qualitative test
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2022 ◽  
Author(s):  
Kahina Saker ◽  
Bruno Pozzetto ◽  
Vanessa ESCURET ◽  
Virginie Pitiot ◽  
Amélie Massardier-Pilonchéry ◽  
...  

The virus neutralization test (VNT) is the reference for the assessment of the functional ability of neutralizing antibodies (NAb) to block SARS-CoV-2 entry into cells. New competitive immunoassays measuring antibodies preventing interaction between the spike protein and its cellular receptor are proposed as surrogate VNT (sVNT). We tested three commercial sVNT (a qualitative immunochromatographic test and two quantitative immunoassays named YHLO and TECO) together with a conventional anti-spike IgG assay (bioMerieux) in comparison with an in-house plaque reduction neutralization test (PRNT50) using the original 19A strain and different variants of concern (VOC), on a panel of 306 sera from naturally-infected or vaccinated patients. The qualitative test was rapidly discarded because of poor sensitivity and specificity. Areas under the curve of YHLO and TECO assays were, respectively, 85.83 and 84.07 (p-value >0.05) using a positivity threshold of 20 for PRNT50, and 95.63 and 90.35 (p-value =0.02) using a threshold of 80. However, the performances of YHLO and bioMerieux were very close for both thresholds, demonstrating the absence of added value of sVNT compared to a conventional assay for the evaluation of the presence of NAb in seropositive subjects. In addition, the PRNT50 assay showed a reduction of NAb titers towards different VOC in comparison to the 19A strain that could not be appreciated by the commercial tests. Despite the good correlation between the anti-spike antibody titer and the titer of NAb by PRNT50, our results highlight the difficulty to distinguish true NAb among the anti-RBD antibodies with commercial user-friendly immunoassays.


2022 ◽  
Vol 22 (1) ◽  
Author(s):  
Yueting Tang ◽  
Jiayu Sun ◽  
Yumeng Yuan ◽  
Fen Yao ◽  
Bokun Zheng ◽  
...  

Abstract Background Serosurveillance is crucial in estimating the range of SARS-CoV-2 infections, predicting the possibility of another wave, and deciding on a vaccination strategy. To understand the herd immunity after the COVID-19 pandemic, the seroprevalence was measured in 3062 individuals with or without COVID-19 from the clinic. Methods The levels of SARS-CoV-2 antibody IgM and IgG were measured by the immuno-colloidal gold method. A fusion fragment of nucleocapsid and spike protein was detected by a qualitative test kit with sensitivity (89%) and specificity (98%). Results The seroprevalence rate for IgM and IgG in all outpatients was 2.81% and 7.51%, respectively. The sex-related prevalence rate of IgG was significantly higher (P < 0.05) in women than men. The highest positive rate of IgM was observed in individuals < 20 years of age (3.57%), while the highest seroprevalence for IgG was observed in persons > 60 years of age (8.61%). Positive rates of IgM and IgG in the convalescent patients were 31.82% and 77.27%, respectively, which was significantly higher than individuals with suspected syndromes or individuals without any clinical signs (P < 0.01). Seroprevalence for IgG in medical staff was markedly higher than those in residents. No significant difference of seroprevalence was found among patients with different comorbidities (P > 0.05). Conclusions The low positive rate of the SARS-CoV-2 IgM and nucleic acid (NA) test indicated that the SARS-CoV-2 outbreak is subsiding after 3 months, and the possibility of reintroduction of the virus from an unidentified natural reservoir is low. Seroprevalence provides information for humoral immunity and vaccine in the future.


2022 ◽  
Vol 6 (6) ◽  
Author(s):  
Wayan Hardinata ◽  
La Karimuna ◽  
Nur Asyik

ABSTRACTThis study aimed to determine the formalin content of shrimp paste traded in the City Central Market and Wua-Wua Central Market. The analytical method used was the Phenylhydrazine method and quantitative test (Titration Method). The qualitative test was done to determine the presence or absence of formalin in the shrimp paste, while the quantitative test was done to determine the amount of formalin contained in the shrimp paste traded in the City Central Market and the Wua-Wua Central Market. This was a descriptive qualitative-quantitative study. The results of this study show that from 6 samples taken at the City Central Market and the Wua-Wua Central Market, five samples were positive for formalin. The average amount of formalin contents at the City Central Market were 77 mg/kg (A2) and 54.6 mg/kg (A3). Meanwhile, the average amount of formalin contents at the Wua-Wua Central Market were 60 mg/kg (B1), 66.7 mg/kg (B2), and 107.2 mg/kg (B3).Keywords: Shrimp paste, Formalin, Traditional marketABSTRAKPenelitian ini bertujuan untuk mengetahui kandungan formalin pada terasi yang diperdagangkan di Pasar Sentral Kota dan Pasar Sentral Wua-Wua. Metode analisis yang digunakan yaitu metode Fenilhidrazin dan uji kuantitatif (Metode Titrasi). Uji kualitatif bertujuan untuk mengetahui ada tidaknya formalin pada terasi, sedangkan uji kuantitatif bertujuan untuk mengetahui berapa kadar formalin yang terkandung pada terasi yang diperdagangkan di Pasar Sentral Kota dan Pasar Sentral Wua-Wua. Jenis penelitian ini yaitu deskriptif kualitatif dan kuantitatif. Hasil penelitian ini memberikan informasi bahwa sampel yang diambil dari 6 sampel Pasar Sentral Kota dan Pasar Sentral Wua-Wua 5 sampel positif mengandung formalin. Rata-rata persentase kadar formalin di lokasi Pasar Sentral Kota (A2) sebesar 77 mg/kg dan 54,6 mg/kg (A3). Pasar Sentral Wua-Wua (B1) 60 mg/kg, (B2) 66,7 mg/kg dan (B3) 107,2 mg/kg. Hasil penelitian menghasilkan simpulan terdeteksinya penggunaan formalin pada 5 sampel produk terasi yang beredar di lokasi Pasar Sentral Kota dan Pasar Sentral Wua-Wua kota Kendari.Kata kunci: Terasi, Formalin, Pasar tradisional.


2022 ◽  
Vol 226 (1) ◽  
pp. S325
Author(s):  
Nir Kugelman ◽  
Chen Nahshon ◽  
Pninit Shaked-Mishan ◽  
Nadav Cohen ◽  
Maayan Lahav Sher ◽  
...  
Keyword(s):  

Author(s):  
Geminsah Putra H Siregar

Cyclamate is an artificial sweetener that is often added to drinks and food. In trade, cyclamate is known by the trade names assugrin, sucaryl, sucrose or sarimanis. The negative effects caused by sodium cyclamate are not immediate, it may have to wait two or thirty years later. The effects include increasing the potential for obesity, dental disorders, learning disorders, emotions, and mental health. testicular wasting and chromosomal damage. The purpose of this study was to determine the presence or absence of cyclamate content in cendol ice. The examination was carried out at the Amami Chemistry Laboratory, Health Polytechnic of the Ministry of Health, Medan, Department of Health Analyst using a qualitative test, namely the color test (deposition) with a total sample of 7 samples taken from cendol ice drink traders. Based on the qualitative test results obtained from 7 samples, 4 positive samples contained cyclamate. By knowing the presence of cyclamate content, it is hoped that producers will use food additives that do not have a negative effect on consumer health. Based on the Minister of Health Regulation No. 033/2012 artificial sweeteners are only intended for low-energy products or for people with diabetes mellitus and not for general let alone especially for children


2021 ◽  
Vol 1 ◽  
pp. 1079-1087
Author(s):  
Mujtahida Rokhaitun Nikmah ◽  
Khusna Santika Rahmasari ◽  
W Wirasti ◽  
S Slamet

AbstractMethylparaben is a preservative that is often added in cosmetic preparations. The addition of methylparaben in cosmetics aims to protect the preparation from fungus so that cosmetic preparations are not easily damaged. The side effects of using methylparaben in the long term are irritation, allergic reactions, inflammation, and skin dermatitis. The purpose of this research was to analyze the content of methylparaben and determine the concentrationof metil paraben in the face cream samples. The qualitative test used Thin Layer Chromatography (TLC) method, mobile phases used were chloroform and methanol (9:1). Quantitative test used High Performance Liquid Chromatography (HPLC) method with methanol and aquabides as mobile phases (6:4). The results obtained in TLC are the sample Rf value is not much different from the standard Rf value, the standard Rf value is 0.60. Of the 10 samples analyzed, 8 spots appeared on samples 1, 2, 3, 4, 5, 6, 8, and 10 with an Rf value of 0.58, respectively; 0.57; 0.58; 0.57; 0.57; 0.57; 0.58; and 0.60. In the HPLC analysis, it was obtained that the sample levels in samples 1, 2, 3, 4, 5, 6, 8, and 10 were 0.33%, respectively; 0.30%; 1.21%; 0.29%; 0.52%; 0.44%; 0.41% and 1.14%. Samples 3 and 10 are not safe to use.Keywords: determination; face cream; preservative; methylparaben; HPLC. AbstrakMetilparaben adalah zat pengawet yang sering ditambahkan dalam sediaan kosmetik. Penambahan metilparaben dalam kosmetik bertujuan untuk menjaga sediaan agar terhindar dari jamur sehingga sediaan kosmetik tidak cepat rusak. Efek samping penggunaan metilparaben dalam jangka panjang yaitu dapat menimbulkan iritasi, reaksi alergi, inflamasi, dan dermatitis kulit. Tujuan dari penelitian ini adalah untuk menganalisis kandungan metilparaben dan mengetahui kadar metil paraben dalam sampel krim wajah. Pengujian secara kualitatif menggunakan metode Kromatografi Lapis Tipis (KLT), fase gerak yang digunakan yaitu kloroform dan metanol (9:1). Pengujian secara kuantitatif menggunakan metode High Performance Liquid Chromatography (HPLC) dengan fase gerak metanol dan aquabides (6:4).Hasil yang diperoleh pada KLT yaitu nilai Rf sampel tidak jauh berbeda dengan nilai Rf standar, nilai Rf standar sebesar 0,60. Dari 10 sampel yang dianalisis yaitu muncul 8 bercak pada sampel 1, 2, 3, 4, 5, 6, 8, dan 10 dengan nilai Rf berturut-turut yaitu sebesar 0,58; 0,57; 0,58; 0,57; 0,57; 0,57; 0,58; dan 0,60. Pada analisis HPLC diperoleh kadar sampel yaitu pada sampel 1, 2, 3, 4, 5, 6, 8, dan 10 secara berturut-turut sebesar 0,33%; 0,30%; 1,21%; 0,29%; 0,52%; 0,44%; 0,41% dan 1,14%. Sampel 3 dan 10 tidak aman untuk digunakan.Kata kunci: penetapan; krim wajah; pengawet; metilparaben; HPLC.


2021 ◽  
Vol 1 ◽  
pp. 905-914
Author(s):  
Nur Wijayanti ◽  
W Wirasti ◽  
Urmatul Waznah ◽  
Achmad Vandian Nur

AbstractTea plants have benefits as antioxidants and help protect body cells from the bad effects of free radicals. The content in dried black tea leaves has tannin compounds that have a good effect on the body. The purpose of this study was to determine the difference in tannin levels in dry tea produced by Pekalongan with UV-Vis Spectrophotometry and to find out that all samples of tea brands met the requirements for consumption limits in tea. The data obtained were the average tannin content of black tea leaf extract from various samples with concentrations used of 8, 16, 24, 32, and 40 g/ml. Data analysis to determine the tannin content using the standard curve method, linear regression y = a + bx. The results obtained from the TLC qualitative test contained sample and comparison spots at UV 254 nm, namely Rf T1 of 0.84 cm, T2, T4, T5, T8, T9 of 0.85 cm, on samples T3, T7, T10, T11 obtained an Rf value of 0.86 cm which has the same Rf value as the comparison of catechins. and the sample T6 obtained an Rf value of 0.81 cm. As for the quantitative test, the highest levels were obtained in samples T1, T3, T6, T8, T10 as much as 0.004 ± 0 g/g while the lowest levels were obtained in samples T2, T4, T5, T7, T9, T11 as much as 0.003 ± 0 g/g It can be concluded that the circulating tannins produced by Pekalongan meet the consumption limit requirements.Keywords: Content; Tea; Tannins; UV-Vis Spectrophotometry AbstrakTanaman teh memiliki manfaat sebagai antioksidan dan membantu melindungi sel-sel tubuh dari efek buruk radikal bebas. Kandungan pada daun teh hitam kering mempunyai senyawa tanin yang memberikan efek baik bagi tubuh. Tujuan penelitian ini mengetahui adanya perbedaan kadar tanin pada teh kering produksi Pekalongan dengan metode Spektrofotometri UV-Vis dan mengetahui semua sampel merk teh memenuhi persyaratan batas konsumsi dalam teh. Data yang didapatkan adalah data rata-rata kadar tanin dari ekstrak daun teh hitam dari berbagai sampel dengan konsentrasi yang digunakan 8, 16,24, 32,dan40µg/ml. Analisis data untuk mengetahui kadar tanin dengan menggunakan metode kurva standar, regresi linier y = a + bx. Hasil yang diperoleh dari uji kualitatif KLT terdapat bercak noda sampel dan pembanding pada UV 254 nm, yaitu Rf T1 sebesar 0,84 cm , T2,T4,T5,T8, T9 sebesar 0,85 cm, pada sampel T3,T7,T10,T11 diperoleh nilai Rf sebesar 0,86 cm yang nilai Rf nya sama dengan pembanding katekin. dan pada sampel T6 diperoleh nilai Rf sebesar 0,81 cm. Adapun untuk uji kuantitatif nya diperoleh kadar tertinggi pada sampel T1, T3, T6, T8, T10 sebanyak 0,004 ± 0 g/g sedangkan kadar terendah diperoleh sampel T2, T4, T5, T7, T9, T11 sebanyak 0,003 ± 0 g/g, Hal ini dapat disimpulkan bahwa tanin yang beredar produksi Pekalongan memenuhi syarat batas konsumsi.Kata kunci: Kadar; Teh; Tanin; Spektrofometri UV-Vis


2021 ◽  
Vol 4 (1) ◽  
pp. 1-11
Author(s):  
Ahwan Abdul

Honey contains various compounds that function as antioxidants, one of which is phenolic compounds. The purpose of this study was to determine the correlation between the phenolic content of multiflora honey from Malang and Alastuwo on antioxidant activity using the DPPH method (2,2-Diphenyl-1-picrylhydrazyl). Qualitative test of phenolic compounds with FeCl3 color reagent, determination of total phenolic content by UV-Vis spectrophotometry using Folin-Ciocalteu method and antioxidant activity test using DPPH method (2,2-Diphenyl-1-picrylhydrazyl). The results showed that qualitatively Malang and Alastuwo honey contained phenolic compounds. The total phenolic content of Alastuwo honey was 0.0278 ± 0.0010 mg GAE/g and Malang honey was 0.0301 ± 0.0004 mg GAE/g. The results of the antioxidant activity test showed that Alastuwo honey had weak antioxidant activity (IC50 of 393.37 ± 10.28 ppm), Malang honey had moderate antioxidant activity (IC50 of 217.20 ± 6.61 ppm) and vitamin C had strong antioxidant activity. (IC50 is 2.22 ± 0.19 ppm). The total phenolic content of Alastuwo and Malang honey correlates with its antioxidant activity.


2021 ◽  
Vol 2094 (5) ◽  
pp. 052031
Author(s):  
A K Miraliyeva ◽  
A S Rashidov ◽  
Z X Ernazarova ◽  
Sh M Masharipov ◽  
G M Mirpayziyeva

Abstract If the measurement produces a numerical result (or the stated result is based on a numerical result), then it is necessary to evaluate the uncertainty of these numerical results. If the test methodology does not provide for a rigorous, metrologically and statistically reliable estimate of measurement uncertainty, the test laboratory should attempt to reasonably assess the uncertainty of the measurement results. This is applicable in the case of test methods both rational and empirical. As well as in the laboratory activities, verification of test methods plays an important role in order to guarantee the competence of the laboratory by checking for the criteria of Kohren, Grabbs and others. In cases where test results are not numerically expressed or based on numerical data (e.g., fit/unsuitable or positive/negative, or based on visual or sensory perceptions or other forms of quality analysis), estimates of uncertainty or other variability of results are not required. Nevertheless, laboratories are advised to have an idea of the variability of the results, if possible. The importance of the uncertainty of qualitative test results is undeniable, as is the fact that the necessary statistical methodology (procedure) exists for the calculations. However, due to the complexity of the issue and the inconsistency in the approaches, it is not currently necessary for laboratories to assess the uncertainty of qualitative test results. However, this issue needs to be considered. The article discusses estimates of uncertainty of analytical measurements taking into account the requirements of regulatory documents. The criteria for verification of measurement methodology based on experimental works are also considered and analyzed.


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