Flash ea1112 ht elemental analyzer

Stable carbon isotope ratios (¹³C/¹²C) were quantified in cotyledons and dried assimilating shoots from plants grown in the greenhouse. Then, 1–2 cm segments of the middle regions of fully expanded cotyledons or assimilating shoots were collected. All samples were oven-dried at 65°C for 48 h to a constant weight.
The measurements of stable carbon isotope ratios were carried out at the Chinese Academy of Forestry’s Stable Isotope Laboratory (Beijing, China) using a Flash EA1112 HT elemental analyzer (Thermo Scientific) coupled with a Delta V advantage isotope ratio mass spectrometer (Thermo Scientific). Stable carbon isotope ratios were expressed as δ¹³C (‰), calculated as follows:
${\text{δ}}^{\text{13}}\text{C}\left(\text{‰}\right)\text{=}\left[\left({\text{R}}_{\text{sample}}{\text{/ R}}_{\text{standard}}\right)\text{-1}\right]\text{×1000}$
where R_sample and R_standard are the ¹³C/¹²C ratios for an individual sample and the reference standard (Pee Dee Belemnite), respectively.

The fully expanded third true leaf of each plant that developed before stage 5.10 was used to quantify the stable carbon isotope ratio (¹³C/¹²C). All samples were oven-dried at 65°C for 48 h to a constant weight. The measurements of stable carbon isotope ratios were carried out at the Chinese Academy of Forestry’s Stable Isotope Laboratory (Beijing, China) using a Flash EA1112 HT elemental analyzer (Thermo Fisher Scientific, Waltham, MA, USA) coupled with a Delta V advantage isotope ratio mass spectrometer (Thermo Fisher Scientific). Stable carbon isotope ratios were expressed as δ¹³C (‰) and were calculated as follows: ${\delta }^{13}\text{C}(‰)=\left[\left(R_{\text{sample}}/R_{\text{standard}}\right)-1\right]\times 1,000,$ where R_sample and R_standard are the ratios of ¹³C/¹²C in the samples and the standard (Pee Dee Belemnite), respectively. The precision of the repeated sample was 0.15‰.

As wing tissue is not part of the active metabolism after adult eclosion, it is generally used for isotope analyses (Wassenaar and Hobson, 1998 (link)). Accordingly, the wings of all E. balteatus specimens were removed with dissection scissors and subsequently sent to the Stable Isotope Mass Spectrometry Facility, Chinese Academy of Forestry (Beijing, China) for hydrogen isotope (δD) measurements as per Zeng et al., 2020 (link). In brief, syrphid wings were cleaned with a methanol–chloroform solution (1:2) and air-dried overnight. Next, the hydrogen isotope ratio (²H:¹H) of the combusted wings was measured using a Flash EA 1112 HT Elemental Analyzer (Thermo Fisher Scientific, Inc, USA) and Isotope Ratio and Mass Spectrometer (Delta V Advantage IRMS, Thermo Fisher Scientific, Inc, USA). Calculations were done using the formula δ²H‰ = (R_sample/R_standard −1) × 1000 in which R is the abundance ratio of heavy isotope to light isotope, namely ²H/¹H. The laboratory error was estimated to be ±2 ‰. Results are expressed in typical delta (δD) notation, in units of per mil (‰), and the relative standard of δ²H was the Vienna Standard Mean Ocean Water (VSMOW).