Qualitative Spot Test Research Articles

Development and validation of an acid/alkaline digestion method for efficient microplastic extraction from wastewater treatment plant effluents: Sulfuric acid concentration and contact time do matter

Accurate analysis of microplastic particles (MPs) in environmental samples requires removal of interferences during sample preparation. Wastewater samples are interference-rich and thus particularly challenging, with concentrated sulfuric acid currently deemed impractical as a reagent. Therefore, this study aimed to establish a straightforward, effective, and safe method employing concentrated sulfuric acid and potassium hydroxide to eliminate interferents from effluent samples obtained from wastewater treatment plants (WWTPs). We found that 80 % sulfuric acid at room temperature with a brief contact time of 5 min was viable through a qualitative spot test involving 37 plastics categorized into three types (I, II, and III) based on their polymer structure's oxygen position. A quantitative assessment revealed that treatments involving H2SO4 and KOH (20 %, 24 h, 48 °C), either separately or in combination, had no discernible physical impact on the overall plastics, except for a subtle one for Type III plastics (e.g., nylon and PMMA) known to be labile under harsh pH conditions. This acid/alkaline digestion (AAD) method, incorporating such conditions for H2SO4 and KOH treatments, yielded a high mass removal efficacy (97.8 ± 2.4 %, n = 13) for eliminating natural particle interferents for primary, secondary, and tertiary effluent samples. Furthermore, the AAD method allowed for the determination of MPs in effluents with high surrogate particle recoveries (e.g., 95.1 % for larger than 500 μm size fraction). This method is readily adaptable to create appropriate protocols for different types of environmental matrices.

The Comparison of Honey Enriched with Laboratory Fermented Pollen vs. Natural Bee Bread in Terms of Nutritional and Antioxidant Properties, Protein In Vitro Bioaccessibility, and Its Genoprotective Effect in Yeast Cells.

The aim of the study was to compare the nutritional value and bioactivity of honey enriched with a 10% addition of natural bee bread and its substitutes obtained as a result of laboratory fermentation of bee pollen. Physicochemical parameters, antioxidant properties, as well as the bioaccessibility of proteins using an in vitro static digestion model were analyzed. The bioactivity of the obtained enriched honeys was tested using the yeast model. The research indicates the similarity of honeys with the addition of "artificial bee bread" to honey with natural ones. During in vitro digestion, good bioaccessibility of the protein from the tested products was demonstrated. The ability of the products to protect yeast cells against hydrogen superoxide-induced oxidative stress was demonstrated using a qualitative spot test, which was stronger in the case of enriched honey than in pure rapeseed control honey. Significant inhibition of the growth of both strains of yeast exposed to bee pollen-enriched honeys was also demonstrated. Furthermore, all tested samples showed significant genoprotective activity against the genotoxic effect of zeocin and the reduction of the number of DNA double-strand breaks by a minimum of 70% was observed.

Nickel, cobalt, and chromium in nail sticker and tip products in Korea.

Nail stickers and nail tips are increasingly used nail products in Korea, and the rest of the world. However, no studies have examined if these specific consumer products might contain nickel, cobalt, and/or chromium, that is, metals known to provoke contact allergy. We aimed to assess the release and content of nickel, cobalt, and chromium in nail stickers and tips by performing qualitative and quantitative analyses, respectively, of 50 convenience samples purchased in Korea. Eighty-six qualitative spot tests were performed to determine the release of nickel, cobalt, and chromium on 35 nail stickers and 15 nail tips across five brands. Subsequently, the metal contents were quantified using inductively coupled plasma-optical mass spectrometry (ICP-MS). According to the spot tests, nickel was released in 7/86 (8.1%) tests before and 10/86 (11.6%) tests after exposure to artificial sweat. Cobalt and chromium (VI) spot test results were negative. However, ICP-MS detected nickel, cobalt, and chromium in 11%, 6.3%, and 16.7% of the samples, respectively. Detection rates were higher in nail tips than in stickers and were most common in rhinestones. Nail stickers and tips may contain nickel, cobalt, and/or chromium.

DIAGNOSTIC ACCURACY COMPARISON OF THE QUANTITATIVE POINT-OF-CARE ECO G6PD AND BREWERS TEST FOR ASSESSMENT OF G6PD DEFICIENCY IN INFECTIOUS DISEASES

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked, hereditary condition caused by mutations in the G6PD gene, that results in protein variants with different enzyme activity levels. G6PD provides reducing power to NADPH (reduced form of nicotinamide adenine dinucleotide phosphate). NADPH effect is critical in red blood cells (RBC) due to the absence of a nucleus. Clinical manifestations are usually mild and are induced by an exogenous agent, such as drugs, infections, or dietary (fava beans). The G6PD deficiency diagnosis is crucial in infectious diseases because both infections and treatment can induce acute hemolysis. Rarely, life-threatening cases can require transfusions of RBC and hemodialysis. The gold standard for the measurement of G6PD activity is a quantitative UV spectrophotometric assay, however, it is inaccessible in most cases. Methemoglobin reduction test (Brewer's test) is a qualitative spot test most used for G6PD deficiency screening, but is imprecise, requires a cold chain, some laboratory infrastructure, trained personnel, and is time-costing. Point-of-care (POC) is a simple and fast semi-quantitative test that is becoming increasingly important when a prompt diagnosis is required and in health care of out-of-reach communities. To compare the diagnostic accuracy of the quantitative POC ECO and Brewers test for assessment of G6PD deficiency. A cross-sectional diagnostic accuracy study was enrolled between May 2020 and December 2021 at the Instituto Nacional de Infectologia Evandro Chagas, Fundação Oswaldo Cruz. Individuals older than 17 years old with a suspicious diagnosis of an infectious disease were eligible. 125 convenience blood samples were tested to compare concordance analysis between Brewers test and POC STANDARD G6PD. The exclusion criteria were hemoglobin concentration < 7.0 g/dL due to technical device limitations. A total of 125 subjects (38 females and 87 males) were recruited. The median age was 42.0 years (range 18–76) in females and 45.0 years (range 19–78) in males. The median of G6PD activity was 7.1 U/g Hb (0.2-17.5). We observed a trend of concordance between the G6PD status (deficient or normal), with low frequencies of discordances in the screenings. The strength of agreement between G6PD tests was classified as almost perfect in all participants (k = 0.82, IC95% = 0.66,0.97) and in subgroups female (k = 0.83, IC95% = 0.59,1.00) and male (k = 0.81, IC95% = 0.59,1.00). The total concordance percentage (number of concordances/total) was 95% in females, 97% in males, and 96% in all participants. Here, we demonstrate POC ECO G6PD test could be performed during medical consultation, guiding the most appropriate therapy almost immediately. In addition to saving time and having comparable results to Brewer's test, it could be performed even in remote areas and with scarce resources, dispensing minimum laboratory requirements. Our findings will be of value to diagnose conditions that could have life-threatening consequences if not timely recognized, such as before initiating primaquine for the treatment of malaria. Therefore, it can improve healthcare in vulnerable isolated communities. We observed a high concordance result between Brewers test and POC STANDARD G6PD, which is becoming the reference test to diagnose G6PD deficiency worldwide.

Overcoming interferences in the colorimetric and fluorimetric detection of γ-hydroxybutyrate in spiked beverages

The high frequency of drug‐facilitated sexual assaults (DFSA) and other criminal acts perpetrated by the adulteration of drinking water or other beverages with γ-hydroxybutyrate (GHB) compels researchers to develop spot tests for its rapid detection, on site, by the broad public. We report a BODIPY-metal complex (1·Fe3+) as a simple colorimetric and fluorimetric indicator based on a ligand displacement design for the sensitive determination of GHB. Assays were developed to detect the presence of GHB in the complex matrices of a broad range of spiked alcoholic and non-alcoholic beverages. The complex enables rapid qualitative spot tests and quantitative assays, and works in both solution and practical solid-state indicator strips.

Urinary Glycosaminoglycan Estimation as a Routine Clinical Service.

Mucopolysaccharidoses, a group of inherited disorders are associated with defects in glycosaminoglycan metabolism. Thus, assessment of urinary glycosaminoglycan is used as a screening test for mucopolysaccharidoses. The detection methods range from qualitative spot tests to quantification using metachromatic dyes. In our laboratory we optimized a spectrophotometric quantitative method using a metachromatic dye, dimethylmethylene blue. Heparan sulfate was used for quantification. The glycosaminoglycan-dye complex showed a marked shift in color with increase in concentration. The color complex was quantified at 520nm. The method was linear from 10-89mg/L. An age matched normal range was obtained in 177 healthy individuals, grouped in 8 different age groups from neonates to adults. Urinary glycosaminoglycan concentration varied distinctly amongst the study population wherein the lowest range in healthy neonates was more than 3 times the upper limit of healthy adults. Urine samples from 10 patients with mucopolysaccharidoses were also included in the study for clinical validation. The method qualified both analytical and clinical validation and was found to be simple, robust and ideal to be offered as a screening test for mucopplysaccharidoses in a routine clinical chemistry laboratory.

Spot-test identification and rapid quantitative sequential analysis of dipyrone

A qualitative spot-test and tandem quantitative analysis of dipyrone in the bulk drugand in pharmaceutical preparations is proposed. The formation of a reddish-violet color indicates a positive result. In sequence a quantitative procedure can be performed in the same flask. The quantitative results obtained were statistically compared with those obtained with the method indicated by the Brazilian Pharmacopoeia, using the Student’s t and the F tests. Considering the concentration in a 100 μL aliquot, the qualitative visual limit of detection is about 5×10-6 g; instrumental LOD ≅ 1.4×10-4 mol L-1 ; LOQ ≅ 4.5×10-4 mol L-1.

Spot-test identification and rapid quantitative sequential analysis of dipyrone

A qualitative spot-test and tandem quantitative analysis of dipyrone in the bulk drug and in pharmaceutical preparations is proposed. The formation of a reddish-violet color indicates a positive result. In sequence a quantitative procedure can be performed in the same flask. The quantitative results obtained were statistically compared with those obtained with the method indicated by the Brazilian Pharmacopoeia, using the Student's t and the F tests. Considering the concentration in a 100 µL aliquot, the qualitative visual limit of detection is about 5×10-6 g; instrumental LOD ≅ 1.4×10-4 mol L-1 ; LOQ ≅ 4.5×10-4 mol L-1.

Effectiveness of screening for neuroblastoma at 6 months of age: a retrospective population-based cohort study

In Japan, a nationwide programme between 1984 and 2003 screened all infants for urinary catecholamine metabolites as a marker for neuroblastoma. Before 1989, this was done by qualitative spot tests for vanillylmandelic acid in urine, and subsequently by quantitative assay with high-performance liquid chromatography (HPLC). However, the Japanese government stopped the mass-screening programme in 2003, after reports that it did not reduce mortality due to neuroblastoma. We aimed to assess the effectiveness of the programme, by comparing the rates of incidence and mortality from neuroblastomas diagnosed before 6 years of age in three cohorts. We did a retrospective population-based cohort study on all children born between 1980 and 1998, except for a 2-year period from 1984. We divided these 22,289,695 children into three cohorts: children born before screening in 1980-83 (n=6,130,423); those born during qualitative screening in 1986-89 (n=5,290,412); and those born during quantitative screening 1990-98 (n=10,868,860). We used databases from hospitals, screening centres, and national cancer registries. Cases of neuroblastoma were followed up for a mean of 78.7 months. 21.56 cases of neuroblastoma per 100,000 births over 72 months were identified in the qualitatively screened group (relative risk [RR] 1.87, 95% CI 1.66-2.10), and 29.80 cases per 100,000 births over 72 months in the quantitatively screened group (RR 2.58, 2.33-2.86). The cumulative incidence of neuroblastoma in the prescreening cohort (11.56 cases per 100,000 births over 72 months) was lower than that in other cohorts (p<0.0001 for all comparisons), but more neuroblastomas were diagnosed after 24 months of age in this cohort (p=0.0002 for qualitative screening vs prescreening, p<0.0001 for quantitative screening vs prescreening). Cumulative mortality was lower in the qualitative screening (3.90 cases per 100,000 livebirths over 72 months) and quantitative screening cohorts (2.83 cases) than in the prescreening cohort (5.38 cases). Compared with the prescreening cohort, the relative risk of mortality was 0.73 (95% CI 0.58-0.90) for qualitative screening, and 0.53 (0.42-0.63) for quantitative screening. Mortality rates for both the qualitative and quantitative screening groups were lower than were those for the prescreening cohort (p=0.0041 for prescreening vs qualitative screening, p<0.0001 for prescreening vs quantitative screening). More infantile neuroblastomas were recorded in children who were screened for neuroblastoma at 6 months of age than in those who were not. The mortality rate from neuroblastoma in children who were screened at 6 months was lower than that in the prescreening cohort, especially in children screened by quantitative HPLC. Any new screening programme should aim to decrease mortality, but also to minimise overdiagnosis of tumours with favourable prognoses (eg, by screening children at 18 months).

Development and validation strategies for qualitative spot tests: application to nitrite control in waters

A general and systematic approach is proposed for the development, optimisation and validation of qualitative spot tests. A simple spot test to control water contamination by nitrite has been developed and was taken as the basis for this purpose. The qualitative information, based on a binary yes/no response, was directly obtained through the visual identification of the colour. Legislation requirements for this parameter in tap waters were selected as the threshold for classifying the samples as positive or negative. The qualitative information provided by this type of test was used for both the optimisation of the test to give a reliable response with respect the threshold and for the validation of the test.

Isolation, characterization, and physical mapping of temperature-sensitive mutants of vaccinia virus

Thirty-nine new temperature-sensitive mutants of vaccinia virus have been isolated, expanding a previously reported collection of mutants ( R. C. Condit and A. Motyczka, Virology 113, 224–241, 1981 ) to a total of 65. The 65 mutants have been assigned to 32 complementation groups, based primarily on a qualitative spot test described previously ( Condit and Motyczka, 1981). Representatives of each complementation group have been assayed for DNA and protein synthesis at the nonpermissive temperature, revealing one new DNA-negative complementation group, three new groups which contain mutants defective in late protein synthesis, and ten new groups containing mutants which synthesize DNA and protein in a normal fashion. Marker rescue has been achieved with 29 of the 65 mutants using cloned DNA fragments from wild-type virus. These 29 mutants together represent 20 of the 32 complementation groups. A preliminary physical map of the mutants is presented.

Electrolytic Reduction of Carbon Dioxide at Mercury Electrode in Aqueous Solution

Abstract Cathodic reduction of carbon dioxide at a mercury pool electrode was investigated in aqueous solutions of NaHCO3, NaH2PO4–Na2HPO4, NaCl, NaClO4, Na2SO4, LiHCO3, and KHCO3 as well as their combinations. The reaction product was confirmed to be HCOO− by a qualitative spot test. HCOO− was quantitatively analyzed by a permanganate titration. The partial current densities of HCOO− formation (ic) and H2 evolution (iH) were calculated. In the present paper, relationships between electrode behavior and solution properties, some of which have been qualitatively described in previous papers, are quantitatively clarified as follows. The electrode potential Ec for constant ic (0.5 mA/cm2) remains constant irrespective of pH and anions in the pH region of 2.4 to 7.8, whereas the potential EH for constant iH (0.5 mA/cm2) varies linearly with a slope of 125 mV/pH. The present experimental results verify Eyring et al.’s presumption that in a relatively high overvoltage region (region 2) the cathodic reduction of CO2 at Hg proceeds with the charge transfer to CO2 as the rate determining step. CO2 reduction and H2 evolution are concluded to proceed independently at the Hg electrode. The dependence of Ec on electrolyte concentration is interpreted in terms of the diffuse double layer theory. The effect of cation species on Ec also is discussed.

Isolation and preliminary characterization of temperature-sensitive mutants of vaccinia virus

Methods have been developed for rapid isolation and genetic analysis of vaccinia virus mutants. These methods include: (1) monitoring mutagenesis by measuring conversion of wild-type, phosphonoacetic acid-sensitive virus to phosphonoacetic acid-resistant virus, (2) screening for mutants by plaque enlargement, and (3) a qualitative spot test for complementation. Twenty-six temperature-sensitive mutants of vaccinia virus have been isolated. All have reversion indices of 10 −4 or less. One-step growth experiments have been done at 40° and 31° with all the mutants and in all cases the virus yield at 40° is less than 8% of the yield observed at 31°. Complementation analysis has been completed on all 26 mutants, showing that these mutants together comprise 16 complementation groups. Twenty-four of the mutants have been analyzed for their ability to synthesize viral DNA at the nonpermissive temperature. The results show that 3 of the 24 have a DNA-negative phenotype. These three mutants fall into two complementation groups. Twenty-four of the mutants have been analyzed for their ability to synthesize early and late viral proteins at the nonpermissive temperature. From this analysis, four phenotypes appear: (1) normal, (2) a phenotype associated with DNA-negative mutants characterized by prolonged synthesis of early proteins and the absence of late protein synthesis, (3) weak or slow late protein synthesis, (4) abortive late protein synthesis.

A qualitative spot test for cystinuria

A qualitative spot test for cystinuria

Detection and Quantitative Determination of Glycine with Pyridine and p-Nitrobenzoyl Chloride

Abstract Glycine in quantities as small as 0.5 µg. can be detected as an orange-red color by a specific reaction with p-nitrobenzoyl chloride and pyridine. The procedure can be used both as a qualitative spot test and as a sensitive quantitative method. In a discussion of the reaction mechanism, it is suggested that the color is due to azlactone formation.

Qualitative Spot Tests for Rubber Polymers

Abstract To eliminate processing difficulties and ensure the production of standard natural and synthetic rubber reclaims, the scrap used as the raw material must be carefully segregated. When mold markings are lost, or large consignments of miscellaneous scrap are received, methods for distinguishing between the basic polymers are necessary. This paper describes a new color reaction which will serve to characterize natural rubber, GR-S, and Perbunan. Confirmatory tests included in the same operation distinguish between the remaining commercially important types. The procedure is sufficiently rapid to be practical in the testing of representative samples from carload shipments, or for establishing the identity of materials on which indecisive results are obtained by less specific methods. For the routine assortment of scrap, spot tests are proposed, which are carried out by holding impregnated filter paper strips in the smoke emitted when the sample is branded with a metal rod heated to redness. Color changes take place which indicate the nature of the polymer. One test distinguishes between natural rubber and GR-S ; a second is specific for Butyl ; a third differentiates Neoprene-GN, Neoprene-ILS, and Perbunan from one another and from the hydrocarbon rubbers. The spot reactions can be carried out very rapidly, and are particularly useful when large numbers of samples must be examined.

Qualitative Spot Tests for Rubber Polymers

Qualitative Spot Tests for Rubber Polymers