mmol/L DDBAB and 1 mmol/L DTAB. Peak identifications: * system peaks.

Fig. 4 Repeatability test of QAs in bromo geramine disinfector

Table 2 Spiked recoveries of DDBAB and DTAB in bromo geramine disinfector (n=5)

Compound	Background/ mg	Spiked/ mg	Found/ mg	Recovery/ %	RSD/ %
DDBAB	1.07	0.8	1.882	101.5	1.47
		1	2.081	100.5	2.13
		1.2	2.286	101.3	1.19
DTAB	0	0.8	0.794	99.3	1.17
		1	0.962	96.2	1.35
		1.2	1.187	98.9	2.29

Table 3 Comparison of developed CE-C4D device with existed devices

Device	LOD/ (μmol/ L)	Size/ (cm×cm ×cm)	Smartphone controlled	Ref.
Automated CE-C⁴D	5	45×35×15	no	[17]
CE-C⁴D of small volumes	0.36	20×33×17	no	[19]
biological fluid
CDC-based CE-C⁴D	12	not reported	no	[20]
Smartphone-based	10	20×20×15	yes	this
CE-C⁴D				work

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