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Modified APHA closed-tube reflux colorimetric method for TOC determination in water and wastewater

Salihu SO, Bakar NKA

Environ Monit Assess, 2018 May 30;190(6):369.
PMID: 29850927 DOI: 10.1007/s10661-018-6727-y

The analysis of total organic carbon (TOC) by the American Public Health Association (APHA) closed-tube reflux colorimetric method requires potassium dichromate (K2Cr2O7), silver sulfate (AgSO4), and mercury (HgSO4) sulfate in addition to large volumes of both reagents and samples. The method relies on the release of oxygen from dichromate on heating which is consumed by carbon associated with organic compounds. The method risks environmental pollution by discharging large amounts of chromium (VI) and silver and mercury sulfates. The present method used potassium monochromate (K2CrO4) to generate the K2Cr2O7 on demand in the first phase. In addition, miniaturizing the procedure to semi microanalysis decreased the consumption of reagents and samples. In the second phase, mercury sulfate was eliminated as part of the digestion mixture through the introduction of sodium bismuthate (NaBiO3) for the removal of chlorides from the sample. The modified method, the potassium monochromate closed-tube colorimetry with sodium bismuthate chloride removal (KMCC-Bi), generates the potassium dichromate on demand and eliminates mercury sulfate. The semi microanalysis procedure leads to a 60% reduction in sample volume and ≈ 33.33 and 60% reduction in monochromate and silver sulfate consumption respectively. The LOD and LOQ were 10.17 and 33.90 mg L-1 for APHA, and 4.95 and 16.95 mg L-1 for KMCC-Bi. Recovery was between 83 to 98% APHA and 92 to 104% KMCC-Bi, while the RSD (%) ranged between 0.8 to 5.0% APHA and 0.00 to 0.62% KMCC-Bi. The method was applied for the UV-Vis spectrometry determination of COD in water and wastewater. Statistics was done by MINITAB 17 or MS Excel 2016. ᅟ Graphical abstract.

Matched MeSH terms: Colorimetry/methods
A DNA based visual and colorimetric aggregation assay for the early growth factor receptor (EGFR) mutation by using unmodified gold nanoparticles

Ramanathan S, Gopinath SCB, Arshad MKM, Poopalan P, Anbu P

Mikrochim Acta, 2019 07 18;186(8):546.
PMID: 31321546 DOI: 10.1007/s00604-019-3696-y

A genomic DNA-based colorimetric assay is described for the detection of the early growth factor receptor (EGFR) mutation, which is the protruding reason for non-small cell lung cancer. A DNA sequence was designed and immobilized on unmodified gold nanoparticles (GNPs). The formation of the respective duplex indicates the presence of an EGFR mutation. It is accompanied by the aggregation of the GNPs in the presence of monovalent ions, and it indicates the presence of an EGFR mutation. This is accompanied by a color change from red (520 nm) to purple (620 nm). Aggregation was evidenced by transmission electron microscopy, scanning electron microscopy and atomic force microscopy. The limit of detection is 313 nM of the mutant target strand. A similar peak shift was observed for 2.5 μM concentrations of wild type target. No significant peak shift was observed with probe and non-complementary DNA. Graphical abstract Schematic representation of high-specific genomic DNA sequence on gold nanoparticle (GNP) aggregation with sodium chloride (NaCl). It illustrates the detection method for EGFR mutation on lung cancer detection. Red and purple colors of tubes represent dispersed and aggregated GNP, respectively.

Matched MeSH terms: Colorimetry
Fulltext Piper sarmentosum Promotes Endothelial Nitric Oxide Production by Reducing Asymmetric Dimethylarginine in Tumor Necrosis Factor-α-Induced Human Umbilical Vein Endothelial Cells

Sundar UM, Ugusman A, Chua HK, Latip J, Aminuddin A

Front Pharmacol, 2019;10:1033.
PMID: 31607906 DOI: 10.3389/fphar.2019.01033

Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of endothelial nitric oxide synthase (eNOS). ADMA is degraded by dimethylarginine dimethylaminohydrolase (DDAH). Elevated levels of ADMA lead to reduction in nitric oxide (NO) production, which is linked to endothelial dysfunction and atherosclerosis. Piper sarmentosum is an herb that has shown stimulation on endothelial NO production by increasing both expression and activity of eNOS. Thus, this study determined whether the positive effect of P. sarmentosum on NO production is related to its modulation on the DDAH-ADMA pathway in cultured human umbilical vein endothelial cells (HUVEC) exposed to tumor necrosis factor-α (TNF-α). HUVEC were divided into four groups: control, treatment with 250 µg/ml of aqueous extract of P. sarmentosum leaves (AEPS), treatment with 30 ng/ml of TNF-α, and concomitant treatment with AEPS and TNF-α for 24 h. After treatments, HUVEC were collected to measure DDAH1 messenger RNA (mRNA) expression using quantitative real-time polymerase chain reaction. DDAH1 protein level was measured using enzyme-linked immunosorbent assay (ELISA), and DDAH enzyme activity was measured using colorimetric assay. ADMA concentration was measured using ELISA, and NO level was measured using Griess assay. Compared to control, TNF-α-treated HUVEC showed reduction in DDAH1 mRNA expression (P < 0.05), DDAH1 protein level (P < 0.01), and DDAH activity (P < 0.05). Treatment with AEPS successfully increased DDAH1 mRNA expression (P < 0.05), DDAH1 protein level (P < 0.01), and DDAH activity (P < 0.05) in TNF-α-treated HUVEC. Treatment with TNF-α caused an increase in ADMA level (P < 0.01) and a decrease in endothelial NO production (P < 0.001). Whereas treatment with AEPS was able to reduce ADMA level (P < 0.01) and restore NO (P < 0.001) in TNF-α-treated HUVEC. The results suggested that AEPS promotes endothelial NO production by stimulating DDAH activity and thus reducing ADMA level in TNF-α-treated HUVEC.

Matched MeSH terms: Colorimetry
Fulltext Antiapoptotic and Antioxidant Properties of Orthosiphon stamineus Benth (Cat's Whiskers): Intervention in the Bcl-2-Mediated Apoptotic Pathway

Abdelwahab SI, Mohan S, Mohamed Elhassan M, Al-Mekhlafi N, Mariod AA, Abdul AB, et al.

Evid Based Complement Alternat Med, 2011;2011:156765.
PMID: 21234328 DOI: 10.1155/2011/156765

Antiapoptotic and antioxidant activities of aqueous-methanolic extract (CAME) of Orthosiphonstamineus Benth(OS), and its hexane (HF), chloroform (CF), n-butanol (NBF), ethyl acetate (EAF) and water (WF) fractions were investigated. Antioxidant properties were evaluated using the assays of Folin-Ciocalteu, aluminiumtrichloride, β-carotene bleaching and DPPH. The role of OS against hydrogen peroxide induced apoptosis on MDA-M231 epithelial cells was examined using MTT assay, phase contrast microscope, colorimetric assay of caspase-3, western blot and quantitative real-time PCR. Results showed that EAF showed the highest total phenolic content followed by CAME, NBF, WF, CF and HF, respectively. Flavonoid content was in the order of the CF > EAF > HF > CAME > NBF > WF. The IC(50) values on DPPH assay for different extract/fractions were 126.2 ± 23, 31.25 ± 1.2, 15.25 ± 2.3, 13.56 ± 1.9, 23.0 ± 3.2, and 16.66 ± 1.5 μg/ml for HF, CF, EAF, NBF, WF and CAME, respectively. OSreduced the oxidation of β-carotene by hydroperoxides. Cell death was dose-dependently inhibited by pretreatment with OS. Caspase-3 and distinct morphological features suggest the anti-apoptotic activities of OS. This plant not only increased the expression of Bcl-2, but also decreased Bax expression, and ultimately reduced H(2)O(2)-induced apoptosis. The current results showed that phenolics may provide health and nutritional benefits.

Matched MeSH terms: Colorimetry
Immunomodulatory effects of Potentilla indica and Dendrophthoe pentandra on mice splenocytes and thymocytes

Ang HY, Subramani T, Yeap SK, Omar AR, Ho WY, Abdullah MP, et al.

Exp Ther Med, 2014 Jun;7(6):1733-1737.
PMID: 24926376

Immunomodulators are agents that are able to stimulate or inhibit the immune response. The leaf extracts from Potentilla indica and Dendrophthoe pentandra were analyzed in vitro for immunomodulatory activity and an MTT colorimetric assay was conducted to determine the proliferation of mice splenocytes and thymocytes. A bromodeoxyuridine assay was performed to analyze DNA synthesis and the Trypan blue exclusion method was conducted to evaluate the changes in total cell population. The results indicated that treatment with P. indica and D. pentandra produced a time- and dose-dependent increase in cell viability and proliferation. Following 72 h of treatment with P. indica and D. pentandra, thymocyte proliferation was augmented by 18 and 41%, respectively and splenocyte proliferation increased by 35 and 42%, respectively, when compared with untreated cells. The present study demonstrated that these extracts may act as potential immunostimulants and, thus, represent an alternative source of immunomodulatory compounds for the treatment of human immune-mediated diseases.

Matched MeSH terms: Colorimetry
Fulltext Dope-Dyeing of Polyvinyl Alcohol (PVA) Nanofibres with Remazol Yellow FG

Fadil F, Adli FA, Affandi NDN, Harun AM, Alam MK

Polymers (Basel), 2020 Dec 18;12(12).
PMID: 33353189 DOI: 10.3390/polym12123043

The lack of aesthetic properties of electrospun nanofibres in terms of colour appearance is the drive in this preliminary study. This research is conducted to study the dyeing behaviour and colorimetric properties of electrospun nanofibres blended with Remazol Yellow FG reactive dye using dope-dyeing method via electrospinning process. This paper reports the colorimetric properties of dyed poly vinyl alcohol (PVA) nanofibres within the range of 2.5 wt.% to 12.5 wt.% dye content. The electrospinning parameters were fixed at the electrospinning distance of 10 cm, constant feed rate of 0.5 mL/h and applied voltage of 15 kV. The resulting impregnated dye of 10 wt.% exhibits acceptable colour difference of dyed PVA nanofibres, with a mean fibre diameter of 177.1 ± 11.5 nm. The SEM micrographs show the effect of dye content on morphology and fibre diameter upon the increment of dye used. Further increase of dye content adversely affects the jet stability during the electrospinning, resulting in macroscopic dropping phenomenon. The presence of all prominent peaks of Remazol dye in the PVA nanofibers was supported with FTIR analysis. The addition of dye into the nanofibres has resulted in the enhancement of thermal stability of the PVA as demonstrated by TGA analysis.

Matched MeSH terms: Colorimetry
Characterization of pH sensitive sago starch films enriched with anthocyanin-rich torch ginger extract

Xue Mei L, Mohammadi Nafchi A, Ghasemipour F, Mat Easa A, Jafarzadeh S, Al-Hassan AA

Int J Biol Macromol, 2020 Dec 01;164:4603-4612.
PMID: 32941902 DOI: 10.1016/j.ijbiomac.2020.09.082

The development of intelligent packaging based on natural and biodegradable resources is getting more attention by researchers in recent years. The aim of this study was to develop and characterize a pH-sensitive films based on sago starch and incorporated with anthocyanin from torch ginger. The pH-sensitive films were fabricated by casting method with incorporation of different torch ginger extract (TGE) concentration. The surface morphology, physicochemical, barrier, and mechanical properties as well as the pH-sensitivity of films were investigated. The film with the highest concentration of TGE showed the lowest tensile strength (4.26 N/m2), toughness (2.54 MJ/m3), Young's modulus (73.96 MPa) and water vapour permeability (2.6 × 10-4 g·m/day·kPa·m2). However, its elongation at break (85.14%), moisture content (0.27%) and water solubility (37.92%) were the highest compared to other films. pH sensitivity analysis showed that the films containing TGE extract, changes in colour by changing the pH. The colour of films changed from pink to slightly green as the pH increased from pH 4 to 9. Thus, the developed pH-sensitive film with torch ginger extract has potential as intelligent packaging for detection of food freshness or spoilage to ensure their quality and safe consumption.

Matched MeSH terms: Colorimetry
Azostix: a rapid test for blood urea

Buttery JE, de Witt GF, Ahmad UO

Med J Malaya, 1969 Jun;23(4):265-8.
PMID: 4242173
Matched MeSH terms: Colorimetry
Fulltext Colorimetric Detection of Dengue by Single Tube Reverse-Transcription-Loop-Mediated Isothermal Amplification

Lau YL, Lai MY, Teoh BT, Abd-Jamil J, Johari J, Sam SS, et al.

PLoS One, 2015;10(9):e0138694.
PMID: 26384248 DOI: 10.1371/journal.pone.0138694

Dengue is usually diagnosed by isolation of the virus, serology or molecular diagnostic methods. Several commercial kits for the diagnosis of dengue are existing, but concerns have arisen regarding to the affordability and performance characteristics of these kits. Hence, the loop-mediated isothermal amplification (LAMP) is potentially ideal to be used especially in resource limited environments. Serum was collected from healthy donors and patients diagnosed with dengue infection. RNA extracted from the serum samples were tested by reverse-transcription-LAMP assay developed based on 3'-NCR gene sequences for DENV 1-4. Results were interpreted by a turbidity meter in real time or visually at the end of the assay. Sensitivity and specificity of RT-LAMP results were calculated and compared to qRT-PCR and ELISA. RT-LAMP is highly sensitive with the detection limit of 10 RNA copies for all serotypes. Dengue virus RNA was detected in all positive samples using RT-LAMP and none of the negative samples within 30-45 minutes. With continuing efforts in the optimization of this assay, RT-LAMP may provide a simple and reliable test for detecting DENV in areas where dengue is prevalent.

Matched MeSH terms: Colorimetry/methods*
Fulltext A Colorimetric pH Sensor Based on Clitoria sp and Brassica sp for Monitoring of Food Spoilage Using Chromametry

Ahmad NA, Yook Heng L, Salam F, Mat Zaid MH, Abu Hanifah S

Sensors (Basel), 2019 Nov 05;19(21).
PMID: 31694284 DOI: 10.3390/s19214813

A developed colorimetric pH sensor film based on edible materials for real-time monitoring of food freshness is described. The mixed natural dyes from edible plants Clitoria sp and Brassica sp were extracted and incorporated into ι-carrageenan film as a colorimetric pH sensor film for monitoring food spoilage and its freshness. The color changes of the developed colorimetric sensor film were measured with chromametry and UV-vis spectroscopy, respectively. Experimental results show that colorimetric pH sensor film demonstrated statistically significant differences (p < 0.05) between CIE-L*a*b* coordinates color system indicated that the developed colorimetric sensor film was able to give a gradual change in color over a wide pH range. The color of the colorimetric sensor film also changes discretely and linearly with factors that contribute to food spoilage using shrimp and durian samples. Moreover, the developed colorimetric pH sensor film has the potential to be used as a safe, non-destructive testing and also a flexibly visual method for direct assessment of food freshness indicator during storage.

Matched MeSH terms: Colorimetry/instrumentation*
Interactions of Flavone and Steroid from A. subintegra as Potential Inhibitors for Porcine Pancreatic Lipase

Ibrahim M, Abdul Azziz SSS, Wong CF, Bakri YM, Abdullah F

Curr Comput Aided Drug Des, 2020;16(6):698-706.
PMID: 31648647 DOI: 10.2174/1573409915666191015112320

BACKGROUND: Obesity is one serious health condition that contributes to various chronic diseases. The inhibition of pancreatic lipase is a promising treatment for obesity.
OBJECTIVE: The present study was designed to investigate anti-porcine pancreatic lipase effect of isolated compounds from Aquilaria subintegra and its mechanism.
METHODS: Compounds were isolated with serial column chromatography and their structure were identified using spectroscopic methods. Isolated compounds were tested for anti-lipase potential activity using colorimetric assay. The prediction of energy binding between isolated compounds and enzyme was described using YASARA software.
RESULTS: Four compounds were successfully isolated from the bark of A. subintegra, namely, 5- hydroxy-7,4'-dimethoxyflavone, luteolin-7,3',4'-trimethyl ether, 5,3'-dihydroxy-7,4'-dimethoxyflavone and β-sitosterol. The results indicated that all compounds displayed promising pancreatic lipase inhibitory activity ranging between of 6% to 53% inhibition. Compound 5-hydroxy-7,4'- dimethoxyflavone was a competitive inhibitor and decreases the enzyme catalysis. Meanwhile, β- sitosterol was a non- competitive inhibitor since the latter was bind allosterically toward enzyme.
CONCLUSION: This finding is significant for further investigation of bioactive compounds from A. subintegra on animal study.

Matched MeSH terms: Colorimetry
Flexible microfluidic cloth-based analytical devices using a low-cost wax patterning technique

Nilghaz A, Wicaksono DH, Gustiono D, Abdul Majid FA, Supriyanto E, Abdul Kadir MR

Lab Chip, 2012 Jan 7;12(1):209-18.
PMID: 22089026 DOI: 10.1039/c1lc20764d

This paper describes the fabrication of microfluidic cloth-based analytical devices (μCADs) using a simple wax patterning method on cotton cloth for performing colorimetric bioassays. Commercial cotton cloth fabric is proposed as a new inexpensive, lightweight, and flexible platform for fabricating two- (2D) and three-dimensional (3D) microfluidic systems. We demonstrated that the wicking property of the cotton microfluidic channel can be improved by scouring in soda ash (Na(2)CO(3)) solution which will remove the natural surface wax and expose the underlying texture of the cellulose fiber. After this treatment, we fabricated narrow hydrophilic channels with hydrophobic barriers made from patterned wax to define the 2D microfluidic devices. The designed pattern is carved on wax-impregnated paper, and subsequently transferred to attached cotton cloth by heat treatment. To further obtain 3D microfluidic devices having multiple layers of pattern, a single layer of wax patterned cloth can be folded along a predefined folding line and subsequently pressed using mechanical force. All the fabrication steps are simple and low cost since no special equipment is required. Diagnostic application of cloth-based devices is shown by the development of simple devices that wick and distribute microvolumes of simulated body fluids along the hydrophilic channels into reaction zones to react with analytical reagents. Colorimetric detection of bovine serum albumin (BSA) in artificial urine is carried out by direct visual observation of bromophenol blue (BPB) colour change in the reaction zones. Finally, we show the flexibility of the novel microfluidic platform by conducting a similar reaction in a bent pinned μCAD.

Matched MeSH terms: Colorimetry/instrumentation; Colorimetry/methods

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