Monolith-coated microcentrifuge tubes for the easy extraction of psychoactive substances from urine samples and liquid chromatography-tandem mass spectrometry determination.

BACKGROUND: Sample extraction is one of the most critical steps in most of the analytical processes. Nowadays, there is a demand for simple approaches that can effectively extract and concentrate target analytes from complex matrices, like biofluids, with accurate and reliable results. RESULTS: A porous monolith of poly(methacrylic acid-co-ethylene glycol dimethacrylate) has been immobilized on the inner wall of a 2 mL commercial polypropylene microcentrifuge tube through radical photopolymerization, using bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as radical initiator and 405 nm laser pointer activation. Photopolymerization parameters were adjusted to obtain a continuous and homogeneous polymer layer (0.16 mm wet polymer thickness and 31 mg dry polymer weight) in the inner tube surface. Extraction efficiency of twelve psychoactive substances was assessed by the evaluation of the effect of sample pH, extraction and desorption times, and desorption solvent volume. Moreover, matrix effect, reusability and stability of monolith-coated microcentrifuge tubes were studied. Sample extracts were measured by liquid chromatography-tandem mass spectrometry, providing limits of quantification (LOQ) from 0.2 to 2.7 µg L-1, recoveries from 80 to 118 %, relative standard deviations lower than 17 %, and a linear range from LOQ to 500 µg L-1. SIGNIFICANCE: The proposed device is suitable for the easy and simple extraction of psychoactive substances from urine samples with a high portability, reduced solvent consumption, low cost, and low environmental impact.

Development of paper-immobilized molecularly imprinted polymers by laser pointer activation for methamphetamine extraction with analysis by ion mobility spectrometry.

A fast, simple, cheap, and versatile strategy has been proposed for the synthesis of paper-immobilized molecularly imprinted polymers (MIPs) by photoactivated bulk polymerization over a piece of nitrocellulose using a 405 nm laser pointer. Polymerization was carried out using a mixture of methacrylic acid and ethylene glycol dimethacrylate, using methamphetamine as template molecule and bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide as radical initiator. After investigation of different polymerization parameters, the following experimental conditions were found to give best results: size of nitrocellulose strip (13.5 × 4.0 × 0.8 mm), type of porogen (acetonitrile), polymerization mixture volume (75 µL), and irradiation times (10 min). Experimental conditions (such as sample pH, extraction and desorption time, and type and volume of desorption solvent) were also adjusted for the extraction of methamphetamine using the proposed paper-MIP. Methamphetamine determination was carried out by ion mobility spectrometry providing a limit of detection of 14 µg L-1 and quantitative recoveries from 81 to 95% using spiked urine and oral fluid samples. The proposed paper-immobilized MIP device allows a simple and selective sample extraction procedure for the determination of methamphetamine in oral fluids and urine with a high portability, minimal solvent consumption, and reduced costs compared to other conventional approaches.

Incidence and long-term outcome of laser pointer maculopathy in children.

PURPOSE: Single center study to evaluate the incidence and long-term outcome of laser pointer maculopathy (LPM). METHODS: Medical records of 909,150 patients visiting our institution between 2007 and 2020 were screened in our electronic patient record system using the keywords "laserpointer," "laser pointer," and "solar." RESULTS: Eight patients (6/2 male/female, 11 eyes) with a history of LPM were identified by fundoscopy and optical coherence tomography (OCT), all of whom were children (6/2 male/female). Mean age at injury was 12.1 years (range 6-16). Five children (62.5%) were injured between 2019 and 2020, three (37.5%) between 2007 and 2018. Median best-corrected visual acuity (BCVA) of affected eyes at first presentation was 20/25 (range 20/50-20/16). Follow-up examination was performed in seven children (10 eyes) with a median follow-up period of 18 months (range 0.5-96). BCVA improved in 4 children (5 eyes; BCVA at follow-up 20/22.5, range 20/40-20/16). Three of these four children were treated with oral steroids. OCT revealed acute signs such as intraretinal fluid to resolve quickly, while outer retinal disruption persisted until the last follow-up in eight of eleven eyes. These lesions resembled lesions of patients with solar retinopathy of which seven cases (11 eyes) were identified between 2007 and 2020. CONCLUSION: Readily available consumer laser pointers can damage the retina and the underlying retinal pigment epithelium, possibly leading to long-lasting visual impairments. The number of laser pointer injuries has increased over the last years. Therefore, access to laser pointers for children should be strictly controlled.

Accessible Low-Cost Laser Pointers for the Reduction of Aryl Halides via Triplet-Triplet Annihilation Upconversion in Aerated Gels.

The search for economic alternatives in the use of expensive scientific equipment represents a way of providing many laboratories access to scientific developments that, otherwise, might be hampered by economic constraints. This inspired the purpose of this work, which was to demonstrate for the first time that we can carry out the photoreduction of aryl halides via green-to-blue upconversion in an aerated gel medium, using a simple economic set-up based on easily accessible and low-cost laser pointers. The optimized set-up consists of three laser pointers connected to a switching-mode power supply. One laser should be aligned to Z-axis and separated 5 cm from the sample, while the light incidence of the other two lasers should be adjusted to 45° and separated ca. 3 cm from the sample. The results of this study were found to be reproducible in random experiments and demonstrated that the photoreduction of several aryl halides can be carry out within 24 h of irradiation with comparable yields and mass balances, to those obtained with other very expensive pulsed laser sources. An economic estimation of the expenses concludes that we can easily reduce by >98% the total cost of this type of research by using the described set-up. Our work offers many groups with limited resources a feasible alternative to work in this area without the necessity of extremely expensive devices.

Sub-Tenon Triamcinolone Acetonide Injection in the Acute Treatment of Handheld Laser-Induced Maculopathy.

Handheld laser (HHL)-induced maculopathy has increased in frequency in recent years and can lead to severe retinal damage and vision loss. Although there is no consensus on the treatment of HHL-induced maculopathy, the use of systemic steroids to limit damage to the retina has been discussed. In this article, we present a patient who underwent early sub-Tenon triamcinolone acetonide injection for HHL-induced maculopathy. To our knowledge, sub-Tenon steroid administration has not been previously reported in the treatment of HHL-induced retinopathy.

Proprioceptive Disturbance in Chronic Neck Pain: Discriminate Validity and Reliability of Performance of the Clinical Cervical Movement Sense Test.

Chronic neck pain is associated with sensorimotor dysfunctions, which may develop symptoms, affect daily activities, and prevent recovery. Feasible, reliable, and valid objective methods for the assessment of sensorimotor functions are important to identify movement impairments and guide interventions. The aim of this study was to investigate the discriminative validity of a clinical cervical movement sense test, using a laser pointer and an automatic video-based scoring system. Individuals with chronic neck pain of idiopathic onset (INP), traumatic onset (TNP), and healthy controls (CON) were tested. Associations between movement sense and neck disability were examined and the repeatability of the test was investigated. A total of 106 participants (26 INP, 28 TNP, and 52 CON) were included in a cross-sectional study. Acuity, Speed, Time, and NormAcuity (i.e., normalized acuity by dividing acuity with movement time) were used as outcome measures. ANOVAs were used for group comparisons and Pearson correlations for associations between movement sense variables and neck disability index (NDI). Notably, 60 of the participants (30 CON, 17 INP, and 13 TNP) performed the test on a second occasion to explore test-retest reliability. Results revealed a reduced NormAcuity for both INP and TNP compared with CON (p < 0.05). The neck pain groups had similar Acuity but longer Time compared with CON. Among TNP, there was a fair positive correlation between Acuity and NDI, while there was a negative correlation between Acuity and NDI among INP. Reliability measures showed good to excellent ICC values between tests, but standard error of measurements (SEM) and minimal detectable change (MDC) scores were high. The results showed that NormAcuity is a valuable measure to identify disturbed cervical movement sense among INP and TNP. While Acuity was similar between the groups, different strategies, such as longer Time, to perform the task among neck patient groups were used. Few differences were identified between the neck pain groups, but altered strategies may exist. Reliability was acceptable, and the test is feasible to perform in the clinic. However, the technical complexity of the automated image analysis is a concern. Future developments will provide more feasible solutions.

Examining the interaction of different factors on pointing precision when using handheld laser pointers.

OBJECTIVE: Laser pointers are common teaching tools used during lessons. The pointing precision may influence the teaching effectiveness. In this study, we examined the effect of four external factors, namely aiming distance, target size, light condition and colour of the laser beam on the pointing precision. RESULTS: Thirty participants (15 males and 15 females; age = 23.2 ± 4.3) were asked to aim at the target black circles with different sizes (diameters = 4 mm, 8 mm, 12 mm and 16 mm) from five various distances (2 m, 4 m, 6 m, 8 m and 10 m) at two brightness conditions (i.e., bright and dark) using two different coloured laser pointers (red and green). Three aiming parameters, namely number of hits, duration per hit and pointing precision were measured. Results showed that the aiming parameters were the highest with the aiming distance of 2 m and the use of green laser pointer towards larger target sizes regardless of the environmental brightness. Among all factors, aiming distance was the most important external factor that could influence pointing precision.

Companion Cats Show No Effect of Trial-and-Error Learning Compared to Dogs in a Transparent-Obstacle Detour Task.

We tested companion cats and dogs in similar indoor conditions using identical procedures in the classic detour task around a V-shaped transparent wire-mesh fence. Besides the control group, we used two types of laser light-pointing demonstration (moving around the fence, or pointing straight at the reward). We found that dogs reached the food reward faster than cats; across consecutive trials, only the dogs showed improvement in their speed and dogs continued to use the same side for detouring after a preceding successful attempt, while cats chose the side for detouring irrespective of their previous successful trials. In addition, 'demonstrating' a detour with the laser did not influence the speed or direction of the detour of the subjects; and dogs looked back to their owner more frequently than the cats did. We discuss the possibility that for dogs, detouring along a transparent obstacle represents a more problematic task than for cats; therefore, dogs strongly rely on their previous experiences. This is the first time that cats were successfully tested in this detour paradigm in direct comparison with dogs. The results are relevant from the aspect of testing cognitive performance in companion cats, which are known to be notoriously reluctant to engage with novel experimental situations.

Effects of standing and walking training using a laser pointer based on stimulus-driven attention for behavioural outcome in spatial neglect: A single-case study.

The therapy for unilateral spatial neglect (USN) is unclear. This case report investigated the effect of standing and walking training using a laser pointer based on stimulus-driven attention for USN. The patient was a right-handed 79-year-old man with cardiogenic cerebral embolism in the right middle and posterior cerebral arteries. Initially, we evaluated the absence of hemiparalysis in the lower limb and sensory disorder; almost all daily activities were performed independently. Intervention effects were verified using the BABA method. The course of the four phases (B1, A1, B2, A2) was conducted for 5 days. In the B1 and B2 phases, standing and walking training using a laser pointer was performed additionally to conventional physical therapy. Outcomes were measured using the Behavioural Inattention Test conventional subtest (BIT-c), Catherine Bergego Scale (CBS), and modified Posner task (MPT). The BIT-c remained unchanged in each phase. CBS scores improved after B1 and B2. In the MPT, the reaction time in the left space reduced after B1 and B2 compared with those in the A1 and A2 control phases. In this case, training may have contributed to the improvement in the response to the neglected space and behavioural assessment of USN.

Integration of transcriptomes analysis with spectral signature of total RNA for generation of affordable remote sensing of Hepatocellular carcinoma in serum clinical specimens.

Hepatocellular carcinoma (HCC) is a major global health problem with about 841,000 new cases and 782,000 deaths annually, due to lacking early biomarker/s, and centralized diagnosis. Transcriptomes research despite its infancy has proved excellence in its implementation in identifying a coherent specific cancer RNAs differential expression. However, results are sometimes overlapped by other cancer types which negatively affecting specificity, plus the high cost of the equipment used. Hyperspectral imaging (HSI) is an advanced tool with unique, spectroscopic features, is an emerging tool that has widely been used in cancer detection. Herein, a pilot study has been performed for HCC diagnosis, by exploiting HIS properties and the analysis of the transcriptome for the development of non-invasive remote HCC sensing. HSI data cube images of the sera extracted total RNA have been analyzed in HCC, normal subject, liver benign tumor, and chronic HCV with cirrhotic/non-cirrhotic liver groups. Data analyses have revealed a specific spectral signature for all groups and can be easily discriminated; at the computed optimum wavelength. Moreover, we have developed a simple setup based on a commercial laser pointer for sample illumination and a Smartphone CCD camera, with HSI consistent data output. We hypothesized that RNA differential expression and its spatial organization/folding are the key players in the obtained spectral signatures. To the best of our knowledge, we are the first to use HSI for sensing cancer based on total RNA in serum, using a Smartphone CCD camera/laser pointer. The proposed biosensor is simple, rapid (2 min), and affordable with specificity and sensitivity of more than 98% and high accuracy.

Multimodal imaging in phototoxic maculopathy: description of findings in a series of 12 patients. / Imagen multimodal en la maculopatía fototóxica: descripción de hallazgos en una serie de 12 pacientes.

OBJECTIVE: To study the differences between solar retinopathy (SR) and the maculopathy produced by laser pointer (LPM) using multimodal imaging. METHOD: A retrospective series is presented of 20 eyes of 12 patients with injuries associated with light, 7 with SR-compatible injuries, and 5 with LPM. At diagnosis, a complete ophthalmological examination was performed, including visual acuity (VA), retinography, and spectral domain optical coherence tomography (OCT). The patients were followed-up for a mean period of 20 months. RESULTS: LPM is common in paediatrics (mean age 15.60±1.5years), and SR affects patients of all ages (mean age 47.56±1.51years). VA at diagnosis in LPM is greater, and recovery is more complete than in solar retinopathy. In conventional retinography, SR is shown as a single lesion in the macular area (100% of cases), while LPM usually presents as multifocal lesions (86% of cases). Infrared reflectance makes this difference clearer. The main sign in OCT is the disruption of the ellipsoid layer and interdigitation zone. This sign is maintained over time, and its size is greater in the SR than in the LPM. Hyper-reflective columns and hyper-reflective reaction of the retinal pigment epithelium are associated with the acute phase. CONCLUSIONS: LPM and SR show significant differences in the type of patient affected, as well as in the signs in multimodal imaging, as well as in functional impairment and their evolution.

Comparison of surgical recordings using cameras with and without laser pointer for focusing in gastrointestinal surgical field in COVID-19 pandemic: A cross-sectional study.

BACKGROUND: Surgical recording has become very important for digestive surgery skill training in the COVID-19 pandemic. In addition to high quality recordings, the directions of vantage points are also important. To assist our vantage point for our camera, we frequently use a laser pointer to increase accuracy in the shooting range. MATERIALS AND METHODS: We recorded surgery more than 2 h with a fixed top-mounted Panasonic HC-V770 camcorder and otherwise with an action-cam Sony FDR. We installed a laser Pointer TaffLED Tactical Red Dot Laser Gun Picatinny Mount Airsoft Rifle HJ 11. We compared focus field video recordings with and without laser pointer guiding. We divided them into four groups: head mounted with, head mounted without, top mounted with and top mounted without. We recorded a total of five digestive surgery cases of superficial, visceral, and deep visceral procedures for each group after adjusting the laser pointer direction to the center of the cameras' focus. RESULTS: The laser pointer on camcorder Panasonic HC-V770 can assist recording on operation fields to prevent the field of view from being blocked by movement of an object compared to either camera without laser pointer. The head mounted Sony FDR-X3000 action-cam can easily depict surgeon's eye while recording and be controlled by the slightest movement of the surgeon's head by tracking with a red dot. CONCLUSION: From either mounting, the laser pointer aided in focusing the surgical field of view and could increase visibility for surgical recording.

Accuracy of acetabular cup placement using an angle-adjusting alignment guide with laser pointer in total hip arthroplasty.

PURPOSE: To evaluate cup-positioning accuracy in total hip arthroplasty (THA) using a novel angle-adjusting alignment guide with laser pointer and determine whether level of surgical experience affects accuracy of cup placement or not. METHODS: We included 117 hips in 104 patients who underwent THA using the novel guide. We retrospectively reviewed 44 hips in 40 patients who underwent THA before the novel guide was introduced. We compared differences in cup angles between the novel guide group and the conventional guide group as well as the discrepancies in targeted angles between the experienced surgeon group and the inexperienced surgeon group. RESULTS: There were 114/117 hips (97.4%) within the Lewinnek safe zone in the novel guide group and 32/44 hips (72.7%) within the safe zone in the conventional guide group. There were significantly fewer outliers in the novel guide group (p < 0.001). In the experienced surgeon group, the mean absolute errors in inclination and anteversion were 2.0 ± 1.7° and 2.1 ± 2.3°, respectively; which were not significantly different from those in the inexperienced surgeon group (2.3 ± 2.1° and 2.8 ± 2.3°, respectively). CONCLUSION: The novel angle-adjusting alignment guide with laser pointer is a simple tool that provides better accuracy of cup position than that obtained using conventional guides. Accurate cup placement is possible using the novel guide, regardless of surgeons' experience.

An Innovative Method for Iris Positioning in a Prosthetic Eye.

AIM: An apparatus named "laser pointer apparatus" is proposed for accurate iris positioning in a prosthetic eye. BACKGROUND: Loss of an eye leads to significant psychological stress due to functional disability and societal response to the facial disablement. Custom-made eye prosthesis is a good option to rehabilitate such defects. Inaccurately positioned iris in a prosthetic eye results in squint eye appearance leading to poor esthetics and poor psychological impact among such unfortunate patients. TECHNIQUE: A new apparatus called a laser pointer apparatus, which is an assembly of an occlusal plane analyzer, web camera, laser pointer, and software, has been introduced for iris positioning in a prosthetic eye. CONCLUSION: Iris positioning is one of the key steps in fabricating an eye prosthesis. Laser pointer apparatus is a reliable method for iris positioning in a prosthetic eye. CLINICAL SIGNIFICANCE: Positioning the iris to the ideal symmetrical position is a cardinal step in the fabrication of an ocular prosthesis. This article aims to introduce a "laser pointer apparatus" to orient iris in a prosthetic eye objectively to overcome the subjective errors.

Optical coherence tomography angiography findings of choroidal neovascularization secondary to laser injury: A case report.

PURPOSE: To report a case of choroidal neovascularization (CNV) secondary to laser injury imaged by optical coherence tomography angiography (OCTA) and treated by intravitreal anti-vascular endothelial growth factor (VEGF). OBSERVATIONS: A 14-year-old boy presented with vision loss and central scotoma in the right eye (RE) in the last month, after having stared at the beam of a laser pointer. At presentation, his best-corrected visual acuity (BCVA) in the RE was 20/40 and spectral-domain OCT (SD-OCT) showed an interruption of ellipsoid zone and the presence of an hyperrelfective lesion in subfoveal region. OCTA examination revealed the presence of a high-flow lesion on both outer retina to choriocapillaris (ORCC) and choriocapillaris segmentations. The patient was treated by one anti-VEGF injection: at one month follow-up his BCVA in the RE was 15/20. SD-OCT revealed the complete resolution of hyperreflective lesion and no detectable flow on OCTA. CONCLUSIONS AND IMPORTANCE: Retinal laser injury may be complicated by CNV. OCTA may non-invasively assess the presence of CNV, as well as treatment-response.

Intravitreal aflibercept treatment for choroidal neovascularization secondary to laser pointer.

A 15-year-old male was presented with blurred vision in his right eye for 2 weeks. The patient had a history of looking with the right eye for 5-6 s at a distance of 20 cm from green laser beam (class 3a, 5 mW, 532 nm). Dilated fundus examinations revealed a yellow lesion in the right eye, resulting in loss of foveal reflection at the fovea. Fundus fluorescein angiography (FFA) images and spectral-domain optical coherence tomography (OCT) scans were compatible with active classic choroidal neovascularization (CNV). A single dose of intravitreal aflibercept was performed to the right eye, and at the 1st month after the injection, the best-corrected visual acuity improved to 20/100 from 20/200. FFA showed staining of the scar with no leakage, and OCT revealed scar formation. At the follow-up visits, during 38-month follow-up, no CNV activity was observed. Intravitreal aflibercept may be an appropriate treatment option in cases with laser pointer injury-induced CNV.

Response to underwater laser pointer in the Orange-finned Anemonefish Amphiprion chrysopterus and three-spot damselfish Dascyllus trimaculatus.

Response of orange-finned anemonefish Amphiprion chrysopterus and three-spot damselfish Dascyllus trimaculatus to red laser-pointer light was studied in Mo'orea, French Polynesia. Four magnificent anemones Heteractis magnifica and their resident fish were observed for typical behaviours (biting, chasing, hiding, posing, lunging and retreating) with and without exposure to laser-pointer light. Lunging behaviour increased significantly for both fish species upon exposure to laser-pointer light; none of the other behaviours changed significantly. We advance the hypothesis that orange-finned anemonefish and three-spot damselfish interpret laser pointer stimulation as a territorial threat.

Retinopatía por puntero láser: presentación de dos casos / Handheld laser maculopathy: two case reports

El uso indebido de los punteros láser, especialmente el recreativo en los niños, puede causar lesiones retinianas que amenazan la visión. El daño retiniano que producen no está bien caracterizado, debido a que la mayoría de las publicaciones son casos aislados o series pequeñas. El tratamiento y el pronóstico visual es variable según la morfología del daño macular que presenten. En algunos casos, no existe tratamiento, y pueden evolucionar a la curación espontánea; sin embargo, otros precisan cirugía. En una serie de 13 casos, uno requirió cirugía, mientras que el resto necesitó solo observación. De estos 13 casos, 3 pacientes se curaron en forma espontánea, con agudeza visual de 10/10.Se describen dos pacientes de 16 y 12 años con disminución de agudeza visual tras el uso indebido de punteros láser. En el fondo de ojo, presentaron alteraciones maculares. La agudeza visual de ambos se recuperó completamente sin tratamiento.

The improper use of laser pointers, especially for recreational use in children, may cause sight-threatening retinal injuries. The retinal damage it is not well characterized because most publications are isolated cases or small series.The treatment and visual prognosis are variable according to the morphology of the macular damage. In some cases, there is no treatment, and spontaneous healing can be developed; however, others require surgery. In a series of 13 cases, 1 required surgery and the rest observation; 3 patients obtained a spontaneous healing with visual acuity of 10/10.We describe two patients aged 16 and 12 years with decreased visual acuity. Macular alterations appear in the fundus of the eye. The visual acuity of both recovered completely without treatment

[Handheld laser maculopathy: two case reports]. / Retinopatía por puntero láser: presentación de dos casos.

The improper use of laser pointers, especially for recreational use in children, may cause sight-threatening retinal injuries. The retinal damage it is not well characterized because most publications are isolated cases or small series. The treatment and visual prognosis are variable according to the morphology of the macular damage. In some cases, there is no treatment, and spontaneous healing can be developed; however, others require surgery. In a series of 13 cases, 1 required surgery and the rest observation; 3 patients obtained a spontaneous healing with visual acuity of 10/10. We describe two patients aged 16 and 12 years with decreased visual acuity. Macular alterations appear in the fundus of the eye. The visual acuity of both recovered completely without treatment.

El uso indebido de los punteros láser, especialmente el recreativo en los niños, puede causar lesiones retinianas que amenazan la visión. El daño retiniano que producen no está bien caracterizado, debido a que la mayoría de las publicaciones son casos aislados o series pequeñas. El tratamiento y el pronóstico visual es variable según la morfología del daño macular que presenten. En algunos casos, no existe tratamiento, y pueden evolucionar a la curación espontánea; sin embargo, otros precisan cirugía. En una serie de 13 casos, uno requirió cirugía, mientras que el resto necesitó solo observación. De estos 13 casos, 3 pacientes se curaron en forma espontánea, con agudeza visual de 10/10. Se describen dos pacientes de 16 y 12 años con disminución de agudeza visual tras el uso indebido de punteros láser. En el fondo de ojo, presentaron alteraciones maculares. La agudeza visual de ambos se recuperó completamente sin tratamiento.

"Jedi sword": A based on laser pointer handheld optical molecular analyzer.

A prototype of a handheld optical molecular analyzer based on household laser pointers of medium power (50-200 mW) equipped with a focusing lens is proposed. Its operating principle is based on the dependence of the attenuation of the laser beam by chromophore, luminophore or suspension on the analyte concentration in the solution. The possibilities of the proposed device are demonstrated by the determination of riboflavin in an injection solution and acetylsalicylic acid and magnesium hydroxide in a Cardiomagnyl® drug. The accuracy of the results is confirmed by fluorimetric, photometric and nephelometric methods. The lower limit of detection of riboflavin, salicylic acid and magnesium hydroxide is 3.5 µg mL-1, 1.2·10-5 mol L-1, 0.4 g L-1 respectively. The linearity range of the calibration dependences obtained in our work is about 1.5 order. The relative standard deviation of the determination results is less than 0.1.